Operating a wastewater treatment plant (WWTP) efficiently is a knowledge required key issue than the entity of treatment plant. In this study, efficiency of WWTP of a metal finishing industry was evaluated and optimized after the process renovation by means of a modern eco-friendly process application. Three processes intensively consuming water and producing wastewater are metal surface pre-treatment, painting, and enamel coating. Based on the characterization studies, it is observed that the process renovation resulted in an improvement in the quality of the raw wastewater leading low pollutant load. Chemical treatment experiment was performed to assess optimum dosages for the WWTP. Also respirometric analyses were conducted in order to evaluate biological treatability of wastewater. Similar results were obtained for all the coagulants tested, but sludge quality after flocculation as well as settleability was better for both commercial and pure FeCl3 solutions. As a result of the observed low pollution load in the raw wastewaters and based on the respirometric analyses, biological treatment step of industrial wastewater was eliminated which was an important constituent of the overall energy requirement of the existing WWTP.