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Abstract: Immersed membrane bioreactor (IMBR) has emerged as a novel potential technology which is considered globally as potent technology, primarily for wastewater treatment. It offers quality improvement in effluents treatment compared to other technological systems. It also offers potential benefits for the bioprocesses where product formation and separation is desired simultaneously in a compact container. This review gives insight for the wide range applications of IMBR focussing on anaerobiosis. It discusses the significance, advantages and drawbacks of IMBR against the conventional methods, highlighting the external membrane bioreactors. While the commercial significance of IMBR is obvious for industrial and municipal wastewater treatment, the current focus is shifting on other applications such as anaerobic bioprocesses. Though the IMBR technology is generally considered hand-in-hand as sustainable technology, the major bottleneck in its application at commercial scale for wastewater treatment seems its economic feasibility and compatibility. Among the technical issues, the membrane fouling is considered as a major problem for which several strategies have been developed to overcome the problem, though there is no complete or universal solution to this problem. [Copyright &y& Elsevier]

Abstract: The impact of anaerobiosis strategy on 1,3-propanediol production during cultivation of Clostridium butyricum VPI 1718 in different size bioreactors was studied. In batch trials with N2 gas infusion, the fermentation was successfully accomplished, regardless of initial glycerol concentration imposed and bioreactor geometry. However, in the absence of N2 continual sparging, significant variations concerning the biochemical response of the strain were observed. Specifically, at 1-L bioreactor, the absence of N2 infusion at high initial glycerol concentration induced lactate dehydrogenase activity and thus lactic acid synthesis, probably due to partial blockage of phosphoroclastic reaction caused by insufficient self-generated anaerobiosis environment. During fed-batch cultivation with continual N2 sparging, the strain produced ∼71gL−1 of 1,3-propanediol, whereas under self-generated anaerobiosis, 1,3-propanediol pathway was evidently restricted, as only 30.5gL−1 of 1,3-propanediol were finally produced. Apparently, N2 infusion strategy paired with bioreactor geometry can alter the biochemical behavior of the particular strain. [Copyright &y& Elsevier]

Abstract: Up-flow oxygen-controlled biofilm reactors equipped with a non-woven fabric support were used as a single reactor system for autotrophic nitrogen removal based on a combined partial nitrification and anaerobic ammonium oxidation (anammox) reaction. The up-flow biofilm reactors were initiated as either a partial nitrifying reactor or an anammox reactor, respectively, and simultaneous partial nitrification and anammox was established by careful control of the aeration rate. The combined partial nitrification and anammox reaction was successfully developed in both biofilm reactors without additional biomass inoculation. The reactor initiated as the anammox reactor gave a slightly higher and more stable mean nitrogen removal rate of 0.35 (± 0.19) kg-Nm−3 d−1 than the reactor initiated as the partial nitrifying reactor (0.23 (± 0.16) kg-Nm−3 d−1). FISH analysis revealed that the biofilm in the reactor started as the anammox reactor were composed of anammox bacteria located in inner anoxic layers that were surrounded by surface aerobic AOB layers, whereas AOB and anammox bacteria were mixed without a distinguishable niche in the biofilm in the reactor started as the partial nitrifying reactor. However, it was difficult to efficiently maintain the stable partial nitrification owing to inefficient aeration in the reactor, which is a key to development of the combined partial nitrification and anammox reaction in a single biofilm reactor. [ABSTRACT FROM AUTHOR]