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Water pollution caused by population growth and human activities is a critical problem exacerbated by limited freshwater resources and increasing water demands. Various sectors contribute to water pollution, with the dairy industry being a significant contributor due to the high concentrations of harmful contaminants in dairy wastewater. Traditional treatment methods have been employed, but they have limitations in terms of effectiveness, cost, and environmental impact. In recent years, membrane separation technology (MST) has emerged as a promising alternative for treating dairy wastewater. Membrane processes offer efficient separation, concentration, and purification of dairy wastewater, with benefits such as reduced process steps, minimal impact on product quality, operational flexibility, and lower energy consumption. However, membrane fouling and concentration polarization present major challenges associated with this technique. Therefore, strategies have been implemented to mitigate these phenomena, including pre-treatment prior to MST, coagulation, and adsorption. Recently, 3D printing technology has gained prominence as one of the latest and most notable advancements for addressing these issues. This comprehensive review examines the drawbacks and benefits of conventional methods employed in dairy wastewater treatment and explores the utilization of membrane technology as an alternative to these approaches. Additionally, the latest technologies implemented to mitigate or alleviate the limitations of membrane technology are discussed.

This study aimed to investigate the performance of composite photocatalytic membranes fabricated by incorporating multiple nanoparticles (TiO2, carbon nanotubes, BiVO4) into polyvinylidene fluoride membrane material for real dairy wastewater treatment. The composite photocatalytic membranes exhibited superior antifouling behavior, lower filtration resistance, better flux, and higher flux recovery ratio than the pristine membrane. Salinity, pH, and lactose concentration are determinant factors that affect filtration resistance and rejection performance during the ultrafiltration of dairy wastewater. Generally, higher irreversible and total resistances and slightly lower chemical oxygen demand (COD) rejections were found at higher salinity (expressed by electric conductivity values of >4 mS/cm) than lower salinity (<4 mS/cm) levels. The presence of lactose in dairy wastewater increased irreversible resistance and severely reduced COD rejection during ultrafiltration due to the ability of lactose to pass through the membranes. It was ascertained that membranes require further treatment after filtrating such wastewater. Lower resistances and slightly better COD rejections were observed at pH 7.5 and pH 9.5 compared to those observed at pH 4. Photocatalytic membranes fouled during the ultrafiltration of real dairy wastewater were regenerated by visible light irradiation. The membrane containing all constituents (i.e., TiO2, carbon nanotubes, and BiVO4) showed the best regeneration performance, exceeding that of the pristine membrane by 30%.

Leachate from Municipal Solid Waste (MSW) landfill has long known to be an environmental concern worldwide. The composition of landfill leachate may contain metals, ammonia, organics, other toxicants and carcinogens, having major environmental concern, with implications for plant, animal and human health. The pollution of soil, surface and ground water is also some of the major immediate concern related to leachate. This problem is growing at alarming rate in some of the developing countries including Ethiopia, and Adigrat happens to one such fast growing small city Ethiopia. However, in the absence of any significant relevant study for Adigrat City MSW leachate, the present work was undertaken to study the physico-chemical characterization of leachate from the Adigrat MSW leachate and investigate its toxicity effect on pea seed germination (Pisum sativum). The characterization was performed on the leachate from Adigrat MSW landfill. Subsequently, the leachate toxicity assessment on pea seed germination was also carried out. The result shows presence of several unacceptable components in the leachate that in some instance was detected at such levels that may pose environmental risk. It was also found that the low pH may add corrosiveness to any contaminated environmental components. Anions (like Cl−) and heavy metals (like Pb, Zn and Cd) detected in the leachate may also be concern for any possible environmental exposure. Additionally, the pea seed germination experiment suggests existence of such components in the leachate that possibly mask its nutritional property during germination.