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This work presents the preparation and modification of hybrid Mg(OH)2/chitosan blended PES membranes with the aim of improving the hydrophilic, antifouling and performance of the resulting membranes. The deposition of additives by blending the polymer with a concentration of 1%, 3%, 5%, and 7% on PES membranes. The influences from varying concentrations of additives were evaluated by analyzing changes in chemical groups, changes in morphological structure, hydrophilicity degree, porosity, filtration properties, and the antifouling propensity of the fabricated membrane. PES membranes with the addition of 5% additive (MC-5) showed the best performance biggest degree of hydrophilicity compared to the other membranes. In terms of performance, the MC-5 membrane produces a PWP of almost 15 folds bigger than that of unmodified PES, with a rejection value of 68.2% and a water flux recovery ratio (FRw) of 82.7%. [ABSTRACT FROM AUTHOR]

Focuses on a novel sewage treatment system, which consists of an upflow anaerobic sludge blanket (UASB) pre-treatment unit and the following downflow hanging sponge (DHS) unit for polishing up the UASB effluent which was developed as a cost-effective and easy-maintenance sewage treatment system for developing countries.

The second generation of our originally proposed sewage treatment system, which consists of a UASB reactor as an anaerobic pre-treatment unit and curtain-type DHS (downflow hanging sponge) reactor as an aerobic post-treatment unit, was installed at a municipal sewage treatment site. A 550-day continuous experiment demonstrated that the whole combined system successfully achieved 94-97% of unfiltered-BOD removal, 81-84% of unfiltered-COD removal, and 63-79% of SS removal, at an overall HRT of 8 h (6 h for UASB and 2 h for DHS units). The combined system performed an excellent organic removal as well as a fairly efficient nitrification, i.e. 52-61% of ammonia-nitrogen removal. Our proposed combined system possesses prominent advantages: requiring neither external aeration input nor excess sludge withdrawal. [ABSTRACT FROM AUTHOR]

Fluorescence in-situ hybridization (FISH) and DO microelectrodes were applied to biofilms developed in a novel reactor named DHS (downflow hanging sponge-cubes), to investigate the mechanisms of simultaneous carbon removal and nitrification. The DHS reactor was employed as an aerobic post-treatment process after an UASB anaerobic pre-treatment process receiving a municipal sewage. The presence ratio of Nitrosomonas and Nitrobacter cells to total cells of the DHS biomass was estimated by FISH technique to be 1.4% and 0.18%, respectively. Cell concentrations of both nitrifying bacteria were in good agreement with the magnitudes of ammonia-oxidizing and nitrite-oxidizing activities evaluated from batch tests. The habitats of both nitrifiers were the interior space of sponge-cubes, rather than within the biofilms attached onto sponge-cube surfaces. DO microelectrodes verify that the sponge-cubes insides were kept aerobically throughout the whole reactor height excluding the inlet vicinity portion. [ABSTRACT FROM AUTHOR]

A novel sewage treatment system was proposed, which consists of a UASB anaerobic pretreatment unit and the following DHS (downflow hanging sponge-cubes) aerobic posttreatment unit, as a low-cost and easy-maintenance process for developing countries. Over six months experiment by feeding sewage our proposed system achieved 94% of total-COD removal, 81% of soluble-COD removal. and nearly perfect SS removal and total-BOD removal at the overall HRT of 8.3 hr (7 hr in UASB and 1.3 hr in DHS unit). Moreover, the DHS reactor was capable of performing high (73--78%) nitrification. Our whole system requires neither external aeration input nor withdrawal of excess sludge. (c) 1997 IAWQ. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]