Physico-chemical treatments for the complete removal of non-ionic surfactants from effluents

Adsorption isotherms for a selection of non-ionic surfactants on activated carbons indicated the effectiveness of the latter in the removal of these pollutants from secondary effluents. The removal efficiencies were found to be improved when the secondary effluent was first flocculated with ferric chloride. This effectively removed some 80% of the non-ionic surfactant in the effluent. Batch adsorption experiments with powdered activated carbon removed 97% of the surfactant at low carbon dosage. A granular carbon with the best adsorption capacity was selected for continuous-flow operation in which non-ionic surfactants, COD and anionic surfactant alkyl benzene sulphonate were monitored. The breakthrough capacity for the non-ionic surfactants was in excess of 6000 bed volumes throughput of flocculated, sand-filtered effluent in a laboratory scale carbon column. Such a procedure is suggested for the complete removal of such pollutants from effluents.