Organic Waste and Pollutants Reduction Through Composting

Abstract

Management of organic solid waste through composting is the sustainable option to prevent leachate and greenhouse gas emissions after disposal/landfilling. Composting reduces a maximum of 65% of the initial volume and also recovers nutrient-rich end product. During composting, the biodegradable organic carbon, micropollutants, and nuisance gases from the organic fractions are biologically transformed into a stabilized product. Millions of indigenous microbial populations act to degrade the waste by releasing off high temperature and gases. The process is largely influenced by the aeration rate, moisture content, C/N ratio, temperature, particle size and volume of the waste material composted. The active thermophilic phase of the composting determines the rate of waste degradation and organic matter transformation during the process. During composting, the waste material undergoes three different temperature phases: (a) initial moderate temperature (less than 40 °C) for a couple of days, (b) the thermophilic temperature (over 40 °C) for few days to several weeks, and finally, (c) the cooling and maturation phase. During the process, the organic carbon and nitrogen are metabolized to moisture, CO2, and other nitrogen gases, significantly reducing the availability of exchangeable carbon and heavy metals in the compost. Furthermore, it also increases the bioavailability of essential plant nutrients total nitrogen (N), ammonium (NH4), phosphate (P2O5), and potash (K2O), and other micronutrients. The release of heavy metals and potential gases during composting is unavoidable, but it can be controlled by adding appropriate bulking agents such as sawdust, dry leaves, wood chips, and optimizing the above-mentioned process parameters. This chapter focusses especially on organic wastes and pollutants reduction through composting. Also, the major influencing factors and process parameters for effective composting of organic waste and treatment of pollutants gases emitted during the process are discussed.