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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]

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]

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]