Design Team Members: Scott Macintosh & Mark Vanderbeek
Supervisor: Ken Oakes, Dept. of Biology
Background
As populations in urban areas continue to increase, the general trend in wastewater treatment has moved towards centralized treatment facilities. These facilities require extensive use of chemical additives, constant monitoring and can be financially burdensome to small municipalities. An alternative treatment approach relies on the natural processes occurring in wetlands. Wetlands have been referred to as nature’s kidneys, and the combination of biological, chemical, and physical processes can effectively purify water. These systems can provide cost-effective solutions, reduce our environmental footprint and can create aesthetically pleasing, diverse ecosystems for naturalists to enjoy. These systems have been utilized for five decades in Canada and currently over 100 of these systems are being used across Canada
Project description
Piping infrastructure must be installed to connect every home’s sewer system to the centralized facility. For residents of rural areas, this is not a feasible option as associated construction costs would be extremely high. Due to these high costs, residents of rural areas often employ septic, or ‘on-site wastewater treatment’, systems. These systems rely on anaerobic bacterial activity and filtration to purify water. Deficiencies in these systems often result in effluent discharge that is high in contaminants detrimental to health of the public and the environment. In locations of close proximity to surface water, inadequately treated effluent is often discharged to the adjacent water body. This may result in high bacterial activity in the water body, leading to human sickness. The objective of this project is to design a residential surface water treatment wetland to be used in conjunction with existing septic systems. This system shall produce enhanced effluent quality, reducing the potential negative impacts.
Design methodology
To evaluate the functionality of the proposed design, the system was broken down into individual components. Initially, filtration of water occurs as it passes through soils. After filtration, effluent is collected and introduced into the wetland. The first process of the wetland is a sedimentation pond, where large particles aggregate and settle. Water then moves onto an aerobic reactor, where bacterial decomposition of contaminants takes place. For each of the major processes; filtration, sedimentation and aerobic decomposition, laboratory experiments have been designed to determine the physical and chemical affects on a variety of typical wastewater parameters. This allows characterization of the water after each process. Laboratory data, used in conjunction with existing models, will then be used to characterize the wetland system such that it produces an effluent complying with Ministry of Environment regulations.