Project team Principal Investigators

(Asian Institute of Technology – School of Environment, Resources and Development) 1. Dr. C. Visvanathan, Professor, Urban Environmental Engineering and Management Program. 2. Dr. Ing. Josef Tränkler, Associate Professor, Urban Environmental Engineering and Management Program.

(Anna University – Centre for Environmental Studies)

1. Dr. Kurian Joseph, Assistant Professor in Environmental Engineering, Center for Environmental Studies, Anna University, Chennai, India. 2. Dr. R. Nagendran, Professor of Environmental Science, Center for Environmental Studies, Anna University, Chennai, India

Research Staff: 1. Mr. P. Kuruparan 2. Mr. Tenzin Norbu 3. Dr. A. Selvam

Preface The Asian Regional Research Programme on Environmental Technology (ARRPET) funded by the Swedish International Development Cooperation Agency (Sida) was broadly aimed at conducting research on environmental issues relevant to Asia. One of the projects undertaken for study in Phase I of ARRPET was Sustainable Solid Waste Landfill Management in Asia. This report is an alternative option to solid waste management based on the application of earthworms and generally termed as vermicomposting. This report describes the various treatments with earthworms from industrial sludge to kitchen waste. It also highlights the biology of these worms and how to maintain and prepare suitable bedding for this biological treatment of solid waste. This report also provides basic information and vermicomposting experiences, should one be involved in vermicomposting or breeding of the worms. It is believed that this report would be useful to any person and government agencies involved in vermicomposting; industrial organizations; researchers as well as to other scholars. We would like to thank Dr. Radha D. Kale, Professor of Zoology, University of Agricultural Sciences, GKVK Campus, Bangalore - 560 065, India for critically reviewing this document and providing inputs, wherever necessary. On behalf of the project team, we take this opportunity to thank SIDA for sponsoring this timely and interesting study.

C. Visvanathan Ing. J. Traenklar

Kurian Joseph R.Nagendran

Table of Contents Project team................................................................................................................1 Preface .......................................................................................................................2 Table of Contents........................................................................................................3 List of Figures .............................................................................................................4 1. INTRODUCTION ....................................................................................................5 2. BIOLOGY OF EARTHWORMS...............................................................................5 2.1. Classification of earthworm..................................................................................6 2.2. Types of Earthworms ...........................................................................................8 2.3. Reproduction........................................................................................................9 3. TREATMENT WITH EARTHWORMS...................................................................11 3.1 Role of earthworms in organic matter recycling ..................................................11 3.2 Vermitechnology and Vermiculture .....................................................................13 3.3 Vermitech System in Waste Management .........................................................14 3.4. Vermitech for Sludge Processing.......................................................................18 3.5 Other applications of vermiculture and vermicomposting....................................21 4. VERMICOMPOSTING PRACTICE ................................................................23 4.1. Bedding Material ................................................................................................23 4.2. Vermicomposting Systems.................................................................................25 4.3. Methods to harvest earthworm and the vermicompost ......................................28 4.4. Common problems and their solutions...............................................................31 4.5. Application of zeolite in vermiculture..................................................................34 5. RESEARCH POTENTIAL .....................................................................................35 6. CONCLUSION......................................................................................................36 7. REFERENCES .....................................................................................................36

List of Figures

Figure Title Page

1 Alimentary canal of an earthworm 2

2 Classification of earthworms 3

3 Occupying levels 3

4 Copulation in earthworms 5

5 Earthworm cocoon 6

6 Earthworm hatchlings emerging from cocoon 6

7 Composition of Municipal Discards 10

8 Vermireactor 14

9 Sludge age and growth rate of E.foetida 14

10 Volatile solid removal pattern for primary sludge 16

11 Vermifilter to recharge groundwater 16

12 Vermifilter with water recovery 17

13 Bedding preparations 18

14 Vermicomposting-(windrow system design) 20

15 Vermireactor 22

16 Worm swag 24

17 Wormbin used for vertical separation 24

1. INTRODUCTION Urban conglomerations, with their ever-increasing population and consumerist lifestyle generate voluminous solid wastes. A substantial portion of solid waste is non-toxic and organic in nature. Existing methods to its treatment and disposal are rather expensive. Vermicomposting technology is one of the best options available for the treatment of organics-rich solid wastes. The term vermicomposting is coined from the Latin word ‘Vermis’

meaning to the ‘worms’. Vermicomposting refers to composting or natural conversion of biodegradable garbage into high quality manure with the help of earthworms. Earthworms play a key role in soil biology; they serve as versatile natural bioreactors to harness energy and destroy soil pathogens. The worms do so by feeding voraciously on all biodegradable refuse such as leaves, paper (non-aromatic), kitchen waste, vegetable refuse etc. Earthworms have been used for waste stabilization for many years, especially in Southeast Asian and European countries. Highlighting the role of earthworms, Charles Darwin called them the unheralded soldiers of the soil. From then on, different experimental studies have been carried out to study the role of earthworms in maintaining the soil fertility and also in the degradation of the organic matter present in the soil. Different scholars have tried the possibility of utilizing earthworms for the break down of organic wastes such as animal wastes, vegetable wastes and municipal sludge. Earthworms maintain aerobic conditions in the mixture, ingest solids, and convert a portion of the organic matter into worm biomass and respiration products, and expel the remaining partially stabilized matter as discrete material (castings). Ronald and Donald (1977a) have reported that the earthworms and the microorganisms act symbiotically to accelerate the decomposition of organic matter. The driving forces behind the introduction of vermiculture and other reuse processes, is the global recognition of the need to recover organic material and return this to the natural cycle. Legislations are being enacted to prevent the dumping of organic material into landfills. Simultaneously, as the cost structures for dumping are increasing, people are becoming more aware of the need to change their practices. There is pressure for waste processing and the consumption of the end products. To be a viable alternative, large-scale vermiculture must be ecologically and commercially sustainable, capable of being operated without subsidy, on a competitive basis. 2. BIOLOGY OF EARTHWORMS The earthworm is a tube shaped segmented invertebrate. Its body holds its shape because it’s full of a liquid called coelomic fluid found between the body wall and the alimentary canal. If one were to view a cross section of the worm body it would resemble a target, with the center representing the internal organs and the outer circle representing the bodywall.

Earthworm has a long, cylindrical body with a pointed head. In some species the posterior end is slightly flattened, while in others the body is cylindrical throughout. Rings that surround the moist, soft body allow the earthworm to twist and turn, especially since it has no backbone. With no true legs, bristles (setae) on the body move back and forth, allowing the earthworm to crawl. Earthworm breathes through its body surface. Detailed morphological and anatomical description of different species of earthworms is available in Aiyyar and Ananthakrishnan (1993). Figure 1 shows the alimentary canal of an earthworm. Food is ingested through the mouth into a bag like structure referred to as crop. In some species a distinct crop is absent. Later the food passes through the gizzard, where ingested stones grind it up. After passing through the intestine for digestion, what’s left is eliminated as castings. 2.1. Classification of earthworm Kingdom : Animalia Phylum : Annelida Class : Oligochaeta Order : Opisthopora Family : Lumbricidae Genus : A large number of genera have been described in literature Species : A large number of species under each genus have been described in literature According to their feeding habits, earthworms are classified into detritivores and geophagous as shown in Figure 2 (Ismail, 1997). Detritivores feed near the soil surface. They feed mainly on the plant litter and other plant debris in the soil. These worms comprise the epigeic and the anecic forms. Geophagous worms, feeding deeper beneath the surface ingest large quantities of organically rich soil. These are generally called as humus feeders and comprise of endogeic earthworms.

Figure 1 Alimentary canal of an earthworm (Lumbricus). Source: Martin, 1976

Epigeic earthworms are surface dwellers serving as efficient agents in fragmentation of organic matters on the soil surface. The anecics feed on the organic matter mixed with soil and live deep in soil and make permanent burrows. Endogeic earthworms live within the soil surface and derive their nutrition from the organically rich soil they ingest. The distribution of earthworm in the soil is influenced by several factors like soil texture, temperature, moisture, pH, inorganic salts and the organic matter (Govindan, 1998) Earthworms are also classified based on their occupying level in the soil and the feeding behavior as shown in Figure 3 (Bouche, 1977 as cited in Ismail, 1997). The Anecic types burrow deep in the soil but come to the surface at night to forage for freshly decaying residues.

