The objectives of this research were to evaluate two different processes using for wastewater reclamation in a high-tech 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.