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Discharge of household greywater into water bodies can lead to an increase in contamination levels in terms of the reduction in dissolved oxygen resources and rapid bacterial growth. Therefore, the quality of greywater has to be improved before the disposal process. The present review aimed to present a hybrid treatment system for the greywater generated from households. The hybrid system comprised a primary stage (a natural filtration unit) with a bioreactor system as the secondary treatment combined with microalgae for greywater treatment, as well as the natural flocculation process. The review discussed the efficiency of each stage in the removal of elements and nutrients. The hybrid system reviewed here represented an effective solution for the remediation of household greywater.

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The study probed into reducing faecal indicators and pathogenic bacteria, heavy metals and ß-lactam antibiotics, from four types of secondary effluents by bioaugmentation process, which was conducted with Bacillus subtilis strain at 45 °C. As a result, faecal indicators and pathogenic bacteria were reduced due to the effect of thermal treatment process (45 °C), while the removal of heavy metals and ß-lactam antibiotics was performed through the functions of bioaccumulation and biodegradation processes of B. subtilis. Faecal coliform met the guidelines outlined by WHO and US EPA standards after 4 and 16 days, respectively. Salmonella spp. and Staphylococcus aureus were reduced to below the detection limits without renewed growth in the final effluents determined by using a culture-based method. Furthermore, 13.5% and 56.1% of cephalexin had been removed, respectively, from secondary effluents containing 1 g of cephalexin L-1 (secondary effluent 3), as well as 1 g of cephalexin L-1 and 10 mg of Ni2+ L-1 (secondary effluent 4) after 16 days. The treatment process, eventually, successfully removed 96.6% and 66.3% of Ni2+ ions from the secondary effluents containing 10 mg of Ni2+ L-1 (secondary effluent 2) and E4, respectively. The bioaugmentation process improved the quality of secondary effluents.

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The wide application of microalgae in the field of wastewater treatment and bioenergy source has improved research studies in the past years. Microalgae represent a good source of biomass and bio-products which are used in different medical and industrial activities, among them the production of high-valued products and biofuels. The present review focused on greywater treatment through the application of phycoremediation technique with microalgae and presented recent advances in technologies used for harvesting the microalgae biomass. The advantages and disadvantages of each method are discussed. The microbiological aspects of production, harvesting and utilization of microalgae biomass are viewed.

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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.

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BACKGROUND: Farwa is an Island in Libya receives petrochemical wastes generated from General Company of Chemical Industries (GCCI) since more than 40 years. AIM: The present work aimed to determine the concentrations of mercury (Hg(+2)) in fish, marine plants and sediment collected from Farwa lagoon to evaluate effect of industrial wastewater from GCCI on the marine environment. METHODS: Hundred and twelve samples of fish, pearl oyster, cuttlefish sediments and marine plants were analyzed to determine Hg(2+) concentration during the period from January to August 2014 by using Atomic Absorption Spectrometer (AAS). RESULTS: The highest concentration of Hg(2+) was detected in Pinctada radiata (11.67 ± 3.30 µgg (-1)) followed by Serranus scriba (6.37 ± 0.11 µg g (-1)) and Epinephelus marginatus (6.19 ± 0.02 µg g (-1)). About 75 % of marine plants contained the maximum contaminations during the summer season. In fish samples Hg(2+) concentrations exceeded the levels provided by international standards. CONCLUSIONS: The fish at Farwa lagoon is heavily contaminated with Hg(2+) which may represent a source for mercury poisoning for human.