Windrow Systems

Windrow systems are a traditional, low technology method for large-scale vermiculture activities. They consist of long beds placed directly on the ground with compostable organic material being applied to the surface and sometimes covered to reduce the incidence of pests.

Windrow systems are relatively inefficient as nutrients are lost through volatilisation and leaching and they require large areas of land. These systems also process organic materials relatively slowly taking between 6 and 18 months to complete processing (Edwards, 1995).

Windrow systems are most suitable to agricultural enterprises where large areas of land are available.

Materials that can be processed

A range of compostable organic materials can be processed in vermiculture units, however some form of pre-processing may be required. Pre-processing usually involves:

�� size reduction – to increase the

surface area for microorganisms

to attack;

Plate 2. Commercially available continuous flow vermiculture units.

Vermi-Converter 2000 – Vital Earth Company Worm Wigwam – EPM Inc. Eliminator 1200 – Pad Engineering

5 . . . . . . . . . . . .

�� mixing – to achieve a suitable structure, moisture content and nutrient balance; and

�� addition of a bulking agent – to improve structure, increase surface area and to absorb excess moisture.

Earthworms more readily process a mixture of compostable organic materials rather than monostreams of specific waste types, for example, just bakery waste (Recycled Organics Unit, 2000).

Common compostable organic materials produced by the C&I sector that are readily processed by vermiculture units include:

�� mixed fruit;

�� mixed vegetables; �� mixed food organics (mixed fruit

and vegetables, breads, meat/

poultry); and

�� mixed garden organics (lawn clippings, non-woody plant materials such as stems, leaves and twigs of various plant species).

The addition of a bulking agent, such as paper or cardboard, is very important when preparing compostable organic materials for processing in a vermiculture unit. Cardboard or paper are carbonaceous materials that absorb excess moisture, increase the porosity and structure of the material and increase the carbon to nitrogen (C:N) ratio.

The C:N ratio is the ratio of the weight of organic carbon to total nitrogen within the material. Some organic materials, such as meat and poultry, are rich in nitrogen. If these nitrogen-rich organic materials are processed in a vermiculture unit, carbon needs to be added to achieve a C:N ratio of 20 to 25 parts carbon to every one part nitrogen (C:N ratio of 20-25:1).

Carbon can be added to a

Plate 3. Shredded cardboard is a common source of bulking agent produced by the C&I sector.

vermiculture unit as shredded paper or cardboard. These high carbon materials are called bulking agents and are common packaging wastes in the C&I sector.

The addition of a bulking agent, such as paper or cardboard (Plate 3), not only increases the C:N ratio but improves the structure and porosity of the material. A bulking agent will also absorb excess moisture and result in a less dense material. All these factors produce a material that is more readily processed by the worm population.

The amendment of compostable organic materials with a bulking agent to increase the C:N ratio may result in the material becoming too dry. Worms need a moist environment, as previously discussed, and so the material that they consume needs to be moist but not too wet.

The final mixture of organic material amended with a bulking agent and water (if necessary) is called feedstock. Feedstock is the result of blending the different components to produce a suitable source of food for the worm population.

These factors are important for acceptance of the feedstock by the worm population. A number of feedstock recipes and the process of mixing a suitable feedstock will be covered in Information Sheet No. 4.

Materials that cannot be processed

Some compostable organic materials cannot be processed in a vermiculture unit.

Materials that are very high in nutrients, such as seafood and dairy products, are not recommended for vermiculture processing in any significant proportion. These materials can cause problems such as anaerobic (low oxygen) conditions that result in worm death.

6 . . . . . . . . . . . .

Microorganisms break down these Management of Overview of best practice

high nutrient materials very quickly vermiculture units guidelines for on-site resulting in rapid oxygen consumption. This can lead to health ^{Vermiculture units can be used to vermiculture technology} and safety issues such as odour ^{process a limited range of The Best Practice Guideline to} production and the attraction of pests ^{compostable organic materials into a Managing On-Site Vermiculture}

_{and vermin.} useful end product called vermicast. Technology series of information sheets provides an excellent

More information on materials that ^{However, effective vermiculture} introduction to the science of can and cannot be processed in ^{processing requires significant} vermiculture and the best practice vermiculture units can be found in ^{management of the unit to ensure} procedures for establishing and

_{Information Sheet No. 3.} reliable performance and to prevent _maintaining

a successful health and environmental issues from _{vermiculture unit.}

developing.

The process of achieving a successful Effective best practice management _{vermiculture organics management}

^{of vermiculture units requires a} system based on these best practice

^{dedicated approach to feedstock} guidelines is illustrated in Figure 4. preparation, monitoring regimes and site hygiene.

Figure 4. Overview of the Best Practice Guideline to Managing On-Site Vermiculture Technology Information Sheets.

7 . . . . . . . . . . . .

. . . . . . . . . . . .

Information Sheet No. 2 How much compostable material is produced?

Simplified waste audit

Quantifying the compostable material in

health and safety risks for staff (Plate 1).

This Information Sheet provides simplified methods that are more effective for quantifying the amount of organic material produced by your organisation.

Rather than conducting an unpleasant and unsafe “waste audit”, simply collect compostable organic materials (eg. food) separately in dedicated bins. The quantity of this compostable material can then be determined. The challenge is to keep general waste out of the “organics only” collection bins (and vice versa), but this is simpler than sorting through mixed garbage.

Unnecessary risks are identified and removed, allowing for simpler and more accurate estimations than typical waste auditing practices.

Implementation

When implementing a source separated collection system, the needs of operations staff must be

Plate 1. Conducting a waste audit of non-source separated waste material. Even if safety clothing is used, this may still involve unnecessary risks if sharps and/or other contaminants are present.

The ROU is the NSW centre for organic resource management, information, research & development, demonstration and training

addressed. If a new operational system is designed without adequate consultation, opportunities to create simpler and more efficient systems may be lost, contributing to problems that prejudice staff against the system.

Staff support is mandatory to maximise the diversion of organics from the waste stream and to minimise contamination levels in source separated material. Don’t be discouraged by the terminology – it’s simply encouraging colleagues to put their waste in the right bin, and making it convenient to do so.

Dissatisfaction with current practices and opportunities for reducing effort, can provide significant motivation for staff to support change. Aim to establish a system that better meets their expressed needs (eg. with respect to bin size, placement, ease of use etc.).

Generate awareness that discarding of waste in the correct bin contributes to environmental improvement and that putting waste in the wrong bin creates unnecessary waste and safety risks for colleagues.

When presenting a new waste management system to staff, confirm that the new system is a result of their expressed needs.

What materials are you looking for?

Prior to selecting an appropriate organics management system, it is important to identify the compostable materials generated by your organisation. Compostable organics may include (Plate 2):

�� Food organics

�� Garden organics

�� Wood and timber

�� Paper and cardboard

Plate 2. Materials you can use in your organics management system.

Food organics need bulking agents when used in organics management systems. They cannot be processed alone! Bulking agents include garden organics, wood and timber and paper and cardboard. Avoid using food organics high in oils and fats, as these may contribute to significant odour problems in your system.

Garden organics can be processed on their own or used as bulking agents with food organics. These materials have a relatively high carbon to nitrogen ratio, complementing the low carbon to nitrogen ratio of food organics.

Wood and timber can be used as bulking agents with food or garden organics. However, if these materials have been chemically treated, they should not be used in your organics management system. It is therefore important for you to know the composition (history) of your wood and timber and any associated health issues.

Paper and cardboard can be used as a bulking agent with food organics and/or garden organics. Due to the high carbon content and very low nitrogen content of paper and cardboard, these feedstock materials cannot be processed alone.

Definitions*

Compostable organics

Compostable organics is a generic term for all organic materials that are appropriate for collection and use as feedstocks for composting or in related biological treatment systems (e.g. anaerobic digestion). Compostable organics is defined by its material components: residual food organics; garden organics; wood and timber; biosolids, and agricultural organics.

Waste Audit

Determination of the quantities and qualities of individual components present in a waste stream.

Source separation

Physical sorting of the waste stream into its components at the point of generation.

Bulking agents

An ingredient in a mixture of composting raw materials included to improve the structure and porosity of the mix. Bulking agents are usually rigid and dry and often have large particles (for example, straw or wood chips). The terms “bulking agent” and “amendment” are often used interchangeably. See also composting amendment.

Carbon to nitrogen ratio

The ratio of the weight of organic carbon (C) to that of total nitrogen (N) in an organic material.

Continued page 5

2 . . . . . . . . . . . .

The assessment process Food organics

The identification of food organics generated by your business will be simpler, safer and more effective if the food organics are collected separately for a period of 2 weeks. This also provides an excellent opportunity for a short-term trial of a separate collection system.

