ALKALINE STABILIZATION OF FRESHWATER SEDIMENTS: EFFECTIVENESS OF MICROBIAL POPULATION REDUCTION
Silt and sediments are constantly being deposited in waterways that must remain navigable. These materials are removed through maintenance dredging. Following removal, sediment must be disposed or used for a beneficial purpose. One popular use of dredged sediment is as fill material in construction projects, however it is important that the sediments used in this way do not have negative impacts on human health. One health concern is with microorganisms introduced into the sediment by Combined Sewer Outfalls and agricultural runoff. There are not strict regulations on sediment disposal. However, biosolids have been the subject of extensive federal promulgations and the United States Environmental Protection Agency has identified 5 processes to reduce pathogens in biosolids. One of these processes is alkaline stabilization or treatment with lime. This treatment is very simple, requiring only the addition of some form of lime to raise the sediment to a pH of 12 and maintain for 2 hours. The US EPA asserts that this method is at least 99% effective at reducing organisms in biosolids. The goal of this study was to determine if the use of alkaline stabilization reduces the amount of microorganisms in sediments obtained from a freshwater stream. Measurements of heterotrophic bacteria, total fungi, Bacillus cereus, Escherichia coli, and total coliforms were used to assess the effectiveness of alkaline stabilization of sediments. It was determined that the amount of microorganisms in the sediment after treatment with hydrated lime and lime kiln dust was reduced, but the decrease was not 99% for all the indicator organisms as predicted by the US EPA guidance for biosolids. Heterotrophs, E. coli, and total coliforms were reduced by greater than 99%, but fungi were only reduced 86.5% and the opportunistic pathogen Bacillus cereus was only reduced by 75%.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:sediment alkaline stabilization bacillus cereus
Date of Publication:01/01/2002