| Three noncentralized wastewater treatment systems and three centralized wastewater treatment systems were evaluated for their efficiency in removing indicators of pathogens from domestic sewage. The parameters used in the evaluation were biochemical oxygen demand, total suspended solids, and fecal coliform. The measure of efficiency was based on (a) the discharge effluent concentration of each parameter as the concentration relates to the maximum permissible Environmental Protection Agency limit, and (b) the percentage in reduction of each parameter from the influent value to the effluent value. For the noncentralized wastewater treatment systems, intermittent sand filtration was found to be significantly better (p < .001) than either peat moss filtration or constructed-wetland filtration were found to be. For the centralized wastewater treatment systems, the sewage treatment plant operating at Daphne, Alabama, was found to be significantly more effective (p < .001) than either the Fairhope, Alabama, plant or the Dauphin Island, Alabama, plant was found to be. In this study, a comparative tool (scoring system) to rank the effectiveness of various systems was developed. The lower the score on this tool is, the more effective the system. The sand filtration treatment scored 1.04, the constructed-wetland treatment scored 3.42, and the peat filtration treatment scored 3.56. Scores for the three centralized wastewater treatment systems were as follows: 0.53 for the Daphne plant, 0.72 for the Fairhope plant, and 0.69 for the Dauphin Island plant. |
PDF Full Text Request