Fouling of RO membranes by phthalate esters contamination

Shortly after the start up of a new RO brackish water desalination plant equipped with polyamide membranes, a severe decline in permeate flow rate was recorded. An extensive water analyses program urgently carried out indicated that the most likely cause for the flux decline was fouling of the membranes by phthalate esters, mainly di-butylphthalate. The origin of the phthalate esters contamination was traced to the newly installed reinforced polyester pipe (16″ diameter, 14 km long), conveying brackish well water to the RO plant. Direct evidence was obtained in laboratory experiments, confirming that di-butylphthalate is indeed a foulant capable of reducing significantly permeate flux. The laboratory data also showed that di-butylphthalate was even capable of destroying the membrane at high concentrations, causing severe leakage of raw water into the permeate stream. With the help of the above findings, the plant was quickly brought back to normal operation.