The world’s economic and urban developments are at the root of various sources of environmental pollution. A number of risks, including diseases and epidemics, are spread depending on the source of pollution, particularly those caused by untreated wastewater discharged into receiving environments. Indeed, environmental protection has become one of the major challenges to economic development. Every day, the oil-producing fields in southeast Algeria produce large quantities of wastewater contaminated with hydrocarbons, solid particles, and suspended solids. The discharge of such effluent into the environment causes significant groundwater contamination, soil erosion, ecosystem disruption, and risks to human health. Minimizing the impact of oil industry activities on people and the environment has become a major concern for oil-producing countries. It is currently an essential component of business development strategy’s part of the implementation of the company’s environmental protection policy in Algeria; the SONATRACH group has implemented a program aimed at eliminating or reducing all significant environmental impacts associated to its activities and services. Deoiling stations have been installed in each production center. These stations treat all oily wastewater from field production units, crude processing units, compression units, and storage tank purges at each center in the region. They ensure the recovery of the oil contained in the water load and the enhancement of the recovered water for reinjection into the fields. The aim of this study is to determine the quality of the oily wastewater produced in the oil fields of southeast Algeria and to study the effects of several doses of a new coagulant on the oily wastewater treatment process implemented at the deoiling station using three techniques, namely coagulation, flocculation, and decantation. At the end of this study, we will be able to formulate conclusions and decisions regarding the reuse of treated water or its safe discharge into the environment.