EARTHWORMS

DETRITIVORES

GEOPHAGUS

Anecic

Epigeic

Endogeic

Figure 2 Classification of earthworms (adapted from Ismail, 1997)

Endogeics

Anecics

Epigeics

LitterDung

Endogeics

Anecics

Epigeics

LitterDung

Endogeics

Anecics

Epigeics

LitterDung

Endogeics

Anecics

Epigeics

LitterDung

Endogeics

Anecics

Epigeics

LitterDung

Figure 3 Occupying levels f th i th il

2.2. Types of Earthworms Ronald and Donald (1977b) have described the six common types of earthworms found in Europe. These are: 1. The native night crawler, or Lumbricus terrestris 2. The common field worm, or Helodrilus caliginosus 3. The green worm, or Helodrilus chloroticus 4. The manure worm, or Eisenia foetida 5. The slim earthworm, or Diplocardia verrucusa 6. The redworm or Lumbricus rubellus. The most common types of earthworms used for vermicomposting are banded worms (Eisenia fetida) and redworms or red wigglers (Lumbricus rubellus). Often found in aged manure piles, they generally have alternating red and buff-colored stripes. They are not to be confused with the common garden or field earthworm (Allolobophora caliginosa) and other species. Table 2.1 highlights some major species of earthworms employed in vermiculture Table: 2.1 Types of composting earthworms Earthworm Species Description

Red Wigglers(Eisenia fetida)

The red wiggler is the most common type of composting worm. It can process large amounts of organic matter and, under ideal conditions, can consume feed proportional to its body weight each day. It also reproduces rapidly, and is very tolerant against variation in growing conditions. Other names for red wigglers include Tiger worms, Garlic worms, Manure worms, and Brandling worms.

Redworms (Lumbricus rubellus)

The redworm is a very good composting worm. In bright light, it is a very wriggly and is not at all suitable for fish bait. Redworms are very effective in aerating and mixing the soil, and consume a large amount of organic material, although less than red wigglers. These worms are commonly found in decomposing animal manures and compost piles. Other names include bloodworms and red wriggler (but not the same as the worm described above).

Red Tiger(Eisenia andrei)

The Red Tiger worm makes an excellent composting worm. It is a close relative of the Red Wiggler (E. fetida) and is commonly used as a bait worm because they exude coelomic fluid, which attracts fish. These worms are very active wigglers in sunlight. Other common name for this is Tiger worm

Blue Worms(Perionyx excavatus)

Blue worms have become more popular in recent years as a composting worm. These worms do very well in warm climates, but their degradative potential drops in the cold. Although these worms eat fairly large amounts of organic materials and are fairly prolific breeders, they are also very sensitive to changes in their growing environment. In such case, these worms will migrate to other suitable area or may move out side the bin. Other common names include Indian Blue and Malaysian Blue worms.

African Nightcrawlers (Eudrilus eugeniae)

The African Nightcrawler can be a good composting worm, but is very sensitive to changes in its environment. The entire contents of some worm bins have been known to move out in less than a day if the prevailing conditions are not suitable for them. These worms also perform much better in warmer climates and are not recommended for areas where the temperature falls below 10° C. The other common name for this worm is the giant nightcrawler.

2.3. Reproduction Earthworms that are sexually mature have a prominent band around their body, which is called as the Clitellum. This is usually visible around 8 - 12 weeks of age. During copulation, the worms will join together at the clitellum (sometimes for quite a long period of time). Reproductive material is exchanged. When the worms separate, a ring of mucus material forms at the clitellum of each worm. This process is known as copulation (Figure 4). Sperm from the other worm is stored in sacs. As the mucus slides over the worm, it encases the sperm and eggs inside. After slipping free from the worm, both ends seal, forming a lemon-shape cocoon approximately 3.2 mm long. Two or more baby worms will hatch from one end of the cocoon in approximately 3 weeks. Baby worms are whitish to almost transparent and are 12 to 25 mm long. Redworms take 4 to 6 weeks to become sexually mature.

Figure 5 Earthworm cocoons

figure 4: copulation in earthworms

The worm will then wriggle backwards, and the mucus ring slips off over the head. The ring seals, forming a 'capsule' (also called an 'egg'). All the necessary reproductive material is sealed inside. The worm capsule, when first deposited is soft and milky white. This quickly hardens and turns a light lemon colour. The capsule goes through various colour changes through different toning of yellow, then to a rusty brown colour. Capsules are almost ready to hatch when they are the rusty colour. The capsule is about the size of a grape seed, but size is related to the size of the worm, with larger worms producing larger capsules. Figure 5 shows the size of cocoons compared to a gem clip. Capsules generally take an average of 1 month to hatch but depending on conditions can take more or less. Worm capsules have been known to survive drought conditions for 12 months or more, hatching when conditions become suitable again. They can even survive in the digestive systems of birds and animals ( Ref to be given by AIT). Each capsule can produce up to 20 baby worms, but the average survival is about 4. ( Ref to be given by AIT). Figure 6 shows the young worms emerging from the cocoon or egg.

3. TREATMENT WITH EARTHWORMS

3.1 Role of earthworms in organic matter recycling The role of earthworms in humificaton and breakdown of plant litter in natural soil has been known since the time of Darwin, but their potential to stabilize the organic refuse into useful components has been known only recently. Edwards (1998) reported five earthworm species (D. veneta, E. eugeniae, P. excavatus and P.hawayana and E. fetida) to be the most potential earthworms for breakdown of organic refuse. Generally most organic wastes can be broken down as such, except for those, which might need some degree of pretreatment prior to feeding. Earthworms are highly adaptable to different types of organic waste, provided, the physical structure, pH and the salt concentration are not above the tolerance level (Seenappa, et al., 1995). In most of the cases, the feedstock is thermophilically composted in windrows (turned twice weekly), for 15 to 30 days before being fed to earthworms. Extensive research on decomposition of animal manure viz. pig waste, cattle dung and poultry waste using earthworms has been done in the United Kingdom. The main emphasis of the research there has been the conversion of animal and vegetable wastes into useful materials and then harvesting earthworms from the waste on a commercial basis (see Butt, 1999). In Wilson, North Carolina, more than five tons per week of swine manure solids is being vermicomposted. Temperature and moisture are controlled through the use of greenhouse curtains, shade cloth, fans, and an automatic mister. Castings are lifted and conveyed from the beds every other month by a retrofitted machine, and a harvester separates earthworms and eggs from the castings (NCSU, 1997). Earthworms convert the smelly organic matter into a dark, odourless, homogeneous material called castings or vermicast which is an ideal plant growth supplement. It is often referred to as 'Black Gold' by gardeners. Earthworms feed partly on the waste itself, but mostly on the microorganisms produced during

Figure 6 Earthworms hatchling, emerging from cocoon.

decomposition. Their movement through the waste assists the break down and aeration of the material, providing ideal conditions for microbes to flourish, which in turn accelerates the decomposition rate of the organic matter. The waste entering the earthworm gut is subjected to biochemical break down by the enzymes secreted in the gutwall of the animal and by the microorganisms therein. The resulting product is a colloidal humus that acts as a slow release fertilizer. The nutrients are easily available to plants, but resist leaching. The rate of decomposition also depends on the type of litter. 3.1.1 Fragmentation and breakdown The rate of organic matter breakdown depends mainly on the type of litter. Very soft plant and animal residues may be decomposed by the soil micro-flora Tougher plant leaves, stems and root material do not break down easily; they are first disintegrated by the soil animals, including earthworms. Earthworms, thus have an important role in this initial process of the organic matter cycle. Soils with few earthworms have a well-developed layer of un-decomposed organic matter lying on the soil surface. Many types of leaves are not acceptable to the earthworms when they first fall on the ground, but require a period of weathering before they become palatable. It is believed that this weathering leaches the water-soluble poly-phenols from the leaves (Edwards and Lofty, 1976). These tiny creatures are responsible for the translocation of the accumulated organic debris from the soil surface to the subsurface layers and during this process much of the organic materials are ingested, macerated and excreted. Earthworms are also known to contribute several kinds of nutrients in the form of nitrogenous wastes (Lakshmi and Vijayalakshmi, 2000). 3.1.2 Consumption and Humificaton Earthworms are reported to consume more organic matter from the soil surface than all of the other smaller soil animals put together (Ronald and Donald, 1977a). The amount they turn over depends on the availability of total suitable organic matter. If the soil physical conditions are suitable, the abundance of earthworms increases until the food becomes a limiting factor. The smaller earthworms that feed on the litter produce cast that are almost entirely fragmented litter, whereas the larger species consume large proportion of soil, and there is less organic matter in their casts. The final process in organic matter decomposition is the humificaton, in which the large organic particles are converted into a complex amorphous colloid containing phenolic materials. Only about one fourth of the organic matter becomes converted to humus (Edwards and Lofty, 1976). The major contributions of earthworms are in breaking up of organic matter, combining it with soil particles and, enhancing microbial activity. They also mix the humified material into soil. 3.1.3 Nitrogen mineralization Earthworms greatly increase the soil fertility, and part of this must be due to the increased amounts of mineralized nitrogen that they make available for the plant

