Nitrogen mass balance and microbiological safety of recovered resources at Lubhu FSTP (Nepal)

This research aimed to develop optimization strategies to maximize the recovery of nitrogen in treated effluent and dried sludge produced at Lubhu faecal sludge treatment plant (FSTP) so as to ensure their biological safety for reuse. The fate of nitrogen, E. coli and helminths eggs removal in each treatment unit of LFSTP were investigated by taking dried sludge, faecal sludge and effluent samples at the inlet and outlet of each treatment unit and analysing them in the laboratory. It was shown that LFSTP can recover 350 kgN/year in dried sludge and 182 kgN/year in liquid effluent. However, the concentration of E. coli and the presence of helminths in both treated effluent and dried sludge were not meeting the recognized standard in different countries for faecal sludge reuse. Further treatment technologies were, therefore, suggested to improve the treatment process and meet the standards. Among proposed options were lime stabilization for treated effluent and vermicomposting for dried sludge.