Solid organic waste processing and disposal techniques

Waste of animal industry, especially poultry breeding, pollute the environment. According to the World Health Organization (WHO), dung and waste waters of pig-breeding farms may transmit over 100 pathogenic agents that may cause infectious diseases such as zoonoses. Also, organic waste are a favourable environment for the development and survivalability of pathogenic flora and may contain pesticides, medicines, weed seeds and other pollutants.

A 400,000 laying-hen poultry plant discharges such an amount of dung that its decompositions results in 700 tons of biogas, including 450 t of methane (65%), 208 t of carbon dioxide (30%), 35 t of hydrogen, indole, skatole, hydrogen sulphide, ammonia and other compounds (5%). Such emissions do substantial harm to the environment, that is why the issue of waste disposal is crucial for such enterprises.

OOO Terra offers the technique of accelerated dung composting using our biocomponents for waste disposal which allows to obtain quality compost during 4-7 days, its cost price being several times lower than in Europe. This product may be used as an organic fertilizer as it is free from all agents that could possibly have negative influence on the soil. The chicken compost rate is up to 10 tons per hectare, the pig/cattle compost rate is up to 30 tons per hectare.

At the consumer’s option, in order to achieve a high yield, we can make compost into loose or granulated AGROPIK-ECO soil forming fertilizer using humus-forming biocomponents. The AGROPIK-ECO fertilizer rate is 350 to 1000 kg per hectare.

Alternative techniques and methods of waste disposal

Taking Waste to Fields

In the times of extensive agriculture, cows that yielded little milk were kept primarily for dung. Cattle rate per unit of land area was very low. Dung was accumulated near the farm or taken to fields where it gradually turned into humus.

Today such a procedure causes a number of problems. Firstly, transportation of a huge amount of drainage (a content of dry matter is 2-5 %) takes considerable costs. Secondly, the soils as well as ground waters may get invasion, infectious and toxic agents. Thirdly, this leads to accumulation of nitrates, copper and zinc in grains, grass and water. Due to this, use of native poultry dung as a fertilizer is prohibited in some states of the USA.

At present, there are several techniques of processing solid organic waste such as cattle and chicken dung. Some of them are listed below.

Burning. This technique is the most expensive and complicated, so it is economically reasonable to use it only for vey large amounts of solid organic waste (no less than 200,000 tons) if their humidity is not exceeding 25%. There are only several efficient solid organic waste burning plants in the world. Such plants can be built and launched the Russian Federation only if the state subsidizes “green energy”, otherwise they are economically unreasonable. A plant that burns 416,200 tons per year of solid organic waste if their humidity is not exceeding 25%, would cost over 150 million euros, the electric power production rate of such a plant being approximately equal to 35 MW.

Biogas is another technique which can be used in the Russian Federation only provided that the state subsidizes “green energy”, otherwise the actual payback period of such a plant is over twelve years.

Synthesis gas. This technique requires permanent presence of high-skilled specialists and is unpredictable in terms of maintenance and operating costs. The organic waste processed should be no more than 25% humid. At present, there are only two plants in the world that use this technique to process cattle and poultry dung. Both plants are still in a test run mode (two years after this technique was introduced) and it is still arguable whether the use of this technique in these plants is economically reasonable. The use of this technology proved to be efficient for wood waste but not dung so far.

Use as fodder. A promising field which arose during development of organic waste processing and disposal systems is the development and use of techniques which ensure maximum extraction of nutriments from dung and drainage.

Research found that cattle dry faeces contain 16% protein, 15% cellulose, 3% fat; pig faeces contain 22% protein, 18% cellulose, 7% fat; chicken dry dung contains 30% protein, 10% cellulose, 2% fat. So, losses of these valuable components should be taken into account during the process of dung disposal, for they could be used as additives to animal and poultry fodder.

It should be noted that up to today almost all countries of the world refrain from issuing official permission to feed cattle and poultry with processed dung. The issue of whether the use of animal industry waste as fodder can be permitted is still being discussed by the scientific community. The reasons that hinder such permission are the non-mainstream nature of such fodder, the possibility of their being polluted by pathogenic flora and/or helminth eggs, the presence of hormonal and other medicines as well as toxic compounds of copper, zinc, mercury and other elements.

Nevertheless, R & D analysis makes it possible to maintain that the issue of using animal industry waste as fodder may gain approval if there is further profound study of their veterinary and sanitary condition.

Passive composting is the technique used in poultry plants and farms in the USSR. This is the simplest and most effective technique but it requires large concrete areas while the resulting compost is of rather poor quality. During passive composting, solid organic waste inside storage piles catches fire which has to be extinguished by expensive equipment. It is also not recommended to store pure organic waste in their pure form because in this case they lose a substantial part of their nutriments, including nitrogen. Such losses are particularly great (up to 40%) when the stored waste gets frozen in winter and thaw out in spring.

Accelerated composting is the most advanced and economically reasonable technique used

all over the world to process large amounts of organic waste from cities, agricultural facilities, various disposal facilities, forest parks etc. This technique requires 20 times smaller concrete areas than passive composting. The possibility of catching fire by solid organic waste is easily managed and prevented. The resulting compost is far better in quality than the compost resulting from passive composting. Also, the compost does not contain pathogenic flora, weed seeds nor helminth larvae, so it can be sold to farmers and gardeners or be used for own needs instead of, or in combination with, mineral fertilizers.

There are many new compost production techniques developed over the past few years. The most common of them used up today is that of a compost arena. The raw material is made into piles by bulldozers and then constantly loosened and stirred using enzymes by piling machines in order to ensure efficient composting. The composting procedure takes place at the temperature of up to 75°C in order to destroy plant seeds and disinfect the compost. If the procedure is held in a proper way, there is almost no odour or water pools under compost piles. The process remains virtually unchanged in winter as well.

International experience shows that it is possible to produce quality fertilizing compost in 8-10 weeks provided that the material is treated heavily and the process parameters are carefully controlled.

In European countries, the price of organic fertilizer is 250 to 300 euros per ton.