TECHNICAL EVALUATION OF SEWAGE SLUDGE PROCESSING TECHNOLOGIES IN INDIA

Abstract

n India, approximate sewage generation from urban centres estimated as 72,368 million litre per day (MLD) with around 35% treatment capacity available nationally. Hence, the sewage sludge produced in STPs is also increasing. Total sludge generation in India is estimated to be 3200 tons per day (dry basis). The previous study conducted by the IIT Roorkee revealed that most of the dewatered sludge satisfies the desired limits of pathogen and heavy metal concentrations set by US EPA Class B Biosolids in India. Class B criteria are restricted for agricultural applications, especially edible parts of crops that should not be exposed to the soil/sludge. Also, it is restricted for grazing of animals, restricted public contact- the risk of exposure etc. Hence, there is a need for effective treatment technologies to manage the dewatered sludge. Thus, the present study evaluates the techno-economical aspects of existing sludge stabilisation technologies in India. Specifically, the composting, thermal treatment, sludge drying bed, solar sludge drying bed, and anaerobic digester technologies are analysed in terms of their mass balance and economic viability. Mass balance and cost analysis were conducted for sludge composting, thermal treatment, sludge drying bed and solar sludge drying bed. Further, each technology's inlet and outlet's physio-chemical and microbiological parameters are assessed. The findings of this study provide valuable insights into the efficiency and cost-effectiveness of different sludge stabilisation technologies and contribute to the development of sustainable and environmentally friendly solutions for the management of sludge in India.