Environmental Impact of Petroleum Refinery Effluent on Groundwater Pollution: A Case Study of Maysan Refinery, Iraq

Abstract

The study aimed to investigate the environmental impact of the refinery's wastewater on groundwater within the refinery and the surrounding area. Six different testing sites were chosen to measure the concentrations of groundwater pollutants according to their distance from the untreated oil effluent discharge lagoon. The study period lasted for six months, as the testing work began in April and ended in September 2023. The results showed a clear effect of untreated petroleum effluent on the properties of groundwater, as the concentrations of petroleum effluent (oil and grease, TOC, phenol) and heavy metals (Ni, Cd, Pb) exceeded the permissible limits, as well as related parameters (TDS, EC, Cl, SO4) according to WHO specifications. As for the concentrations of the parameters (BOD, COD), there was no clear effect of the effluent on them, and on the contrary, their values began to increase at the testing sites far from the refinery. The groundwater was greatly affected by a distance of 5 km from the effluent collection lagoon (testing sites:GW1, GW2, GW3, and GW4), and it was not suitable for human use until after it was treated. As for the remaining of the distance (testing sites:GW5, GW6) to the nearest residential area (from 5 km to 9 km), the groundwater was limited to use for irrigation according to WQI guidelines. The study recommends that, in order to reduce pollution of refinery effluent, the responsible administration should use regular wastewater networks, construct a treatment plant for this effluent, and discharge the treated effluent to the nearest water source