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Compost Symposium

ECONOMIC VIABILITY OF COMMERCIAL COMPOSTING OF FISHERIES WASTE BY PASSIVE AERATION

Extracts from

Dr. S. P. Mathur

The Compost Council of Canada Symposium

Montreal, Qc. Canada

September 1994

ECONOMIC VIABILITY OF COMMERCIAL COMPOSTING OF FISHERIES WASTE BY PASSIVE AERATION
by

L.A. Hayes¹, R. Richards² and S.P. Mathur³

Shigawake Organics Ltd., 252 Route 132, Shigawake, Québec, G0C 3E0 ³

Dr. Sukhu Mathur Compost and Peat Specialist Inc., 75 Foxleigh Cres., Kanata, Ontario K2M 1B6

Abstract

Wastes from finfish and soft shellfish fisheries and aquiculture are exceptionally rich in a variety of plant nutrients and devoid of problematic metals, pathogens and inert contaminants. Although highly valuable as fertilisers, their proper agricultural utilisation by soil interment faces operational and climatic hurdles; and is challenged by the sporadic nature of availability of the waste. Shigawake Organics Inc. therefore attempted composting to optimise utilisation of the waste on their farm in the Gaspé area of Quebec. Environment Canada's DRECT Program and Agriculture Canada assisted Shigawake Organics to ascertain technical feasibility of composting fish wastes by a passive (natural) aeration technique and develop a model of economic viability in view of all considerations relevant to a farm-based commercial operation. The model will be presented for profitable composting of fish waste with peat.

1. Introduction

2. The Compost Feedstock

3. The Technology of Passive Aeration Composting

4. The Site and Permits at Shigawake Organics

5. Production of Composts

References

1. Introduction

This report represents a coming together of many interests. The decline in cod fishery is directing the industry's attention towards aquiculture and other marine biomass resources. At the same time it is being increasingly realized that to abuse a resource is to lose a resource. Portions of a biomass resource when improperly disposed generally cause pollution that perturbs habitats, and contributes to climate change affecting whole ecosystems, including the local work force. Alternate or additional employment and wealth, however, can be generated for the local human population by closing nature's loops locally through technologies that are economically and environmentally sustainable.

It is therefore not surprising that commercial composting of fish wastes by a technique that requires low capital and operational costs was supported by Environment Canada's DRECT program to encourage waste reduction; by the Environmental Partners program to improve the local ambience, by Proctor and Gamble Inc's Compost Fund to encourage ecosystem integration, by the provincial governments, and the National Research Council of Canada's IRAP programs to bring more science to industry; by ACOA (Atlantic Canada Opportunities Agency) and others to create employment; and by Agriculture Canada to enhance the environmental sustainability of farming. But, all these interests came together only because Ms. Lois Saunders, an interested citizen and government worker from Colinet, Newfoundland, wrote to the Federal Ministry of Environment asking "what are we supposed to do with the fish offal you don't want us to spread on open pastures anymore". "Do you know if we can compost it with the local bog". To go from there to where we are today we will deal below with the fish offal, bog, wood wastes and passive aeration composting, to arrive at how to profit from helping the planet.

2. The Compost Feedstock

These were fish wastes and peat or wood wastes, namely sawdust and shavings or tree bark.

2.1 Fish Wastes
Commercial fishing and aquiculture generate large proportions of waste called offal (that was made to fall off the boat), 'morts', racks, gurry, scrap, chum etc. The waste may be 80% or higher when landed catches are found to be unfit as food, when there are massive kills in aquiculture, or when only roe (eggs) is harvested from herring or other fishes. About 30% of the population during aquiculture turns up as 'morts', while there is usually a by catch of non commercial sizes and species and some squashed fish in dragnets. Filleting of fish, such as of the groundfish family culls 40 to 60% of the total processed (see Mathur, 1991 and Martin and Patel, 1991). About 30% of the fish sliced into steaks, or canned, is scrapped. The discarded exoskeletons and other parts of processed shellfish such as lobster, crab and shrimp comprise 30 to 80% of the landed weight. According to Green and Mattock (1979), processing of fin fish, crab and shrimp can generate 30 to 60%, 75-85% and 40-80% solid waste, respectively.

