干旱区生态环境知识资源中心

Safety and development of agriculture and landscape in and and semi-arid regions, where good quality water is scarce, is necessary for the usage of marginal water quality. Municipal wastewater is marginal quality water and using this source for irrigation can be an important consideration when its disposal is being planned in and and semi-arid regions. On the other hand, usage of municipal wastewater for irrigation needs special management in order to avoid environmental and health hazards. With regards to health problems, it is very important to generate minimum contact between the effluent and people or the aerial parts of the plants. For this purpose, treated secondary municipal wastewater of Isfahan plant was used to five irrigation treatments. These treatments were: furrow irrigation with normal water (FN), drip irrigation with wastewater (DI), subsurface drip irrigation in 15 cm depth with wastewater (SDI15), sub-surface drip irrigation in 30 cm depth with wastewater (SDI30), furrow irrigation with wastewater (FW). The results of this research show that the application of DI and SDI sand filters caused a decrease in wastewater index pollution: 50.1% BOD5, 98.92% total count, 97.61% total coliform, 93.24% fecal coliform, 57.14% nematode, 81% total nitrogen, 52% N-NO3, 84% N-NH4 and 44% total suspended solid. In addition the application of SDI system caused a decrease in the moisture of soil surface, so there was decreased total coliform and fecal coliforms in soil surface. The average values for these parameters showed no significant difference (5% level) between SDI treatments and FN. The result of this research also showed that in the case of SDI due to minimal leaching, prevalence contamination (such as N-NO3) is minimized as a result of the usage of wastewater in depth and ground water. In addition, in SDI treatments, the maximum EC and SAR leaching were observed in 60 cm depth whereas in the FW this leaching was observed deeper than 90 cm.