Recycling the wastewater of the industrial park in Northern Taiwan using UF-RO system: in-situ pilot testing and cost analysis

In Taiwan, every industrial park equips a wastewater treatment plant (WWTP) to collect wastewater streaming from all the factories. These effluents, though showing high total dissolved solids (TDS) and fluctuating composition, would be a valuable water resource for industrial use after large scale purification, especially in the drought seasons. In this study, a pilot plant was installed for reclaiming the effluents from the industrial park WWTP through the membrane process. A modified spiral-wound ultrafiltration (UF) membrane with backwash function was utilized for the pretreatment of the reverse osmosis (RO) system. Evaluation results showed that the pilot plant was performing stably during the two-month operation. After the RO desalination, the quality of the reclaimed water basically met the requirement standards of intermediate-pressure boiler feedwater (150 ∼ 750 psig) of the Environmental Protection Agency, United States (USEPA). The backwashable spiral wound UF membrane provided suitable water quality for RO influent (SDI < 4) and helped reduce the cost compared to using hollow-fibre UF membrane. The total cost of recycling one-ton effluent included US$ 0.35 for construction and US$ 0.45 for operation/maintenance.