WCW24

Lagoons are common for wastewater treatment in smaller-sized municipalities. Over time, lagoons accumulate sludge that must be cleaned out to maintain storage capacity, reduce odours and meet effluent compliance. The cost of cleaning out lagoons can be high and varies widely depending on the size of the lagoon, the amount of sludge and the options available for beneficial reuse or disposal of the sludge. A high cost of cleaning lagoons can often be a barrier for undertaking this important maintenance procedure. Some options for cleaning out sludge include dewatering lagoons and removing sludge with heavy equipment, dredging sludge with barges, and using lagoon crawlers that drive into lagoons and pump out sludge. A relatively new approach is bioaugmentation of lagoons with microbes that accelerate degradation of sludge in situ. Bioaugmentation is not capital intensive and has been used successfully in other jurisdictions. However, it has not been used extensively in Ontario. Bioaugmentation products are typically proprietary, and the suppliers claim successful use of these products to reduce sludge, Fats Oils and Grease (FOG) and when adding in a collection system, raw sewage loadings. The Town of Bruce Mines and the Ontario Clean Water Agency (OCWA) partnered to trial bioaugmentation in the Town's sewage lagoons as the lagoons required sludge removal and the Town had limited capital funds for the work. The key questions the trial set out to answer is whether bioaugmentation would work in a cold climate, and how much sludge could be removed by bioaugmentation. The results of this study showed bioaugmentation could be an approach to remove sludge from lagoons in situ at a lower cost than traditional methods. In this case study, the results of bioaugmentation exceeded expectations. After one-year of bioaugmentation show a sludge reduction of 6,849 m3, which is a 56% overall reduction across the two cells. Reduction was not equal in the two cells as there was a 40% reduction in cell #1 and 64% reduction in cell #2.