Composting sewage sludge: evaluation of process, resulting product and costs

Abstract

Sewage sludge is the waste generated in greater quantity in STPs and its final destination, usually landfills. This provision is certainly not the best option for several aspects: a) landfill has its cost deposition; b) legislation from 2014 will require disposal in specific landfills therefore more expensive and certainly more distant points of production; c) the sewage sludge contains high moisture and generates manure that must in turn be contained and treated; d) the sewage sludge contains organic matter and nutrients that could be applied in the agricultural and forest area with fertilizer / soil conditioner. The use of sludge in agriculture has been used by some STPs. However, from 2011, when the CONAMA Resolution 375/2006 came into force, there was great difficulty of STPs meet the tolerances for pathogenicity indicators for Class A sludge, especially virus scans. Another cool alternative found for use in sewage sludge agriculture is framed it as Organic Compound Fertilizer Product Class D, through the MAP. The sludge to be mixed with a carbon source, allows the temperature rise which would possibly allow the mass and pasteurizing the reduction or elimination of pathogenic organisms. Therefore, this project is consistent with the viability of the compound from sewage sludge (activated sludge and decantation pond) and 3 carbon sources (eucalyptus bark, sugarcane bagasse and rice husk) studying the composting process, the possible elimination of pathogens by the temperature rise, improving the quality of the compound of phosphorus and possible solubilization of natural phosphates in the process, substrate production from the compound, and production costs and the estimation of transport and application of composted sludge in forest area in the region. For it will install a composting yard in SABESP ETE - Botucatu, located within the FCA-Unesp, where part of the experiments will be developed. (AU)