Optimized scaling-up towards commercial ultrafiltration-pre-concentration-based integrated sewage resource recovery for cleaner production

Abstract

The technical and economic feasibility of sewage-pre-concentration-based resource recovery for cleaner production (CP) subject to scaling up remains unknown. A pilot-scale ultrafiltration (UF) pre-concentration system, which optimizes the use of UF, enhanced coagulation process (ECP) and air-backflushing (AB), is established coupling with anaerobic digestion (AD) in this study to demonstrate its scaled-up performance of CP-oriented integrated resource recovery. Results show that 90% of organic matter recovery is achievable with only 2–3% of mineralization under optimized AB during over 100d operation. The efficient and stable concentration performance mainly results from cake layer induced by optimized AB with minimal carbon loss and maximal productivity. AD of the optimized concentrate obtained a methanisation of 61.3% and a digestate with improved dewaterability and pathogens limitation for efficient nutrient recovery. Energy balance of the whole system in different working scenarios reveals that the optimized net energy production was 0.2537 kWh/m3. Considering integrated permeate reclamation and energy and nutrient recovery with similar case study, the whole system in optimized scenario could achieve a net operational profit of 0.9188 CNY/m3 with a minimized payback time of approximately 6 years, which is a moderate and acceptable value. Above results demonstrate the promise of implementation of UF pre-concentration for sustainable CP-oriented integrated resource recovery.