DEMONSTRATING WATER STEWARDSHIP THROUGH INTEGRATED WASTEWATER MANAGEMENT: THE CITY OF KINGSTON, ONTARIO, CANADA

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1 DEMONSTRATING WATER STEWARDSHIP THROUGH INTEGRATED WASTEWATER MANAGEMENT: THE CITY OF KINGSTON, ONTARIO, CANADA Bruce C. Anderson (1), An Dong (2), and Allen Lucas (3) (1) Department of Civil Engineering, Queen s University, Kingston, Ontario, Canada (2) Department of Environmental Science and Engineering, Fudan University, Shanghai, P.R. China (3) Utilities Kingston, Kingston, Ontario, Canada Abstract The City of Kingston (through Utilities Kingston, the asset management company responsible for utilities operations) has recently completed a significant upgrade at one of its two wastewater treatment facilities (Ravensview Water Pollution Control Plant, Ravensview ). This project was the largest infrastructure project ever undertaken in Kingston, and it was planned and executed with a major focus on public participation throughout, and with a view toward creating something more than just another sewage treatment plant. This paper provides details about the biological treatment component selection process for Ravensview (a biological aerated filter, BAF), including information from lab-scale and pilot-scale testing and full-scale operation, as well as information about the current operation of Ravensview in support of its new role in the creation of three important products, namely clean water, clean biosolids and green energy. In addition to the technical details, this paper includes an important focus on the societal benefits being realized and being planned for at Ravensview, in keeping with the overall goal of the upgrade. The projects and activities around these benefits are facilitating the role of this wastewater treatment facility in its larger capacity of an environmental centre that will provide continuing public education to foster a stewardship attitude among all citizens of Kingston, and serve as a template for other communities that are now facing federally-mandated requirements for improved wastewater treatment in their locations. Keywords: advanced wastewater treatment, biological aerated filtration, source water protection, integrated wastewater management, public education, water stewardship 865

2 1. INTRODUCTION 1.1 The City of Kingston The City of Kingston, Ontario, is one of the older cities in Canada, and briefly served as Canada s capital in the mid 1800 s. The City is situated at the eastern end of Lake Ontario (the last of the Great Lakes in the east), as this lake joins the St. Lawrence River with water flowing eastward to the Atlantic Ocean. Given this setting, it is not surprising to hear Kingston referred to as Canada s freshwater sailing capital, and water based activities are an important part of the Kingston economy, both past and present (e.g. sailing, swimming, recreational fishing, tourism, transportation and history). These water resources also serve as the source of drinking water for the City (intake from Lake Ontario), and as the receiver of treated wastewaters (discharged to both the Lake and the St. Lawrence River from the two wastewater treatment plants in the City). It is again not surprising to learn that the protection and preservation of these resources, in turn to protect and enhance the aquatic ecosystem, is an important mandate of the City, and part of the overall goal of Kingston to be Canada s most sustainable city. The challenge of realizing this goal lies in the age and historic design of Kingston, with combined sewers (conveying dry weather wastewater, and wet weather wastewater mixed with stormwater runoff) being a significant ongoing source of concern for the City. The age and performance of the older wastewater treatment plant (Ravensview) has also been of concern recently (despite the fact that this plant has normally functioned within the compliance requirements set by the provincial Ministry of Environment, MOE), and this plant has therefore been the focus of the largest infrastructure upgrade in the City s history over the past 5 years. This paper presents an overview of this important project, from both the technological perspective as well as from the perspective of wastewater management fitting into the larger role of water stewardship for Kingston. 1.2 Kingston and Water Stewardship A recent survey of Canadians living in urban centres across the country found that the majority of those surveyed (80%) were worried about the water quality at their local beaches and swimming holes [1]. It was also found that in certain parts of the country with rudimentary or no wastewater treatment, this fear was based mainly on the perception of raw sewage discharge directly into these water resources; elsewhere a similar fear about water quality was found, but the reasons for this fear were unknown. Interestingly, participants from areas with high level wastewater treatment were significantly less worried about water quality (but were still concerned nonetheless). It might be concluded from this survey that the presence of advanced wastewater treatment is only one component of successfully creating a stewardship attitude among urban citizens; the other important component must be a public education and awareness program that allows residents to understand the value and limitations of integrated wastewater management for water resource protection (to create an informed 866

