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An alternative design of the membrane aerated biofilm reactor (MABR) was developed to overcome some of the current technical and economical limitations preventing full scale applications of the process. The ZeeLung TM system uses a new dense hollow-fibre membrane with an unprecedented thin diameter. Two pilot units treating a synthetic high-strength industrial wastewater (4700 mgCOD/L, 145 mgTKN/L) operated successfully for 16 months. They performed simultaneous COD removal, nitrification and denitrification. The very high specific surface area (810 m 2 /m 3 ) allowed the surface loading rate to be kept low enough (3.6 gCOD/(m 2 .d)) to maintain a relatively thin biofilm (200 to 350 mm) and use low-pressure air (41 kPa) instead of high-pressure pure oxygen. Intermittent air and liquid mixing at high frequency and low shear were compared: they were equally effective in enhancing substrate transfer, but failed to stabilize biofilm accumulation. Air sparging additionally prevented the acidification of the bulk by stripping CO 2 . Water Environ. Res., 83, 3 (2011).

A new hybrid membrane-aerated biofilm reactor (MABR) technology that enables energy-neutral treatment of municipal wastewater is introduced. The process, which removes nitrogen using conventional nitrificationdenitrification, was demonstrated at pilot-scale, treating primary effluent. The new MABR membrane product can operate in a high mixed liquor suspended solids (MLSS) environment, making it suitable for use in a conventional activated sludge reactor to increase oxygen transfer and nitrification capacity. The pilot achieved removal rates of 91% for TSS, 83% for COD, 95% for ammonia, and 66% for total inorganic nitrogen. MABR technology has the potential to transfer oxygen very efficiently, at an aeration efficiency of 6 kg O 2 /kWh.

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Thermal hydrolysis (TH) and biological hydrolysis (BH) are two main and growing anaerobic digestion pretreatment technologies. In this study, municipal wastewater sludge samples were collected from the Guelph Wastewater Treatment Plant (WWTP) in Ontario, Canada. The effects of temperature on BH treatment, including BH at 42 °C (BH42), 42 °C followed by 55 °C (BH42+55), 55 °C followed by 42 °C (BH55+42), and 55 °C (BH55) were evaluated for anaerobic digestion performance enhancement and compared with TH treatment at 165 °C. The TH, BH42, BH42+55, BH55+42, and BH55 treatments caused the reduction of volatile suspended solids (VSS) by 22.6%, 17.5%, 24.6%, 23.1%, and 25.9%, respectively. The soluble chemical oxygen demand (sCOD) content of the sludge increased by 377.5%, 323.8%, 301.3%, 286.9%, and 221.7% by the TH, BH55, BH42+55, BH55+42, and BH42 treatments, respectively. Volatile fatty acids (VFA) constituted around 40% of the sCOD in the BH-treated sludge and 6% in the TH-treated sludge. The cumulative methane yields (NmLCH4/g COD fed) of sludge treated by BH55+42 and TH were respectively 23% and 20% higher than that of the untreated sludge. For BH pretreatment, sludge treated by BH55+42 produced more methane than those treated by BH42+55, BH55, and BH42. The methane yields of the combined sludge treated by the TH and BH55+42 treatments were in the ranges of 248.9 NmLCH4/g COD to 266.1 NmLCH4/g COD fed, and 255.3 NmLCH4/g COD to 282.2 NmLCH4/g COD fed, respectively.

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