Composting of food and agricultural wastes

Abstract

The rapid increase of world population in the last years accompanied by the intensification of human activities brought serious environmental problems such as the pollution of soil, water, and air, forest destruction, etc. In the future these negative impacts may cause global climatic changes (greenhouse effect) and might be a menace for the existence of the human race. Immediate measures to avoid the negative influence of human activities are necessary. Many industrial processes result in a large amount of wastes. Food and agriculture industry are among the oldest of human practices, but as a source of wastes it does not make any exception from other industrial activities. In the near future the management of food and agricultural wastes will play an important role in the conservation of the natural resources in many countries, including the Balkan region. The term "composting" is used here to define the process of controlled biological maturity under aerobic conditions, where organic matter of animal or vegetal origin is decomposed to materials with shorter molecular chains, more stable, hygienic, humus rich, and finally beneficial for the agricultural crops and for recycling of soil organic matter (Sequi, 1996). The process is mediated by different microorganisms actuating in aerobic environment: bacteria, fungi, actinomycetes, algae, and protozoa, which participate naturally in the organic biomass or are added artificially (Tuomela et al., 2000). The process can be described by the follow equation: organic matter + O2 → compost + CO2 + H2O + NO3- + SO42- + heat Now the interest regarding the composting process is related to the following points: 1. Environmental point of view, because during this process the biomasses are transformed to material rich in nutritional substances that can improve the structural characteristics of the soil (Sommer and Dahl, 1999). 2. Hygienic point of view, because during the process the organic matter is disinfected by the influence of the high temperatures (Dumontet et al., 1999). 3. Energy management point of view, because during the process energy is released through the degradation of large organic molecules (Schaik et al., 2000; Sonesson et al., 2000). The term "composting" is usually used (although it is not correct) for the description of aerobic stabilization of the organic matter (solid wastes), obtained without separation of different fractions (Sequi, 1996; Tuomela, 2002). Compost offers many benefits to the landscape and garden. For example, compost (1) improves soil tilth condition and structure; (2) increases the soil's ability to hold water and nutrients; (3) supports living soil organisms; (4) helps to dissolve mineral forms of nutrients; (5) buffers soil from chemical imbalances; (6) may provide biological control of certain soil pests; and (7) helps to return organic materials to the soil and keeps them out of landfills and waterways. Compost can be used as a mulch, a liquid "fertilizer," or incorporated into the soil or potting mixes. © 2007 Springer Science+Business Media, LLC.