Food organics include the following subcategories. These categories are useful in identifying suitable handling and processing technologies:

Material	Detail
Fruit and vegetable
material
Bread, pastries and	Including rice and
flours	corn flours
Meat and poultry
Fats and oils
Seafood	Including shellfish,
	excluding oyster
	shells
Food soiled paper	Hand towels, butter
products	wrap etc.
Biodegradeables	Cutlery, bags,
	polymers
Dairy	Solid and liquid
Recalcitrants	Large bones, oyster
	shell, coconut shells
	etc.

Use the following steps to identify the quantity and nature of your food organics:

1. Identify primary locations/ sources of generation of the food;
2. Consult with staff to identify current practice – what they like/dislike and existing inefficiencies;
3. Design separate organics collection system in consultation with staff employed at operation level to ensure that the system design meets their needs

A source separated organics collection system must meet the needs of operational staff within your

3 . . .

organisation. If the new system is �� placed next to each garbage/ designed without adequate waste bin; and consultation, problems may arise that may discourage staff from disposing ^{�� located so that the same amount} of materials correctly into “food ^{of effort is required to place}

_{only” bins.} material in the “food only” bin

or the garbage bin (if one With staff support, the diversion of requires a lid to be removed, or organics from the waste stream will is a little further away the other be maximised (maximising may receive both waste streams). environmental benefits and cost savings), and contamination rates of ^{Promote the commencement of the} _{the organics stream minimised} trial period. Have someone from

(minimising unnecessary effort and ^{kitchen management or elsewhere} _{safety risks).} communicate to all staff the purpose, timeframe and process of quantifying Aim to establish a system that meets the amount of compostable materials

the expressed needs of staff (eg. with produced. respect to bin size, placement, ease of _{use etc.)} Let staff know they will play a

valuable role in ensuring the success Confirm with operational staff that of the project. Also engage them in the new system will meet their needs. the process to identify improvements

in the system and to make it more

4. Install source separate collection

consistent and efficient for use.

bins with appropriate signage etc

5. Collect organics generated over Install the new source separate _{a two-week period} collection bins. Make sure that all bins are placed at the same time to The waste audit results will inform avoid confusion, organics ‘leakage’ selection of a processing technology to the waste stream or contamination that is capable of meeting your

of organics collected. Where organisations needs. possible, ensure that “organics only” _{bins are:} In order to obtain reliable and

accurate estimates of the volume and �� a standard size and distinct composition of your organisation’s colour with consistent clear organics stream, it is important to signage; sample organics over a period of at least two weeks. In addition, it may ^{�� readily recognisable from} be necessary to spend one week ^{garbage bins;} preparing for the audit – ironing out

any bugs in the process. You should ^{�� obviously marked/labelled;} record audit information on Form 1 _{�� appropriate size, location and} (attached to this Information Sheet).

number;

. . . . . . . . .

The steps involved are summarised below:

�� Collect the filled separated “food organics only” bins on a daily basis);

�� Remove waste contaminants (plastics, drink containers etc.) – document type and source of contamination;

�� Estimate seasonal variation from 7. Contamination

�� Tip contents of bins containing _{business records, staff numbers} ^{only small amounts of material} etc. to establish peak volumes of ^{Contaminants in food organics} together to minimise the number _{material that would be expected} comprise anything not compostable, of bins being weighed; _{during busy periods.} including:

^{�� Weigh the filled bins on a} Data on seasonal fluctuations in ^{�� individual portion wrappers platform scale;} catering, generation of garden ^{(plastic or foil);} _{�� Record the weight on the data} organics etc. can be obtained from

_{recording sheet supplied, business records and consultation} �� plastic bags, cling wrap films

attached to this Information ^{with operational staff. and plastic cutlery;}

^Sheet; 6. Tools and materials required ^{�� glass;}

�� stainless steel cutlery, foil and

^{�� Use the bottom of a bucket to} The materials required to determine

other metals;

^{compress the food organics} the amount and composition of the

firmly into each bin so that the _{food organics are listed below:} contents are reasonably well ^{�� ceramics, and}

^{packed; �� Platform scales} �� drink containers.

�� Estimate total food organics �� Data recording sheets (attached)

Contamination increases the

volume from the size of the bin

workload and labour costs of an

and the amount of material in it �� Tubs for estimating composition _{organics management system. In}

^{(compressing material avoids} addition, contaminants make work counting low density materials ^{�� Food waste collection bins} _{very unpleasant (removal of} (eg. cabbage/lettuce leaves) as a _{�� Stickers for identifying bins}

contaminants) and create safety ^{full bin);} hazards for staff (glass and metals, �� Tongs for removing _{see Plate 3).}

�� Tip bin contents into shallow _contaminants tubs for visual (percentage)

8. Monitor solid waste stream to ^{estimates of organics �� Gloves (heavy duty kitchen} identify any organics ‘leakage’;

composition; _gloves)

Improve organics diversion success

�� Combine your contaminants into _{�� Scrubbing brush and access to through education. Remember to}

^{one bin and weigh them; water for cleaning out bins} address any problems in system

�� Empty tubs into a garbage skip _{�� Educational posters for staff} ^{implementation immediately. All} _{or bin for collection;} staff working at operational level room

should understand clearly how the �� Wash out “food organics only”

�� Presentation materials for staff ^{separation system works, and should} bins and return to kitchen staff; _meeting have had the opportunity to contribute to system design to ensure �� At the end of each week, Supplier information and prices for it is convenient and efficient for their calculate the total weight of the _{this equipment is contained in} use. food organics material and the _{Appendix No. 1.} average volume of each type of There should be no general waste material identified; contamination of the collected food

4 . . . . . . . . . . . .

Plate 3. Contaminants such as glass may be encountered during waste audits – especially if a source separation system has not been developed.

organics and no leakage of food organics into the general waste. If this does occur, rectify the problem by communicating directly with those responsible and encouraging them to help achieve successful outcomes.

1. Improve organics diversion rate and maintain through consultation and education.
2. Bin hygiene

Bins must be cleaned and maintained to control odours. Water and a long handled scrubbing brush can be used to achieve this. In some instances, a small amount of detergent may also be required.

11. Bin size

Consider bin size and how bins need to be handled in your system. Food organics can be very dense and heavy, ranging in weight from 0.4 kg to over 0.8 kg per litre. At the upper end of this scale, a 120 litre bin could weigh over 90 kg, which is both unsafe and well in excess of the maximum capacity of the bin.

Given the nature of food organics, 80 litre wheelie bins are the most appropriate size available for food organics collection. Larger bin sizes can be too heavy (when full) for collecting dense food material.

Continued from page2

Waste Stream

Flow of materials from a point of generation to ultimate disposal.

Contamination

Contaminants within this context include physical inorganic materials (metals, glass etc.), non-biodegradable organic materials (plastics), chemical compounds and/or biological agents that can have a detrimental impact on the quality of any recycled organic products manufactured from source separated compostable organic materials.

Feedstock

Organic materials used for composting or related biological treatment systems. Different feedstocks have different nutrient concentrations, moisture, structure and contamination levels (physical, chemical and biological).

* Recycled Organics Unit (2001a).

12. What happens now?

After the two-week sampling period, you should have a clear understanding of the volume and composition of food organics generated within your organisation. You should also have estimates of variation across the annual business cycle. This information (in combination with other factors) can be used to identify a system that best suits your requirements.

5 . . . . . . . . . . . .

Identifying your food organics materials

Empty bin contents Collect the separate

into shallow tubs for food organics bins on

visual (%) estimation a daily basis of food organics composition.

Remove waste contaminants (glass,

Combine your

plastics, drink

contaminants into

containers etc.),

one bin and weigh

document type and

them.

source of contamination.

Minimise the number of bins you use

Empty tubs into

(combine contents of

skip/bin for

bins that only have

collection.

small amounts of material in them).

Compress the organics into each

Wash out bins and bin so that the

return to kitchen contents are

staff. Bins must be reasonably well

cleaned and packed. You can

maintained to control use the bottom of a

odours. bucket to do this.

Calculate the total

weight of the food

organics material Weigh the filled bins

and the average on a scale. Record

volume of each type the total volume and

of material identified. weight on data recording sheets.

Estimate seasonal

variation from

business records.

. . . . . . . . . . . .

Plate 4. Quantifying the amount and type of garden organics produced by your^{Garden organics} organisation may be difficult, but it is still important if you want to use this material _{Garden organics material can form a} in your new organics management system.

substantial proportion of the solid waste stream, particularly during summer and after storm events.

In some instances quantifying the garden organics produced by your organisation may be difficult. Nevertheless, you should try to characterise this component of your waste stream.

Garden organics materials include the following subcategories, which are useful in identifying suitable handling and processing technology:

Material	Detail
Putrescible	grass clippings
garden
organics
Non-woody	leaves, sapwood,
garden organics;	prunings (<10 mm ∅)
Woody garden	branches, twigs
organics;	(>10 mm ∅)
Trees and
limbs;
Stumps and
rootballs.

Use the following steps to quantify and identify the nature of your garden organics (Plate 4):

1. Consult with relevant staff

Consultation with relevant staff members is essential to determine the amount of garden organics material produced. Identify materials present and the quantities of materials generated. If possible, ask gardening staff to fill out Form 2 for a two week period to characterise the garden organics generated.

