IMPROVEMENT ON FILTERABILITY IN THE AEROBIC TREATMENT OF CARBOXYMETHYL CELLULOSE (CMC) WASTEWATER

CMC is chemically modified from natural cellulose and widely applied in various industries. CMC wastewater consists mainly of sodium glycolate, sodium chloride and water. With extremely high COD and salinity, high concentration CMC wastewater cannot be biologically treated, but with COD and salinity around 15000 and 30000 mg/L respectively, low concentration CMC wastewater can be aerobically treated. In a CMC factory, the treatment of low concentration wastewater with aerobic MBR was successful except for one serious problem: poor filterability. Two trial solutions: adding micronutrients and applying MBBR were expected to improve the filterability. In the experiment, adding micronutrients was achieved by mixing filtered natural water into the wastewater, rather than dosing chemicals into it. The treatment efficiency of both solutions was close, but adding micronutrients showed distinguished performance in improving filterability, which includes higher filtration flux and slighter membrane fouling. Adding micronutrients also effectively improved the filterability under severe salinity shock.