Success Story: Guelph Optimizes its Sewage Treatment
Sewage treatment plants in Ontario are expected to require billions of dollars worth of upgrades and expansions over the next decade to replace worn out infrastructure, build additional capacity and improve facility performance. Rather than incur the huge capital costs of new infrastructure and expensive new technology, a viable alternative can sometimes be “optimization.”
What is Optimization?
Optimization is a process in which a facility closely examines its operations, practices and management to find ways to improve efficiency. In some cases, making minor operational changes can yield big improvements in the quality of a wastewater facility’s treated effluent.
Optimization programs typically involve the fine-tuning of each individual component of the facility. For example, operators might monitor the influent and effluent concentrations from each treatment component, make a series of process control adjustments (e.g., alter flow distribution, modify chemical dosages, etc.) and determine which adjustments improve performance.
Optimization programs also involve general “troubleshooting” of the plant – looking for design deficiencies, process bottlenecks and operator problems. In addition, these programs usually place a major emphasis on operator training to ensure a well run plant.
Although the optimization process itself requires an investment in staff and other resources, the program has the potential to create significant cost savings. A finely-tuned facility can often reduce operational costs, as well as defer or avoid costly upgrades and purchases of expensive new technologies. In some cases, an optimization program can even avoid the need to build new infrastructure (e.g., to meet local growth) by tapping into the latent capacity of existing infrastructure to treat higher volumes of wastewater.
Guelph: An Example of Successful Optimization
The City of Guelph’s population is slated to grow by at least 50 percent by 2030 under the provincial Growth Plan for the Greater Golden Horseshoe. To meet this anticipated growth, the City proposed expanding its sewage treatment facility at an estimated capital cost of $20 million.
The Guelph facility discharges into the Speed River, a small waterway that cannot assimilate large loadings of wastewater at low flow. Therefore, in order to expand, the facility would need to improve the quality of its treated effluent being discharged into the river. Despite being a modern, tertiary treatment plant, the Guelph facility could not meet the stringent treated effluent standards required of an expanded facility.
In 2008, rather than committing to an expansion, the City decided to undertake an optimization program to get the most out of its existing infrastructure. The program examined each treatment process looking for bottlenecks and assessing cause-and-effect relationships to identify opportunities to improve the performance of the facility and increase its capacity. The program focused heavily on developing the facility’s “human infrastructure” by investing in staff training and skills development to enable the staff to improve the facility’s process control.
As a result of the program, the facility reduced the concentration of ammonia in its treated effluent such that it could consistently meet the stricter effluent limits required for an expanded facility. Similarly, operations staff achieved lower chlorine limits by improving the process control of the existing chlorine removal system. Previously, facility managers believed that they needed to install a new UV disinfection technology, at an estimated cost of $5 million, to replace chlorine disinfection.
The program also untapped enough new processing capacity that the existing plant could be re-rated to meet all of the anticipated future needs. Accordingly, the optimization program helped the City avoid spending an estimated $20 million to expand the facility.
Optimization as First Priority
The Ministry of the Environment (MOE) has long supported the idea of optimization. For decades, up until the early 1990s, MOE operated a comprehensive program to train and support facility operators. In the late 1990s, the governments of Ontario and Canada helped over 25 municipal facilities in the Great Lakes basin improve the quality of their effluent through the “Municipal Sewage Treatment Plant Optimization Program.” In 2009, the ministry, in partnership with Environment Canada, Durham Region and the Water Environment Association of Ontario, began developing a ‘Guidance Manual for Optimization of Sewage Treatment Plants.’
Yet, not enough facilities take full advantage of this option. Many facilities (particularly smaller ones) lack the specialized staff, expertise and sensor equipment required to run an optimization program. In addition, federal and provincial funding programs often favour the traditional design and construction approach over improvement of existing operations.
The ECO encourages MOE to expand its support of optimization by providing financial and technical assistance for optimization programs – either directly or through the Ontario Clean Water Agency – especially for smaller facilities. Further, before granting any approvals for expansions or upgrades, MOE should first ensure that the facilities are obtaining optimal performance from their existing infrastructure.
| Previous section: Ottawa’s Overflow Woes |
| Next section: When Bigger Isn’t Better: Decentralized Wastewater Treatment Systems |
| This is an article from the 2009/10 Annual Report to the Legislature from the Environmental Commissioner of Ontario. |
Citing This Article:
Environmental Commissioner of Ontario. 2010. "Success Story: Guelph Optimizes its Sewage Treatment." Redefining Conservation, ECO Annual Report, 2009/10. Toronto, ON : Environmental Commissioner of Ontario. 87-89.
