Reduced sludge production in a polyvinyl alcohol gel-based oxic-anoxic-oxic configured pilot-scale plant

Abstract

Sludge production in wastewater treatment is one of the main offsets in the operation and maintenance of a biological wastewater treatment plant (WWTP). One of the primary management strategies can be curtailing the production in a liquid treatment stream. A polyvinyl alcohol (PVA) gel-based oxic-anoxic-oxic process was investigated for the wastewater treatment performance and reduced sludge production. Average removal of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), and ammonia were >90% at 4.4 and 5 hours hydraulic retention time. The average specific sludge production was 0.41 ± 0.15 kg VSS/kg BOD removed in the reactor system. After modeling the sludge production in the oxic-anoxic-oxic settling process, it best fits at a yield coefficient (Y) of 0.053, which was 1/10th of the typical Y value in conventional WWTPs. The results and comparative assessments indicate that the treatment process can support sludge reduction and satisfactory wastewater treatment performance. The pilot-scale plant discharges high-quality effluent water that meets the new and more stringent standards and is fit for reuse, i.e., circular economy. It is a promising and sustainable system suitable for developing countries with varying temperatures.

Keywords

• Integrated fixed-film activated sludge process
• Biofilm process
• Biological wastewater treatment
• Sludge reduction
• Yield coefficient