Effects of Treated Municipal Wastewater Injection withDifferent Irrigation Methods on Soil Quality Parameters

摘要

Safety and development of agriculture and landscape in arid 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 animportant consideration when its disposal is being planned in arid and semi-arid regions. On theother hand, usage of municipal wastewater for irrigation needs special management in order toavoid environmental and health hazards. With regards to health problems, it is very important togenerate minimum contact between the effluent and people or the aerial parts of the plants. Forthis purpose, treated secondary municipal wastewater of Isfahan plant was used to five irrigationtreatments. These treatments were: furrow irrigation with normal water (FN), drip irrigation withwastewater (DI), sub-surface drip irrigation in 15 cm depth with wastewater (SDI15), sub-surfacedrip 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 adecrease 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 and44% total suspended solid. In addition the application of SDI system caused a decrease in themoisture 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) betweenSDI treatments and FN. The result of this research also showed that in the case of SDI due tominimal leaching, prevalence contamination (such as N-NO3) is minimized as a result of theusage of wastewater in depth and ground water. In addition, in SDI treatments, the maximumEC and SAR leaching were observed in 60 cm depth whereas in the FW this leaching wasobserved deeper than 90 cm.