Green River

Nova Scotia’s Solar Sewage Solution

One of Bear River, Nova Scotia’s biggest tourist attractions is its sewage treatment plant. Pleasing to the eye and almost completely odorless, the 80,000-gallon facility is located right in the heart of the small town’s tourist district. Every year, close to 2,000 people visit the plant.

Bear River became the home of Canada’s first solar aquatic system (and the first fully operational system in North America) in 1995. A solar aquatic system (SAS) is different from a conventional treatment system because it uses the processes of nature to help purify waste.

Before it built the SAS, the community of Bear River was pumping raw sewage directly into the river. Situated in a small valley, the town had little available land to build a larger, traditional treatment plant, so SAS was the most cost-effective option. "The operating cost is about the same as other systems," reports Nelson Porteus, public works coordinator for Annapolis County.

The SAS concept is simple. First, solids are removed and composted. Then, sewage passes through several rows of clear plastic solar tanks housed in a large greenhouse. The $400,000 Bear River facility (whose cost was shared by the federal and provincial government) is 2,400 square feet with 12 solar tanks serving 60 families. Each tank contains plants, bacteria, algae, snails and other aquatic life forms. As sewage flows from one tank to the next, the organisms in the tanks consume and absorb organic materials.

Next, the sewage is filtered through an artificial pond that resembles a wetland. The pond is divided into three sections, each containing different organisms that work together to digest the waste. Any leftover solids are collected and composted. The effluent is disinfected by exposure to high levels of ultraviolet light. Finally, pure enough to drink, it is discharged into Bear River.

There are advantages to SAS: It is low-energy, low- waste and more attractive than conventional treatment facilities. But Porteus warns against overestimating the benefits of the technology. "It doesn’t run energy-free," he says. "Its effectiveness isn’t all it could be when compared to conventional systems, and it requires heat in the wintertime." Despite these minor problems, Bear River seems happy with its plant. "The community is comfortable with this greenhouse approach," says L.M. Emms, municipal services director of Annapolis County.