It was estimated (Mathur, 1991) that processing of ground fish alone in Canada generates about 140,000 to 200,000 metric tonnes of waste that is disposed. A corresponding estimate for seafood processing waste in the U.S. is 2 million metric tonnes per year.

Environmental concerns and regulations in North America have made it costly (CAD 20 to 70 per ton) to dispose fish wastes by dumping on open seas (>20 km from shore), or by appropriate land filling. Low technology land burial and open surface dumping, of such wastes is likely to be prohibited and regulations enforced in more and more jurisdictions, due to the nuisances of malodours and scavengers, and the eventual contamination of surface and groundwater by such disposal.

Fish wastes include whole waste fish, offal that contains viscera, and racks that remain after filleting. The racks include skin, heads, fins, tails and backbones. Finfish wastes are thus rich in proteins and bones, and contain some lipids (fats and oils). Herring waste from roe harvesting, about 95% of the total landing, is particularly oily. Dogfish gurry, being from a (sand) shark is boneless but contains cartilaginous skeletal parts, the tough sharkskin, tail, fins and viscera, usually in a thick suspension. Shellfish scraps contain about 33% protein and 33% chitin (poly-N-acetyl glucosamine) (Martin and Patel, 1991). Chitin and crustaceans of a Ca and P compounds constitute the shellfish exoskeletons. The crustacean waste also contains unextracted meat and organs. The finfish and soft shellfish wastes carry up to 8% N, 7% P and 15% Ca and all the elements essential to life. (It should be noted that the hard molluscan shells e.g. of clams, are of no organic value as they are mostly Ca carbonate).

Martin and Patel (1991) have discussed and referred to other reviews of various means of utilizing fish wastes. The wastes can be cooked and dried to produce fish meal. Small proportions of fish meal can be included in animal feeds. Larger proportions can taint animal products like, milk, eggs or meat with fishy smells. Various types of fish sauces are made by fermenting different whole small fishes or specific fish organs. Fish tissues are degraded into soluble proteins, peptides and amino acids mainly due to endogenous fish enzymes (biological catalysts), and flavour is contributed by certain naturally-occurring or introduced bacteria or fungi. Salt is added to control the degradation. Specific sauces are popular in small geographical areas. Fish silage production involves (i) chopping or mincing, (ii) blending with the acid, e.g. formic or H₂SO₄ + HCl, and (iii) digestion and storage. Attempts have been made to reduce transportation costs of the liquid silage and fish hydrolysates, by drying the products through vacuum desiccation, spray drying, or drum drying. Fish silage, hydrolysates and meal have difficulty in competing in the animal feed market with widely available plant protein sources, e.g. soybeans, oilseed cakes and cottonseed, partly because the capital-cost of producing the easily transported fish meal is rather high. Also, as size of the population that is solely dependant on fisheries declined so that the tolerance of communities for the odours associated with production of certain fish by-products, e.g. fishmeal.

All technologies designed for specific marine wastes are challenged for commercial viability by the variable volume and sporadic nature of availability of the feedstock. And, most require specialized skills in the labour force employed.

2.2 Problems in Direct Use of Fish Wastes
Direct use of the fish wastes for land manuring, or land spreading, is generally discouraged by the uniquely obnoxious odour of putrefying fish. Such use even in areas where it is permitted is therefore restricted mainly to immediate ploughing in of the waste before or at the time of planting. This can not be done is summer when crops are standing although that's when most of the fish waste is generated. Ploughing is also difficult when the soils are excessively wet, or frozen.

