Harvesting wastewater energy safely and reliably through the Wetwell
Harnessing the carbon-free thermal energy in wastewater to heat and cool our buildings could eliminate almost one-third of the harmful Greenhouse gas emissions that threaten our planet. However, sewage is most readily available at wastewater treatment plants that are typically located far away from dense urban settings that have the highest building heating and cooling demand. Noventa’s WET™ systems address this challenge by tapping into large sanitary sewers that run deep below our streets and public rights-of-way.
Building on the knowledge and experience of Noventa’s leadership team and the lessons learned from HUBER’s 42 RoWin® and ThermWin® installations over the past 15 years, Noventa’s WET™ systems are adapted to each individual setting. Typically, they include a Wetwell through which the sewer is accessed, two separate distribution pipe networks that transport sieved wastewater and thermal energy, and an Energy Transfer Station (ETS) where energy is transferred between wastewater and a building’s HVAC system.
Using HUBER’s innovative ROTAMAT RoK4® pumping station assembly, Noventa is able to access sewers at any depth as evidenced by our Toronto Western Hospital WET™ project. Installed in over 1,200 municipal and industrial wastewater applications worldwide for over twenty years, the HUBER RoK4® removes the solids and grit found in raw sewage. An integral part of the HUBER ThermWin® system, the RoK4® is housed in the Wetwell that is typically constructed close to the sewer and connected by a pipe at the 5 o’clock mark. This allows wastewater to flow via gravity into the RoK4® 6mm perforated screen basket located at the bottom of the Wetwell. Solids and grit are held back and transported up through the Wetwell and back to the sewer via a slow-moving auger assembly.
This screening process ensures that only sieved brown water is pumped to the HUBER RoWin® heat exchanger, avoiding the need for macerators that regularly break down and, along with the plate frame heat exchangers, require regular cleaning. More importantly, with the Huber ThermWin® system, Noventa is able to ensure that wastewater is managed at the bottom of the Wetwell and not at the Energy Transfer Station above ground or inside the customer’s building.
The Wetwell at Noventa’s TWH WET™ project sets a new high-water mark as the largest such purpose-built structure in the world anchoring the largest wastewater energy project in the world. The TWH Wetwell will be 35 feet in diameter and 165 feet deep and will house 6 Huber RoK4® XL units. However, once completed, it will be largely inconspicuous - except for the manhole cover at grade which will be used for access.
Importantly, the TWH WET™ system Wetwell will access one of the largest trunk mains in the City of Toronto (the 10ft diameter Mid-Toronto Interceptor) which has over 600 litres/second of dry weather low flow. Noventa’s expert team will tap into this sewer without disrupting flow - demonstrating Noventa’s ability to overcome challenging conditions.