Fouling characteristics and fouling control of reverse osmosis membranes for desalination of dyeing wastewater with high chemical oxygen demand

Fouling of reverse osmosis (RO) membranes is a severe problem for desalination of dyeing wastewater with high chemical oxygen demand (COD). In this paper, fouled RO membranes in a pilot-scale desalination system of biologically treated dyeing wastewater containing high COD (143-228 mg/L) with or without injection of non oxidizing biocides were analyzed. The two non-oxidizing biocides used are K5030 (a kind of isothiazoline biocide) and FR110 (an inorganic base type of combined chlorine agent), respectively. For the RO membrane from the system without non-oxidizing biocide injection to the influent, a typical biofihn occurred on the RO membrane in a short operation time of 19 days. The injection of non-oxidizing biocides caused a decline of nearly 99.0% in active biomass on the RO membrane. Burkholderiales ruled mature biofilm, on the RO membrane without injection of non-oxidizing biocide. Pseudoxanthomonas exhibited a certain resistance to non-oxidizing biocides and ruled the bacterial community on the RO membrane with injection of non-oxidizing biocides. Fe, P and Al were major inorganic elements on RO membranes, decreasing with injection of non-oxidizing biocides. Hydrophobic neutral (HON) fraction was the most major organic component of dissolved organic matter (DOM) on RO membranes, decreasing notably with injection of non-oxidizing biocides.