Faecal Sludge Treatment and Circular Economy: A Case Study Analysis

Abstract

With the success of Swachh Bharat Mission in building toilets for all, faecal sludge is an undeniable outcome of the intervention. The faecal sludge from the on-site sanitation systems such as septic tanks and pits has to be safely managed to convert it to resource-recoverable by-products. From the sanitation circular economy, management of faecal sludge should benefit the environment by generation of less waste, promote innovation and develop markets for reuse of the by-products. The chemical characteristics of faecal sludge show high nitrogen, phosphorus, carbon, moisture as well as high gross calorific value. The paper presents the case study of faecal sludge treatment plant (FSTP) based on thermal technology in context with circular economy. The recovered resources are evaluated in terms of economy and assessments are made to make it a case for economic model through revenues by exploring new avenues for its resource utilization. With more research and development in the field of utilization of the FSTP output resources in diversified areas, FSTPs can play a pivotal role in the sanitation circular economy, especially in addressing the sanitation value chain on the whole. Thermal FSTP utilizes the process thermal energy to achieve biosafety of the by-products, and the design is innovatively integrating nutrient recovery, water recovery and energy recovery during the faecal sludge treatment. The thermal treatment process converts faecal sludge into biochar, treated water and thermal energy. These recovered resources have the potential to positively contribute to the circular economy, which is scientifically analysed in this paper.