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Ensuring the effluent quality despite fluctuations in influent flow rate and organic load to municipal wastewater treatment plants is critical. This study investigated the performance of a membrane bioreactor (MBR) in handling hydraulic and organic loading shocks during wastewater treatment. The ability of the MBR to remove COD, BOD5, and turbidity from synthetic wastewater was evaluated at steady-state and after applying five levels of organic shock loads (1.5×-4×) and four levels of hydraulic shocks (1.2×-4.7×). Due to the short-term shock-loadings no discernible effect was observed on the mixed liquor suspended solids implying biological stability. The average COD removal in MBR exposed to organic and hydraulic shock loads was 93.8% and 94%, respectively, similar to average BOD5 removals of 94.4% and 93.6%. The membrane retained suspended particles well throughout the process. However, it became quickly fouled only by applying a strong hydraulic shock. The MBR guaranteed the quality of the effluent. [ABSTRACT FROM AUTHOR]

Membrane costs and biofouling limit applications of membrane bioreactors (MBRs) for wastewater treatment. Here, powdered activated carbon (PAC) utilization in the formation and performance of a self-forming dynamic membrane consisting of activated sludge and PAC during hybrid wastewater treatment process was studied. Short-term agitation helped (non)biological particles to quickly uniformly settle on mesh filter, forming more uniform PAC-containing dynamic membranes (PAC-DMs). PAC adsorbed adhesive materials, resulting in an increase in average floc size and DM permeability while decreasing biofouling. The most efficient PAC concentration was 4 g L−1 considering techno-economics, i.e. the highest effluent quality (turbidity of 19.89 NTU) and the lowest biofouling (transmembrane pressure rise of 2.89 mbar). Short-term performance of hybrid PAC-DM bioreactor (PAC-DMBR) showed stability in effluent quality improvement including 92%, 95%, 83%, 84% and 98% reductions in turbidity, chemical oxygen demand, total dissolved solids, total nitrogen, and total phosphorous, respectively. Accordingly, adopting hybrid PAC-DMBR has potential to alleviate biofouling and capital cost. [ABSTRACT FROM AUTHOR]

The aim of this research is benefiting from the synergistic effect of the simultaneous presence of Fe3O4 and ZrO2 in the form of Fe3O4-coated ZrO2 (Fe3O4@ZrO2) nanoparticles within the structure of PAN membrane to reduce membrane fouling. The role of Fe3O4 nanoparticles in increasing the pore size and magnetic saturation as well as the role of ZrO2 in decreasing surface roughness and hydrophobicity can mitigate membrane fouling in magnetic-assisted membrane bioreactors. For this purpose, Fe3O4, ZrO2, and Fe3O4@ZrO2 nanoparticles were embedded into PAN membrane structure and magnetic (MnM), hydrophilic (HnM), and magnetic-hydrophilic (HMnM) membranes were synthesized. H1M (1ZrO2/PAN) membrane with a contact angle of 31 degrees, M1N (1Fe3O4/PAN) with a pore size of 90 nm, and H3M (3ZrO2/PAN) membrane with an RMS roughness of 13.5 nm were the most hydrophilic, porous, and smoothest membranes, respectively. High sensitivity to magnetic field along with high porosity, high hydrophilicity and low surface roughness simultaneously exist within the structure of MHMs membranes, such that MH1M (1Fe3O4@ZrO2/PAN) indicated 116% greater flux, 121% greater flux recovery, and 85% less total filtration resistance in comparison with the blank membrane in magnetic membrane bioreactor, at a magnetic field intensity of 120 mT and MLSS = 10,000 mg/l. As an overall conclusion, the output of this research was compared with other research in term of normalized flux. Results reveal that at MLSS = 10,000 mg/l, HRT = 8 h and TMP = 0.3 bar, MH1M membrane has normalized flux equal to 1.56 g/m2 h bar which is an acceptable value compared to normalized flux reported by other researchers. [ABSTRACT FROM AUTHOR]

In this work the influence of fabrication conditions (ion strength, surfactant utilization) on the macro- (particle size distribution, PSD) and microscopic [pore size distribution (PoSD), specific surface area] structure of agarose beads was investigated. The main purpose was achieving uniform sized and porous beads with improved mechanical strength for bioseparation and chromatography applications. Therefore, PSD, PoSD, mechanical resistance, and flux through packed bed of the fabricated beads (4, 6, and 8% wt/wt) were analyzed. Based on porosimetry results, it was found that increasing ion concentration or presence of surfactant (the key variable for narrowing PSD) decreases the span value of PSD (p-value <0.05); thus, leading to a more uniform distribution. Moreover, as a result of controlling PSD, the PoSD changes from micro- to meso- and macropores in higher ion charged solutions. Furthermore, the obtained PoSD affects mechanical resistance of the prepared microspheres either as single beads or packed in a column. Mesoporous 6%-agarose beads showed the highest flux due to elevated mechanical resistance and elastic characteristic. Mesoporous 4%-beads showed the highest elasticity, and thus lower flux through column. These results demonstrate that manipulation of both macro- and microscopic characteristics of the beads should be commensurate with the intended application i.e., bioadsorption chromatography. [ABSTRACT FROM AUTHOR]

In this research membrane bioreactor (MBR) technology as a novel and practical technology was studied for treatment of saline petrochemical wastewater. Membrane fouling and permeability, mixed liquor properties such as change of flock size, and effluent characteristics of MBR were measured in presence of various salt concentrations in the feed. The results showed that the increasing the salinity reduced cake layer, total membrane resistances and increased the membrane permeability and sludge particle size. Also, COD removal efficiencies were up to 91% in all trials. These results indicate that the MBR was highly efficient for treating saline petrochemical wastewater. [ABSTRACT FROM PUBLISHER]

This study investigated the long-term filtration of mesh filter with the formed dynamic membrane in bioreactor. The trend of transmembrane pressure (TMP) variations highly corresponded to the thickness and compactness index of dynamic membrane. The dynamic membrane was fractionated by applying two cleaning protocols, that is, rinsing and chemical cleaning. The desorbed fraction, consisting of soluble microbial products (> 70%), provided a stickiness surface for formation of consecutive biomass layer which featured a high concentration of extracellular polymeric substances (> 75%). The chemical oxygen demand (COD) removal was 70%, 89%, and 92% for period of 0–26, 26–49, and 49–67 day, respectively, which indicated that further development of dynamic membrane increased the TMP without improvement in the effluent quality (TMP: 50–200 mbar, COD removal: 89%; TMP: 200–600 mbar, COD removal: 92%). The averageand TN removal was about 76% and 21%, respectively. The effluent turbidity fell less than 2 NTU after 26 days of filtration. [ABSTRACT FROM PUBLISHER]

A novel method was developed to assess the viability of activated sludge present in a biological wastewater treatment process and signify its distinction from respirometric activity. The respirometric activity and viability of activated sludge at high cell density, such as typically encountered in membrane bioreactors, were investigated in batch and fed-batch systems. The method for measuring the viability of activated sludge was based on the sludge permittivity monitored online by a capacitive sensor. Results from permittivity measurement were compared with usual biological activity measurement through oxygen uptake rate determination. The similar downward trend was observed for both measurements. The respirometric activity and permittivity, respectively, reduced to 50% and 68% of initial value in the fed-batch system and 18% and 27% of initial value for the batch system which was due to quantitative and qualitative changes in the microbial culture in the activated sludge. The novel method allows to made distinction between viable versus dead and inactive versus active microbial cells in the activated sludge system and can be used for better and more efficient control of the biological processes. [ABSTRACT FROM PUBLISHER]