The fish proteins, lipids, and chitin are easily broken down by (nonliving) exoenzymes and autolytic enzymes in dead cells, even under conditions in which the decomposer organisms themselves are not active. The intestines and muscle tissues of fishes are particularly rich in enzymes that degrade various components of flesh, e.g. proteins, scales and skin. Fish wastes have been studied as sources of such degradative enzymes (Martin and Patel, 1991). Enzymes are essential to all life but life is not essential for all enzyme activities. Enzymes can act even under conditions suboptimal for microbial activities e.g. at -20^oC (Mathur, 1982). Even under cool conditions therefore volatile ammonia is released rapidly from these wastes by the exoenzymes while the organisms that assimilate it or convert the ammonia to nitrate are not active. The nitrate-producing organisms may also be suppressed by high ammonia concentrations. At the same time, fish lipids being mostly of the unsaturated type oxidize rapidly in air to produce foul rancid odours. Aerobic (in presence of air) and anaerobic decomposition of fish wastes in soil or ordinary hot composts is therefore so rapid (and malodorous) that much of the ammonia is lost by volatilisation. More so, because the calcium present in the waste makes them alkaline and thus promotes ammonia loss. This decreases the fertiliser value of the waste. The loss and odour dissipation may be even greater when the compost is force-aerated or turned as fresh air carries more ammonia, and the heat promotes volatilisation. Usually, corrective measures have to be taken with variable effectiveness.

When the wastes are buried or land filled decomposition of the fish wastes occurs under the anaerobic conditions that generate particularly malodorous reduced S and N compounds like cadaverine and putrescence that have evocative names, and hydrogen sulphide (the rotten egg gas). Anaerobic composting of fish wastes therefore poses problems of smell, transport, application and aesthetic utilisation without adverse environmental impacts. The impacts may be mainly due to most of the nitrogen in the product being in forms that can be easily volatilized or washed away, not in the form of the stable humus that is formed by aerobic composting.

2.3 Challenges in Composting of Fish Wastes
As fish wastes have narrow C/N ratio, and are or become alkaline, they need to be mixed with acidic or acidogenic material(s) with a wide C/N ratio. Because fish wastes, particularly from finfish, tend to be wet and dense they need to be mixed with a water-absorbing loose material. However, in most circumstances even the inclusion in fish waste composts of mildly acidic materials of low permanent buffering capacity (e.g. river mud, citrus and banana wastes) may not prevent loss of most of the ammonia nor provide a naturally well-aerated mix. Materials of wide C/N ratio like fresh wood by-products have their own oxygen demand particularly when they are mixed with fish waste that generates ammonia as the ammonia neutralises and promotes autooxidation of the phenols released from wood wastes. The phenols normally, otherwise, slow down decomposition by inhibiting the micro-organisms involved in the process. When a mixture of fish wastes and wood by-products therefore is actively aerated by forcing air, and/or by turning of the composts, the loss of ammonia is exacerbated. At the same time active oxidation of the mixture generates more heat that may cause further odour generation due to chemical 'charring' of the waste that is similar to singing of hair. Further aeration to cool the mass promotes ammonia loss, and the need for biofilters and/or scrubbers of high capacity. Conversely, if the aeration is withheld, decomposition of the fish waste would continue under the anaerobic (oxygen-deficient) conditions that generate the highly malodorous amines and sulphamines and H₂S.

2.4 Use of Peat or Wood By-products for Fish Waste Composting
In 1983, a team of researchers in Canada realized that fish wastes should be composted aerobically by being mixed (bulked) with and enveloped in a material that (a) has a wide C/N ratio, (b) is acidic and hydrophilic enough to trap ammonia in solution; (c) has high capacities for adsorbing and complexing ammonium and calcium ions; (d) is fluffy enough to be well aerated so that malodours of anaerobic decomposition are not created but the process oxidatively generates the acidic sulphate and nitrate ions that help dissolve the basic phosphates in bones and soft crustacean shells; (e) deodorizes any malodours generated even transiently; (f) provides heat insulation; and (g) though biodegradable will not decompose fast enough to generate high heat (>45^oC) by itself so that its own oxygen demand is not great, and the compost can mature in a short Canadian summer without having to be turned or actively aerated.