growth. There have been reports of increase in the amount of nitrogen in the soil in which the earthworms are reared (Edwards and Lofty, 1976). This may be due to the decay of the bodies of dead earthworms, which are rich in proteins. Govindan (1998) reported that earthworm body contains 65% protein, 14% fats, 14% carbohydrates and 3% ash. Similarly, Ronald and Donald (1977a) reported that 72% of the dry weight of an earthworm is protein and that the death of an earthworm will release up to 0.01 g of nitrate in the soil. Also, earthworms consume large amount of plant organic matter that contains considerable quantities of nitrogen, and much of this is returned to the soil in their excretions. Hand et al., (1988) have reported that nitrogen mineralization would be greater in the presence of earthworms and this mineral nitrogen is retained in nitrate form. 3.1.4 Effects on the C/N ratio Plant roots in general cannot assimilate the mineral nitrogen unless the Carbon/Nitrogen (C/N) ratio is in the order of 20:1 or lower (Edwards and Lofty, 1976). Earthworms help to lower the C/N ratio of fresh organic matter during respiration (Ronald and Donald, 1977b). To assess the role of earthworm in lowering the C/N ratio, the consumption of the carbon must be measured, and this can be done approximately, by measuring the respiration. But the disadvantage of laboratory studies is that they do not always reflect the actual situation. Daniel and Karmegam (1999) conducted an experiment in vermicomposting using selected leaf litter and cow dung mixtures (1:1) and showed a substantial variation in the C/N ratio, Electrical conductivity, NPK (Nitrogen, Phosphorus, Potassium) and organic carbon compared to controls without earthworms. There was a remarkable reduction in C/N ratio of vermicompost than in the compost. Similar results were obtained on utilization of weeds (B. diffusa, P. odorata, S. acuta and T. portulacastrum) as substrate for vermicomposting (Daniel and Karmegam, 2000). 3.2 Vermitechnology and Vermiculture Vermitechnology represents a relatively new and environmentally sound approach in the management of Municipal refuse (Loehr et al., 1988). Earthworms have the potential to be used in Vermitechnology systems for industrial or municipal applications. Such systems require significant investments of capital up front. Their commercial viability depends on what payments a producer of waste will pay as well as what price can be obtained for the vermicast and associated products that come out at the end of the process. The demand for compost worms from this source really depends on additional facilities being set up. Approximately 60% or more of household waste in Asian region is of an organic type that could be recycled using Vermitechnology. Many Governments in this region have committed to reduce the amount of organic wastes going to landfill. There are thus environmental, economic and regulatory reasons for an increase in demand for compost worms. One area that is poised for development in future is ‘contract waste management’ using vermiculture. Vermitech is an integrated operation and quality assurance process which focuses on product quality and public health.

Vermitech System has a number of benefits: No odour Cost effective Pollution free Valuable end product Destruction of pathogens Low green house emissions Established on site - no cartage Scalable to suit any volume Environmentally Sustainable process

3.3 Vermitech System in Waste Management In many of the developing countries the prevailing method of solid wastes disposal is open dumping (UNEP, 2001). This practice has become increasingly expensive and hazardous to the environment. Therefore, the need to explore and recognize the role of earthworms in waste management is rather urgent. For millennia, earthworms have been preparing soil for the colonization and evolution of plants. They have played a commendable role in human directed ‘agriculture’. Their value in supporting the waste disposal and management systems is being realized by the day. Earthworms, in dense culture and in large quantities, can physically handle virtually any biological waste. Vermitech, based on this inherent ability of earthworms has the capacity to handle large quantities of organic wastes and is seen as a viable industrial process capable of sustained commercial operation. The core of the Vermitech system are the process beds in which millions of worms are regularly fed with organic waste and from which worm stabilised organic matter, referred to as vermicompost, is harvested for sale to agricultural markets. The Vermitech system of waste management can be used to process streamed or even un-streamed shredded wastes. The worms will convert all the organic material including the paper labels on plastic bottles and the cardboard lining of milk cartons leaving a totally converted dry residue of comprising castings and inorganic solids which can be separated by simple screening. 3.3.1. Composition of Municipal Solid Waste With the dawn of consumerist culture and the drastic variation in the composition of waste problem is of its disposal (Figure 7). The solid waste so generated can be of two types: biodegradable or organic and non- biodegradable. The organic waste includes mainly kitchen waste, straw, hay, paper and animal excreta and ash, stone, cinders, plastics, rubber and metals generally dominate the non biodegradable portion of the waste. The residential and the commercial portion make up to about 50 to 70 percent of the total Municipal solid wastes (MSW) generated in a community. The actual percentage distribution of the various components depends on the following factors:

Extent of the construction and demolition activities Extent of the municipal service provided Types of water and wastewater treatment facilities that are used and Standard of living

3.3.2. Feeds for Vermitech systems 3.3.2.1 Animal manures Use of animal manure as primary feed for earthworms is very common in Vermitech systems. For instance, Vermiculture Production Centre in Pinar del Rio Province, one of the largest of Cuba's 170 vermicomposting centres uses cow manure as its primary feedstock for earthworms, in addition to pig and sheep manure, sugar cane pulp, coffee pulp, and other crop residues. Cattle solids are the most suitable of all animal wastes for earthworm biomass increase They usually do not have materials that deter the growth of earthworms. Cow dung slurry is a suitable substrate for vermicomposting, both when mixed with solid materials or on applying to the surface of bedding materials containing earthworms. Hand et al. (1988) have reported that the mixture of slurry with paper

8%

15%

7% 8%

31%

11% 3%

9%

4%

4%

wood food scrapsYard trimmings glassMetals Paper & Paper boardother inorganics TextilesRubber and leather Plastics

Figure 7 Composition of Municipal Discards (Robert and Paul, 1997)

tissue waste produce better growth of earthworms and cocoon production per unit of slurry consumed. Horse manure is also suitable for the growth of earthworms. Horse manure contains 0.7 % of nitrogen, 4.38 % of protein and 60 % of organic matter, trace amounts of phosphoric acid and potassium oxide (Ronald and Donald, 1977a) and can therefore be applied directly as feed. Further, the use horse manure does not warrant the addition of any other material for moisture retention, aging or porosity and above all, it does not require to be checked for acidity. Waste from the piggeries is probably regarded as the most productive refuse for growing the earthworms. If in the form of slurry, the solids from the waste must be separated either by sedimentation or other mechanical means. Edwards (1998) reported the presence of some inorganic salts and some ammonia in pig wastes, which have to be washed out and then pre-composted for about two weeks or longer prior to earthworm inoculation. Poultry wastes are higher in protein content, nitrogen and in terms of phosphoric acid than any other animal manure (Ronald and Donald, 1977a). The fresh waste generated from the poultry farms contains significant amount of inorganic salts, and if used directly might threatened the survival of the worms (Edwards, 1998). These wastes have to be pretreated by composting, washing or simply by aging process to reduce the inorganic salt content and the heating potential. 3.3.2.2 Paper pulp and card board solids Paper and cardboard are excellent materials, both for feeding and for the bedding of earthworms due to their cellulose content. Earthworms convert cellulose into its food value faster than the proteins and other carbohydrates (Ronald and Donald, 1977a). These wastes do not need any special pretreatment and can be applied directly as a feed. 3.3.2.3. Compost and waste products Spent mushroom compost is also a good medium to grow earthworms. According to (Edwards, 1998) it is low in plant nutrients. Brewery waste needs no modification, in terms of moisture and the worms can process it quickly. 3.3.2.4. Urban waste In Hobart City Council, Tasmania, (Australia) earthworms digest about 66 cubic yards of municipal biosolids per week, along with green mulch. Zeolite mixed in with the feedstocks helps balance the pH and absorb ammonia and odors. About two-thirds of this volume becomes vermicompost, which is then sold to the public. The City of Hobart is currently saving $56,000 per year from avoided landfill tipping fees, and they are receiving an equal amount of revenue from their sales of vermicompost. Similar observations in Indian context are also available (Datar et al., 1997). 3.3.2.5 Kitchen and Yard Waste Vegetable scraps from kitchen and other yard wastes provide ideal feed bed for growing earthworms. Ram Mohan (2001) has reported on the usefulness of

predigested food waste for growing Lampito mauritii and Perionyx excavatus species. In a study carried out at the Anna University campus in Chennai, India the author has reported a compost yield equivalent to 20% of the original weight of the waste in 30 days. In the south of France, 20 tons of mixed household wastes are being vermicomposted on daily basis. After the initial pretreatment of the waste, the organic materials are processed in 'lombricubateurs' (earthworm tanks) with a capacity of 15 ton per day, using 1000 to 2000 million redworms , Eisenia andrei.)

