Pilot Scale Modified High-Rate Contact Stabilization Process for Energy-Neutral Wastewater Treatment

Abstract

Our study explores the performance of a pilot-scale modified high-rate contact stabilization (HiCS) process for the first time. In this study, the amount and composition of extracellular polymeric substances (EPS) produced by the HiCS under different operating conditions (hydraulic retention time (HRT), dissolved oxygen (DO), sludge retention time (SRT) and influent carbon/nitrogen ratio) and organic carbon, nitrogen and phosphorus removal efficiencies are investigated. Increasing the organic matter harvesting from wastewater will be achieved with the operation of the bioreactor at short SRTs and recycling a part of stabilized sludge to the primary settling tank to improve the bioflocculation and improving organic matter harvesting. In the pilot plant, effluent COD concentrations varied between 80-200 mg/L, corresponding to COD removal efficiencies of 60 to 80%. Compared to stabilization tank, around 20% increase in the EPS production was observed in the contact tank. The modified pilot scale high-rate CS process in our study performed better than its counterparts in the literature. Therefore, the developed process seems promising for using it in full-scale applications.