It was concluded that horticultural sphagnum (blonde) peat and light brown peat that is used neither for fuel nor horticulture meet the above requirements fully. Some wood byproducts also meet many of the same requirements except that they do decompose during composting. Wood has lower acidity and buffering capacity than peat but a higher bulk density so that a cm³ of wood waste weighing 0.3 g with a buffering capacity of 25 meq/100 g is as effective in trapping ammonia as a cm³ of peat weighing 0.06 g with a buffering capacity of 125 meq/100 g. Both have low fertilizer value by themselves although peat tends to be richer in N. While peat has high market acceptability as a soil conditioner wood byproducts are more widely available, and are often being disposed in an environmentally inimical manner. For example, open dumps and stockpiles of wood wastes may contaminate water with leachates and emit the highly potent greenhouse gas methane.

The peat used for composting does not have to be the milled air-dry product available in bags. It should be moist, loose and be fine screened only after the composting. Some of the coarse material can be put back at the base of compost piles. In effect, the peat itself does not decompose significantly during the composting. It becomes valorized due to the nutrients from the fish waste. Shigawake Organics is indeed using rough unscreened peat that has been drained of excess water by simple stockpiling with more than satisfactory results.

One possibly negative consideration was that peat harvesting may affect some wetland ecosystems. However, it is now proven that harvested peatlands (cut over peat) can be restored to new wetland ecosystems which sequester carbon rather than contribute methane to the atmosphere, as virgin peatlands do. Methane is 28 times more forcing than carbon dioxide as a greenhouse gas. At the same time, peat applied to mineral soils helps to restore soil organic matter and does not contribute much CO₂ to the atmosphere. In fact, more than 80% of the peat applied to land remains there even after 10 years so that peat is 5 to 8 times more effective in rebuilding soil humus than uncomposted manure, crop residues and green manuring. Wood byproducts also build more soil humus than animal and crop wastes (Janssen 1984).

On the economic side, a market exists for high-priced, limed and fertilized peat for use in greenhouses, house plants, and home gardens. By composting with fish waste the peat becomes limed and fertilized completely so that it can be a substitute for the enriched peat neutralized and supplemented otherwise at considerable cost. High quality composts can also be generated from some wood byproducts, particularly if they have been partly decomposed such as while in old stockpiles or dumps.

2.5 Sawdust and Shavings

Sawdust and shavings, like other wood wastes, are low in N and P and therefore are composted best in combination with other counter-balancing materials, or with N and P fertilizers. Wood wastes contain hemicelluloses and celluloses that degrade easily, and the recalcitrant lignins that contribute heavily to humus formation. During decomposition phenolic compounds and polymers release bioinhibitory phenols, terpenes and tannins periodically so that the process of wood waste composting is staggered rather than continuous (Mathur, 1991). This problem is mitigated when wood-based composts contain sufficient ammonia-generating compounds, e.g. proteins, chitin, urine and urea. Ammonia raises the pH value of the compost. The slightly alkaline pH in the presence of air causes neutralization and autooxidation of phenols to produce semiquinone free radicals and hydro quinones which polymerize, by themselves, or through enzymatic catalysis, into insoluble humus-like polymers, thus removing the bioinhibitory compounds from an active role (Mathur, 1991).

Mixtures of sawdust and shavings, or bark chips alone are more suitable for composting than pure sawdust alone. And, in general, partly decomposed old wood waste may be better than the freshly generated. Sawdust deters air movement and creates greater oxygen demand as it is denser and tends to degrade faster and to a greater extent than peat, bark or shaving. Finer materials are more accessible to microbial and chemical action. Presence of the lighter and larger shavings of wood with the sawdust makes it suitable for composting with fish waste. This has been confirmed by trials at Shigawake Organics. Sawdust and shavings are being also tested at Belchertown (New England Small Farms Institute), Massachusetts, for composting with rabbit manure or aquiculture morts by the passive aeration technology, with encouraging initial results.

