EFFECT OF IRRIGATION SYSTEMS WITH SECONDARY TREATED WASTEWATER ON GROUNDWATER CONTAMINATION

The impact of Drip and sprinkler irrigation systems with secondary treated wastewater on groundwater was investigated six monitoring wells including 3 sallow wells and other deep wells were installed at two field trials grown with canola and soybean and irrigated with drip and sprinkler irrigation systems. Samples of groundwater were taken from all of the monitoring wells and analyzed for a range of chemical parameters. The findings demonstrated that the salinity of groundwater under drip irrigation was comparable to that of secondary treated wastewater and was less than half of that under sprinkler. The drip irrigation system had lower nitrate concentrations than the sprinkler system. It seems that irrigation systems could affect nitrate concentration in groundwater according to the water table depth. The amounts of heavy metals in the groundwater of both irrigation systems were negligible and comparable. The microbial load of the groundwater samples under the two irrigation systems by secondary treated wastewater was similar and substantial. It is not quite clear from the short-term monitoring period that irrigation with secondary treated wastewater has absolutely affected groundwater quality. Some evident effects could be occurred by the most soluble and mobile components, such as total dissolved solids and nitrate under drip irrigation and sprinkler irrigation systems, respectively. These results indicate that irrigation system could affect the mobile components of the treated wastewater such as TDS (764 and 1953 mg/l), TSS (25.8 and 26.3) and nitrate (48.4 and 62.7 mg/l) concentration for drip and sprinkler irrigation systems, respectively in groundwater.