If gardening staff cannot give you accurate estimations of garden organics generated, it will still be useful to have garden staff provide a guesstimate of the amount of each material produced.

2. The audit process

8 . . .

Over a two week period, encourage �� Make notes of any storm events gardening staff to record the volume etc. that may have influenced the and composition of the garden amount of material organics generated. In addition, generated/collected during the identify current practices with your audit period. garden organics – are they stock _{piled, mulched, burnt, dumped in a} Note: If your garden organics have _{skip etc.?} been size reduced/shredded prior to

auditing, the volume of material will Use the following steps to determine be significantly reduced. the amount and type of garden

_{organics produced by your} 3. Exclude materials from the audit

^{organisation:} If materials such as lawn clippings _{�� Have gardening staff count the} are usually left uncollected on lawn _{number of grass catchers,} areas, then do not count this material _{trailers, trucks, and/or skips} in the audit. Leaving this material on _{filled with garden organics each} the ground is the optimal choice – not _day. requiring further effort or management. The goal of the �� Determine the volume of each organics management system is to type of storage medium. improve poor practice, not to change best practice where it already occurs.

�� To determine the overall volume of materials generated on a daily 4. Check the audit results basis, multiply the number of

_{times a container is filled by its} After the two week period, it will be _volume. useful to feed data back to gardening staff and confirm the audit results.

�� Estimate the total volume of Determine if the results are typical or material generated on a weekly atypical of what is usually produced. basis by adding the daily totals

_together. Identify the effects of season or the impact of other events such as storms

�� Try to characterise the on the amount and type of material proportion of different garden produced. organics generated on a daily/weekly basis.

. . . . . . . . .

Form 2. Auditing your garden organics

9 . . . . . . . . . . . .

Wood and timber

Wood and timber materials can be a substantial proportion of the solid waste stream for some types of enterprises. These materials have a very high carbon to nitrogen ratio, complementing the low carbon to nitrogen ratio of food organics.

Wood and timber organics include the following subcategories, which are useful in identifying suitable handling and processing technologies:

Material

off-cuts crates pallets and packaging saw dust timber shavings

For use in your organics management system, you should consider only saw dust and/or timber shavings, and only if the material is from wood that exposes staff to unnecessary risks. is not painted or treated. The use of other wood and timber materials may ^{The audit process} create more problems than benefits. _{As with garden organics and food}

Avoid chemically treated or composite ^{organics, collect residual wood and} wood products timber materials over a two week

period.

Avoid using chemically treated wood and composite wood materials, as _{�� Remove any contaminants} they contain dangerous chemical compounds (eg. formaldehyde, �� Place the residuals in easy to creosote, etc.) that may pose potential weigh containers and weigh on a health risks to your staff. daily or weekly basis (depending

on quantity produced)

Use wood materials that are already

^{in a form to be processed} �� Identify type and source of For OH&S reasons and also for ease contamination (if any) of management, it is best to use wood and timber materials that are already ^{�� Dispose of material, as is usual} in a form to be processed (saw dust ^practice

^{and shavings).} �� Clean containers (if necessary)

Size reduction of materials adds

�� At the end of the two-week considerable time to the processing _{period calculate the quantity and} of the wood and timber, requires _{composition of material} expensive equipment and also _{generated using Form 3.}

10 . . . . . . . . . . . .

Paper and cardboard

Paper and cardboard materials can be a substantial portion of the solid waste stream for many enterprises. Whilst not wanting to impact on effective paper recycling, some of this material may be useful to the organics management system. Paper and cardboard has a very high carbon to nitrogen ratio – complementing the very low carbon to nitrogen ratio of food organics.

If you have not established a paper recycling system, the guidelines are provided in “Office Paper, Recycle it” NSW EPA (1990).

Use pre-shredded paper/cardboard

For ease of management and to facilitate the organics management system, only use non-waxed paper and cardboard. The size reduction of paper and cardboard can be difficult and time consuming without expensive equipment. So be sure to identify shredded paper and cardboard. It will be much easier to use in your organics processing system.

The audit process

As with other materials, monitor the amount of paper produced by your organisation over a two-week period. Quantify volumes generated on a daily/weekly basis, identifying contaminant levels and the effects of special events etc. on volumes generated. To quantify materials produced, your organisation should:

�� Collect paper in easy to weigh containers or as per existing system;

�� Weigh paper on a daily/weekly basis using platform scales as identified previously;

�� Determine the volume of paper generated from the size of the containers.

�� Identify type and source of contamination (if any);

�� “Dispose” of or recycle paper through regular practice;

�� At the end of the 2 week period, calculate the amount of material generated weekly.

11 . . . . . . . . . . . .

If you don’t have a paper recycling system, provide a copy of the previous page and Form 4 to someone else who is interested in developing paper recycling in your organisation.

Estimating variation across the annual cycle

maximum expected volumes. If the “audit” is conducted during a quiet period – use business records (eg. purchasing, reservations, bookings etc.) and consult with operational staff to estimate maximum expected volumes.

Document maximum expected organisation. The selection of an appropriate organics management system can be made according to this identification of specific compostable materials produced.

Vermiculture units are suitable for processing the following compostable organic materials:

If large quantities of compostable materials that do not fall into these categories are produced by your organisation, an alternative organics management system, for example composting, should be implemented that more readily processes these types of materials.

More information on alternative organics management systems, such as composting, can be found in On-Site Composting: Technology Options and Process Control Strategies (Recycled Organics Unit, 2001b) or visit http://www.recyledorganics.com.

Information Sheet No. 3 Can vermiculture work for you?

=

Vermiculture processing Food organics suitable for vermiculture processing

The use of vermiculture for

The ROU is the NSW centre for organic resource management, information, research & development, demonstration and training

The trials performed by the Recycled Organics Unit also found that food organics can be processed using vermiculture, however, materials need to be prepared into a suitable feedstock.

The definition for food organics contains the following subcategories:

Material	Detail
Fruit and
vegetables
Bread, pastries	Including rice and
and flours	corn flours
Meat and poultry
Fats and oils
Seafood	Including shellfish,
	excluding oyster shells
Food soiled paper	Hand towels,
products	butter wrap etc.
Biodegradeables	Cutlery, bags,
	polymers
Dairy	Solid and liquid
Recalcitrants	Large bones,
	oyster shell,
	coconut shells etc.

Of these categories, the trials performed by the Recycled Organics Unit indicated that seafood, dairy, and monostreams of bread, pastries and flours and meat are not suited to vermiculture processing in any significant quantity.

Also, previous qualitative experience has indicated that as higher proportions of bread, meat and dairy are combined with fruit and vegetables in a mixed food organics feedstock, the capacity of vermiculture technology to process this material, is significantly decreased (Kater, 1998; Recycled Organics Unit, 2000).

As a result of these studies, the Recycled Organics Unit recommends that on-site vermiculture technology is suitable for the following categories of food organics material: �� only fruit and vegetables; or

�� predominantly fruit and vegetables with a relatively small proportion of bread and meat/poultry.

Although it may be possible for vermiculture to process a wider range of food materials, the risk of problems occurring and the management skill and effort required to sustain the process means that vermiculture processing is not appropriate for C&I sector on-site applications.

Choosing a suitable processing technology

Performing an audit of all compostable organic materials produced on-site will allow an identification of the types and quantities of compostable materials produced by your organisation.

If large quantities of fruits and vegetables were identified in the audit, vermiculture technology may be a suitable option for processing this compostable material. However, if materials that are difficult to process using vermiculture make up a significant proportion of your total material, a different form of processing technology, for example on-site composting or a source separated collection system for centralised processing, will be more suitable.

More information on other forms of processing technology can be found in “Implementing an Organics Management System: A planning and implementation workbook for the commercial and industrial sector” (Recycled Organics Unit, 2001a) or from http://www.recycledorganics.com.

Definitions*

Compostable organics

Compostable organics is a generic term for all organic materials that are appropriate for collection and use as feedstocks for composting or in related biological treatment systems (e.g. anaerobic digestion). Compostable organics is defined by its material components: residual food organics; garden organics; wood and timber; biosolids, and agricultural organics.

Food organics

The Food Organics material description is defined by its component materials, which include: fruit and vegetable material; meat and poultry; fats and oils, seafood (including shellfish, excluding oyster shells); recalcitrants (large bones >15mm diameter, oyster shells, coconut shells etc.); dairy (solid and liquid); bread, pastries and flours (including rice and corn flours); food soiled paper products (hand towels, butter wrap etc.); and biodegradeables (cutlery, bags, polymers). Such materials may be derived from domestic or commercial and industrial sources. The definition does not include grease trap waste. Food organics is one of the primary components of the compostable organics stream.

Composting

The process whereby organic materials are pasteurised and microbially transferred under aerobic and thermophilic conditions for a period of not less than six weeks. By definition, it is a process that must by carried out under controlled conditions yielding mature products that do not contain any weed seeds or pathogens.

