Reclamation of industry wastewater as a renewable source for cooling water system: A case study for a semiconductor plant / Yim Yan Han

Deionized water is generally used to rinse the integrated circuit (IC) crystal chips in semiconductor manufacturing. Wastewater generated in the semiconductor manufacturing need to be collected and treated as regulated by Department of Environment (DOE) Malaysia. On the other hand, cooling systems are major water consumers in the industry. The treated industry wastewater from semiconductor usually contains less inorganic and has the potential to be reused as make-up water in the cooling tower water system. The aim of this study is to determine the critical parameters of the make-up water for cooling water tank and create a baseline of recommended water quality for cooling water if reclaimed water from treated semiconductor effluent is used as alternative water source of make-up water for cooling water. Comparison of reclaimed water characteristic was reviewed and to evaluate the appropriateness and effectiveness of the reclaimed water to be reused as cooling water. The related mass balance data of used water quantities in the whole plant indicated the reuse and recovery of used water could be appropriately carried out in the plant. A representative semiconductor plant was selected as this case study which this plant has installed a wastewater recycling system that draws over 382 cubic meter/day treated industrial wastewater before discharge to environment. Total amount of collected reclaimed wastewater used in wastewater recycling system for cooling make-up water need to have close monitoring and nine critical parameters were identified which affects cooling water system�s efficiency; pH, conductivity, total hardness, total calcium hardness, total alkalinity, free chlorine, total silica, total iron and total bacteria count. This wastewater recycling system was operated since January 2017 and without any major breakdown. Total reclaimed wastewater has reached 1990 cubic meter/year in the past one year and cost saving reached about RM 202k per year