2.6 Tree barks
Like other wood wastes, tree barks are also poor in N and P, and contain carbohydrates, lignins and resins. But unlike other wood wastes barks may contain up to 22% of their weight in tannins, which are water-soluble polyphenols based on gallic acid. Tannins, as per their role of protecting trees from pathogens, inhibit cellulose decomposition, and are toxic to many organisms (Bollen and Lu, 1969). On the other hand, tannins readily form water-insoluble, humus-like stable complexes with proteins, as in the tanning of leather.

3. The Technology of Passive Aeration Composting

The purpose of countermarching peat, sawdust, or bark with fish waste to conserve ammonia, and eliminate malodour generation and dissipation, would have been partly defeated if the compost had been force-aerated or turned.

The ammonia generated within the hot compost mass combines with the carbonate ions of the carbon dioxide produced there to form ammonium carbonate. This salt is stable under moist conditions only if the carbon dioxide concentration is high as within a compost, but not under normal atmospheric conditions. Consequently ammonia loss occurs when air is passed through a compost it is exposed to the atmosphere during turning. The escaping ammonia would contribute to pollution and acidification unless it is recaptured for the compost through the use of costly biofilters and/or scrubbers.

Forcing air and/or turning of composts aerates, warms and retains the whole mass at a high temperature for a long period. High temperatures, however, inhibit the oxidation of volatile ammonia and malodorous sulphides to nonvolatile nitrate and sulphate, particularly the former. Organisms that oxidize ammonia to nitrate can not tolerate high temperatures and very high concentrations of ammonia. Nor can they compete with organisms that use oxygen for oxidizing the more abundant carbon present. Turned composts or force-aerated static pile composts without a colder envelope therefore tend to lose ammonia that causes odour problems and decreases the fertilizer value of the product. The loss of the nitrogen also prolongs composting because then more of the carbon has to be oxidized before a stable C/N ratio is reached as, ideally, eventually only ten units of carbon will be retained in humus for every unit of nitrogen in the product. And yet, the compost has to have enough oxygen. To solve these dilemma, a team of scientists in Canada devised the Passively Aerated Windrow System (PAWS).

PAWS has two essential features, passive aeration and envelopment; these are explained below.

The air in the middle of a compost pile or windrow is warmed up by the heat generated by oxidation of the waste by the decomposer organisms. Warm air naturally rises upwards and outwards of the composting mass. As nature abhors vacuum, the warm air is replaced by cooler air mostly from or through other parts of the compost, setting up a mostly internal circulation until the air is almost uniformly warm and oxygen-deficient thus creating anaerobic pockets that generate malodours. That is why composts usually have to be force-aerated or turned. Another reason is that peripheral parts of the compost mix also have to be subjected to the high heat in the interior in order to kill weed seeds and disease-causing organisms all over. In the PAWS, both needs for turning are eliminated. First, by placing open-ended air intake pipes at the base, with holes only on the top side so that the heat generated in the compost mass itself energizes the movement of fresh oxygen-rich air into the mix. The rate of air-intake in effect is controlled by the heat generation or the rate of activity and oxygen demand of the decomposer organisms. Thus the overheating caused by chemical oxidation due to excessive aeration, which generates hair-singing and charring-type smells, is avoided. Overheating can also cause a collapse of activity as some microorganisms are killed by >70^oC heat. Consequently, up to 90% of the air forced for active aeration systems is for cooling rather than warming the compost.

The second need for turning is avoided in PAWS by enveloping the decomposing mass in already sanitary (hygienic, weed seed and pathogen-free) peat or mature compost. Thus, PAWS, in a sense, is an in-vessel technology. The 'vessel walls', that is the peat or mature compost, do not decompose much, and are cooler than the interior so that they trap hot vapours by condensation and chemical adsorption in an environment where more oxygen is available for their oxidation to innocuous and beneficial compounds. In effect, the envelope acts as a scrubber and a biofilter in intimate contact with the compost, and as a screen against insects and vermins. Being in appropriate temperature (mesophilic) range the envelope supports oxidation of ammonia to nitrate, thus replenishing the ammonia-neutralizing capacity of the envelope throughout the process.