*Recycled Organics Unit, (2001b)

2 . . . . . . . . . . . .

. . . . . . . . . . . .

required

Selection of a vermiculture unit

Selection of the type and size of vermiculture unit required will vary from site to site depending on a number of factors. These factors include:

�� type of materials to be processed;

�� cost;

�� purpose of the vermiculture unit;

�� availability of complementary materials;

�� vermiculture processing capacity for the organic material; and

�� availability of space and other site specific constraints.

In order to determine what size vermiculture unit is required a ‘waste’ audit needs to be conducted to determine the quantity and type of

Information Sheet No. 4

Guide to feedstock preparation anddetermining what size vermiculture unit is

materials you produce. This auditing process has been detailed in Information Sheet No. 2.

Establishing a source separated collection system is essential for the collection of compostable organic material for processing in a vermiculture unit. This process is also detailed in Information Sheet No. 2.

Following this, you need to evaluate whether vermiculture technology is suited to processing the materials that are produced by your organisation. This process is detailed in Information No. 3.

Plate 1. Feedstock for successful vermiculture processing requires a combination of size reduced organic materials and a carbonaceous bulking agent.

The ROU is the NSW centre for organic resource management, information, research & development, demonstration and training

Feedstock composition

The volume of compostable material a vermiculture unit can process (see processing capacity) will vary depending on the type of material being processed, the size of the unit, the amount of worms housed in the unit, and management of the unit.

Vermiculture units more readily treat a mixture of organic materials than ‘monostreams’ of a single material.

Preparing material for processing

Organic materials to be processed by a vermiculture unit should be size reduced to enable effective processing by the worm population (Plates 2 and 3).

The addition of a bulking agent is required to form a feedstock that will support problem free processing.

Plate 2. Fruit and vegetables prior to size reduction using a bucket and spade method.

Plate 4 shows a final feedstock of size reduced fruit and vegetables blended with a cardboard bulking agent.

The importance of a bulking agent

A bulking agent is a carbonaceous material, such as paper or cardboard, that is added to a feedstock to increase the carbon to nitrogen (C:N) ratio and to help achieve a suitable moisture level, thereby improving the structure and porosity of the feedstock.

An ideal C:N ratio of a feedstock for vermiculture processing is 20 to 25 parts carbon to 1 part nitrogen (20-25:1). Maintaining this C:N ratio is especially important when processing organic materials that are high in nitrogen such as meats and poultry.

If the C:N ratio is not ideal, these high nutrient materials will decompose rapidly and problems such as odour development and pest attraction may occur.

The addition of a bulking agent also increases the structure and porosity of a feedstock. These factors result in a more suitable environment for the worms and hence processing will be more effective.

Cardboard and office paper are common residual materials of the C&I sector and these materials can provide an excellent on-site source of bulking agent if they can be size reduced.

Bulking agents need to be size reduced and thoroughly mixed with the organic materials to create a suitable feedstock (Plate 4).

In some instances achieving the desired C:N ratio and moisture content may require the addition of water. Feedstocks containing materials such as breads, for example, tend to be quite dry yet are high in nitrogen. A moisture content of approximately 80% is ideal for a vermiculture feedstock mixture.

A number of generic recipes (by weight and by volume) for feedstock mixtures comprising organic materials commonly produced by C&I sector organisations are shown in Tables 1 and 2.

Plate 4. Blended feedstock of mixed fruit and vegetable and cardboard bulking agent ready to be processed by a vermiculture unit.

Plate 3. Fruit and vegetables after size reduction using a bucket and spade method. Note the very watery texture. Shredded cardboard can be added to soak up the excess water.

2 . . . . . . . . . . . .

Table 1. Feedstock recipe guide (by weight) for compostable organics material and cardboard bulking agent. Feedstock type1 Maximum sustainable processing capacity (kg/m2/wk) Components3 Composition by weight (%) Composition by weight (kg) Ratio of organics to bulking agent Fruit 41.0 6.8 Vegetables 41.0 6.8 Cardboard 18.0 2.9 Fruit and/or vegetables + cardboard 16.5 Total: 100.0 16.5 4.7:1 Fruit 22.0 2.2 Vegetables 20.0 2.0 Bread 3.0 0.3 Meat/poultry 9.0 0.9 Cardboard 21.0 2.1 Water 25.0 2.5 Mixed food organics + cardboard 10.0 Total: 100.0 10.0 2.6:1
Lawn clippings and non-woody plant materials 70.0 4.0 Water 30.0 1.8 Garden organics 5.8 Total 100.0 5.8 No bulking agent required
Pre-consumer fruits and vegetables 51.0 6.8 Post-consumer plate scrapings (mixed food organics) 30.0 4.0 Cardboard 19.0 2.5 Miscellaneous food organics + cardboard (eg. Café food scraps) 13.3 Total: 100.0 13.3 4.3:1

¹ Note that this data is a result of extensive applied trials that have shown such feedstock mixtures can support sustained vermiculture processing

without resulting in negative environmental impacts or system failure (Recycled Organics Unit, 2000). ² Processing capacity is the maximum amount (kg) of compostable organics that can be added to a vermiculture unit per week without causing system failure. System failure is evident when the processing technology produces problematic environmental emissions and/or declines in processing efficiency and/or produces a product of unacceptable quality (Recycled Organics Unit, 2000b). Overfeeding of a vermiculture unit will exceed the maximum processing capacity resulting in problems and management requirements.

³ Shredded paper is a common C&I sector waste material that can be used as a bulking agent when combined with compostable organics material. However, no data is available at present on appropriate mixing rations to enable processing in vermiculture units. Experimentation with blending ratios is recommended in order to use shredded paper as a bulking agent.

. . . . . . . . . . . .

Table 2. Feedstock recipe guide (by volume) for compostable organics material and cardboard bulking agent. Feedstock type1 Maximum sustainable processing capacity2 (L/m2/wk) Components3 Composition by volume4 (%) Composition by volume4 (L) Ratio of organics to bulking agent Fruit 34.0 8.0 Vegetables 35.0 8.5 Cardboard 31.0 7.5 Fruit and/or vegetables + cardboard 24.0 Total: 100.0 24.0 2.2:1 Fruit 14.0 2.5 Vegetables 14.0 2.5 Bread 5.0 1.0 Meat/poultry 5.0 0.9 Cardboard 48.0 8.6 Water 14.0 2.5 Mixed food organics + cardboard 18.0 Total: 100.0 18.0 0.8:1
Lawn clippings and non-woody plant materials 94.0 28.3 Water 6.0 1.7 Garden organics 30.0 Total 100.0 30.0 No bulking agent required
Pre-consumer fruits and vegetables 38.0 8.3 Post-consumer plate scrapings (mixed food organics) 16.0 3.4 Cardboard 46.0 9.9 Miscellaneous food organics + cardboard (eg. Café food scraps) 21.6 Total: 100.0 21.6 1.2:1

¹ Note that this data is a result of extensive applied trials that have shown such feedstock mixtures can support sustained vermiculture processing

without resulting in negative environmental impacts or system failure (Recycled Organics Unit, 2000). ² Processing capacity is the maximum amount (kg) of compostable organics that can be added to a vermiculture unit per week without causing system failure. System failure is evident when the processing technology produces problematic environmental emissions and/or declines in processing efficiency and/or produces a product of unacceptable quality. (Recycled Organics Unit, 2000b). Overfeeding of a vermiculture unit will exceed the maximum processing capacity resulting in problems and management requirements.

³ Shredded paper is a common C&I sector waste material that can be used as a bulking agent when combined with compostable organics material. However, no data is available at present on appropriate mixing rations to enable processing in vermiculture units. Experimentation with blending ratios is recommended in order to use shredded paper as a bulking agent.

⁴ Note that all volumes are for size reduced feedstock components.

. . . . . . . . . . . .

Mixing a suitable feedstock

Preparing a suitable feedstock for processing in a vermiculture unit is a crucial step in ensuring a healthy environment for the worm population.

Many failures of vermiculture units can be attributed to the addition of unsuitable feedstocks or excessive quantities of feedstock. Problems that can result from an unsuitable feedstock include:

�� feedstock too moist – resulting in anaerobic (low oxygen) conditions;

�� feedstock too dry – not suitable for worm movement and habitation;

�� feedstock containing components that cannot be readily processed by the vermiculture unit – such as seafood or dairy material;

�� feedstock loading rate too high – too much feedstock applied to the unit resulting in feedstock build up, anaerobic (low oxygen) conditions and worm death;

�� feedstock particles too large – size reduction is necessary for effective processing (eg. particles >50 mm should be size reduced).

Some generic vermiculture feedstock recipes have been given in Tables 1 and 2. The steps for preparing a suitable feedstock are given below and will follow the recipe for a mixed fruit and vegetable feedstock (by volume).