A 725-bed Rideau Regional Hospital in Ontario Vermicomposts 375 kg of wet organics produced each day. After reducing the bulk of the food waste by 50% by removing the water the worm feed is prepared by mixing with shredded newspaper. Earthworms are inoculated into the feed and grown in soil bedding. 3.3.2.6. Industrial Wastes Wastes from the canning plant and potato chip or corn chip manufacturing unit are excellent food for worms (Ronald and Donald, 1977a). Wastes generated from vegetable oil factory (flowers and plants) are also considered suitable as feed (Kale,1998). The food waste from domestic households and restaurants and other yard waste are used as feed and are also good growth media for earth worms. Wastes from logging and carpentry industries and sugar factories are also used as substrate to feed earthworms. When the earthworms are reared in the ratio of 1:1 sawdust and pressmud, the cast generated shows 1.2 times more CFU (Colony Forming Units) than saw dust and 1.6 times more than the pressmud (Parthasarathi et al., 1999). Earthworms can partially detoxify wastes. The fly ash waste generated from the thermal power plants is creating a major disposal problem due to its heavy metal content although it is supposed to be very rich in microbial biomass. It was found out that the organic waste, sisal green pulp, parthenium and green grass cuttings admixed with 25% of fly-ash proved to be a potential valuable material for E. foetida biomass (Saxena et al., 1998). The vermicompost so produced contains higher NPK content than the other available commercial manures. In some cases, earthworms are also used in the management of distillery waste containing wastes of malt, spent grain wash, yeast and molasses settled at the bottom of the lagoon. Seenappa, et al., (1995) observed that the total volume of cow dung leaf litter should be proportional to the total volume of distillery waste and pressmud to have positive impact on the growth and production of worm biomass. Lakshmi and Vijayalakshmi (2000) reported that the filter pressmud from the sugar factory could be used as a feed in the vermicomposting units. It is seen that after worms have worked on it, this pressmud is converted to nutrient rich manure and its physico chemical features improved after vermicomposting. 3.3.3. Choice of earthworm There are many earthworm species that have the potential to be used in waste management and in sludge stabilization systems. Since earthworm growth and

reproductive rates are the way of indicating their potentials, proper choice of earthworm is an important factor that might affect the rate of waste and sludge stabilization. Neuhauser (1998) has used five species of earthworms to determine the optimum temperature for growth and reproduction in dewatered (10-12 % solids) aerobically digested sludge for twenty weeks. He estimated the over all reproductive capability of four species namely, D. veneta, E. eugenia, P. excavatus and P.hawayana by using the total number of cocoons produced over the study period and found E. foetida to be the appropriate species to use in vermistablisation studies. Ismail (1997) reported that the local worms could be used effectively in the combined process of litter and soil management since the introduction of foreign species may create a complex chain of interaction amongst the soil organisms that may lead to the competition among the species for the food. 3.4. Vermitech for Sludge Processing This is a relatively new process known as vermicomposting or vermistablisation of sewage sludge (bio solids). It is not a true composting, as the process does not involve heat. It is a very complex mechanical, chemical and biological transformation. Given the nature of the worm behavior and the bed design and management, the resultant product has a higher stabilization and soil supplement value than traditional composting which relies on mechanical incorporation of sludge with green waste in large compost heaps. Maximum reduction of the volatile solids is a goal of any sludge stabilization system. If earthworms are to be useful in stabilizing sludge they must increase the rate of volatile solids reduction, thereby increasing the stabilization rate. Figure 8 shows the reactors used by Loehr et al. (1988) for vermistablisation studies. According to them E. foetida increases the rate of volatile solid sludge destruction when present in aerobic sludge. There are many fundamental factors that have to be evaluated to assure the technical and economic success of sludge conversion. Pre-treatment of the sludge prior to feeding and the appropriate loading rate are vital to ensure ideal environment for worm activity ensuring the conversion of all wastes. Under favorable conditions, earthworms and microorganisms act symbiotically to accelerate and enhance the decomposition of the organic matter. Increase in the sludge solids destruction rate reduces the probability of putrefaction occurring in the sludge due to anaerobic conditions. The rapid degradation of organic matter may be due to the increased aeration and other factors brought about by the earthworms (Loehr, et al., 1988). Bhiday (1995) reported that the aerobic and the anaerobic stages of the sludge help convert the organic matter into the right form for rapid consumption and digestion by the earthworms.

3.4.1. Factors affecting the stabilization of the sludge The role of earthworm in stabilization of municipal sewage sludge is greatly linked to the aerobic condition of the sludge, ash content or the sludge age, the moisture content and the loading rate. 3.4.1.1. Sludge age

Figure 9 Sludge age and growth rate of E. foetida (Neuhauser, 1988)

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53

52

51

50

Ash content (%)

3 cm

3 cm

26 cm

6 cm

26 cm

Stabilized solidsaccumulation

effluent drain

No 2 gravel (19 - 38 mm)

No 1 gravel (13 - 19 mm)

sand ( > 0.6 mm)

Figure 8 Vermireactor (adapted from Loehr, et al., 1988)

It is also very important to relate the rate of earthworm growth to the age of the sludge, i.e., the time after the sludge is removed from the aerobic reactor and dewatered. As the sludge ages, its nutritive value to the earthworm decreases rapidly after about twelve weeks removal from the digester, whereas the ash content of the sludge increases with the time, an indication of sludge stabilization (Loehr et al., 1988). Figure 9 shows the relationship between sludge age, ash content and worm growth. 3.4.1.2. Moisture content of the sludge Both excessive and insufficient moisture can adversely affect earthworm growth. A series of experiments were conducted to determine the moisture content of the media that will exist in vermistablisation units. In an experiment conducted by Neuhauser (1988), an aerobically digested sludge was dewatered to moisture content of 75% and exposed to a temperature of 250C. E. foetida species were placed and their growth recorded for four weeks. It was found out that optimum worm growth occurred when the total solid content of the media was 9-16 %. 3.4.1.3. Nutrient content of the sludge In some cases, the nutritional value of the sludge also plays an important role in the stabilization of the sludge as well as the growth of the worms in it. The major concerns being the nitrogen and the phosphate content in the sludge. The waste from the mining industries that contains sulfur is also fed to the worms, which else if not, creates a major disposal problem as well as nuisance to the public. Kale and Sunitha (1995) investigated the use of sulfur waste residue in a vermicomposting system by mixing it with organic matter. According to them, the optimum mixing ratio of the sulfur waste residue to the organic matter is 4 percent, at which, they observed the maximum number of young earthworms. 3.4.1.4 Loading rate Loading rate of the sludge should be carefully monitored according to the type of sludge and its moisture content and other chemical properties. It has been reported that, at a loading rate, as high as 1 kg of volatile solids/m2/week operation of LSVS reactors involved in stabilizing the primary sludge will be satisfactory (Loehr, et al., 1988). At the same time, the optimum loading rate for the waste activated sludge and the aerobically digested sludge were recorded to be 1 kg/m2/week and 1.2 kg/m2/week, respectively (Figure 10). Failure occurred in those reactors, where the liquid no longer flows through the accumulated sludge solids, resulting in ponding of the media and development of anaerobic conditions. Other possibilities to make these waste more palatable to the worms is to aerate the sludge in rotor drums to encourage the aerobic microbes before feeding them to earthworms. This study clearly indicates the stabilization of a primary sludge or the removal of volatile solid in liquid sludge vermistablisation (LSVS) units. The liquid that drained from the reactor contains the by-products of the stabilization that occurred in the reactor.