The PAWS technology has been proven to be effective in all aspects for composting wastes from seafood processing, pulp and paper mills, all types of farm animals, and kitchens. This was done by researchers from Agriculture Canada, National Health and Welfare Canada, Correctional Services Canada, Environment Canada, Universities in New Brunswick, Newfoundland, Maine and Minnesota, and others (Mathur, 1992).

The PAWS technology is employable for both short and long windrows. For the smallest short scale, the compost heaps are 1.5 meter (5½ ft) high, trapezoidal in cross-section, with base and top planes of 3 m x 2 m, and 2 m x 0.3 m, respectively. A basal 10 to 15 cm (4" to 6") layer of peat or any mature compost is laid in a fluffy state on the ground. Two 3 m long standard PVC or ABS soil pipes, 10 cm in diameter with perforations 1.2 cm in diameter are placed lengthwise on the basal layer about 0.6 m from the margins. The two parallel rows of perforations at 5 cm intervals are about 10 cm apart on the two sides of the apex. Such pipes are routinely used for discharging and spreading effluents from septic tanks in North America, and for collecting leachates from landfills. Mixtures of layers of materials to be composted are placed on the pipes to a height of about 1.3 meter, and then the mass is covered with peat or any mature compost as an envelope.

On the medium scale, passively aerated windrow with one series of pipes placed cross the base can be of any length, 1.5 m high and 3.1 m wide.
Even larger passively aerated piles have been found to be effective for composting farm manures containing straw or wood shavings as litter. Two pipes were joined to provide aeration ducts of 6.1 m length to build windrows of 6 m width and 3 m height. A further modification recently achieved obviates the need for the aeration pipes by using a open plenum below the composting mass that is placed directly on a perforated platform. This has so far been tested successfully for farm manures only.

The length of the medium and large scale passively aerated windrows has no technical limit.

The mature compost or peat used in PAWS is generally about 20% to 40% of the compost mix by volume, nearly a quarter of which is used in the base. The 40% value is for conditions where some peat is mixed in with the waste such as when composting whole fish or their viscera. Wood wastes and mature compost can be used instead of peat in some situations.

Temperatures in the interior of the windrows rise within 2 or 3 days, attaining the thermophilic range of 45 to 65^oC within 10 days even at ambient temperatures of 4 to 10^oC. The oxygen concentration decreases during the warming up phase to less than 5%, but as the mixture heats up to 45^oC or so fresh air starts to be pulled through the pipes. Thereafter, the oxygen concentration generally stays between 13 and 18% during the thermophilic phase which may last for as long as 8 weeks, depending upon the bioxidizability of the material. When the composting mass cools down to 30^oC or ambient conditions, the compost can be reheaped for curing and the pipes reused for another windrow.

A current Environmental Partners project of Environment Canada with the Bonaventure English Harbour Development Association at Trinity, Nfld., is attempting to use PAWS channels with removable roofs. Here the windrows are enclosed on the sides, and of rectangular shape 50 ft long, 8 ft wide and 8 ft high. Thus the compost is better protected from wind and rain.

More details on the system and the research behind it are available in the references given at the end of this report.

4. The Site and Permits at Shigawake Organics

The site has the following features:
(i) good drainage;

(ii) away from streams and water bodies (> 1 km);

(iii) away from habitation (> 1 km);

(iv) sufficient space for operation and manoeuvring of equipment;

(v) wind protection from a ridge on one and treed areas on two sides;

(vi) easy accessibility.

One undesirable feature of the site is that it is within 1 km of a local dump site where various wastes, including fish offal, are disposed by shallow burial, and also within 1 km of farms where fish waste is dumped openly (to be disposed by natural scavengers). The area therefore has a well-primed population of scavengers, e.g. seagulls and crows. This problem is being addressed by seeking elimination of the wasteful practices.