1. Feedstock should be prepared daily. Storage of feedstock and unprocessed food organics components should be avoided as this can result in odour production and pest attraction.
2. Wear gloves and an apron whilst handling materials and preparing feedstock.
3. Collect source separated mixed fruits and vegetables from collection point (eg. kitchen).
4. Place the raw size reduced food organics (Plate 2) in a tub or tray suitable for mixing.
5. Size reduce by chopping with a spade (Plate 3).
6. Estimate the volume of raw organics material – using buckets of known volume is

helpful for this task, or mark the inside of tub for different volumes.

1. Determine the quantity of bulking agent required (see Table 2) to obtain a suitable C:N ratio, moisture content and structure (Plate 5).
2. Combine the raw organics material and bulking agent thoroughly. A fork or shovel is useful for this task (Plate 6).
3. Check the moisture content is suitable by performing the ‘fist test’ (also known as ‘squeeze test’).

Take a hand dull of feedstock and squeeze firmly (Plate 7). Some moisture should be released between the fingers however the feedstock should not be saturated.

If the feedstock is too moist, it may be beneficial to allow the bulking agent in the feedstock to absorb moisture for 10 minutes and then checking the moisture content again. The bulking agent may absorb more of the moisture over time. If the feedstock is still too moist, more bulking agent

Plate		5.	Blending			of	a	Plate	6.		Use a fork or			Plate 7. ‘Fist test’ used	Plate 8. Final feedstock of
cardboard bulking agent with								shovel		to		blending	the	to determine the correct	mixed fruit and vegetables
raw	fruit			and	vegetable			feedstock components.						moisture content for the	blended with a cardboard
feedstock to soak up excess														feedstock.	bulking agent.
water and to raise the C:N
ratio to an optimum level.

5 . . . . . . . . . . . .

should be added. This will increase the C:N ratio, which is not ideal, but may be the balance of variables possible.

If the feedstock is too dry (which may be the case for feedstocks made from dry materials such as bread), water should be added and the moisture content checked using the ‘fist test’.

10. The final feedstock should have a suitable moisture content, a good structure and a C:N ratio of between 20-25:1 (Plate 8).

Feedstocks should be applied immediately to a vermiculture unit, and then the tools used and site should be cleaned, ensuring no food material is left exposed to the environment as this can result in odour generation and pest attraction.

Maximum processing capacity

The processing capacity of vermiculture technology refers to the maximum amount of organic material that can be added to a vermiculture unit per unit time (eg. week) without causing system failure.

Vermiculture units have a limit to the amount of organic materials that can be processed over time.

If the maximum processing capacity is exceeded, problems can arise such as anaerobic (low oxygen) conditions, worm death, odour production, pest attraction and ultimate system failure.

The maximum processing capacity of a vermiculture unit is dependent on the type of materials being fed to it (feedstock composition) as worms process different organic materials at different rates.

As discussed in Information Sheet No. 3, the installation of a

6 . . .

vermiculture unit will only be successful if the appropriate compostable material is processed in the unit at an appropriate loading rate.

Trials performed by the Recycled Organics Unit found that fruit and vegetables are the most appropriate organic materials for vermiculture processing

Seafood, dairy, and monostreams of bread and meat are not suited to on-site vermiculture processing in any significant quantity.

Also, previous qualitative experience has indicated that as higher proportions of bread, meat and dairy are combined with fruit and vegetables in a mixed food organics feedstock, the capacity of vermiculture technology to process this material, is significantly decreased (Kater, 1998; Recycled Organics Unit, 2000).

As a result of these studies, the Recycled Organics Unit recommends that on-site vermiculture technology is suitable for the following categories of food organics material (Plate 9):

�� only fruit and vegetables; or

�� predominantly fruit and vegetables with a relatively small proportion of bread and meat/poultry.

Although it may be possible for a vermiculture unit to process a wider range of food materials, the risk of problems occurring and the management skill and effort required to sustain the process means that vermiculture processing is not appropriate for C&I sector on-site applications.

The maximum processing capacity of a vermiculture unit in relation to two feedstocks with varying compositions is shown in Figure 1, based on research performed by the Recycled Organics Unit (see Appendix No. 4).

Note that a mixed food organics and cardboard feedstock, containing meat and bread material, requires a higher proportion of bulking agent (due to the higher nitrogen content in meat and bread) and can be processed by a vermiculture unit at a lower application rate than the fruit and vegetable and cardboard feedstock.

The maximum processing capacity is expressed as the volume of feedstock applied per square metre of bedding surface per week (given appropriate siting, worm population and management).

Plate 9. Food organics suitable for processing in vermiculture units include only fruit and vegetables or predominantly fruit and vegetables with relatively small proportions of bread and meat/poultry.

. . . . . . . . .

What size vermiculture unit do I require?

The size of the vermiculture unit required for on-site processing of compostable organic materials will be calculated from the results of an audit of waste produced on-site as previously discussed. The size the process is likely to fail.

The processing capacity of a number of example feedstocks is shown in Table 3. This table will aid in calculating the surface area (m²) that is required to process the volumes of organic materials produced on-site.

Figure 2. The size of a vermiculture unit required to adequately process the amount of organic material produced onsite is dependent on the size of the surface feeding area. The surface feeding area for an example vermiculture unit is shown below. This unit has a surface feeding area of

0.53 m².

calculated is actually the number of square metres (m²) of surface feeding area that is required (Figure 2).

The size/number of vermiculture units selected must be large enough to effectively process the volumes of organic materials produced on-site. If your vermiculture unit is too small, This can be done by following these steps:

1. The type and volume of food organic material is found by the audit (Information Sheet No. 2).
2. Volume of feedstock – calculate the volume of feedstock (raw size reduced food material +

Minimum feeding area (1 m²) Minimum feeding area (1 m²)

7 . . . . . . . . . . . .

Table 3. Processing capacities and estimated surface feeding area required for suggested feedstocks Feedstock Composition Maximum processing capacity of blended feedstock (L/m2/wk)* Volume of feedstock from your site after blending with bulking agent where appropriate (L/wk) Calculated surface feeding area of vermiculture unit required (m2) Mixed fruit and/or vegetables �� Mixed fruit �� Mixed vegetables �� Bulking agent 24 a Mixed food organics �� Mixed fruit �� Mixed vegetables �� Meat/poultry �� Bread �� Bulking agent 18 b Garden organics �� Lawn clippings �� Garden organics 30 c Miscellaneous organics (eg. Café food scraps) �� Pre-consumer mixed fruits and vegetables �� Post consumer plate scrapings (mixed food organics) �� Bulking agent 24 18 a b 2#2 mm 24 x a ==2#2 mm 30 x c ==2#2 mm 18 x b ==2# 22 m m 18 m 24 x ba =+=

* Based on maximum loading rates calculated by the Recycled Organics Unit (2000). ^# Where x is the calculated surface feeding area required based on the amount of feedstock to be processed on-site.

bulking agent) to be processed each week (and the amount of bulking agent necessary to make the process work). This can be calculated using Table 1 or 2.

1. Feeding area required – calculate the surface feeding area required (m²) according to the equation in Table 3 and the feedstock type (see Figure 2).
2. Use this calculated surface feeding area requirement to select one or more vermiculture unit/s that will provide the required surface feeding area.

Stocking the unit with worms

The types of worms used in vermiculture units are not worms that are commonly found in gardens.

Worms used in vermiculture units tend to process larger amounts of organic material, reproduce in confined environments (such as vermiculture units), and cope well with disturbances (such as feeding and maintenance procedures) when compared with other common species (Appelhof, 1997).

Eisenia fetida (Tiger worm) is the worm most commonly used in vermiculture units in warm climates (Plate 10). These worms process relatively large amounts of organic materials and naturally occur in manure, compost and decaying leaves. These worms also reproduce quickly, have a relatively wide tolerance to temperatures and moisture (for worms), and are readily handled (Edwards, 1988).

Other names for Eisenia fetida include the ‘Tiger worm’, ‘Redworm’ and ‘Red wiggler’.

When establishing a vermiculture unit, the correct type of worm needs to be incorporated at a sufficient quantity to process the organic materials produced on-site.

Depending on the feedstock types, a worm application rate of between 10 and 18 kg per metre of bedding

8 . . . . . . . . . . . .

surface (10 – 18 kg/m²) is recommended as a sufficient rate to quickly establish maximum processing capacity (Recycled Organics Unit, 2000).

When establishing a vermiculture unit, it is important to provide a suitable environment for the worm population. The unit must be filled with bedding material to provide a safe and desirable habitat for the worm population.

The most suitable bedding material is mature vermicast that is composed of organic materials already processed by a worm population. Approximately 30 cm of mature vermicast will provide an excellent habitat for the worms. This amount of bedding will result in a more established environment ultimately increasing the processing capacity of the unit.

Introducing the worm stock to a vermiculture unit should be performed in the morning. This will ensure the worm population does not exit the unit, as daylight will deter the worms from escaping. Alternatively, a bright light can be used to encourage the worm stock to burrow into the new environment.