3.5 Other applications of vermiculture and vermicomposting

3.5.1 Applications in aquaculture The most common method of solid waste disposal in aquaculture is land spreading, which causes pollution of soil, surface and ground water bodies resulting in untimely death of aquatic organisms. Vermicomposting of such waste controls water and soil pollution, thereby ensuring better survivability and growth of fish, prawn and other aquatic organisms within its natural habitat. The application of vermicastings, which is a high-grade organic fertilizer to the aquaculture ponds, reduces the input cost and makes the aquaculture process more profitable. It also helps in combating the harmful effects against chemical fertilizer if so ever present in the receiving water. Large-scale vermiculture has the potential of supplying earthworm meal as a substitute for fishmeal. Earthworm meal contains all the essential amino acids required in fish feed. The methionine and lysine availability is higher than that of the normal fishmeal. There is also an increasing demand for protein-rich raw materials in other animal-feed industry. 3.5.2 Vermifilter to Recharge Ground Water

02000400060008000

1000012000140001600018000

0 30 60 90 120 150 180 210 240

Time, days

Vola

tile

solid

s, m

g/l

Drainage Added liquid sludge

Figure 10 Volatile solid removal patterns for primary sludge (Loehr, et. al., 1988).

Figure 11 Vermifilter to recharge ground water

(Bhawalkar, 1995)

Plants: Arum, Cannas, Banana

Recharge of groundwater

Sewage Inlet

30-cm. bed of vermicastings

Earthworm increases the hydraulic conductivity and natural aeration by granulating the clay particles. They also grind the silt and sand particles, increasing the total specific surface area, which enhances the ability to adsorb the organics and inorganics from the wastewater. This is ideal for dilute wastewater (such as sewage). Figure 11 shows the vermifilter that could be used to recharge ground water. The loading rate of wastewater is calculated as 2m2/m3 of sewage. Earthworms ensure bio-sanitation and prevent sewage sickness through effective regeneration of adsorption ability with their bacterial farming along with their grazing act on surplus bacterial biomass (Bhawalkar, 1995).

3.5.3 Vermifilter with water recovery Figure 12 shows a typical vermifilter unit with water recovery. It is possible to have single or multiple stage vermifilter depending on the strength of the wastewater and desired quality of renovated water. In principle, a single unit can produce any given purity of water by increasing the recyclable ratio, which reduces the organic loading. The first stage achieves roughing filtration and the second stage achieves polishing (Bhawalkar, 1995). 4.VERMICOMPOSTING PRACTICE Vermicomposting practices vary from place to place and country to country. Literature on this aspect is readily available (Edwards and Lofty, 1976; Kale, 1998). A general account on Vermicomposting practice as applicable to many regions is summarized below. 4.1. Bedding Material It is important to provide earthworms with an environment that is close to the moisture content of the earthworms themselves. Their body wall must be moist for respiration to occur. However, the bedding cannot be fully saturated, or the earthworms will suffocate. The required moisture content of approximately 75% should be maintained. The bedding should be damp, about the consistency of a damp sponge. Although there are a number of commercially available bedding materials made from things like coconut fiber or peat moss, newspaper and cardboard make a very suitable bedding material because it is readily available, provides excellent moisture retention, and preparation is relatively simple.

Vermicastings (30 cm)

Sand 2 cm Rubble 10 cm Boulder 30 cm

Figure 12 Vermifilter with water recovery (Bhawalkar, 1995)

For reuse Recycle

Pump

Liner with clay or PCC

Wastewater inlet

In general, materials needed for preparing the bedding are: Newspaper (black & white only) or shredded paper, it works as a carbon

source or it also looks into the prevention of protein poisoning if so ever occurred.

Garden soil (worms need the grit for digestion, but don't use potting soil because it may contain chemicals)

Crushed eggshell that may serve as a source of calcium. Grits or pebbles for proper drainage, to be used in the bottom layer of the

bed. 4.1.1 Bedding Preparation As shown in Figure 13, for the bedding preparation, some shredded and soaked newspapers (as a source of cellulose and to retain adequate moisture), and some crushed eggshells (for calcium supply) are needed. Garden soil and crushed eggshell are mixed well before putting them in the bin. Earthworms are placed in the bin along with bedding material. The worms will retract down in the bedding layer to avoid the light. With its lid open the bin is placed near a light for an hour to encourage the worms to move down into the new bedding material.

4.1.2 Feeding Vegetable and fruit scraps, tea bags, eggshells, stale bread, and houseplant trimmings etc., are used as feed. Dairy products and slaughterhouse wastes are to be avoided during the initial stage, as these can attract undesirable insects and create malodour. Heavily salted foods are also to be avoided as they might trigger the migration of worms from the bin or their death. It is best to collect food scraps separately in a small bucket and feed the worms once or twice a week. Following this procedure, (Norbu, 2002) observed that partial burial of the food (in the vermi bed), not only removed the ants and other mites but also created a better environment for the worms to feed.

4 lbs. shredded newspaper

1.5 gallons cool tap water

4 lbs. shredded newspaper

1.5 gallons cool tap water

4 lbs. shredded newspaper

4 lbs. shredded newspaper

1.5 gallons cool tap water

1.5 gallons cool tap water

1 handful garden soil

1 crushed egg shell

Putting into the bin

1 handful garden soil

1 crushed egg shell

1 handful garden soil1 handful garden soil

1 crushed egg shell1 crushed egg shell

Putting into the binPutting into the bin

Figure 13 Bedding preparations

4.1.3. Ideal environment for earthworms The following are the environmental conditions, which are vital and may affect the breeding, cocoon production and hatching of young earthworms.

4.1.3.1. Temperature In Vermicomposting, temperatures are kept generally kept below 350C (Riggle and Holmes, 1994). Most worm species used in vermicomposting require moderate temperatures from (10-350C). While tolerances and preferences vary from species to species, temperature requirements are generally similar.. In general, earthworms tolerate cold and moist conditions far better than they can hot and dry conditions (Slocum, 2001). 4.1.3.2. Moisture Earthworm requires plenty of moisture for growth and survival. They need generally moisture in the range 60 –75 %. The soil should not be too wet else it may create an anaerobic condition and drive the earthworms from the bed (Ronald and Donald, 1977a). It is very important to moisten the dry bedding material before putting them in the bin, so that the over all moisture level is well balanced. 4.1.3.3. pH Edward and Lofty (1976) and Chan and Mead (2003) have reported that earthworms are pH sensitive and generally most of them survive at pH ranging from 4.5 to 9. The alteration of pH in the wormbed is due to the fragmentation of the organic matter under a series of chemical reactions. As cited by Edwards and Bohlen, (1996) in Chan and Mead, (2003), the soil pH is a major factor limiting the abundance and distribution of earthworms. 4.1.3.4. Feed The first step in starting a vermicomposting unit is to arrange for regular input of feed materials for the earthworms. These can be in the form of nitrogen rich material like goat manure cattle dung and pig manure. When the material with high carbon content is used with C/N ratio exceeding 40: 1, it is advisable to add nitrogen supplements to ensure effective decomposition. All organic matter should be added only as a limited layer as an excess of the former may generate heat (Ismail, 1997). Generally, 5–10 % of the feed is assimilated in the body of the earthworms and the rest are excreted in the form of a nutrient rich cast (CAPART, 1998). 4.2. Vermicomposting Systems Vermicomposting systems are employed purposely for volume reduction, extraction of organic (pollutant) load, cost and energy reduction and rapid processing. Any of the following systems may be adopted for vermicomposting

6 m

7m

AA

Drainage

Water sprinkler system

2.5

m

Figure 14 Vermicomposting, (windrow system design)

1 m

air f

low

(Cross section on A-A)

Temperature probeBoundary wall0.15m thick concrete

wall

Separation wall

1m

depending on the availability of space, nature of waste / bedding material, quantity of waste to be processed etc. 4.2.1 Windrow system This system of vermicomposting deals with construction of windrows under shade to avoid direct sunlight (Box 1). The first layer of a new windrow should be 10 to 15 cm high. Redworms can be reared at production centre in a concrete nursery or shallow rectangular boxes prior to their inoculation in the windrows. A typical windrow system is shown in Figure 14. The worms feed from the bottom till the top of the bed. The windrow has to be monitored daily and when signs of surface feeding are noticed, another 7 to 10 cm layer of feedstock can be added. Thick layers of feedstock are avoided because they impede oxygen penetration into the windrow. This can cause the worms to migrate to the upper surface before lower layers are thoroughly digested, creating anaerobic fermentation. The windrows are irrigated with center post sprinkler up to twice daily to maintain optimum moisture content of 80 % throughout the windrow.

