Sludge Management: Biosolids and Fecal Sludge

Abstract

Sludge, biosolids, and faecal sludge are generated during management of wastewater and the contents of latrines. The direct disposal of untreated sludge is not desirable because it: 1) has odors, 2) is comprised primarily of water which makes transport and disposal expensive, and 3) contains harmful environmental pollutants and pathogens. Several processes can decrease pathogen concentrations in sludge: 1) stabilization, 2) thickening, 3) dewatering, and 4) other processes that include composting. Stabilization uses biological, chemical, and/or thermal processes to reduce organic matter, water content, and odors and also provides some pathogen reduction. Thickening and dewatering can reduce volume and increase the concentration of total solids. Thickening is performed prior to stabilization while dewatering is the final method of volume reduction before ultimate disposal of stabilized sludge (drying beds and mechanical processes). Other methods of sludge processing including composting, heat drying, and combustion