Feasibility Study of Using Drip System in Irrigation with Effluent from Wastewater Treatment Plants in Mashhad

The use of unconventional water sources (e. g. wastewater treatment plants effluent) as well as the use of high efficient irrigation systems (e. g. drip irrigation systems) has found special merit in today''s water resource management in agriculture. Drip irrigation systems، however، can lead to operational problems such as clogging، precipitation and corrosion of pipes and emitters، especially when effluent from wastewater treatment plants is used as the main source of irrigation. Such problems can shorten the irrigation system life cycle and increase the maintenance costs، significantly. In this research، the quality of effluents from the city of Mashhad Wastewater Treatment Plants (Olang، Parkand Abad 1، and Parkand Abad 2) were evaluated in order to assess the feasibility of using drip irrigation systems. For this purpose، the main parameters of importance in clogging and corrosion of drip irrigation systems such as pH، total dissolved solids، total suspended solids، Iron، Manganese and total coliform bacteria contents of the effluents were measured regularly over a period of one year. The results of the study indicated that the use of drip irrigation system is strongly limited due to the high concentration of bacteria in the effluents (4. 8-7. 3 log CFU/100 mL)، which can initiate clogging of pipes and emitters. In regard to other effluent quality parameters including pH (7. 3-8)، TDS (800-1200 mg/L)، TSS (42-138 mg/L)، Iron (0. 2-0. 6 mg/L)، Manganese (0. 1-0. 4 mg/L) and langelier saturation index (LSI) (-0. 7-0. 6)، application of drip irrigation systems also encountered limitations in the range of low to moderate levels. In summary، in order to reduce the operational problems associated with drip irrigation systems، the use of advanced methods for further treatment of the effluents such as filtration، membrane treatment، and the use of appropriate chemicals are recommended.