Box 1. VERMICOMPOSTING IN WINDROWS Vermicomposting Technology is used by Periar Maniammai College of Technology for Women (PMCTW) campus, Thanjavur, TamilNadu, India for decomposing the organic wastes produced in the campus. Wastes from various sources such as hostel, kitchen, canteen, college and agricultural fields of the campus are collected and segregated manually. The slurry from three biogas plants (two cow dung based and one night soil based) is also used for the production of vermicompost. The segregated biodegradable wastes and slurry from the biogas plants are fed into the composting bed. The size of the bed is 3m (Length) X 1m (width) X 0.5m (height). 350 numbers of such surface level beds are available, covering an area of 5 acres of land. Each bed consists of about one ton of waste and 5kg of earthworm (Eisenia Foetida, a California worm). The bed is prepared by filling alternate layers of cow dung and solid waste of 150 – 200 mm thickness, and then earthworms (approximately 5 kg) are introduced in the bed. To ensure aerobic condition and to reduce the temperature the material is turned at specific intervals. Turning is done manually using long rakes. First turning is given 4 to 7 days after filling and the second turning is given after 5 to 10 more days. Water is sprinkled over the beds periodically to maintain sufficient moisture content. 30 days are required for complete decomposition. After 30 days the decomposed material is collected and sieved. The end product resembles dark brown colour humus or soil. The net weight of harvest from each bed is estimated as 30-40% of the input weight. During these 30 days the 5 kg of worm is increased into 6 kg of worms. The total life cycle of the worms is about 220 days. They produce 300-400 young ones within this life period. The length of these worms are 2-3 inches and reddish brown in colour, and adapted to all climatic conditions. Though these are different kinds of worms in the known 3000 species of worms, this particular type belongs to the surface dwellers, feed only on plant and animal waste. This consumes the waste per day almost equivalent to its weight. The beds are covered with coconut leaves to avoid sunlight. Avoiding sunlight, watering and aeration are the important prerequisites for the effective production of worms and vermicompost. The end product of the sieved compost is used as a soil conditioner or manure for the agricultural fields and nursery of the campus. Farmers from near by villages are buying this compost for their land. The production cost of compost is estimated as Rs 1.40 and it is sold for Rs.3. The cost of worms of 1 kg (contains not less than 2000 worms) is Rs.1000. Source: Field Study and Discussion with Plant in Charge Dr. Sukumaran and Ms.Jayalakshmi, 2003

4.2.2 Wedge System This modified windrow system maximizes space and simplifies harvesting because there is no need to separate worms from vermicompost. Organic materials are applied in layers against a finished windrow at a 45-degree angle. The piles can be constructed inside a structure or outdoors if they are covered with a tarpaulin or compost cover to prevent leaching of nutrients. A front-end loader is used to establish a windrow 1.2 to 3 m wide by whatever length is appropriate. Spreading a 30 to 45 cm layer of organic materials the length of one end of available space starts the windrow. Up to 0.45 kg of worms is added per square meter of windrow surface area. Subsequent layers of 5 to 7.5 cm of organics are added weekly and preferably more addition in colder seasons. After the windrow reaches two to three feet deep, worms in the first windrow will eventually migrate toward the fresh feed. Worms will continue to move laterally through the windrows. After two to six months, the first windrow and each subsequent pile can be harvested. 4.2.3. Reactor Systems Reactor systems have raised beds with mesh bottoms. Feedstocks are added daily in layers on top of the mesh or grate. Finished vermicompost is harvested by scraping a thin layer from just above the grate, and then it falls into a chamber below. These systems can be relatively simple and manually operated or fully automated with temperature and moisture controls.

Figure 15 Vermireactor

4.3. Methods to harvest earthworm and the vermicompost Growth rate of earthworms is very fast and a mature adult can attain up to 1500 mg body weight and attain reproduction capability within 50-55 days of hatching

from cocoon (The Hindu, 2002). Redworms daily consume organic matter at the rate equal to their body weight. On an average, one million worms weigh approximately one ton. One million worms doubling every two months can become 64 million worms at the end of one year. Organic waste after being eaten by the worms may yield half the weight in dry Vermicompost. Since the worms double their number at least every 60 days, potentially large quantity of worm bio mass will be available as pro-biotic food for animal, after the first year. Therefore, after one year of the process 64 million worms could consume approximately 64 tons organic waste daily and produces approximately 32 tons of Vermicompost per day. This production can be done on a two acres. In large-scale windrow vermicomposting, mechanical harvesters are used. At the time when the height of the pile is more than 65 cm, irrigation is discontinued and the windrow allowed to partially dry. To draw the worms to the windrow surface, a layer of fresh feedstock is added and a brief irrigation is applied to moisten the outer layer. After five to seven days, a front-end loader is used to skim the top 10-cm of the windrow, removing with it approximately 80 % of the worms. A second feeding and loader pass can bring the worm harvest to 90 to 92 %. Population density is always estimated before harvest so that worms can be used to inoculate new windrows. For small-scale vermicomposting, windrows, reactors or any of the following methods (whichever is appropriate) may be adopted: 4.3.1 Migration Method / Side way separation In the migration method, the bedding is moved to one side of the bin and the fresh bedding is placed on the empty side. The new feed is put into the side with the new bedding. Gradually the worms will migrate towards the fresh bedding. The old bedding is left for about a month to allow the new capsules to hatch. The compost is then removed and some more fresh bedding is added. 4.3.2 Light Retraction Method In the Light retraction method, new bedding is prepared for the worms. The contents of the existing bin are emptied onto a sheet of plastic. The bedding is then piled into mounds (one large or several small ones, whichever is easier). A bright light is placed over the mounds or is exposed to sunlight. The worms quickly move away from the light source, burying down to the bottom of the pile. After 10 to 15 minutes, the top of the bedding is scraped off. This procedure is repeated till the worms huddle together at the bottom of the pile, with very little bedding material. The worms are then placed immediately into the new bedding. 4.3.3 Sifting method A sifting method can also be used to harvest the worms. In this method, the worms and bedding are sifted through a coarse screen. Castings fall through the mesh, while the worms stay behind. The sifting is done quickly and with a gentle shaking, before the worms get a chance to wriggle down through the wire. There are also

special harvesters available that work in a similar way. These are mainly used in large worm farms, where large amounts of worms need to be harvested quickly. 4.3.4 Using worm swag When using the worm swag (Figure 16), harvesting becomes very easy, with virtually no lifting. The swag is opened at the bottom, and the castings squeezed out into a bucket. This is called a flow-through system, which means it is fed at the top and harvested at the bottom. Once the Swag is established, castings can be harvested on a weekly basis. Some flow-through systems will have a grate at the bottom to either rake the castings out, or wind a handle and the castings drop out the bottom into a tray. 4.3.5 Vertical separation

In this method three trays are used, as the first working tray becomes full, a new empty tray is simply put on top, and feeding begins in the new tray, as the worms will migrate upwards through the trays seeking food (Figure 17). A piece of nylon or mesh window screening, a bit bigger than the surface of the box is laid flat on the surface of the vermicompost. (big enough to flatten against the sides and some overlap at the top). The box is filled up with fresh bedding on top of the screen and feeding with kitchen scraps is continued. The worms migrate up through the screen into the new bedding as the food runs out below.

Figure 17 Wormbin used for vertical separation

Figure 16 Worm swag

4.4. Common problems and their solutions The most common problem is the unpleasant odours caused by lack of oxygen in the compost due to overloading of food waste, and when the bin contents become wet. The solution is to stop adding food waste until the worms and microorganisms have broken down the initial feed and to gently stir up the entire contents to promote aeration. The drainage holes may be checked for blocking. If the drainage is insufficient additional holes can be drilled. Worms have been known to crawl out of the bedding if conditions are not favorable for them. If this migration is not triggered by moisture content of the soil, then the bedding may be acidic. Avoid adding citrus peels and other acidic foods to the bedding as these might reduce the pH of the bedding soil. One can overcome this acidic medium by adding a little garden lime and cutting down on acidic wastes. 4.4.1 Fruit flies To control fruit flies:

♦ Fresh food scraps should not be added,

♦ The food scraps may be buried under the bedding,

♦ Calcium carbonate (lime from stone, not "quick lime") may be sprinkled in the bin, or

♦ A petri-dish filled with vinegar may be placed in the bin.

