Environmental impact of zinc in galvanizing process in Thailand using life cycle assessment (LCA)

Abstract Zinc is one of the widely used non-ferrous metals in various industrial applications. Currently, galvanized steel, or zinc-coated steel, is in high demand due to its anti-corrosion properties, leading to widespread usage. However, if the processes are not properly managed and waste is released into the environment, it can pose harmful effects on human health and ecosystems. In recent years, reports of unauthorized galvanizing plants without proper waste management have raised concerns about health and environmental impacts on workers and local communities. This research examines the quantity and flow pathways of waste generated by galvanizing plants in Thailand and assesses the environmental impacts of waste management using material flow analysis and life cycle assessment with STAN and SimaPro software. Waste was categorized according to codes specified by the Ministry of Industry, and from 2017 to 2020, waste code 11 01 (waste from the chemical treatment and coating of metal surfaces) was the most prevalent, followed by code 11 05 (wastes from hot galvanizing processes) and code 12 01 (wastes from the shaping and surface treatment of metals and plastics), accounting for 76.87%, 19.33%, and 3.68% of total waste, respectively. Most waste was managed under code 049 (other recycling methods), followed by code 053 (acid/base recovery) and code 052 (metal recovery), representing 78.88%, 16.44%, and 2.56% of total waste, respectively. Waste code 11 01 was primarily managed under codes 049 and 053. The environmental impact assessment found that waste management each year mainly impacted marine and freshwater ecotoxicity, human non-carcinogenic toxicity, and human carcinogenic toxicity. The most significant environmental impact resulted from burning waste contaminated with hazardous substances. The study found that 2020 had the highest volume and environmental impact of waste, making it the baseline scenario (S0) for comparing alternative waste management strategies. Results showed that Scenario S3, which involves recycling most of the waste, effectively reduces environmental impacts compared to the S0 scenario.