No abstract

Greywater is one of the most important alternative sources for irrigation in arid and semi-arid countries. However, the health risk associated with the microbial contents of these waters limits their utilization. Many techniques have been developed and used to generate a high microbiological quality of greywater. The main problem in the treatment of greywater lies in the nature of pathogenic bacteria in terms of their ability to survive during/after the treatment process. The present review focused on the health risk associated with the presence of pathogenic bacteria in greywater and the treatment technologies used for the disinfection processes.

Microalgae have high nutritional values for aquatic organisms compared to fish meal, because microalgae cells are rich in proteins, lipids, and carbohydrates. However, the high cost for the commercial production of microalgae biomass using fresh water or artificial media limits its use as fish feed. Few studies have investigated the potential of wet market wastewater and slaughterhouse wastewater for the production of microalgae biomass. Hence, this study aims to highlight the potential of these types of wastewater as an alternative superior medium for microalgae biomass as they contain high levels of nutrients required for microalgae growth. This paper focuses on the benefits of microalgae biomass produced during the phycoremediation of wet market wastewater and slaughterhouse wastewater as fish feed. The extraction techniques for lipids and proteins as well as the studies conducted on the use of microalgae biomass as fish feed were reviewed. The results showed that microalgae biomass can be used as fish feed due to feed utilisation efficiency, physiological activity, increased resistance for several diseases, improved stress response, and improved protein retention.

Detergent compounds are classes of the organic micro-pollutants in the laundry wastewater. The disposal of these compounds into the soil has several adverse effects on their composition. In the present study, changes in the soil characteristics, which included saturated hydraulic conductivity (K sat ), EC, pH, exchangeable sodium percentage, cation exchange capacity (CEC), and sodium adsorption on ratio were examined after the irrigation with laundry wastewater. Ten clothes were washed with one full cap of powder (PLD) and liquid laundry (LLD). Laundry greywater samples were used for the irrigation of soil. The results revealed that the pH of soil increased from 3.85 to 4.42 and 4.09 after irrigation by PLD and LLD greywater, respectively. The EC of the irrigated soil increased from 50.32 to 152.5 and 147.6 μS/cm, respectively. The CEC was raised to 79.93 and 41.39 meq/100 g, while K sat was reduced to 7.38 × 10 −10 and 7.11 × 10 −10 cm/s, respectively. These findings highlighted the negative effects of laundry greywater discharge on soil properties.

Nanotechnology involves material with nanoscale dimension that range from 0.1 to 100 nm, to make devices, systems and materials with essentially new characteristics and applications due to their large surface area to volume ratio. Zinc oxide nanoparticles (ZnO NPs) are widely known due to its wide band gap and high exciton binding energy. ZnO NPs are normally synthesized by chemical methods which involve the use of hazardous and expensive chemicals, resulting in toxic and environmentally hazardous by-products. Green synthesis of ZnO NPs by plants extract is non-toxic and economic. Therefore, this paper aims to explore the potential of plants extract in the green synthesis of ZnO NPs. Moreover, the capability of Coriandrum sativum leaf extracts to produce ZnO NPs in degrading dyes in textile wastewater is also discussed.