♦ A plastic sheet or piece of old carpet or sacking may be kept on the surface of the compost in the bin 4.4.2. Temperature Heat causes more problems for vermicomposting than cold. A red wiggler becomes inactive once the temperature of the bedding rises above 29oC. This could be avoided by placing the bin under shade at all times, if placed outdoors during the warm seasons. Evaporative cooling of the moist bedding keeps the bin cooler than the air temperature, but may need to add more water during the summer. The greater danger of overheating the worms arises from heat produced within the bin, which could be reduced substantially by feeding small amount of food frequently rather than a bulky food at one time. In general, worms like cool weather. They are at their highest activity and reproductive levels as the weather cools in the fall and warms in the spring. 4.4.3. Aeration It is important to construct the bin to allow adequate airflow. Holes may be drilled on the upper sidewall of the bins for air circulation. Holes drilled on the lid may allow water inside during the rainy season. The type of bedding used also influences air circulation. Coarser bedding such as chopped leaves allows more air to circulate than fine textured bedding such as peat moss or shredded paper. As the composting process progresses, the bedding

becomes more finely textured. This can be alleviated to some extent by periodically adding fresh bedding. Other ways to promote aeration includes occasional fluffing of the bedding material, avoidance of deep bedding (a maximum of 30 cm), over-feeding and over-watering. 4.4.4. Acidity (pH) The decomposition of organic matter produces organic acids that lower the pH of the bedding soil. The best way to deal with this is to add several cups of ground limestone to the bedding and in the application of Zeolite in proper amount. Limestone will serve dual purpose - maintaining the acidity and acting as a source of calcium to the worms. Other products, which can be used, are powdered limestone, dolomite limestone. Baking soda should be avoided because of its high sodium content. 4.4.5. Mite Pests Insects are attracted to earthworm beds due to its moist and organic environment. If the bedding is not properly maintained, acidity build up in the bedding soil may invite the mites as they are attracted towards an acidic, moist environment. Although small populations of mites thrive in all worm beds, they might create problems when present in excessive numbers. The mite populations at high levels can also cause worms to bury deep in their burrows without feeding. 4.4.5.1 White or Brown Mites White or brown mites are not predaceous and tend to feed only on decaying or injured worms. However, during infestations, these mites can devour much of the food in earthworm beds, depriving earthworms from the nutrients. 4.4.5.2 Red Mites These mites first appear as small white or gray clusters, resembling mould, which under magnification would reveal the clusters of juvenile red mites in various stages of development. The adult red mite is smaller than white or brown mites with bright red colour and an egg-shaped body with four pair of legs. The red mites are known to be parasitic on earthworms. It attaches to the worm and relishes its coelomic fluid. They are also capable consuming the cytoplasmic fluids from egg capsules. 4.4.5.3 Mite Prevalence and Prevention Proper care of worm beds can prevent a harmful buildup of mites. One or more of the following conditions are usually associated with high mite population:

♦ Excess water -- Beds that are too wet create conditions that are more favorable to mites than to earthworms. Excessive wetting of beds may be avoided by adjusting watering schedules, improving drainage, and turning bedding frequently

♦ Overfeeding – Excess food can lead to an accumulation of fermented feed in worm beds and lower the pH of the beds. The feeding schedules may be adjusted

and modified according to seasonal variations. The pH of beds should be maintained to neutral (pH = 7), using calcium carbonate as the buffering agent

♦ High moisture content feed or fleshy feed -- vegetables with high moisture content can attract high mite populations in worm beds. Use of such feed should be limited, and if still, high mite populations persist, this feed should be discontinued until mite populations are under control. 4.4.5.4 Mite Removal Several methods have been suggested for removing mites from earthworm beds. However, any type of mite removal, physical or chemical, will only be temporary unless worm-bed management is altered to make conditions less favorable for mites. The following techniques range from low- to high-intensity measures.

♦ The worm beds should be exposed to sunlight for several hours, however one should make sure that the earthworms are not directly exposed to sunlight. The amount of water and feed should be reduced. This will further encourage the mites to leave the beds.

♦ Moistened newspapers or burlap (jute) bags may be placed on top of the beds, and these can be removed as mites accumulate on them. This procedure may be repeated until mite populations are substantially reduced.

♦ Pieces of watermelon or potato slices may be placed on top of the worm beds. The peels could then be removed with the mites.

♦ The bed may be watered heavily without flooding. This will compel the mites to move up to the surface. The mites can then be scorched using a hand-held propane torch. This procedure may be repeated several times, at three-day intervals, if needed.

♦ Light sulphur dusting will kill the mites. Or bed may be wetted (as suggested above) and then the sulphur added directly to the mites. Sulphur should be applied at the rate of approximately 2 g per 0.93 square meter of bed. Sulphur will not harm the worms, but in time, it may increase the acidity of the bed. In the past, some chemical pesticides have been used in worm beds. However, due to their biomagnification, it is not advisable to use these chemical compounds. Although safer miticides do exist in the market they are not specifically made for the Vermibed. 4.4.6. Odour Problems One of the biggest impediments towards backyard composting is the malodour that might develop if the beddings or bins are not properly maintained. In limiting the malodours, one should

♦ Reduce the amount of food

♦ Stir the bin thoroughly, especially at the bottom

♦ Add paper if the bedding is soggy

♦ Apply zeolite proportionately And if odours still persist, the best solution may be to start over, using new bedding, a minimal amount of scraps. 4.5. Application of zeolite in vermiculture Zeolite is a very unique mineral with a cage-like skeletal structure that allows it to trap, hold and exchange materials from its internal structure. It is an insoluble and chemically stable aluminium silicate mineral that was formed from the glass component of volcanic ash millions of years ago. Zeolite is employed in commercial systems using large numbers of earthworms to stabilise organic waste and to produce vermicast by treating various organic wastes, including domestic organic matter, abattoir waste, green waste, fruit and vegetable waste, wood pulp and cardboard, sewage sludge, animal manures, etc. The application of zeolite with correct blend of carbon and nitrogenous wastes could considerably reduce the odour problem, and it is due to this reason that large-scale operations are virtually odourless and are operating in relatively low costs. In vermiculture, nitrogen values decrease rapidly, mainly due to volatilization. By applying Zeolite, the nitrogen can be trapped through cation exchange; it further prevents the atmospheric loss. In an acidic medium, the leaching of heavy metal from the waste threats the fertility of the soil and lives of earthworms. This too can be mitigated by using zeolite. Heavy metals are exchanged and trapped in the zeolite, and cannot be extracted by plants or earthworms. This process also inhibits bioaccumulation of heavy metals in worms. Zeolite helps to raise and lower the pH of wastes through cation exchange, as distinct from lime, which will only raise the pH. To obtain maximum benefits from zeolite in vermiculture, it is important to have the zeolite well mixed with the organic waste. Typical applications will use 3 to 5% of zeolite on a weight to volume basis (30 – 50) kg of zeolite per cubic metre of waste. 4.5.1. Benefits of zeolite Zeolite provides the following benefits: (http://www.squirmy-rms.com/zeolite.htm)

♦ Improves the conversion i.e., reduces the time required to convert organic waste to a valuable by-product, vermicast.

♦ During the conversion process zeolite reduces or eliminates the production of foul or unpleasant odours by absorbing gases such as ammonia and hydrogen sulphide.

♦ Ties up some undesirable materials such as heavy metals and prevents their release to the environment as well as reducing potential bio-accumulation of these elements in worms.

♦ Provides a 'safer' environment for worms by buffering pH.

♦ Increases the nutrient value of the vermicast by tying up nitrogen which otherwise would be lost.

♦ Adds to the cation-exchange capacity of vermicast, which helps promote sustained release of nutrients for plant growth.

♦ Water Absorption / Desorption: the ability to reversibly absorb water without any chemical or physical change in the zeolite matrix. (Desorption is the release of the water). 5. RESEARCH POTENTIAL There is a greater need to find out an alternate solution for the sustainable solid waste management in tropical countries. The consumption of organic wastes by earthworms is an ecologically safe method in the natural conversion of many of our organic wastes into an extremely environmentally beneficial product. The tiny creatures' ability to devour virtually any organic waste-livestock manure, rotten food, even ratty T-shirts and excrete it as premium organic fertilizer (dubbed "black gold" by organic farmers for its nitrogen richness) is proving profitable for a host of non-squeamish entrepreneurs. Research findings, developmental programs and application aspects of MSW composting by earthworms in tropical countries need to be propagated and commercialized. Due to its simplicity and flexibility vermiculture may be carried out on large centralized scale or suburban to household scale with normal composting methods. At least 9-12 months are required to obtain homogeneous organic matter of comparable maturity. The vermitechnology could be used to compost MSW (for recycling organic matter) as a pretreatment prior to land filling. Research on this field could include the following: 1. Comparison of vermicomposted MSW and windrow composted MSW in respect of the following aspects:

♦ Volume reduction

♦ Leachate characteristics after landfilling

♦ Methane Gas emission

♦ Variations in pH, acidity, nutrients 2. Comparative study of the stabilization rate of heavy metal and toxic substances in MSW 3. Comparative study of the stabilization rate of pathogenic and toxic microorganisms 4. Comparative study of the decomposition rate of MSW by adding different ratio of sludge cake 5. Optimizing the Vermicomposting process to achieve most efficient process outcome by changing important variables such as

