A comparison of two simple titration procedures to determine

Science knows quite a number of possibilities to determine volatile fatty acids in waste water and sludges. The simplest and cheapest method, however, developed so far is titration with acid and base. Different suggestions on how to apply this principle abound. This paper compares a method developed in South Africa with a German approach. Both methods were developed for effluents of treatment processes, i.e. for the control of anaerobic fermentation processes. Nevertheless these procedures are increasingly being applied to influents, too, e.g. for the control and optimisation of enhanced biological phosphorus removal from waste water. In order to promote the advantages of titration, it is crucial to find a procedure which provides both optimum accuracy and simplicity. Taking into account a minimal modification of the original German method, it shows that the accuracy of both methods is equivalent for all media investigated in this study (waste water, primary sludge, highand low-load activated sludge). Hence it is simplicity that becomes decisive for method selection in most cases. In this respect the German method is regarded as superior because it only requires acid, uses one pH point less and enables S a calculation by a simple explicit equation. But whenever there is additional interest in the specification of carbonate alkalinity, the South African procedure is recommended.