Evaluation of wastewater reclamation processes in a high-tech industrial park

The objectives of this research were to evaluate two different processes using for wastewater reclamation in a hightech industrial park area in Taiwan. The major units of the first AC–RO–IE system included sand filter, an activated carbon (AC) bed, microfiltration module, a reverse osmosis (RO) membrane and ionic-exchange (IE) columns. The second DAF–AC–RO system was comprised of coagulation/flocculation, dissolved air flotation (DAF), an activated carbon bed, microfiltration module and reverse osmosis membrane units. This study was carried out at a pilot-scale plant in situ that operated for approximately 1 year. According to the long-term experimental results, both the AC–RO– IE and the DAF–AC–RO processes illustrated excellent performances on inorganic and organic contaminant removal. Comparing the removal efficiency of the filtration–AC units in the AC–RO–IE system with the coagulation–DAF–AC units in the DAF–AC–RO system, the removal efficiency of TDS, SiO2 and COD increased by 19.8%, 70.1% and 44.4% in the latter system, respectively. In addition, the combination of PAC–coagulation and DAF units could improve hardness removal, modify the form of dissolved silica, and reduce the SDI and MFI values. It showed good potential as a pretreatment unit in wastewater reclamation processes. Therefore, based on the reclaimed wastewater quality and process operational stability, the DAF–AC–RO system was suggested as a potential process for further application.

Based on a long-term in situ investigation on the evaluation of two wastewater reclamation systems in a high-tech industrial wastewater treatment plant, the specific conclusions derived from this study were as follows: 1. Both the AC–RO–IE and the DAF–AC–RO processes illustrated excellent performance on inorganic and organic contaminants removal. The quality of the reclaimed wastewater was suitable for high-tech process water or make-up water in the industrial park area. 2. Comparing the removal efficiency of the filtration–AC units in the AC–RO–IE system with the coagulation–DAF–AC units in the DAF– AC–RO system, the removal efficiency of TDS, SiO2 and COD increased by 19.8%, 70.1% and 44.4% in the DAF–AC–RO system, respectively. 3. In the DAF–AC–RO process, the combination of PAC–coagulation and dissolved air flotation units could improve the dissolved species and hardness removal, modify the form of dissolved silica, and reduce the SDI and MFI values. It showed good potential as a pretreatment unit for RO membranes in wastewater reclamation processes. 4. Based on reclaimed wastewater quality and process operational stability, the DAF–AC–RO system is suggested as a potential process for further application.