Fouling or scaling in membrane systems is one of the most significant operational challenges in water and waste-water treatment applications, and this month's patents examine a number of solutions to this issue. Chemicals manufacturer Kurita has filed an application that details the addition of cinnamaldehyde and a solvent for an antimicrobial effect on reverse osmosis membranes to prevent biofouling. One key issue quoted in the documents is that other antimicrobial biofouling preventatives, such as sodium hypochlorite and per-acetic acid, produce oxidising species that could damage the membrane itself - something that Kurita's technology aims to avoid. Furthermore, biocides are often toxic to humans, and it can be very difficult to prevent contamination of the produced drinking water, making large numbers of the chemicals unusable in RO systems. It is important to note that in the example tests presented, however, only up to 97% of the biofouling inhibitor was rejected - bringing into question the invention's proposed use in systems producing drinking water.
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