Detection of polar organic substances relevant for drinking water

Testfilter systems help in the study of the persistence of organic compound s. Hence, they are remedial measures to control pollution of the environmen t. The filters used as biological fixed-bed reactors should enable the simu lation of the biological degradation of organic compounds before they reach the waterworks. The German chemical industry has used filters based on act ivated carbon for more than 20 years in order to determine the microbial po orly degradable fraction of the dissolved organic carbon in the sewage effl uents. The testfilter systems proved to work well on the basis of group and 'sum' parameters. The new challenge was to investigate whether the testfil ter concept holds also for a diversification of drinking water relevant and non-relevant single compounds. Therefore, the first task was to develop an alytical methods for classes of drinking water relevant compounds in the ve ry complex matrix of waste water. Thereafter, these methods were applied fo r the detection of the selected compounds in the testfilter systems and the ir occurrence in the receiving waters. Methods of analysis were developed f or the following classes of chemical compounds: aliphatic amines, aromatic sulfonates, halogenated carboxylic acids and organic phosphates. Furthermor e the formation of yet unknown drinking water relevant compounds was studie d. As a result it was concluded that the major reasons for the formation of these compounds are: (1) formation of by-products during various steps in the chemical synthesis; (2) chemical reactions in the influents of the trea tment plants; and (3) metabolism in the waste water treatment plant. Experi ments with compounds like 6-[methyl(phenylsulfonyl)amino]hexanoic acid (HPS ) and nitrilotriacetic acid (NTA) which are known from the literature to be well degradable, confirmed that the testfilters can be utilized for simula ting the performance of the underground passage. On the other hand, persist ent compounds, for which 1,5-naphthalenedisulfonate is a characteristic rep resentative, remained in the filter system without being degraded. As far a s the testfilters are concerned it was concluded that the activated carbon retains its adsorption capacity to a certain extent even after a long time of operation. Because it is not possible to distinguish between microbial d egradation and adsorption, it was necessary to develop a modified filter se t-up for testing single substances. (C) 1999 Elsevier Science Ltd. All righ ts reserved.