From Big Medical Encyclopedia

COMPOSTING (Latin compositus compound) — the way of neutralization of household, agricultural and some industrial solid garbage based on decomposition of organic matters by microorganisms.

To. is the simplest method of neutralization and waste recycling in fertilizer and it is eurysynusic in many countries of the world. An indispensable condition of use of this method of neutralization of garbage is contents in them not less than 25% of easily decaying organic components at humidity from 30 to 65%.

Are not subject To. hospital garbage, an offal from vetlaboratoriya and excrements. Impurity radioactive, disinfecting (acids, alkalis) and other toxicants, and also toxic chemicals, pitch and tar are not allowed to compost.

At To. there is a disintegration of an organic compound series and synthesis humin substances (see) therefore in weight the maintenance of batteries available to plants increases (nitrogen, phosphorus, potassium, etc.).

Neutralization of garbage at To. results from death of the most part of pathogenic microorganisms (except sporous forms), eggs of helminths and larvae of flies under the influence of high temperature (not lower than 50 °) and antagonistic influence of microorganisms, and also owing to modification of organic matter garbage (see), turning under influence biol, processes of decomposition in the humus harmless in a dignity. the relation and being good fertilizer.

Area of the territory of fields K. on each 10 thousand people makes apprx. 2 hectares. At withdrawal of the site under fields K. provide sanitary protection zones in 300 m from residential quarters, stadiums, parks. Under unfavorable conditions this distance can be increased to 500 m. Around fields K. two parallel forest belts are created. Distinguish several methods K.

A composting in stacks without pretreatment of garbage. Is the most widespread method of neutralization. Neutralization during the use of this method is reached in 6 — 14 months.

Brought on fields K. garbage by means of bulldozers creates in stacks in the form of trapezes or in shaft with a width of bases of 3 — 4 and 2 — 3 m, 1,5 — 2 m high (in northern districts of the country up to 2,5 m high) and 10 — 25 m long. Stacks have parallel ranks with journey between them 3 m wide. For deodorization, preservations of heat and prevention of reproduction of flies cover a surface of stacks with a layer of the earth or peat in 15 — 20 cm. The sublayer of compost weight shall defend from the level of subsoil waters not less than on 1 m.

In the conditions of a midland of RSFSR at normally proceeding processes in stacks of a spring and summer bookmark self-heating and decomposition of organic matter begins in 3 — 5 days after registration of stacks. Temperature of compost weight increases to 60 — 70 ° and keeps at this level 15 — 20 days, and then decreases to 40 — 45 ° and 2 — 4 months remain. During the subsequent period To. temperature in stacks does not exceed 30 — 35 °.

At an autumn and winter bookmark self-heating begins in 25 — 30 days after registration of stacks. Temperature does not exceed 50 — 60 ° and keeps during 2 weeks. In the next 2 — 3 months temperature of compost fluctuates within 24 — 36 °, and with approach of summer is established at the level of 32 — 36 °.

Duration To. it is possible to reduce if stacks to scoop and humidify. So, in GDR the garbage unloaded from garbage trucks is watered by means of the special car with a sewer deposit. In 3 days the grab create a stack 1 m high, 2 — 3 m wide and maintain within 30 days (the first cycle) then material of stacks is shoveled the grab, creating new stacks (the second cycle). In 30 days operation is repeated. Total period of neutralization makes 3 months.

In 1929 — 1930 the method of acceleration of fermentation in stacks by intensive airing is developed. This method which received the name «Indore process» was that compost masses was filled on spicate lattices that promoted air circulation in stacks.

In Germany the composting without pretreatment of waste is known as the Baden-Baden method. Acceleration of processes of neutralization of garbage is reached by the organization of air circulation in stacks on the perforated concrete pipes laid in the basis of a stack.

The fan sucks away air from a stack and sends it to the furnace where it is used during the burning of large waste.

The composting in stacks with a preliminary razmelcheniye is more preferable since the period of maturing of compost is reduced. Was widely adopted To. shredded garbage by the Dorr-Oliver method. Schematically it looks so. Garbage trucks deliver waste in the bunker, from to-rogo it moves on a sieve for department of small fractions and further in a crusher. The crushed material is passed through openings (to dia. 32 mm) in the bottom. Shredded weight is cleared of glass, humidified to 40 — 60% and keeps within stacks on the open area. Stacks have trapezoid section with a width of bases of 4 and 2 m, 2 m high. For two days temperature in them increases to 60 — 70 °. During maturing of a stack 2 — 3 times scoop. Process To. borrows apprx. 9 weeks.

A composting in stacks with preliminary fermentation. For preliminary fermentation use forced ventilation (air consumption of 0,5 — 0,7 m 3 on 1 kg of the processed weight), maintain optimum humidity, and also provide sufficient nutrition with nitrogen due to addition of a sewer deposit. Sometimes for the purpose of acceleration of activity of microorganisms add certain bacterial cultures. To this method K. the Dano-biostabilizator method belongs.

A composting in stacks with a preliminary razmelcheniye and fermentation. There are many modifications of this method and various systems of installations are applied. The garbage arriving on the plant passes a stage of a razmelcheniye on crushers and then comes to the biotank where it develops in the form of a stack and is humidified. The garbage which passed preliminary To. in cameras of fermentation, are still unsuitable to the use; they are subjected to additional fermentation in stacks.

Use of compost. Quality of compost depends on starting materials. Fresh compost represents the friable, loose, komkoobrazny mass of gray color with a specific smell. Compost from municipal solid waste is applied as organic fertilizer in number from 15 to 50 t/hectare. For providing safe conditions of use compost shall meet certain requirements (tab).


See also Biothermal methods .

Bibliography: Gulyaev N. F. and Mirnyi A. N. Biothermal installations for a composting of household waste, Nauch. works of the Academician of communes, hoz-va, century 115, page 119, M., 1975; Gulyaev N. F., Karasyov M. N. and Zolotov and Central Committee and y G. 3. Structure and norms of accumulation of household waste, in the same place, page 5, bibliogr.; Prokhorov A. N. and Nikogosov of X. H. Utilization of solid city waste, M., 1975; Raznoshchik V. V., Karasyov M. N. and Suvorov V. N. Field methods of neutralization and processing of household waste in compost, M., 1970; Sanitary cleaning of the cities (from municipal solid waste), L., 1974, bibliogr.; Collecting, removal and neutralization of household waste, the lane with it., under the editorship of N. F. Gulyaev, M., 1971.

V. P. Padalkin.