The use of wastewater sludges in agriculture is widespread throughout the world. The nurients (especially organic matter and minerals) present in sludges can reduce or completely eliminate the need for commercial fertilizers. However the disposal or reuse of inadequately treated sewage sludge poses a serious health risk to humans and animals. The aim of this study was to evaluate a method for sludge decontamination, consisting of alkaline treatment with ammonia at 22 degrees C, to establish its effect on the survival of Ascaris suum eggs. The experiments showed that alkalinization of sewage sludge with 1% NH4OH reduced the viability of A suum eggs. Treatment efficacy seemed to be correlated with the quantity of NH4OH added, not the pH achieved. The use of this method to decontaminate wastewater sludge prior to using it as manure in agriculture is suggested. (C) 1997 Elsevier Science Ltd.