Sprinkle the worm stock carefully over the surface of the vermiculture unit. The worms will quickly burrow into the bedding material. Ensure the bedding material is moist but not too

Plate 10. Tiger worms (Eisenia foetida) are a common worm species used in vermiculture units.

wet. The ‘fist test’ should be used to ensure the moisture content of the bedding material is suitable moisture for the worm stock. This procedure is described in detail in Information Sheet No. 6.

A period of acclimatisation is necessary for the worm stock when introduced to this new environment. Refrain from applying feedstock for a week after introducing the worms to allow them to settle. Gradually introduce the feedstock over two to four weeks until the maximum processing capacity is reached.

To purchase worms and bedding material (vermicast) for a vermiculture unit, look under “worm

farms”	in	the	Yellow		Pages	or
advertisements			in	gardening
magazines.
Space availability

The type of vermiculture unit selected for on-site processing of compostable organics material needs to suit the availability of space for the site. For example, a stacking tray unit may offer the same feeding area but take up less floor space than a continuous flow unit.

When determining how much space is required for vermiculture processing, it is important to consider that other equipment is required for a vermiculture process to operate successfully.

This equipment includes:

�� size reduction equipment (eg. mixing tub, bucket and spade for soft food organics, shredder for cardboard);

�� material handling and feedstock preparation equipment (eg. buckets, mixing tubs, garden fork);

Definitions*

Source separation

Physical sorting of the waste stream into its components at the point of generation.

Compostable organics

Compostable organics is a generic term for all organic materials that are appropriate for collection and use as feedstocks for composting or in related biological treatment systems (e.g. anaerobic digestion). Compostable organics is defined by its material components: residual food organics; garden organics; wood and timber; biosolids, and agricultural organics.

Processing capacity

The maximum amount (mass or volume) of feedstock that can be added to a processing technology (e.g. composting technology) per unit time (e.g. per week) without causing system failure. System failure is evident when the processing technology produces problematic environmental emissions and/or declines in processing efficiency and/or produces product of unacceptable quality.

Bulking agent

An ingredient in a mixture of composting raw materials included to improve the structure and porosity of the mix. Bulking agents are usually rigid and dry and often have large particles (for example, straw or wood chips). The terms “bulking agent” and “amendment” are often used interchangeably. See also composting amendment.

Carbon to nitrogen (C:N) ratio

The ratio of the weight of organic carbon (C) to that of total nitrogen (N) in an organic material.

Anaerobic

In the absence of oxygen, or not requiring oxygen.

* Recycled Organics Unit (2001)

�� monitoring and maintenance

equipment (eg. thermometer,

pest deterrent devices);

9 . . . . . . . . . . . .

�� dry storage areas for bulking agent and area for blending feedstocks; and

�� washing up area (eg. sink, hose) and bin wash area.

Example

A summary of the steps required for determining the scale of vermiculture processing technology and the size of the vermiculture unit required for your operation is shown in Figure 3.

10 . . . . . . . . . . . .

Caution

The Recycled Organics Unit has been called out to fix many failed vermiculture processing operations.

Rectifying a failed system is much, much more work than managing a system effectively.

This package does not claim to be the only way for installing and maintaining a successful on-site vermiculture operation. However, applied research and extensive experience confirms that the processes and processing capacities communicated in this package provide a sound basis for problem free vermiculture processing, as is deemed necessary for successful application of this technology in C&I sector on-site applications.

11 . . . . . . . . . . . .

Information Sheet No. 5 Guide to installing a vermiculture unit

=

Where to locate a vermiculture unit

When installing vermiculture technology to process organic material, careful consideration should be given to the siting (or location) of the vermiculture units and the ancillary equipment.

Determining the most suitable location of an on-site, mid-scale vermiculture unit is dependent on a number of factors. These include:

�� accessibility;

�� maintaining climatic conditions

(shading and controlling

temperature and moisture);

�� security measures;

�� proximity to neighbours;

�� areas for storage of materials and feedstock preparation;

�� noise and odour considerations;

�� leachate;

�� pest exclusion; and

�� availability of services such as water and power if required.

Site selection for an on-site vermiculture installation is important both for efficiency of handling materials, and because worm activity is dependent upon environmental conditions including temperature and moisture.

Effective proper placement and management (of a unit of suitable size) will ensure effective operation without any adverse impacts on people or the environment (Plate 1).

Plate 1. Example of an on-site, mid-scale vermiculture unit installation in a nursing home.

The ROU is the NSW centre for organic resource management, information, research & development, demonstration and training

When locating a vermiculture installation, consideration of the required area should include the actual vermiculture unit, area for feedstock preparation and storage, and also area for equipment such as size-reduction equipment, monitoring and maintenance equipment.

This process of calculating the size of vermiculture technology required to process a given volume of material has been covered in Information Sheet No. 4.

Site selection

The selection of a suitable site for the location of a vermiculture unit is important in order to maintain both operational efficiency and vermiculture processing capacity. The location should be easily accessible from related operational activities, as feedstock material will need to be transported to the vermiculture installation.

The vermiculture units should be placed at a distance from neighbours and public areas but not in an area that is subject to vandalism.

Security measures should be in place to prevent any interaction with the treatment process by unauthorised personnel.

The placement of the vermiculture installation should be adjacent to or on route to the existing waste management and recycling area (Figure 1). This will increase the efficiency of the source separated collection system (see Information Sheet No. 2).

Vermiculture management activities

Storage of material

Ideally, food materials should be processed immediately to avoid any odour production. Compostable work practices may require short-term storage of compostable organics material prior to processing in the vermiculture unit. Short-term storage of spoiled food is common place in many commercial kitchens. Such spoiled food is often stored overnight in cool storage for disposal the next day. Storage areas should be kept clean and tidy and any spillage cleaned up immediately to prevent pest attraction and odour production.

Material should be stored in sealed containers (eg. in 80 L mobile garbage bins).

Feedstock preparation

A feedstock preparation area should be located adjacent to the vermiculture installation. This area should ideally include a small storage area to house equipment required for size-reduction, measuring and blending of the feedstock mixture, as well as clean-up equipment including brushes and hoses (Plate 2). Equipment such as garden forks and wheelbarrows or similar should be accessible to enable use of the vermicast product.

Details on the types of equipment required for feedstock preparation and supplier information is contained in Appendix No. 1.

Figure 1. Example of an on-site mid-scale vermiculture installation operated at a commercial catering establishment. This establishment generates primarily mixed food organics including a small amount of food-soiled paper. The material storage, feedstock preparation areas and vermiculture units are located adjacent to the waste disposal bins, the kitchen and the delivery dock.

. . . . . . . . . . . .

Plate 2. Equipment used for feedstock preparation and clean up including hose, garden forks, watering can, mixing tub, brushes and brooms.

Storing vermicast for use

When the vermicast product is removed from the vermiculture unit, it should be stored on site for use on the gardens of your organisation.

Specialist storage bins are available which aid in maturing the vermicast whilst in storage (Plate 3). Mobile garbage bins (MGB’s) are also a suitable storage unit. 120 L MGB’s are a good size for this purpose as they are still moveable once reasonably full.

See Information Sheet No. 7 for a guide to using the vermicast product.

Plate 3. Vermicast maturing bin.

Environmental and health considerations

Effective siting of the vermiculture units will minimise any adverse effects on people or the environment.

Environmental and health issues that need to be considered when siting vermiculture units include:

�� microclimate;

�� noise production;

�� odour production;

�� site hygiene;

�� sustainable loading rates; and

�� sustainable feedstock recipe.

These issues are very important for an effective vermiculture processing operation and with careful consideration, problems such as complaints from neighbours, pest attraction and health issues will be minimised.

Microclimate

Vermiculture units should be situated in an area where there is a degree of protection from extremes of weather (eg. temperature).

Worms are very susceptible to changes in climatic conditions. The acceptable temperature range for the Tiger worm (Eisenia fetida), a common species used in vermiculture systems, is 15 to 25 ^oC (Edwards, and Bohlen, 1996; Edwards, 1998) with an optimal temperature of 20^oC (Murphy, 1993).

This optimal temperature range refers to the bedding temperature and not the ambient air temperature. Control should be exercised over the environment of the worms to maintain temperatures within the ideal range to maximise the efficiency of the vermiculture process.

Definitions*

On-site, Mid-scale

A category of on-site composting or vermiculture-based technology with the ability to process between 20 and 250 kg of compostable organics per day. Such systems are usually comprised of an in-vessel processing unit (composting or vermiculture-based) and size-reduction equipment (eg. garden type petrol driven chippers or shredders). Procedures involved in the management of the processing system may involve a combination of manual labour and small mechanical equipment. Mid-scale systems are often used for the treatment of compostable organics produced by the commercial and industrial sector, hospitals and institutions etc.

Feedstock

Organic materials used for composting or related biological treatment systems. Different feedstocks have different nutrient concentrations, moisture, structure and contamination levels (physical, chemical and biological).

