Removal of volatile compounds from the wastewaters by use of pervaporation

Abstract

The increasing contamination of soil and waters with volatile organic compounds, such as halogen derivatives or petrochemical hydrocarbons, poses a serious hazard due to the carcinogenic effect of most of the compounds. Their low concentrations as well as the presence of other hindering substances make it difficult to treat. Therefore, the standards concerning the contamination of both wastewater and drinking water are constantly getting stricter and stricter. The key issue is therefore to find a process which would facilitate the treatment of any contaminated water and pervaporation seems to comply with such requirements. The objective of this work was to apply dense polymer membranes to pervaporative separation of toluene from wastewaters. The investigation studies involved the tests on composite membranes made up from polydimethylsiloxane (PDMS) as well as polyoctylmethylsiloxane (POMS). The membranes were made and offered for investigation by GKSS/Forshungszentrum Geesthacht, Germany. Both membranes tested showed very good properties in the separation of toluene, reaching 90% removal of that compound, although better selectivity and enrichment of the permeate was achieved for POMS membrane. Compared to POMS, much higher fluxes were accomplished for PDMS membrane, especially the water flux. It was probably due to the more hydrophilic character of the PDMS polymer itself. The results of experiments confirm that pervaporation applied to the separation of organic compounds from waters and wastewaters is a very promising method. As a result of the process it is possible to achieve high concentrated permeate and almost complete removal of contamination.