Enhanced sewer self-purification with porous media: Performance evaluation with various organic loading rates and flow intermittency

Abstract

Enhanced sewer self-purification is an emerging technology which supports wastewater management. To support this, we studied the removal performance of channels for enhanced sewer self-purification. Effects of organic loading rate and flow intermittency on the aerobic removal performance of biomass grown on porous sponge media were investigated. Biomass was developed until media surface clogging occurred inside two airtight channels named channel A and B, respectively. Headspace-gas oxygen consumption rates were considered as the aerobic removal performance. During surface clogging, oxygen consumption rates ranged between 12.0–16.3 gO2 m−2 d-1 for channel A fed with peptone and oleic acid and 33.2–52.4 gO2 m−2 d-1 for channel B fed with oleic acid only. The effect of flow intermittency was investigated after biomass detachment. The rates for each channel after biomass detachment were 26.6–39.7 gO2 m−2 d-1 for channel A and 78.8–88.3 gO2 m−2 d-1 for channel B. Findings highlight that even with a fully clogged surface, aerobic removal is still 63–73 % of the highest recorded rates after biomass detachment. Further, rates increased with increased organic loading rates, remained stable even with very low organic loading rate, was influenced by the type of organic substrate used, and did not significantly change with intermittent flow.