It has been recognized by the whole world that textile industry which produce large amounts of wastewater with strong color and toxic organic compounds is a major problematical industry requiring effective treatment solutions. In this study, reverse osmosis (RO) membranes were tested on biologically treated real dye bath wastewater with and without pretreatment by nanofiltration (NF) membrane to recovery. Also membrane fouling and reuse potential of membranes were investigated by multiple filtrations. Obtained results showed that only NF is not suitable to produce enough quality to reuse the wastewater in a textile industry as process water while RO provide successfully enough permeate quality. The results recommend that integrated NF/RO membrane process is able to reduce membrane fouling and allow long-term operation for real dye bath wastewater.

A lab-scale electrodialysis (ED) which consisted of 11 pieces of cation-exchange membranes and 10 pieces of anion-exchange membranes was used to treat concentrated brine of Reverse osmosis (RO) membrane. The effect of operating parameters such as applied voltage, flowrate, and operating mode was investigated to measure the performance of a lab-scale ED. Three different voltages (5, 10, and 15 V) and flowrates (20, 30, and 40 L/h) were applied in order to optimize the operating conditions of the ED system. The maximum TDS removal efficiencies were 85%, 97%, and 98% for 5, 10, and 15 V, respectively. It was concluded that the desalination efficiencies were almost the same at flowrates values of 20, 30 and 40 L/h. The TDS concentration of the treated brine in the concentrate compartment rises to the highest value of 25,400 mg/L with desalination rate of 92.5% after five cycle operation. Moreover, the desalinated brine can be used as fresh water.

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Background: Membrane bioreactor (MBR) systems used for wastewater treatment (WWT) processes are regarded as clean technologies. Degradation capacity of the predator bacterium, Bdellovibrio bacteriovorus, was used as a cleaning strategy for reducing membrane fouling. Method: Wastewater with different sludge age and hydraulic retention time were filtered through Poly(ether)sulphone (PES) membranes using dead end reactor. Change in filtration performance after cleaning of membrane surface by B. bacteriovorus was measured by comparison of flux values. Bacterial community of the sludge was determined by 16SrRNA sequence analysis. Community profile of membrane surface was analyzed by fluorescent in situ hybridization technique. Results: After cleaning of MP005 and UP150 membranes with predator bacteria, 4.8 L/m2·h and 2.04 L/m2·h increase in stable flux at steady state condition was obtained as compared to the control, respectively. Aeromonas, Proteus, and Alcaligenes species were found to be dominant members of the sludge. Bdellovibrio bacteriovorus lysed pure cultures of the isolated sludge bacteria successfully. FISH analysis of the membrane surface showed that Alfa-proteobacteria are the most numerous bacteria among the biofilm community on the membrane surface. Conclusion: Results suggested that cleaning of MBR membranes with B. bacteriovorus has a potential to be used as a biological cleaning method.

Abstract This paper offers a feasible solution for the treatment of membrane concentrate produced from textile industry, using the Fenton, Advanced Fenton (AF), ozonation and hydrodynamic cavitation (HC) and combination of these processes. The study investigated the optimum oxidant and catalyst concentrations, optimum operational conditions and comparison of these processes. The potential formation of chlorinated organic compounds after oxidation of membrane concentrate was also investigated by analyzing total organic halogen (TOX) and polychlorinated biphenyl (PCBs). Also, toxicity analysis was performed with Vibrio fischeri photobacteria to identify the production possibility oxidation intermediates which are more toxic and difficult to treat than the targeted contaminants. Maximum removal efficiencies in chemical oxygen demand (COD), and color were 18.8% and 60.7% respectively using HC alone at a cavitation number (CN) of 0.1. Maximum COD, total organic carbon (TOC), and color removal efficiency at molar concentrations of 175 mM H2O2 and 35 mM Fe2+ and pH 3 after 30 min was 87.1, 80.8 and 99%. Combined HC with Fenton showed the highest removal efficiency in terms of COD, TOC, and color. It was also stated that the use of high oxidant concentrations masks the synergistic effect of HC on Fenton processes due to the scavenging effect.