Investigation of the possibility of using of wastewater for agriculture (Case study: Shahrekordʼs municipal sewage treatment plant)

Abstract:
Background and Objectives: The aim of this study was to examine the possibility of reuse of wastewater of Shahrekordʼs sewage treatment plant for agriculture and determine the restrictions of use of wastewater in drip irrigation system in terms of influence on emitter clogging potential.
Materials and Methods: For this purpose, some of physical, chemical and biological parameters of wastewater quality of Shahrekordʼs sewage treatment plant, in April-September 2015, were measured on a monthly basis and then compared with the Iranian Environmental Protection Organization standards, World Health Organization standards (WHO), World Food and agricultural organization (FAO) and the standard of water quality classification according to the emitter clogging potential.
Results: According to the results of water quality, the average amount of fecal and total coliforms in wastewater during the study, were 6416.8 and 16966.7 (MPN/100ml), respectively; that was outside of the recommended permissible range by the Iranian environmental protection organization standards for wastewater use in agriculture, so more chlorination is necessary, before wastewater discharge. In addition, based on the average value of microbiological parameters, fecal coliform and the number of intestinal nematodes (0 N/100ml) and according to World Health Organization standards, the use of wastewater for irrigation of plants that can be eaten raw, is not possible. Also according to FAO standard, wastewater application in terms of average amount of bicarbonate concentration in this period (4.64 me/L), had low to moderate limitation for crops. restriction Degree on use of wastewater in drip irrigation system in terms of average amount of total coliform count, level of pH (7.65) and water hardness (251.1 mg/L), was Moderate, and in the terms of average value of concentration of dissolved solids (405.5 mg/L), the concentration of suspended solids (35.2 mg/L), electrical conductivity (0.66 dS/m), iron (0.024 mg/L) and manganese (0.013 mg/L), was low. In addition, according to the negative value of langelier saturation index during the study period (-1.03), the possibility of sediment in the water, there weren’t.
Conclusion: According to the low potential of emitter clogging duo to physical and chemical agents, biological agents, considered as the main cause of emitter clogging when wastewater of Shahr-e kordʼs sewage treatment plant, use in drip irrigation systems. Thus, drip irrigation systems can be used in program of reuse of wastewater of sewage treatment plant in Shahr-e kord for irrigation of cereal and industrial crops resistant to high concentrations of bicarbonate and with consideration the use of managements such use of appropriate filter, acidification, flushing of laterals and especially chlorination of the irrigation system.