The researchers evaluated how well waste stabilization ponds in Birjand, Iran treated the city's sewage. They tested samples from different stages of the treatment process over a year. The results showed that the final effluent from the maturation pond did not meet Iran's environmental standards for agricultural use. The levels of BOD5, COD, and turbidity were too high, indicating that the ponds were not working effectively. The study suggests that the performance of the stabilization ponds in Birjand needs improvement.