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The prime objective of the present study is to evaluate the performance of novel up-flow anaerobic hybrid membrane bioreactor (An-HMBR) treating high-strength wastewater (synthetic) using polyurethane foam as filter media. Treatment efficiency of the entire An-HMBR varied from 88-97% corresponding to 0.67-3.90 d of hydraulic retention time (HRT) with organic loading rate of 6.4-1.06 kg COD m d. The modified Stover-Kincannon model was the most appropriate model for An-HMBR and anaerobic hybrid bioreactor (excluding membrane). The suspended growth system in An-HMBR could be described by both modified Stover-Kincannon and Grau second order model. The attached growth system in An-HMBR followed conventional Monod's kinetics. A novel combination of suspended, attached and membrane in single reactor increased the solid retention time to as high as 756 d at 3.9 d HRT which not only improved the COD removal efficiency but also enhanced the performance of the membrane.

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The performance and chemical oxygen demand (COD) mass balance of a lab‐scale anaerobic hybrid membrane bioreactor (An‐HMBR), treating high strength wastewater, at mesophilic temperature, was investigated. Long‐term (275 days) operation was carried out at various hydraulic retention times (HRTs), namely, 3, 2, 1, and 0.5 days corresponding to organic loading rate (OLR) of 1.06, 1.6, 3.2, and 6.4 kg COD/m3d, respectively. An‐HMBR achieved, COD removal of 97–87% at HRT of 3–0.5 days, respectively. The study showed that polyurethane foam as attached growth media adsorbed mixed liquor suspended solids and thereby reduced the load on the membrane by 42%. During COD mass balance, an additional 4–5% of COD balance was achieved by consideration of COD conversion to biomass. The results suggest that unknown COD fraction varies between 33 and 37%, which was attributed to the loss of gaseous as well as oversaturation of dissolved methane. Consideration of oversaturation leads to a COD mass balance of over 95%.