Leachate

Liquid released by, or water that has percolated through, waste or recovered materials, and that contains dissolved and/or suspended substances and/or solids and/or gases.

Processing capacity

The maximum amount (mass or volume) of feedstock that can be added to a processing technology (e.g. composting technology) per unit time (e.g. per week) without causing system failure. System failure is evident when the processing technology produces problematic environmental emissions and/or declines in processing efficiency and/or produces product of unacceptable quality.

Compostable organics

Compostable organics is a generic term for all organic materials that are appropriate for collection and use as feedstocks for composting or in related biological treatment systems (e.g. anaerobic digestion). Compostable organics is defined by its material components: residual food organics; garden organics; wood and timber; biosolids, and agricultural organics.

Continued page 4

3 . . . . . . . . . . . .

The temperature of the bedding material within a vermiculture unit can be influenced by the ambient air temperature and from direct sunlight. The lower the mass of bedding, and/or the higher the surface area to volume ratio of the bedding, the more it will be effected by daily fluctuations in air temperature and moisture.

When siting a vermiculture unit, ideally the units should be placed in an area not exposed to full summer sun. A location that is shaded in summer, yet sunny in winter is ideal.

Alternatively, an enclosed area may be suitable, but again only if the area is shaded and well ventilated so as to be relatively cool during hot summer periods. It may be possible to locate the vermiculture installation in an enclosed area where the temperature is already controlled via air conditioning.

If the units are located indoors in a temperature controlled environment, an ideal temperature range would be approximately 20-25^oC, consistent with the desirable temperature range for people. A reverse cycle air-conditioner (such as Plate 4) would provide good temperature control in a relatively constant environment such as the coastal New South Wales region.

Situating a vermiculture unit indoors is a luxury and is often not possible. Most vermiculture units are located outdoors and if this is the case, the minimum degree of climate control should be shade, especially in summer.

A shaded area such as a veranda is suitable for a vermiculture unit. However, if this is not possible, shade cloth covering the unit would also suit.

During summer months, damp hessian or old carpet should cover the surface of the bedding mass to prevent the units from drying out (Windust, 1997). In extreme temperatures, evaporative cooling can be used to lower the temperature of the entire vermiculture unit. This involves draping a wet cloth over the unit and moving air over the unit by the use of a fan or a breeze (Appelhof, 1997).

Additional layers of hessian, carpet underlay or similar can also be placed over the bedding surface during colder months to help insulate the bedding and to retain heat generated by the decomposition process.

Plate 4. Example of a reverse-cycle air-conditioner used for climate control.

Noise production

The production of noise from size-reduction equipment, such as a shredder or chipper, may pose problems if this equipment is located in close proximity to offices, neighbours or public areas.

Such equipment should be operated in accordance with proper occupational health and safety procedures, including the wearing of ear and eye protection.

Odour production

The generation of offensive odours may occur if a vermiculture unit is not managed effectively.

If a vermiculture unit produces odours, management procedures should be implemented to identify and rectify the problem. These management procedures are covered in Information Sheet No. 6.

The production of odours can also

result in the attraction of addition pests and vermin relative to current waste disposal practices. This may pose health risks and should be rectified immediately.

4 . . . . . . . . . . . .

Site hygiene

Ensuring the vermiculture installation is clean and hygienic is important to minimise odour production and to avoid potential occupational health and safety issues.

Any spillage of compostable material, vermicast or leachate should be cleaned up immediately. No food materials should be left exposed as this will attract pests and create odour problems.

Ensure staff wear gloves at all times when handling materials and that they wash their hands after any contact with the vermiculture operation. This will avoid cross contamination with any germs that may be present on spoiled food material.

Sustainable loading rates

The application of feedstock to a vermiculture unit at sustainable rates will minimise the accumulation of unprocessed feedstock within the units. Feedstock accumulation will result in temperature increases and will make the unit undesirable to the worm population. If this situation is not rectified, system failure will occur.

Loading rates depend on the type of organic material within the feedstock mixture. See Information Sheet No. 4 for some feedstock recipes and suitable loading rates.

Suitable feedstock recipe

The application of compostable organics to a vermiculture unit will only be successful if the material is in a suitable form for vermiculture processing. This involves only processing suitable organics, size reducing the material, amendment with a bulking agent and ensuring a suitable moisture content and structure. Information Sheet No. 4 has a comprehensive guide to feedstock preparation that will help you to produce a suitable feedstock for successful vermiculture processing.

Other considerations

Further considerations that should be addressed when installing a vermiculture unit include:

�� leachate production;

�� pest attraction;

�� related services; and

�� security.

Leachate production

The generation of leachate from a vermiculture unit is undesirable and can be rectified by effective management procedures. These are covered in Information Sheet No. 6.

If a vermiculture unit produces leachate, this liquid must be collected to avoid potential problems such as odour. The leachate should be collected and either re-treated in the vermiculture unit (small volumes only) or removed. See Information Sheet No. 7 for a guide to using leachate (vermiculture liquid).

Pest attraction

When installing a vermiculture unit, opportunities for pest attraction should be minimised.

Where units are enclosed in small areas, this may include the installation of pest deterrent devices.

Crawling insects can be deterred by standing the units in moats (buckets of water and detergent, Plate 5 or in salt water). Alternatively, the legs of the vermiculture unit can be coated in axle grease or sticky pest traps (see Appendix No. 1 for equipment suppliers).

Flying insect pests can be deterred using various baits or traps, for example fluorescent (black-light) zappers or devices such as in Plate 6.

Plate 5. Legs of free-standing vermiculture units can be placed in buckets of water and detergent to prevent crawling pests such as ants from entering the units.

Plate 5. Flying insect attraction devices. See Appendix No. 1 for supplier details

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Ensuring the area is thoroughly clean after any feedstock preparation, and storing all materials in sealed containers, will minimise pest attraction and probably represents a significant improvement over current practice.

Related services

Services such as water, and in some instances power, are required for effective vermiculture operations.

The availability of these services should be considered when installing vermiculture units and locating storage areas.

Water supply will be required for adding water to units during summer months, and for washing containers. Wash water from cleaning containers should be disposed of in gardens or the sewer.

Electricity may also be required for the operation of specific vermiculture technologies, but is generally not necessary.

Security

Security concerns (eg. vandalism) are often over stated. Be aware that the units contain decomposing material, which in itself usually provides necessary deterrent for potential vandals. The only serious instances of vandalism, in the authors experience, have resulted from locating units in areas already known to be subject to vandalism and/or are secluded out of hours congregation areas.

Some common sense is required when installing your vermiculture unit. For example, do not install units where they will disrupt existing popular activities and therefore give rise to antagonistic attitudes.

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Information Sheet No. 6
Management and maintenance of a vermiculture unit
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		Best practice management & maintenance	temperature, moisture content, and sampling vermicast; and

The ROU is the NSW centre for organic resource management, information, research & development, demonstration and training

Feedstock preparation & application

The preparation of a suitable feedstock is crucial in maintaining a successful vermiculture unit.

Many problems can result if the feedstock is inappropriate to the vermiculture unit. These can include:

�� feedstock too moist – resulting in anaerobic (low oxygen) conditions, worms need oxygen to survive;

�� feedstock too dry – not suitable for worm habitation;

�� feedstock recipes that contain components that are difficult to process by vermiculture technology – such as seafood, dairy products and hard materials (eg. bones);

�� feedstock loading rate too high – too much feedstock applied to the unit resulting in feedstock

accumulation,		anaerobic	(low
oxygen)	conditions		and
subsequent worm death;

�� feedstock too acidic/alkaline/ high in salts; or

�� feedstock particles too large – size reduction is necessary for effective processing.

The preparation of an appropriate feedstock involves careful consideration of the raw feedstock components. Vermiculture units process a mixture of compostable organics more readily than monostreams of single organic materials, for example, just bakery waste (Recycled Organics Unit, 2000).

A number of feedstock recipes have been given in Information Sheet No. 4 and these recipes are an excellent guide to preparing a suitable feedstock. Plates 4, 5, 6 and 7 show the steps in preparing a mixed fruit and vegetable feedstock.

The actual proportions of raw ingredients in a feedstock are not as crucial as the overall feedstock texture based on structure and moisture content. The addition of a bulking agent will influence the feedstock texture.

The addition of a bulking agent, such as paper or cardboard, is necessary to provide an adequate environment for worm habitation. Bulking agents increase the particle size of the feedstock which increases porosity and the carbon to nitrogen (C:N) ratio. These factors are essential for a feedstock suitable for processing by a vermiculture unit

The addition of moisture may also be necessary if the feedstock contains raw ingredients that are quite dry, for example breads.

The ‘fist test’ can be used when preparing a feedstock to estimate the moisture content of the material.

The method for performing the fist test is given later in this Information Sheet under ‘Moisture Content’.

This method is used for determining the optimum bedding moisture content. However, since the worms will inhabit the feedstock whilst they process it, the feedstock moisture content should also be at this optimum moisture content.

