The role of insects in sewage disposal beds

Abstract

In recent years, the increasing emphasis on the importance of controlling pollution in our natural waterways has led to many studies of the factors involved in the biological stabilization of domestic and industrial waste materials. The present investigation has sought to clarify the part that insects play in two popular waste treatment processes—trickling filters and oxidation ponds. The larvae of psychodid flies are extremely common in trickling filters, and aid in effecting better stabilized effluents by helping to keep the filter zooglea in a healthy state; the zooglea is responsible for the biological oxidation of organic matter and becomes inefficient if allowed to develop unchecked by scouring organisms. Pilot plant studies are described. Many species of insects are found in oxidation ponds, the most abundant and important of which are the larvae of midges which burrow into bottom deposits of the ponds. They help to keep the bottom sludges in good condition, aid in removing suspended materials from the substrate undergoing purification, and thereby reduce the biochemical oxidation demand of the final effluent. Laboratory experimental results and field observations are presented.