Hazardous process chemical and water consumption reduction through cleaner production application for a zinc electroplating industry in Istanbul

Abstract

The metal finishing industry consumes a range of chemicals that are considered hazardous to human health and the environment. The technology and processes used in metal finishing operations such as electroplating of metal parts and rinsing operations are the major sources of environmental pollution. The aim of this study is to achieve a more efficient use of raw materials and water and to reduce the rinsing water consumption and hazardous waste generation for the selected zinc electroplating plant. This can be achieved through source reduction and material reuse and recovery that will lead to reduction in total amount of waste, emissions and waste toxicity. The zinc electroplating process and its resulting environmental loads were investigated within the scope of the study, by considering the cleaner production (CP) opportunities. The proposed source reduction options include (a) closed loop cleaning system that eliminates hazardous chemical consumption as a technology modification and (b) counter current rinsing and drag-out tank application as an on-site reuse/recovery/recycling. The CP assessment methodologies implemented in the study cover on-site plant auditing and mass-balance analysis of zinc electroplating process. In order to determine all involved inputs and outputs, measurements and data collection were performed for the related process flows as a part of the mass-balance analysis. The selected CP opportunities were evaluated in terms of their environmental benefits and economic feasibility. The results of the study indicate that implementation of the closed loop cleaning system prevents hazardous chemical consumption by utilizing aqueous cleaning solutions instead of toxic solvents resulting in 14.7% chemical and 80% water consumption reduction during pre-treatment of metal parts while implementation of counter current rinsing application for the entire zinc electroplating process reduces the rinsing water consumption by 62% thus, decreasing the end-of-pipe treatment cost.