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Direct contact membrane distillation technology was considered as a promising and efficient technology for the treatment of textile wastewater. In this study, hydrophobic polytetrafluoroethylene and polyvinylidene fluoride membranes for the treatment of selected model compounds of textile wastewater (e.g., phenol, aniline, and sulfanilic acid) were explored comparatively in a bench-scale direct contact membrane distillation technology test unit. The effect of various operational parameters including temperature, flow rate, and concentration on the rejection performance was investigated systematically. The results indicated that an increased feed temperature and a faster cross flow velocity contributed positively to the direct contact membrane distillation performance. Limited rejection for phenol and aniline was witnessed, which can be due to their relatively lower boiling point. A > 99% of sulfanilic acid rejection was obtained under the same conditions. Furthermore, the polytetrafluoroethylene membrane always presented enhanced performance compared with the polyvinylidene fluoride samples. In brief, the direct contact membrane distillation process could be potentially used as a promising technique for the treatment of textile wastewater.

In this study, the feasibility of utilizing an anaerobic osmotic membrane bioreactor (OMBR) for the treatment of a refractory acid dye, Lanaset red G.GR, is demonstrated. The experimental results show that an increased sludge concentration and reversed salt accumulation exacerbate membrane fouling, which leads to flux decline. The excellent rejection performance of the forward osmosis (FO) membrane and salt accumulation could lead to a reduction of microbial activity and an increase in soluble microbial product (SMP) and extracellular polymeric substance (EPS) contents. These consequences will affect the OMBR performance. Moreover, the FO membrane demonstrated a limited rejection of aniline-type intermediates. These overall findings suggest that the OMBR process is a good option for the treatment of dyeing wastewater. Further improvements on the membrane materials and membrane surface properties to alleviate fouling, salt reverse osmosis as well as the remaining color issues are still necessary before practical application becomes possible.

It is highly desirable to develop affordable, energy-saving, and highly-effective technologies to alleviate the current water crisis. In this work, we reported a low-cost electrochemical filtration device composing of a conductive cotton filter anode and a Ti foil cathode. The device was operated by gravity feed. The conductive cotton filter anodes were fabricated by a facile dying method to incorporate carbon nanotubes (CNTs) as fillers. The CNTs could serve as adsorbents for pollutants adsorption, as electrocatalysts for pollutants electrooxidation, and as conductive additives to render the cotton filters highly conductive. Cellulose-based cotton could serve as low-cost support to ‘host’ these CNTs. Upon application of external potential, the developed filtration device could not only achieve physically adsorption of organic compounds, but also chemically oxide these compounds on site. Three model organic compounds were employed to evaluate the oxidative capability of the device, i.e., ferrocyanide (a model single-electron-transfer electron donor), methyl orange (MO, a common recalcitrant azo-dye found in aqueous environments), and antibiotic tetracycline (TC, a common antibiotic released from the wastewater treatment plants). The devices exhibited a maximum electrooxidation flux of 0.37 mol/h/m2 for 5.0 mmol/L ferrocyanide, of 0.26 mol/h/m2 for 0.06 mmol/L MO, and of 0.9 mol/h/m2 for 0.2 mmol/L TC under given experimental conditions. The effects of several key operational parameters (e.g., total cell potential, CNT amount, and compound concentration) on the device performance were also studied. This study could shed some light on the good design of effective and affordable water purification devices for point-of-use applications.

Forward osmosis (FO) is an emerging membrane separation technology in environmental and industrial process. This paper presents cellulose triacetate (CTA) membrane containing graphene oxide (GO) nanosheets via blending to enhance membrane performance in forward osmosis (FO) process. GO nanosheets with various loading were added into the casting solution to prepare the modified FO membranes. The prepared membranes were characterized by morphology analysis and permeability measurement. The result showed that the GO nanosheets effectively improved the performance of the CTA membranes. The CTA-0.2GO membrane had the highest water flux, reached 1.5 times as high as that of CTA membrane.