Effect of the Use Treated Wastewater on Microbial Contamination of Soils of Urban Landscapes

Background & objective: Microbial contamination is one of the main concerns about the use of treated wastewater in irrigation. Therefore, the present study conducted to investigate the effect of treated wastewater on microbial contamination of urban landscape soils in Zahedan. Material & methods: In this study, a 1600 m2 plot of palm trees in Zahedan were irrigated with treated wastewater and one plot were irrigated with well water (control treatment) were selected. From the soil of two plot, a random sample of 16 samples from 0 to 50 cm depth were collected in 1397. Sampling were done from treated wastewater and well water. Physical, chemical and microbiological properties of treated wastewater and well water and microbial parameters of soil samples were measured according to standard methods. Data were analyzed using a randomized complete block design with MSTAT-C softwares. Results: Based on the results of analysis of variance, the application of treated wastewater has a significant effect on the microbial parameters of irrigated soils in a 1% statistical level. The results of comparison of meanings by LSD showed, the application treated wastewater at compared to well water significantly (p<0.05) were increased total coliforms, fecal coliforms and egg parasites of soils to 93.3%, 86.8% and 80% respectively. Also, the soil microbial parameters of palm trees were higher than that of the control treatment and the standard limit for agricultural land. Conclusion: The chemical quality of Treated Wastewater of the Zahedan was consistent with the standards of the Iranian environmental organization in terms of its application in agriculture. However, number of the total coliforms, fecal coliforms and egg parasites of treated Wastewater, as well as in the surface soil of palm trees were irrigated with this wastewater was relatively high that could be accepted for limited irrigation according to the Global Health Guidelines.