♦ Variety of earthworm

♦ Various moisture content

♦ Thickness of the bedding layer 6. CONCLUSION Vermicomposting for resource recovery and recycling of MSW is one of the fastest growing sectors in waste management. The application of Vermitechnology and vermiculture is not new for composting, as it is a natural contributor for farming and gardening. In North America, Europe, Asia and African regions, and in several other countries earthworms are being used for various waste treatment options. They could help waste managers for minimizing waste input to landfills and saving precious groundwater resources. In addition, vermicomposting will be helpful for managing domestic solid waste problems and could stabilize wastes with low toxicity, pathogens and heavy metals. The eco-solid waste management could successfully promote vermicomposting as a viable alternative for the disposal of solid wastes. 7. REFERENCES Aiyyar, M. E. and Ananthakrishnan, T. N. (1993). A manual of Zoology, Volume-I, S. Viswanathan Publishers and Printers, Chennai, India Bhiday, M.H. (1995). Wealth from Waste. ‘Vermiculturing’ Tata Energy Research Institute, New Delhi, India. ISBN 81-85419-11-6. Bhawalkar U. S, (1995), ‘Vermiculture Ecotechnology’, Bhawalkar Earthworm Research Institute, Pune, India Butt, K. R. (1999) Inoculation of Earthworms into Reclaimed Soils: The UK Experience. Land Degradation and Development 10, 565-575. CAPART (1988), ‘Vermicompost’, Council for Advancement of People’s Action and Rural Technology, Centre for Technology Development, New Delhi. India Daniel, T and Karmegam, N.(1999). Bio- conversion of selected leaf litters using an African epigeic earthworm, E. eugeniae. Eco. Env. & Cons. 5 (3): pp 271- 275. Daniel, T and Karmegam, N. (2000). Asian Journal of Microbiology, Biotechnology and Environmental Sciences, Global Science Publications, India, Vol. 2 No. (1-2), pp 63-66.

Datar M T, Rao M N, and Reddy S. (1997). Vermicomposting - a technological option for solid waste management. J. Solid Waste Tech. and Management 24(2): 89–93.

Edwards, C.A. and Lofty J.R., (1976), Biology of Earthworms. Bookworm Publishing Company, Crawfordsville, Indiana. ISBN 0-916302-20-2. Publisher details to be checked

Edwards, C.A., (1998). Breakdown of animal, vegetable and industrial organic waste by earthworms, ‘Earthworms in waste and environmental management.’ edited by Edwards, C. A & Neuhauser, E. F SPB Academic Publishing, Netherlands. ISBN 90-5103-017-7. Govindan, V.S., (1998). Vermiculture and Vermicomposting, Ecotechnology for pollution control and Environmental Management. pp. 48- 57. Hand, P., Hayes, W. A., Satchell, J.E., Frankland, J.C.,(1988). The vermicomposting of cow slurry, ‘Earthworms in waste and environmental management.’ edited by Edwards, C. A. & Neuhauser, E. F. SPB Academic Publishing, Netherlands. ISBN 90-5103-017-7. Ismail, S.A., (1997). Vermicolgy ‘Biology of earthworms’ Orient Longman Limited, Chennai, India. ISBN 81-250-10106. Kale, R. D. (1998). Earthworm: Nature’s gift for utilization of organic wastes, ‘Earthworm Ecology’, edited by Edwards, C.A. St. Lucie Press New York. ISBN 1-884015-74-3. pp 355- 376. Kale, R. D. and Sunitha, N.S., (1995). Efficiency of earthworm E. eugeniae in converting the solid waste from aromatic oil extraction units into vermicompost, Journal IAEM, Vol. 22, No. 1, pp 267- 269. Lakshmi, B.L and Vijayalakshmi, G.S., (2000). Vermicomposting of sugar factory filter pressmud using African earthworm species E. eugeniae, Pollution Research, Vol.19, No.3, pp.481-483. Loehr, R.C., Martin, J.H., Neuhauser, E.F., (1998). Stabilization of liquid municipal sludge using earthworms, ‘Earthworms in waste and environmental management.’ edited by Edwards, C. A & Neuhauser, E. F. SPB Academic Publishing, Netherlands. ISBN 90-5103-017-7. Martin, J. P (1976) Darwin on Earthworms, The Formation of Vegetable Moulds, Bookworm Publishing Company, ISBN: 0-916302-06-7 NC State University (1997). Snapshots of Selected Large-Scale Vermicomposting Operations – data from Vermicycle Organics, Inc., Charlotte, North Carolina, United States Neuhauser, E.F., (1998). The potential of earthworms for managing sewage sludge, ‘Earthworms in waste and environmental management.’ edited by Edward, C. A. & Neuhauser,E.F. SPB Academic Publishing, Netherlands. ISBN 90-5103-017-7. Norbu, T (2002), Pretreatment of Municipal Solid Waste by Windrow composting and Vermicomposting, AIT Masters Thesis, No EV-02-27. Parthasarathi, K., Ranganathan, L.S., Thirumalai, M., Parameshwaran, P., (1999). Mono and polyculture vermicomposting pressmud enhance macronutrients, Asian Journal of Microbial Biotech & Env. Science, Global Science Publication, India. Vol. 1, pp 63-65.

Ram Mohan, K (2001). Composting of food wastes from Anna University campus, Masters thesis, Anna University, Chennai, India Riggle, D. and Holmes, H. (1994). New horizons for commercial vermiculture. Biocycle Vol. 35(10): p.58-62. Robert, E. L. and Paul, A. R., (1997). Municipal Solid Waste, ‘Problems and Solutions,’ Lewis publishers, USA. ISBN 0-1566702151. Ronald, E.G., Donald, E.D., (1977a). Earthworms for Ecology and Profit, Vol. 1, ‘Scientific Earthworm Farming.’ Bookworm Publishing Company, Ontario, California. ISBN 0-916302-05-9. Ronald, E.G. and Donald, E.D., (1977b). Earthworms for Ecology and Profit, Vol. 2, ‘Earthworm and the Ecology’. Bookworm Publishing Company, Ontario, California. ISBN: 0-916302-01-6. Saxena, M., Chauhan, A., Asokan, P., (1998). Fly ash vermicompost from non-ecofriendly organic wastes, Pollution Research, Vol.17, No.1, pp. 5-11. Seenappa, C., Jagannatha, C.B., Kale, R. D. (1995). Conversion of Distillery waste into organic manure using earthworms E. eugeniae, Journal IAEM, Vol. 22, No. 1, pp 244-246. UNEP (2001). United Nations Environment Programme, State of the Environment, South Asia 2001, ISBN: 92-807-2037-2. Internet sources/references: Casting and soil, http://www.yelmworms.com as of March 2003 Chan, K.Y and Mead, J.A, (2002). ‘Soil Acidity limits colonization by Aporrectodea trapezoids, an exotic earthworm’, Urban & Fischer Verlag, http://www.urbanfischer.de/journals/pedo as of March 2003 Earthworms in Hospital Waste management, http://members.tripod.com/eco_logic/hospital.htm as of March 2003 Slocum, K., (2000). “Maintaining the Flow in Continuous Flow Systems”, http://www.wormdigest.org/articles/index.cgi as of March 2003 Marry Appelhof, Site for vermicomposting; http://www.wormwoman.com/acatalog/index.html as of March 2003 Frankel, S. Zorba, (2001). “VermiCo Leads an Industry: Moving Forward Together”, http://www.wormdigest.org/articles/index.cgi as of March 2003 The Composter's forum. http://www.oldgrowth.org/compost/forum_vermi as of March 2003 The Hindu, ‘Red earthworm for vermicomposting’, Online edition of India's National Newspaper Thursday, Jan 17, 2002:

http://www.hinduonnet.com/thehindu/seta/2002/01/17/stories/2002011700160400.htm as of March 2003 Vermicomposting, http://journeytoforever.org/compost_worm.html as of March 2003 Vermicomposting basics, http://taxodium.env.duke.edu/cee/ecofoot/vermicomposting.html as of March 2003 Vermicomposting, URL:http://www.yelmworms.com/vermicomposting.htm as of March 2003 Vermicomposting forum, http://www.oldgrowth.org/compost/forum_vermi2/index.cgi as of March 2003 Vermicomposting, Indoor Composting with Earthworms, http://www.state.ma.us/dep/recycle/files/vermi.htm as of March 2003 Zeolite – The Perfect Worm Bin Companion http://www.squirmy-worms.com/zeolite.htm as of March 2003