Biodegradation of Synthetic Detergents Evaluation By Community Trials

used in the trials described in Part 1 of this paper'. The sampling and analytical work was carried out by the Water Pollution Research Laboratory (WPRL) using the same methods as in the previous trial. An additional analytical method was required in these trials, however, for the determination of trace quantities of nonionics in the influent and effluent sewage streams. The WPRL employed the thin-layer chromatographic procedure, developed by Patterson et all4 for this analysis: this method was found to be satisfactory.Abstract The biodegradability of ethoxylates based on synthetic primary alcohols and on iso-octylphenol has been evaluated by field trials with a trickling filter sewage treatment plant serving a small community. Ethoxylates based on synthetic alcohols showed good biodegradability in the trickling filter, even in winter. This is in line with laboratory tests. Effluents were practically non-foaming and on further aeration an ultimate biodegradability of 99?!0 was achieved. Ethoxylates based on iso-octylphenol biode-graded in winter to an extent of some 20% only. In summer, values as high as 80% were obtained. In general, however, ethoxylates of this type cannot be considered biodegradable. Effluents showed a considerable tendency to foam, even under summer conditions. Introduction In Part 1 of this paper' wedescribed thecommunity trials carried out toevaluate the biodegradability of a range of alkylbenzene sulphonates. The present work extends the trials to cover ethoxylates based on synthetic primary alcohols and on iso-octylphenol. Most workers have found ethoxylates, based on linear primary alcohols, to be readily biodegradable in laboratory biodegradation tests. Our own laboratory tests also showed these materials to be highly biodegradable but we wished to confirm this by trials carried out under practical sewage treatment conditions. Published evidence concerning the biodegrada-bility of branched chain alkylphenol ethoxylates is very conflicting. The majority of workers have found, in laboratory-scale tests, that these materials are not biodegradable-'. Other workers, using both laboratory-scale and practical-scale tests have found them to be biodegradabl@-l*. Swisher13 attributes the main causes for these discrepancies to (i) failure to make sufficient provision for bacterial acclimation and (ii) failure of the cobalti-thiocyanate analytical method to respond to biodegradation intermediates which still show substantial foaming and other surface activity. We wished to establish the order of biodegradatiofi obtained on a material of this type under practical sewage treatment conditions with acclimatization already established and where the method of analysis was based on the thin-layer chromato-graphic procedure of Patterson et all4.