FIELD STUDY OF NUTRIENT CONTROL IN A MULTICELL LAGOON

Lagoons are well known as acceptable methods of treating both municipal and industrial wastes. Their ability to meet the secondary treatment standards promulgated by the Federal Water Pollution Control Act Amendments is in question. These standards have caused the system to be re-evaluated in terms of efficiency. Modifications to existing lagoon facilities appear feasible. This study concentrated on nutrient removal in a serially arranged, multicell aerated, facultative lagoon system over a three-year period. The hypothesis of the study was that nitrogen and phosphorus would be controlled by selective alum addition and nitrification. A six-cell lagoon system located in the St. Charles Communities at Waldorf, Maryland was chosen as the research site. Using the St. Charles system, this researcher, employed by the Charles County Community College, La Plata, Maryland, under the sponsorship of the Environmental Protection Agency, conducted the three-year study. The lagoon system was modified in order to have two independent three-cell systems, one of which was the control and the other the test. Each system contained an aerated first cell. Alum addition to the third cell of the test system proved to be more efficient than alum addition to the first cell in removing total phosphorus, biochemical oxygen demand (BOD) and suspended solids. A plastic-media, trickling filter tower was installed at the effluent station of the third cell of the test system. Consistent nitrification was established; however, seasonal effects caused the system to be less efficient during the winter months. Lagoons that have been modified to implement these forms of nutrient control should be considered as viable, economic means of meeting current secondary standards.