Turbidity, Plankton and Mineral Content of the Detroit Water Supply

Abstract

Artificial purification of water has made rapid progress in the past few decades. Treatment to make water safe from pathogenic bacteria from sewage, and to settle its turbidity and make it clear for use, are the main aims in the purification process. It has been found in the operation of the filter plant that the process is greatly affected by turbidity, plankton, and mineral content of the raw water used. It is the purpose of this paper to show the importance of these three factors in the purification of water at Detroit, Michigan. The Great Lakes are the source of the Detroit Water Supply. The intake is located at the head of Belle Isle in the Detroit River, and the outlet of shallow Lake St. Clair. The latter, a part of the straits connecting Lake Huron and Lake Erie, occupies 460 square mile, and contains the large delta of St. Clair River. Lake St. Clair has an average depth of 10 feet, and at no place is it more than 22 feet deep. The bottom is muddy and easily stirred up, and the shores are polluted to a considerable extent from habitations along them. However, the volume of water is practically unlimited as far as a source of water supply is concerned and it is flowing, although slowly (figure 1). The turbidity of the water in the Detroit River is generally low because of the settling effect of Lake St. Clair and the larger lakes above. The Detroit Filtration Plant deals with a turbidity of 35 parts per million. Water for domestic use ordinarily has a turbidity of considerably less than 5 p.p.m. People like a water that appears clear.