Organic Compounds Responsible for the Fouling of Ultrafiltration Membrane Treating Algae-Laden Water.

Fouling comparisons of the organic fractions in surface and algae-laden waters make it possible to determine the main compounds responsible for the fouling of ultrafiltration (UF) membranes. This study examined the fouling of UF membranes and its relationship to the characteristics of the organic fractions found in drinking-water supply. Four types of water were prepared by combining natural organic matter (NOM) from lake water with algal organic matter (AOM) from four algae species commonly found in freshwater.

Biodegradation and Metabolism of Tetrabromobisphenol A (TBBPA) in the Bioaugmented Activated Sludge Batch Bioreactor System by Heterotrophic and Nitrifying Bacteria.

  Tetrabromobisphenol A [2,4'-isopropylidenebis(2,6-dibromophenol)] has been identified in wastewater samples collected from the Guelph municipal wastewater treatment plant (GWWTP). In order to assess the kinetics and metabolic mechanisms of the dissolved TBBPA, bench scale experiments were completed with batch bioreactors. The biodegradation test was conducted by taking aerobic sludge from the conventional activated sludge reactor (CAS) and membrane bioreactor (MBR), and bioaugmenting both reactors with soil based strains of Bacillus brevis and Bacillus pumilus.

Matrix interference reduction for the analysis of carbohydrate in wastewater using H-point standard addition method.

Soluble microbial products, consisting of protein, carbohydrate and humics, are generally considered as the main membrane foulants during the performance of membrane bioreactors. Nitrate and nitrite have been proved to affect the determination of carbohydrate when anthrone-sulfuric acid photometric method is used. In this study, three chemical analytical methods based on photometric assay, including the standard curve method, conventional standard addition method and H-point standard addition method, were assessed for the quantification of carbohydrate in order to reduce the interference.

Changes in hormone and stress-inducing activities of municipal wastewater in a conventional activated sludge wastewater treatment plant.

Conventional municipal wastewater treatment plants do not efficiently remove contaminants of emerging concern, and so are primary sources for contaminant release into the aquatic environment. Although these contaminants are present in effluents at ng-μg/L concentrations (i.e.

Pretreatment of poultry manure anaerobic-digested effluents by electrolysis, centrifugation and autoclaving process for Chlorella vulgaris growth and pollutants removal.

Different pretreatments (electrolysis, centrifugation and autoclaving) coupled with Chlorella vulgaris biological system was used for the treatment of poultry manure anaerobic-digested effluents. The pretreated effluents were used as the growth medium for algal cultivation. The pollutant removal efficiencies of the combined treatments were determined.

Filtration behaviour and fouling mechanisms of polysaccharides.

This study investigated filtration behaviors of polysaccharides solutions, both alone and in mixture with proteins, in the short-time constant flux filtration with the focus on factors affecting the transmembrane pressure (TMP) increase rate, the irreversible filtration resistance, and the membrane rejection behavior. The results showed that the TMP increase rates in the short-time constant flux filtration of alginate solutions were significantly affected by the calcium addition, alginate concentration, and flux. Although the addition of calcium resulted in a decrease in the TMP increase rate, it was found that the irreversible fouling developed during the filtration increased with the calcium addition, implying that the double-sided effect of calcium on membrane filtration and that the TMP increase rate observed in the filtration does not always reflect the irreversible membrane fouling development.

Removal of tetrabromobisphenol A by conventional activated sludge, submerged membrane and membrane aerated biofilm reactors.

The goal of this study was to compare removal efficiencies of tetrabromobisphenol A (TBBPA) using typical wastewater treatment technologies, and to identify the most significant mechanisms of removal. Two types of municipal wastewater reactors were studied: a full-scale conventional activated sludge (CAS) reactor with tertiary treatment; and three pilot-scale membrane bioreactors (MBRs) having different sludge retention times (SRTs). All four reactors were fed the same influent.

Interference by the activated sludge matrix on the analysis of soluble microbial products in wastewater.

The objective of this study was to demonstrate the effects of complex matrix effects caused by chemical materials on the analysis of key soluble microbial products (SMP) including proteins, humics, carbohydrates, and polysaccharides in activated sludge samples. Emphasis was placed on comparison of the commonly used standard curve technique with standard addition (SA), a technique that differs in that the analytical responses are measured for sample solutions spiked with known quantities of analytes. The results showed that using SA provided a great improvement in compensating for SMP recovery and thus improving measurement accuracy by correcting for matrix effects.

Influence of filtration conditions on membrane fouling and scouring aeration effectiveness in submerged membrane bioreactors to treat municipal wastewater.

Membrane fouling and scouring aeration effectiveness were studied using three large pilot-scale submerged membrane bioreactors (MBRs) operated at a series of permeate fluxes, scouring aeration intensities and cyclic aeration frequencies to treat municipal wastewater. The results showed that when operated at the sustainable conditions, the MBRs had a stable reversible fouling resistance. At unsustainable conditions, the reversible fouling resistance increased exponentially as filtration progressed.

Use of chemical coagulants to control fouling potential for wastewater membrane bioreactor processes.

Chemical coagulation with ferric chloride, alum, and an organic polymer were used to control the fouling potential of mixed liquors for submerged membrane bioreactor (MBR) processes in treating municipal wastewater. Their filterability was evaluated using a submerged hollow fiber ultrafiltration apparatus operated in constant permeate flux mode. The collected transmembrane pressures over filtration time were used to calculate the membrane fouling rates.

Interrelated effects of aeration and mixed liquor fractions on membrane fouling for submerged membrane bioreactor processes in wastewater treatment.

The interactions of mixed liquor fractions and their impacts on membrane fouling were examined at different sparging aeration intensities for submerged hollow-fiber membrane bioreactors (MBR) in wastewater treatment. The mixed liquor samples were fractioned by size into MLSS, colloids quantified by colloidal TOC, and dissolved solutes. The experimental results showed that their significance in membrane fouling was strongly related to aeration intensity.

Membrane filtration coupled with chemical precipitation to treat recirculating aquaculture system effluents.

Effluents from recirculating aquaculture systems (RAS) contain high concentrations of nitrogen and phosphorous wastes and thus often require proper treatment to prevent potential detrimental impacts on receiving water bodies. The purpose of this study was to evaluate the feasibility of membrane filtration coupled with chemical precipitation as a pretreatment step with emphasis on phosphorus removal from RAS effluents. Chemical precipitation tests were conducted by adding magnesium chloride and alum at different chemical concentrations and pH values, respectively.

Identification of wastewater sludge characteristics to predict critical flux for membrane bioreactor processes.

The effects of sludge characteristics on critical flux were examined using a submerged membrane bioreactor pilot plant operated under different process conditions to treat municipal wastewater. The sludge in the membrane tank was characterized by measuring colloidal particle concentration, extracellular polymeric substances (EPS), mixed liquor suspended solids (MLSS), temperature, time to filter (TTF) and diluted sludge volume index (DSVI). The colloidal particle concentration was represented by the colloidal total organic carbon (TOC), which is the TOC difference between the filtrate passing through a 1.