The authorizations required to use the site were met by obtaining permits from the local municipal and regional governments, and of Quebec ministries of both agriculture and environment. The site was fully documented, surveyed and tested. An inventory of waterways, and water supplies (e.g. wells within 5 km of the site), habitation, plant and animal life in the area was made. Surface soil and core samples were taken and standpipe stations (piezometers) established to monitor groundwater quality. If and when the groundwater is found to be affected, the site will be made impermeable.

Important steps taken to forestall pollution included never placing the fish waste directly on land, but always on a base of the bulking agent or mature compost.

5. Production of Composts
Various combinations and configurations have been tested at Shigawake Organics but the main production is by the passively aerated windrow system of Agriculture Canada.

The composts have been monitored for several parameters including temperature, pH, Eh (redox potential), H₂S, NH₃ and %O₂. Details of the methodology and observations have been given in Hayes (1993).

Table 1 presents data on the peats and wood byproduct used at Shigawake Organics. The low N and wide C/N ratio of the sawdust and shavings is noteworthy.

TABLE 1. KNOWN PROPERTIES OF COMPOST RAW MATERIALS USED BY SHIGAWAKE ORGANICS, (ON DRY MATTER BASIS, EXCEPT FOR MOISTURE AND PH).

Table 2 presents data on some of the composts prepared at Shigawake Organics. As expected the peat-based composts tended to be richer in nitrogen than the wood-based composts. One of the composts (#1 in Table 2) indeed was richer in N than almost all others summarized in Table 3.

TABLE 2. PROPERTIES OF SOME COMPOSTS PREPARED BY SHIGAWAKE ORGANICS LTD., BY PAWS IN 1991 (EXCEPT PH AND % MOISTURE, ALL ON DRY MATTER BASIS)

TABLE 3. PROPERTIES OF VARIOUS PEAT OR SAWDUST COMPOSTS (ON DRY MATTER BASIS, EXCEPT PH AND MOISTURE).

Shigawake Organics has found it beneficial to utilize professional help in designing the packages, and in formulating, and getting approval for, the text printed on the bags.

References

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Green, J.H. and Mattock, J.F. In Food Processing Wastes eds. J.H. Green & A. Kramer. AVI, Westport, Connecticut.

Hayes, L. 1993. Composting of Fish Offal. Final Report on Environment Canada DRECT project with Sigawake Organics Ltjd. DR-63 Contract #KE144-0-6448/0/-SZ. Environment Canada, Ottawa.

Janssen, B.H. 1984. A simple method for calculating decomposition and accumulation of young soil organic matter. Plant & Soil. 76: 297-304.

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Preston, C.M., Ripmeester, J.A., Mathur, S.P. and Levesque, M. 1986. Application of solution and solid-state multinuclear NMR to a peat-based composting system for fish and crab scrap. Canadian J. Spectroscopy. 31, 63-69.

Rynk, R. (Editor). 1991. On-Farm Composting Handbook. Cooperative Extension, Northeast Regional Agricultural Engineering Service # NRAES-54, Ithaca, N.Y. pp. 186.

Seabright, 1991. A rural waste composting project in Trinity harbour area for the Bonaventure-English Harbour Development Association. Seabright Coporation, Memorial University of Newfoundland, St. John's, Nfld., Canada.

WCI Waste Conversion Inc. 1992. Development of Waste Collection and Prototype Composting Operations. A Report to the Solid Waste Management Steering Committee of Correctional Service Canada and Department of National Defence Canada, Kingston, Ont. pp. 75.

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NGO

If you are a project manager or program manager for a project in a developing country and need expertise in sustainable agriculture, agricultural or fish environmental issues such as smell, water or soil contamination please contact us.  We have state of the art methodologies based upon sound and proven research in agricultural and biological science.  We are adept at technology transfer and can assist you with your work.
 

Shigawake Organics Limited,
252 Route 132, Shigawake Qc G0C 3E0

418-752-2549 (418-752-7242 Fax) 

Contact e-mail:   informatics@sympatico.ca
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