Low-cost, reliable, and highly efficient removal of COD and total nitrogen from sewage using a sponge-filled trickling filter

Abstract

Development of low-cost and reliable reactors demanding minimal supervision is a need-of-the-hour for sewage treatment in rural areas. This study explores the performance of a multi-stage sponge-filled trickling filter (SPTF) for sewage treatment, employing polyethylene (PE) and polyurethane (PU) media. Chemical oxygen demand (COD) and nitrogen transformation were evaluated at hydraulic loading rates (HLRs) ranging from 2 to 6 m/d using synthetic sewage as influent. At influent COD of ∼350 mg/L, PU-SPTF and PE-SPTF achieved a COD removal of 97% across all HLRs with most of the removal occurring in the first segments. Operation of PE-SPTF at an HLR of 6 m/d caused substantial wash-out of biomass, while PU-SPTF retained biomass and achieved effluent COD 0.99) to a first-order kinetic relationship. For a comparable COD removal, CO2 emission by PU-SPTF was 3.5% of that of an activated sludge system. HIGHLIGHTS A sponge-filled trickling filter (SPTF) system with random packing of sponge media is examined for sewage treatment.; COD removal of 97% was achieved in both PE-SPTF and PU-SPTF at an HLR of 6 m/d and feed COD 350 mg/L.; Total nitrogen removal was 93 and 92% by PE-SPTF and PU-SPTF reactors, respectively.; Energy consumption in SPTF is ∼25 times lower than that in a conventional activated sludge process.;

Keywords

• co2 emission
• low-cost sewage treatment
• polyethylene sponge media
• polyurethane foam media
• total nitrogen removal
• trickling filter