Evaluation of physicochemical and microbiological contamination of wastewater treated by aerated lagoons and their reuse in irrigation of zucchini and lettuce crops

Abstract

Due to low rainfall and aridity in Morocco, many authors reported the use of wastewater. However, the wastewaters present a risk to the environment and public health. This study assessed the health risks of wastewater from the wastewater treatment plant of Errachidia. The microbiological parameters include intestinal enterococci, total coliforms, and fecal coliforms, while physicochemical parameters were temperature, conductivity, pH, Total suspended solids (TSS), Biological oxygen demand (BOD5), and chemical oxygen demand (COD). Then, the contamination of irrigated zucchini (Cucurbita pepo L.) and lettuce (Lactuca sativa L.) by treated wastewater was evaluated via fecal coliforms, Salmonella, and Escherichia Coli. The obtained results showed that the temperature and pH were significantly variable following the seasons with the highest values in summer. The highest values of BOD5 (171 mg of O2/l) and COD (280 mg of O2/l) were also recorded in the summer. The conductivity was superior in January (2710 us/cm), while TSS was superior (100 mg/l) in February. Total coliforms were the most dominant (132.4 ± 13.17 CFU/100ml), followed by the intestinal enterococci (51.80 ± 45.65 CFU/100ml), and fecal coliform (95.2 ± 66.67 CFU/100ml) with highest values in March. In zucchini, Fecal coliforms (7.7 ± 1.64 UFC/g), Salmonella (0.00 UFC/g), and E. coli (7.3 ± 1.77 UFC/g) were inferior compared to Moroccan standards. In lettuce, fecal coliforms were 73.06 ± 2.13.54 UFC/g) and Salmonella were 0.00 UFC/g, while E. coli was 7.18 ± 1.51 UFC/g, which is significantly superior compared to the value of standards estimated at 00 ± 00 UFC/g. These results demonstrated the lower contamination of wastewater treated in the WWPT of Errachidia, which new for arid areas in Morocco. However, more research is needed to investigate the heavy metals and other pollutants in wastewater before their use in agriculture.

Keywords

• Wastewater reuse
• Physicochemical properties
• Microbial contamination
• Irrigation of crops