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A pilot scale membrane bioreactor hybrid system (MBR-HS) was evaluated for municipal wastewater treatment. This novel system comprised of a granular activated carbon-sponge fluidized bed bioreactor (GACS-FBBR) followed by a submerge membrane bioreactor (MBR) with the capacity of 2 L/min. The results indicated that the MBR-HS could effectively remove 90% DOC and 95% NH₄-N. PO₄-P removal efficiency was remained stable at about 70% throughout the experiment. Specific oxygen uptake rate (SOUR) of activated sludge increased from 0.72 to 2.21 mg O₂/g VSSh for the first 10 days and then followed by a steady stage until the end of experiment. Sludge volume index (SVI) was always below 50 mL/g, demonstrated an excellent settling properties of sludge. The system also showed an achievement in terms of low trans-membrane pressure (TMP) development rate. The TMP increasing rate was only 0.65 kPa/day, suggesting GACS-FBBR can be a promising pre-treatment for MBR., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The performance of a novel sponge-submerged membrane bioreactor (SSMBR) was evaluated to treat primary treated sewage effluent at three different activated sludge concentrations. Polyurethane sponge cubes with size of 1 × 1 × 1 cm were used as attached growth media in the bioreactor. The results indicated the successful removal of organic carbon and phosphorous with the efficiency higher than 98% at all conditions. Acclimatised sponge MBR showed about 5% better ammonia nitrogen removal at 5 and 10 g/L sludge concentration as compared to the new sponge system. The respiration test revealed that the specific oxygen uptake rate was around 1.0-3.5 mgO(2)/gVSS.h and likely more stable at 10 g/L sludge concentration. The sludge volume index of less than 100 mL/g during the operation indicated the good settling property of the sludge. The low mixed liquor suspended solid increase indicated that SSMBR could control the sludge production. This SSMBR was also successful in reducing membrane fouling with significant lower transmembrane pressure (e.g. only 0.5 kPa/day) compared to the conventional MBR system. Further study will be conducted to optimise other operating conditions.

The membrane bioreactor system (MBR) with pre-treatment of sponge tray bioreactor (STB) was evaluated at different operating conditions for treating primary treated sewage (PTS). The result indicated the successful removal of DOC with the efficiency of higher than 95%. The highest nutrient removal efficiency of 83.6% (NH(4)-N) and 75.5% (PO(4)-P) was observed at sludge concentration of 330 mg/L. Specific oxygen uptake rate (SOUR) of activated sludge in MBR kept increasing up to 6 mg O(2)/g VSS h during stage IV. The sludge volume index (SVI) of less than 100mL/g during the operation indicated the good settling property of the sludge. At highest sludge concentration of 5 g/L, trans-membrane pressure (TMP) was increasing dramatically during first 15 d up to 25 kPa; however it was only 6 kPa at lower sludge concentrations. It is concluded that the system showed the highest performance at stage III with sludge concentration of 330 mg/L., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The new attached growth sponge tray bioreactor (STB) was evaluated at different operating conditions for removing organics and nutrients from primary treated sewage effluent. This STB was also assessed when using as a pre-treatment prior to micro-filtration (MF) for reducing membrane fouling. At a short hydraulic retention time (HRT) of 40 min, the STB could remove up to 92% of DOC and 40-56% of T-N and T-P at an organic loading rate (OLR) of 2.4 kg COD/m(3) sponge day. This OLR is the best for the STB as compared to the OLRs of 0.6, 1.2 and 3.6 kg COD/m(3) sponge day. At 28 mL/min of flow velocity (FV), STB achieved the highest efficiencies with 92% of DOC, 87.4% of T-P, and 54.8% of T-N removal. Finally, at the optimal OLR and FV, the STB could remove almost 90% of organic and nutrient, significantly reduce membrane fouling with HRT of only 120 min., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The effects of polyurethane sponge size and type on the performance of an up-flow sponge bioreactor were studied using different sponge cube sizes (1 x 1 x 1 cm, 2 x 2 x 2 cm and 3 x 3 x 3 cm) and types of sponge (S28-30/45R, S28-30/60R, S28-30/80R and S28-30/90R). The reactors were operated under anaerobic conditions in an early stage and an aerobic condition in a latter stage. The results indicate that there was no significant difference in the organic and nutrient removal rates between sponge types. The medium size sponge (2 x 2 x 2 cm) had the best performance in terms of both biomass growth and pollutants removal. Under anaerobic condition, the COD, TN and TP removal efficiencies were up to 70%, 45% and 55%, respectively, and significantly improved under aerobic conditions (e.g. >90% TOC, 95% COD, 65% TN and 90% TP). The external biomass grew faster under anaerobic conditions while internal biomass was dominant under aerobic condition., (2009 Elsevier Ltd. All rights reserved.)

Abstract: In this study, laboratory-scale anaerobic fluidized bed bioreactors (AFBBRs) using granular activated carbon as bedding material were employed for treating a primary treated sewage effluent (PTSE) with or without refractory organic pollutants (ROPs). A new starch based flocculant (NSBF) combining a nature starch based cationic flocculants and trace nutrients was prepared and applied in the AFBBR. The impact of NSBF on the performance of AFBBR was mainly evaluated in terms of organic and nutrient removal and microbial activity. Membrane fouling based on critical flux was assessed when the bioreactor used as pretreatment for microfiltration. The results indicated that the addition of NSBF in AFBBR (NSBF–AFBBR) not only attained improved organic (9–10%) and nutrient removal (10–20%), higher biomass growth (3.0gbiomass/LGAC) and net bed expansion (18cm), but also doubled the critical flux (from 15L/m3 h to 30L/m3 h) in the microfiltration system. In addition, NSBF–AFBBR could retain 10% better DOC removal efficiency at different recirculation rates for treating PTSE with ROPs. When increasing organic loading rate from 21.6kgCOD/m3 d to 43.2kgCOD/m3 d, NSBF–AFBBR achieved comparatively constant organic removal of 55% whereas the efficiency in AFBBR alone decreased dramatically from 47% to 34%. Thus, NSBF could act as a performance enhancer for AFBBR. [Copyright &y& Elsevier]

Abstract: This study aims at evaluating the impacts of flocculant addition to a submerged membrane bioreactor (SMBR). Three types of common flocculants (FeCl3, PACl and chitosan) were tested based on the performance of organic and nutrients removal, respiration test and fouling control. The data showed that all of the flocculants not only could keep high removal efficiencies of DOC and COD (>90%) compared to SMBR alone, but also exhibited different advantages and disadvantages according to the properties of the flocculants. For instance, inorganic flocculants strongly affected the nitrification process and organic flocculant addition slightly reduced the phosphorus removal efficiency in SMBR. After adding FeCl3 and PACl, NH4-N removal decreased to 31.9% and 11.1%, while T-N removal dropped to 22% and 0.5% respectively. Although flocculants addition improved sludge settleability and oxygen transfer to some extent, organic flocculant obtained more stable sludge volume indexes (SVI) and specific oxygen uptake rates (SOUR) than those of inorganic flocculants. Inorganic flocculants, on the other hand, led to more reduction of soluble microbial products (SMP) present in mixed liquor and lower membrane fouling rates (1.3 and 2.6kPa/day for FeCl3 and PACl respectively). [Copyright &y& Elsevier]