Microbiological quality assessment of treated municipal wastewater effluents for crop irrigation purposes

Massive crop production demands enormous volumes of water for irrigation. Water scarcity has led growers to look for suitable alternative water sources. Treated wastewater for agricultural purposes has been documented; however, high microbial loads pose a high risk to consumers of contaminated produce. This study evaluated the microbiological quality of treated wastewater from three artificial canals belonging to two treated municipal wastewater plants in Sinaloa, Mexico. Fecal coliforms, Escherichia coli, and Salmonella were quantified by standard methods in 60 treated wastewater samples. Fecal coliforms and E. coli were quantified from 4.0x102 to 3.9x107 CFU/100 mL and 1.0x102 to 1.0x107 CFU/100 mL, respectively. Salmonella was isolated from 45 samples, with the highest value of 16.14 MPN/L. Most of the examined samples exceeded the national and international microbial limits in water for agricultural purposes. Therefore, treated municipal wastewater from central Sinaloa, Mexico, is unsuitable for agricultural irrigation.