Montague Sludge Dewatering System

The Town of Montague, PEI, will install a geotextile dewatering system that will increase the quality of wastewater effluent, optimize facility performance, and help protect the town’s existing social and economic fabric. Of the 750 m3 of wastewater treated on average every day, the town’s wastewater treatment plant (WWTP) is able to remove only a small portion of waste sludge for agricultural land spreading. An installed pumping system will divert pre-treated effluent through high-strength geotextile bags, which will passively filter the effluent and create drier and lighter weight sludge. After one year of settling in the bags, plant operators will apply the dried class B biosolid as a nutrient additive to sod fields one kilometre from the WWTP. The revenue from the sale of biosolids would be in addition to the approximately $40,000/year savings in operating costs from reducing the amount of sludge pumped through the WWTP along with the effluent. The municipality will repurpose the geotube bags for landscaping, erosion and weed control when they have outlived their use. A 2012 pilot study showed that geotubes could increase sludge thickening at the plant by almost 15 per cent. The upgrade could increase the tonnage of sludge removed from the plant from 13.2 tonnes to 27.7 tonnes of sludge per year. This would result in safer operational Mixed Liquor Suspended Solid (MLSS)* levels. In addition, it currently takes over one hundred 3,000 Litre trucks to haul the biosolid mixture for land application per year. The closer proximity of the sod fields and the increased extraction of water from the sludge will require only four dump trucks for transport per year. Thus reducing the amount of transport required for field applications by over 3,500 kilometers/year, resulting in significant GHG reductions. The facility currently operates within environmental regulations; yet, the inability of the plant to handle current sludge levels has increased the risk of a complete bypass and release of raw, undigested sewage into receiving waters. The social and economic impacts of such an event would be significant, as the downstream mussel farming operations would shut down indefinitely. Montague’s Town Council accepted the project as part of PEI’s Gas Tax Capital Investment Plan. Once the engineering consultants have completed the plans for the project the town will hold further public consultation to emphasize the importance of the project and to receive any additional input. *The concentration of suspended solids in the activated sludge process. If levels are too high the WWTP can become overloaded, which reduces the dissolved oxygen required for biological wastewater degradation. (Project description from original funding application)