Micropollutant Removal Efficiency of Advanced Wastewater Treatment Plants: A Systematic Review.

Introduction: Various review papers have been published regarding the occurrence and fate of micropollutants (MPs). MPs in the aquatic environment are still not well reviewed to generate comprehensive summaries with a special focus on their removal from wastewater using conventional and advanced treatment processes. Therefore, this review aimed to provide a synopsis of the efficiency of the advanced wastewater treatment plants in the removal of MPs. Materials and methods: A systematic search of published literature was conducted on the National Library of Medicine (NLM) database, Web of Science, Joanna Briggs Institute (JBI) database, Scopus, and Google Scholar, based on studies with evidence of removal of MPs in the wastewater treatment process. Screening of the published articles was made using pre-specified inclusion and exclusion criteria. Results: Amongst the 1545 studies searched, 21 full-length articles were analyzed that showed 7 treatment options related to the removal of MPs from wastewater. MPs from wastewater effluents were successfully and effectively removed by advanced treatment techniques. Advanced Oxidation Processes (AOPs), membrane processes, and adsorption processes have all been shown to be potential solutions for the removal of MPs in advanced treatment plants (WWTPs). But, there are 2 critical issues associated with the application of the advanced treatment options which are high operational cost and the formation of dangerous by-products and concentrated residues. Conclusion: This study identified that the removal of MPs using WWTPs was commonly incomplete with varying removal efficiency. Therefore, the adaptation and scale-up of the cost-effective and efficient combined wastewater treatment technology are vital to creating an absolute barrier to MPs emissions.

Determination of pesticide residues in the serum of flower farm workers: A growing occupational hazards in low income countries.

Ethiopia is one the major exporter of cut flowers in East Africa. However, the sector is blamed for the intensive use of pesticides which leads to exposure of workers. This study aims to investigate the level of pesticides in blood serum of flower farm workers as a predictor to occupational exposure. A cross-sectional laboratory based study was conducted in central Ethiopia among 194 flower farm workers. Blood sample were collected from 100 study participants (50 from farm workers and 50 civil servants as control). Blood-serum separation, extraction, and clean-up was performed following standard analytical methods. Ten organochlorine pesticides (OCPs) (o,p'-DDT, p,p'-DDD, p,p'-DDE, p,p'-DDT, heptachlor, heptachlor epoxide, endosulfan, dieldrin, methoxychlor, dibutychloridate), and three pyrethroids (cypermethrin, permethrin and deltamethrin) were detected in the serum of the study participants. From the detected pesticides p,p'-DDT and p,p'-DDE were observed at high mean concentration (81.5 ± 83.5, and 12.5 ± 6.7 ng/mL),(38.0 ± 31.8 and 6.84 ± 7.4 ng/mL) in the flower farm and controls, respectively. From the Mann-Whitney U-test, there is a significant difference for total DDT (P < 0.02), p,p'-DDE (P < 0.001), cypermethrin (P < 0.001), heptachlor (P < 0.04), heptachlor-epoxide (P < 0.001) and dibutyl chlorendate (P < 0.01) among the flower farm workers and controls. Multinomial regression revealed, being flower farm worker is a significant predictor of moderate to high residues of p,p'-DDE, total DDT, heptachlor-epoxide and dibutyl chlorendate. The pesticides under study were detected more frequently in the flower farm workers than controls which is an indicative for occupational exposure to pesticides and strict regulation is important for the safety of workers.

Evaluation of Waste Stabilization Pond Efficiency and Its Effluent Water Quality: a Case Study of Kito Furdisa Campus, Jimma University, Southwest Ethiopia.

Waste stabilization pond (WSP) technology is one of the most promising wastewater treatment methods. In developing countries, including Ethiopia, only a small proportion of the wastewater is being treated. Discharge of untreated wastewater into receiving water bodies may lead to disruption of ecological integrity, economic, and public health risks. However, there is limited evidence on WSP efficiency and effluent water quality in Ethiopia. A laboratory-based cross-sectional study was conducted on 60 wastewater samples. A standard method of procedure was used to collect and analyze samples. SPSS version-24 was used for statistical analysis and a paired t-test was used to test for statistical significant differences. A statistically significant difference (p < 0.001) in the removal efficiency of BOD5 up to 75.3% (117 mg/L effluent) and COD up to 56.5% (457.5 mg/L effluent) was recorded. A statistically significant difference (p < 0.001) in the removal efficiency of TN up to 79% (17.4 mg/L effluent), TP up to 69.2% (4.8 mg/L effluent), and PO4 -3 up to 71% (3.36 mg/L effluent) was recorded. Whereas, a statistically significant difference (p < 0.001) in the removal efficiency of total coliforms up to 99.99% (3.4 × 103 MPN/100 mL effluent) and fecal coliforms up to 94.3% (8.54 × 102 MPN/100 mL effluent) was recorded. The overall efficiency of the treatment plant was 73.5% and its water quality index of the effluent water quality of WSP was 30. The finding showed that the efficiency of the WSP was judged as satisfactory and the effluent water quality of WSP is unsuitable for the discharge into the environment. Therefore, to improve the efficiency of the WSP and to produce adequately treated water, it required adequate preliminary treatment, modification of the design, desludging of the pond, additional treatment, and frequent monitoring and maintenance of the pond.

Efficiency of Treatment Plant and Drinking Water Quality Assessment from Source to Household, Gondar City, Northwest Ethiopia.

Introduction: Access to safe drinking water is essential to health, and it is a basic human right. However, drinking water treatment plant efficiency and its water quality are not well investigated in low-income countries including Ethiopia. Methods: A laboratory-based cross-sectional study was conducted among 75 water samples. Data analysis was carried out using SPSS version 22 to generate descriptive statistics, and one-way ANOVA was used to test statistically significant difference. Results: Physicochemical qualities of the water samples from tap water sources were found to be pH (6.88 ± 0.05), turbidity (5.15 ± 0.006 NTU), electrical conductivity (170.6 ± 0.1 µS/cm), residual chlorine (0.19 ± 0.003 mg/L), and fluoride (1.17 ± 0.009 mg/L). The removal efficiency of turbidity, total hardness, and nitrate was found to be 94.4%, 52.3%, and 88.7%, respectively. Removal efficiency of the treatment plant for total coliforms up to 91.6% (15 ± 0.26 CFU/100 mL in tap water) and faecal coliforms up to 99% (1.51 ± 0.03 CFU/100 mL in tap water) was recorded. Parameters of pH, temperature, and faecal coliform were statistically significant different at p < 0.05 in tap water source. The overall efficiency of the treatment plant (68.5%) and the water quality index (76) were recorded. Conclusion: Based on the results, some of the investigated parameters of water quality (turbidity, residual chlorine, total coliform, and faecal coliform) were found to be not within the permissible limits of WHO guideline values for drinking water quality. The water quality index of the water samples was categorized under good water quality. To adequately treat drinking water and improve the treatment plant, adequate preliminary treatments like screening to reduce the incoming organic loading, proper chlorination of the drinking water system, and frequent monitoring and maintenance of the treatment plant system are required.