Background and purpose: The aim of this study was to evaluate the quality of wastewater treatment plant effluent in Qazvin (Alvand) industrial area for discharge into the environment and reuse.

Materials and methods: The study was conducted over a period of nine months in 2015-2016. Ninety samples of wastewater were collected to determine the concentrations of BOD₅, COD, TSS, TC, FC, and heavy metals (lead, cobalt, and Cd). The levels of pollutants were evaluated according to the standards of Iran Environmental Protection Agency for discharge to the environment and reuse.

Results: The mean concentration of COD in the effluent during autumn, winter and spring were 145.20±52.66 mg/L, 316.50±279.80 mg/L, and 177.00±124.2mg/L, respectively. The average concentration of BOD₅ were found to be 79.40±26.76 mg/L, 154.25±122.86mg/L, and 72.00±13.74 mg/L in autumn, winter, and spring, respectively. The mean values for total coliform and fecal coliform were 6×10² MPN/100 mL and 6.21×10² MPN/100 mL, respectively. The average lead and cobalt concentrations were found to be 0.21±0.11 mg/L and 0.004±0.003 mg/L, respectively. The cadmium concentration was reported to be minimal.

Conclusion: Current results showed that the wastewater quality conformed with EPA's standards for reuse, but the use of wastewater for agriculture, due to the biological and cumulative effect of some elements, should be done based on health principles.