Plates 4, 5, 6 and 7. Preparation of mixed fruit and vegetable feedstock. Raw size-reduced fruit (far left) combined with cardboard bulking agent (left). Mixed thoroughly (right). Final feedstock of size reduced mixed fruit and vegetables with cardboard bulking agent (far right). Note the good structure present in the final feedstock mix. See Information Sheet No. 4 for more information.

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Monitoring & management of vermiculture units

Effective monitoring and management of vermiculture units is essential for the process to operate effectively and efficiently.

The monitoring and management procedures described in this Information Sheet are quick and easy to perform ‘field tests’.

The procedures described below are effective ways of ensuring a vermiculture process is operating effectively. It should be noted, however, that a wider range of testing procedures might be relevant for specific installations.

Monitoring procedures will be described for:

�� worm activity;

�� feedstock accumulation;

�� oxygen;

�� temperature;

�� moisture content; and

�� sampling vermicast.

Suppliers and approximate prices of associated equipment required for these tests are detailed in Appendix

1.

Details of further tests, performed in a laboratory, that maybe necessary to ensure the final vermicast product is safe for use will also be described. These include taking a sample to be analysed for:

�� pathogens; and

�� heavy metal concentrations.

Note that these tests may only be relevant if the operator intends to sell the vermicast product commercially.

A number of more complex tests can be performed during vermiculture processing, for example salt content

4 . . .

(measured by the electrical conductivity test), pH, and total Definitions* carbon and nitrogen content. These tests, however, require laboratory Compostable organics analysis and are not normally Compostable organics is a generic term for all necessary for on-site, mid-scale organic materials that are appropriate for _processing. collection and use as feedstocks for

composting or in related biological treatment A form for recording weekly systems (e.g. anaerobic digestion). _{management and maintenance} Compostable organics is defined by its

material components: residual food organics;

procedures and for monitoring _{system performance has been} garden organics; wood and timber; biosolids, included in this Information Sheet ^{and agricultural organics.}

^{(Form 1).} Best Practice _{Monitoring & testing safety} For any area of waste management this represents the current ‘state-of-the-art’ in ^tips achieving particular goals. Best practice is dynamic and subject to continual review and

The monitoring and management procedures discussed here are not ^improvement. hazardous however a few safety precautions need to be observed. ^{On-site, Mid-scale}

A category of on-site composting or _{�� Gloves – should be worn when} vermiculture-based technology with the ability _{handling feedstocks and} to process between 20 and 250 kg of compostable organics per day. Such systems

vermicast.

are usually comprised of an in-vessel _{�� Apron – protects clothing whilst} processing unit (composting or vermiculture-based) and size-reduction equipment (eg. ^{handling material and preparing} garden type petrol driven chippers or ^feedstocks. shredders). Procedures involved in the management of the processing system may ^{�� Safety glasses – should be} involve a combination of manual labour and ^{worn during size reduction} small mechanical equipment. Mid-scale ^procedures. systems are often used for the treatment of compostable organics produced by the

^{�� Ventilation – activities such as} commercial and industrial sector, hospitals and size reduction and feedstock _{institutions etc.} preparation should be conducted in a well-ventilated area. Feedstock

Organic materials used for composting or

�� Equipment – should be used related biological treatment systems. Different safely, and tasks should be feedstocks have different nutrient supported by standard operating concentrations, moisture, structure and procedures that define safe and contamination levels (physical, chemical and

effective operating practice. biological).

�� Hygiene – if handling materials Vermicast or feedstock, hands should Solid organic material resulting from the biological transformation of compostable

always be washed with soap and _{warm water afterwards.} organic materials in a controlled vermiculture

process.

Continued page 5

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Indicators of system stress

Effective monitoring and management of a vermiculture unit will result in a reliable and efficient organics managment system. Particular occurrences within the system may indicate system success or failure and these should be regularly investigated as indicators of system health.

The hierarchy of system performance indicators (shown in Figure 2) is as follows:

1. Worm activity – is the first indication that a system is stressed. Worms will attempt to escape the vermiculture unit if conditions are unsuitable for habitation.
2. Feedstock accumulation – feedstock will accumulate if the worms are no longer processing it but are attempting to escape. The feedstock will accumulate and cause the conditions to be even more unsuitable for worm habitation.

3.	Oxygen	–	if	feedstock		4.	Temperature			–		finally
	accumulates, oxygen levels will						temperature will rise within the
	decrease and cause				anaerobic		unit	as	the		feedstock
	conditions. This will add to the						accumulates and decomposes.
	uninhabitable conditions of the
	unit.

Indicators of system stress

Figure 2. Hierarchy of indicators of system stress. Regular monitoring of indicators of stress will ensure problems are identified promptly, allowing operators to correct these problems to maintain overall performance.

1. Worm activity is the first indicator that a vermiculture unit is performing well or is under stress. Worm activity should be monitored regularly and any change in activity should be noted.

2. Feedstock will accumulate if a unit is not adequately processing the

Feedstock accumulation feedstock. If feedstock is accumulating, indications are that the processing rate is too high or the feedstock is not suitable.

3. Oxygen levels will become low (<10%) if the unit is stressed. If oxygen levels drop, management should be implemented such as tossing of the beds and the cause of the oxygen level drop should be investigated.

4. Temperatures will be high (>30 ^oC) if the unit is stressed. Temperature should be regularly monitored to prevent temperatures becoming this high. Temperature is the final indication of a stressed vermiculture unit.

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=Worm activity

Worm activity is an effective qualitative method for assessing system performance.

Worms will behave according to the degree of stress that they are under. If the vermiculture unit is not suitable for habitation by worms, they will attempt to escape. For this reason, observations of worm activity are usually the first indication that a vermiculture unit is under stress.

Worm activity should be monitored regularly using a classification system. An example of such a system is shown in Table 1. This system uses various categories of worm activity to define the performance of a vermiculture unit.

Some examples of worm activity exhibiting system stress are shown in Plates 8, 9 and 10. These units are under significant stress and maintenance procedures should be performed well before a vermiculture unit reaches these levels.

If worm activity is monitored regularly, system stress and ultimate system failure can be prevented. The method for observing worm activity is given below.

Materials

�� Classification system of worm activity (such as Table 1).

�� Gloves

Methods

1. Worm activity should be monitored within a vermiculture unit at least once per week.
2. Observe worm activity prior to feeding.
3. Scrape back a section of feedstock to expose the bedding surface (see Figure 3 for a description of the zones of worm habitation).
4. Observe the regions were worms are congregating, for example, if the majority of worms are throughout the feedstock then the system is performing well, but if the worms are on the edges of the feedstock or feeding from below the feedstock, the system is under some stress.
5. Record observations.

Management

Management of stressed vermiculture units will vary depending on the category of worm activity. The regions that the worms do not inhabit tend to indicate where the problems are occurring. These may include:

�� Worms are not in feedstock but feeding from below or edges of feedstock – this indicates the feedstock is unsuitable which may be due to particle size, moisture, temperature, or feedstock content. The feedstock recipe should be revised.

�� Worms are actively trying to escape the unit – the system has failed and all aspects should be reconsidered (ie. feedstock, bedding depth, climate control, monitoring and maintenance procedures).

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Plates 8, 9, and 10. Worm activity indicating severe system stress. Worms are trying to escape vermiculture unit through base (left), worms are on top of the hessian covering and not in the feedstock layer (centre), worms are trying to escape unit through unit rim (right).

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Table 1. Observations of worm activity and indicators of vermiculture unit performance.

Category	System Performance	Diagnostic Indicator
A	No system stress – optimal/good performance	�� Worm population mostly located in feeding layer. No detrimental temperature increase (<30 oC).
	Some system stress –	�� Worm population largely in feeding layer. Some below feeding layer and some
B	moderate system	trying to escape unit indicated by worms massing around unit rim. Some
	performance	detrimental temperature increase in feeding layer (>30 oC).
	Moderate/high system	�� Population largely around sides of unit and trying to escape through unit lid or
C1	stress – sub-optimal	accumulating on	surface of	hessian.	Significant	detrimental	temperature
	performance	increase in feeding layer (30 – 35 oC).
C2	Moderate/high system stress – sub-optimal performance	�� Little worm population in feeding layer. Most worms feeding from underneath feeding layer. No substantial detrimental temperature increase (<30 oC).
D	System failure	�� No worms in feedstock. Worm population extensively swarming in corners of unit or around unit lid and escaping unit.

Form 1. Weekly management and maintenance form for an on-site vermiculture unit. Management and maintenance procedures should be performed at least once per week to ensure the unit is operating efficiently.

	Weekly Management and Maintenance Form
	Monitoring
Date	Worm activity (see criteria above)	Feedstock accumulation (cm)	% Oxygen concentration		Temperature (oC)
			Centre of feedstock	Below bedding surface	Centre of feedstock	Below bedding surface
Maintenance
Date	Add water (L)		Tossed beds		Removed leachate (L)
General comments
Date	Comment or description of weekly performance					Staff initial