Enhanced Sludge Reduction Using External Bioaugmentation at a Full-Scale Municipal Wastewater Treatment Plant

One the biggest burdens facing municipal wastewater treatment plants are the expenses of hauling and disposing of residual biosolids, or sludge. In 2007, United States municipal wastewater treatment plants produced about 7.7 million dry tons of biosolids, according to sources relying on EPA estimates. Hauling costs, tipping fees and the availability of land application sites forces many administrators to search for new ways to reduce the quantity of sludge produced by the wastewater treatment process. A full-scale activated sludge wastewater treatment plant selected an emerging technology to enhance degradation of biosolids without any digestion process at the plant. The results show that using an external source of genus Bacillus bacteria added to the outer reaches of the sewer collection system improved operational performance at the plant and will save the municipality an estimated $96,000 of operating expenses in the first year of treatment. This report describes the plant performance improvements, the evaluation metrics, the history and discussion of the plant process, and the environmental impacts resulting from external bioaugmentation introduced to the sewer collection system.