The Baima canal restorer by Todd Ecological is a case of ecological engineering in combination with the creation of public space. A city canal was polluted with the sewage of thousands of inhabitants, thus creating health, safety, and odor problems. John Todd installed a linear restoration element in the canal that aerates and supports the growth of aquatic plants that take up nutrients to counter the eutrophic effects of sewage. Along the growth-supports, there was also built a new pedestrian transportation route.
Description of the Process
Wastewater entering the end of the canal is re-cycled to the top of the canal for treatment. An anoxic zone at the top of the canal allows for denitrification. The fine bubble aeration system distributes air along the canal from blowers locat- ed on a central floating barge. Low-intensity and uniformly distributed aeration circulates the water while forcing it past biologically active zones. The Restorer automatically inoculates the system with beneficial bacteria at two locations. A variety of bacteria species were selected specifically for their ability to aid in sludge and grease digestion as well as nitrogen removal.
The City of Fuzhou’s wastewater issues are typical of many developing world cities. The odors from the Baima Canal in particular were a major issue with adjacent temples, elementary school, and many residential apartment buildings. A 600-meter canal named Baima, considered one of the worst in the city, had extreme problems with odor and floating solids created by the influx of 750,000 gallons per day of untreated domestic sewage.
Rather than re-piping the polluted water to a remote wastewater treatment facility, the city government sought an affordable and low maintenance treatment system within the canal itself. In 2002, John Todd Ecological Design collaborated with Ocean Arks International to design a 500-meter linear Restorer for their Chinese partners on the Baima canal using 12,000 plants composed of 20 native species. Constructed with a walkway down the center, the Restorer has met water quality goals and created a prized recreation area for the members of the community. The plant root zones and fabric media of the Restorer provide biophysically diverse surface areas necessary for effective biological treatment of wastewater.
Result of project
The Restorer system succesfully met the goals set by the City of Fuzhou. The Restorer was able to reduce odors, eliminate floating solids, and drastically improve the asthetics of the neighborhood. Furthermore this technology reduced the negative impact of the pollutants in the canal on downstream aquatic ecosystems. The clarity of the water in the canal increased from less than 6 inches to several feet, while meeting several secondary effluent standards.
Role of different stakeholders in the system during the realization and maintenance of the project
The project was eventually decommissioned due to the dredging lobby in the city of Fuzhou. The Baima canal restorer was removed.