Composting to Recycle Biowaste

Abstract

If agriculture is to be made sustainable, few activities like composting are very important. Composting not only allows organic waste of agricultural origin to be recycled and returned to the soil, but also provides a solution for managing much of the waste, which is currently a major problem. If urban organic waste is selectively collected and composted, it no longer represents a problem for the city, and, if wisely applied, will enrich the soil, thus promoting the preservation or improvement of the organic matter reserves of the soil, an important component in the soil protection strategy of the EU. This review paper considers up-to-date aspects of our knowledge on composting, presenting a discussion of materials suitable for composting, the composting process itself, and the biochemical and microbiological aspects of this process. Special attention has been given to the question of maturity, marking the end of the composting process, and to the quality of the end-product. Although it is not part of the composing process, information is also provided on the related field of anaerobic digestion. The use of municipal solid waste (MSW) compost in agriculture has many benefits to soil, crops, and environment. If the fermentation is correctly managed, pathogens are killed during the heat period. Compost can reduce the incidence of variant plant diseases. A very important parameter for the composting material is the C/N ratio, the optimal value is 25–30. Composting recycles organic household, yard waste, and manure into useful humus-like end-product, i.e., the compost. There are two major approaches to composting. In active (hot) composting there is high temperature and the end-product has high quality, while passive composting is slower and is more common in the garden composting. Composting is a microbiological process, done by aerobic bacteria. The microbes can be classified to the metabolic types on the carbon and energy sources utilized by the cell. Compost is used in the agriculture as organic fertilizer; there is organic matter input to the soil and also reduces P fixation. Maturity means in what stage of the composting process the material has progressed, and in the mature compost the biological activity has slowed. The maturity can be estimated by the C/N ratio, oxygen uptake, and germination test. The parameters for the assured compost quality label are the potentially toxic element content, the organic pollutants, and the hygienic requirements. In the European Union, composting, the recycling of biowaste, becomes one solution of sustainable agriculture. It plays an important role in the developing countries also. Although it is not part of the composing process, information is also provided on the related field of anaerobic digestion: it is an alternative way of recycling biowaste producing biogas.