An investigation of the effect of sewage outfall on algal communities in the Cheboygan River.

Abstract

Waste water treatment is a method used to reclaim water used by society for personal and industrial uses. Waste water treatment involves two types of processes, primary and secondary treatment. Primary treatment involves the filtering and settling out of suspended solids from the sewage water. Secondary treatment involves a reduction of the BOD of the water using bacterial digestion to reduce the organic load of the water. Phosphate and nitrate concentrations are usually reduced, chlorine added, and the water released into a river or lake. Sewage outfall may have a significant effect on aquatic communities in the river where it is released. The following study is designed to investigate the effect of sewage outfall on algal communities. Originally the study was to include all divisions of algae, however, the only division that made up a significant component of the community was the diatoms. Therefore, the study was modified to investigate diatoms communities only. After analyzing the data collected, the following conclusions are made. The sewage outfall does not seem to be affecting the biomass of the diatom communities. Species richness does not appear to be affected by sewage outfall. Community structure seems to be changing below the sewage outfall with Amphipleura pellucida, Amphora ovalis, Amphora perpusilla, and Navicula tripunctata becoming more abundant below the oufall. This aspect of the study may warrant further investigation of the effect of the sewage outfall from the Cheboygan Waste Water Treatment Facility on algal communities. Ammonia levels increased as the river flowed past the sewage outfall. The increased ammonia levels may have affected the algal community structure, but more conclusive data needs to be collected.