Biological treatment and biofouling in membrane treatment systems
As the world’s population increases, the demand for water will increase accordingly. The corresponding demand for water puts a strain on the available sources of water and the technologies to reclaim water from non-potable sources. The use of membranes is quickly emerging as the prominent treatment technique for water purification. While the increase in use of membrane technology is providing the water that the world demands, operational problems such as fouling are limiting the potential of these membrane processes. Fouling due to biological growth, otherwise known as biofouling, is the foremost form of fouling that affects current membrane treatment systems. The use of covalently attached organo-selenium as a surface modification to reverse osmosis membranes was studied as a potential biofouling inhibition agent. The efficacy of the organo-selenium surface treatment was tested within a flow-cell system which exposed the membrane samples to high nutrient medias at low-flow, simulating a worst-case condition for biofouling to occur at the membrane surface. The surface treatment was also tested within a bench-scale reverse osmosis system, where the membranes were exposed to normal operating conditions for a reverse osmosis system. Within the low-flow system, the organo-selenium surface treatment was able to achieve a range of 2.01 to 3.98 logs of inhibition of total biomass. Within the RO system, the organo-selenium surface treatment was able to achieve between 2.2 and 3.8 logs of total biomass inhibition. However, when the polypropylene feed spacer also received the surface treatment, total biomass inhibition was increased to 5.9 logs.