Advanced treatment of semiconductor wastewater by combined MBR–RO technology

Abstract

The combination of membrane bioreactor and reverse osmosis (MBR–RO) is becoming an attractive technology for wastewater reclamation and reuse. In this work, the combined MBR–RO technology was applied to treat the semiconductor wastewater through a two-phase (I, II) operation. To demonstrate the feasibility of this technology, the operational performances of MBR and RO were investigated in Phase I. The good operational stability, high contaminant removal efficiency of the combined system, as well as qualified treated water for reuse were observed. To understand the possible fouling characteristics of RO membrane in a long-term operation, the antiscalant addition and chemical cleaning in RO process were abolished in Phase II. The membrane autopsy analysis showed that the dominant foulants on the RO membrane surface were loose inorganic deposits with plate-like morphology, while the biological and organic fouling were ignorable. The major component of the foulants was BaSO4, with small amounts of SrSO4 and deposits involving Ca, Si, Al, Mg, Fe and Zn. The foulants could be effectively removed by chemical cleaning of HCl–NaOH/EDTA. After the cleaning, the RO membrane permeability was recovered to the fresh one. This work provides a deep understanding of treating the semiconductor wastewater by MBR–RO technology for industrial application.