3 and engaged citizenry). The Ravensview upgrade is therefore seen as an excellent model for this multi-faceted approach to wastewater engineering, as is described in this paper. As noted, this upgrade project was the largest infrastructure project ever undertaken in Kingston, and it was planned and executed with a major focus on public participation throughout, and with a view toward creating something more than just another sewage treatment plant. Interestingly, this project was conceived in recognition of the importance of protecting local source waters, and before programs like the provincial source water protection activities (as an outgrowth of the 2005 Ontario Clean Water Act; see for local details) or the current federal focus on a national standard for wastewater effluent (through the Canadian Council of Ministers of the Environment, CCME). It is notable that the CCME initiative has now identified treatment plants across the country that will need to upgrade over the short- (within 10 years) or longer-terms (up to 30 years); given this, the current state of the Ravensview facility means that Kingston is already exceeding current (and future) expectations and requirements of treatment efficiency, and is therefore affording an enhanced level of source water stewardship that can serve as a model for other jurisdictions. 2. THE RAVENSVIEW UPGRADE PROJECT 2.1 Background Ravensview was originally constructed in 1957, and upgraded/expanded in 1974 and 1994 respectively. Before the current project, the rated treatment capacity was 72,800 m 3 /d (average daily), with a peak hourly flow of 152,500 m 3 /d. The plant was a chemically assisted primary treatment facility serving the downtown and Kingston east areas (Figure 1); solids processing included anaerobic stabilization, solids dewatering and off-site land spreading. Typical effluent quality criteria (as per MOE) were 25/25/1.0/0.04 BOD 5 /SS/TP/Total residual chlorine (in mg/l, generally as annual average concentrations). For the period 1999 to 2003, the plant performance was summarized as follows [2]: effluent suspended solids concentration consistently below compliance limit (with about 89% SS removal); effluent BOD 5 concentration highly dependant on extraneous flows from combined sewer system, with monthly average and annual average values variable (with 60-70% removal efficiencies, as a function of particulate matter removal in the clarifiers); effluent TP removal efficiencies were proportional to the amount of metal salts added during the treatment process (as ferric chloride), with effluent values typically below the compliance limit (and 65-75% removal efficiency) 867

4 Figure 1: Location of Kingston and Ravensview (image from mapquest.ca) 2.2 Need for upgrade On-going economic development and urban growth in the serviced Kingston area in the 5 year period prior to 2004 was rapidly consuming the existing hydraulic capacity of Ravensview, and at times during this period the average daily flow capacity was exceeded. An additional driver for change was the on-going program in collection system upgrade and elimination of extraneous flows (as stormwater runoff), resulting in a stronger influent wastewater loading; as a result, the plant was also approaching the provincially mandated compliance limits noted above (particularly for the soluble constituents). In conjunction with this, it was recognized early on that a more reliable process for the removal of soluble organics and nutrients would be required in the near future (e.g. installation of a secondary or biological treatment component), which would ensure that the plant was achieving its principal goal of source water protection in the St. Lawrence River over the longer term. The need for a better treatment system, to provide additional hydraulic capacity for urban growth and significantly improved treatment performance for both the liquid and solids streams, was foreseen by the City of Kingston long before this became a requirement in the province and the country (as per CCME in 2009), and represents an excellent example of the city s pro-activity in water stewardship for the region. To facilitate the selection of an appropriate treatment technology, and in accordance with regulatory requirements, Utilities Kingston (through J.L. Richards & Associates Ltd., and XCG Consultants Ltd.) undertook a Class Environmental Assessment update which investigated various upgrade options at the plant to meet MOE requirements (Policy F-5) and to service the projected long-term growth in the area. One of the recommendations from this study was biological aerated filtration (BAF) as the preferred secondary treatment process, along with a hydraulic expansion of Ravensview to 95,000 m 3 /d average daily flow. While the BAF process had been investigated and implemented in Europe (see review in [3]), in Canada there were only three BAF units in operation (with 2 other facilities in the design phase). 868

5 Given this lack of BAF design and operational experience in Canada, and the fact that this BAF facility would be the largest such facility in Canada once implemented, it was deemed very important that a comprehensive lab and pilot testing program precede the actual BAF design, to ensure appropriate local data on system performance were available to the design team. It was also reasoned that this unique BAF application had the potential to serve as a template for other communities, hence the importance of getting it right before implementation. Finally, the design team recognized that, by implementing the BAF process at Ravensview (as the largest infrastructure project in Kingston history), Kingston had a chance to be a leader in innovation in water stewardship, through the highlighting of the critical importance of wastewater management in Canada. This again can be seen as an example of the foresight of this project by the City of Kingston and Utilities Kingston, since the discussion about the state of wastewater management in Canada (and the need for improvement) is currently becoming more commonplace in the national media [4]. 2.3 Research and testing program for system selection The testing program consisted of both pilot testing on site, and laboratory testing at Queen s University. The pilot testing was conducted specifically to assess the applicability of two different BAF technologies (Biofor supplied by Degrémont Ltd., and Biostyr supplied by John Meunier Inc.) for treating existing raw sewage to meet the target effluent requirement for the upgraded facility (including seasonal effects on operation); this side-by-side real time testing also allowed for a comprehensive comparison between the different BAF technologies. Due to the relatively low concentration of the raw sewage at Ravensview, as well as some operational constraints during pilot testing, a laboratory scale research program was also conducted in the Department of Civil Engineering, Queen s University. In this phase a scaled Biostyr system was constructed to investigate in detail the treatment performance and mechanisms of the BAF process, using synthetic wastewater. Specific research objectives here included investigation of the physical properties of the filtration medium, investigation of the BAF performance for high strength wastewater treatment (robustness testing), examination of important operational parameters (e.g. organic and hydraulic loading, aeration and backwash regime) on overall performance, and a preliminary kinetics study to model substrate removal in the BAF reactor. 869

6 Figure 2: Pilot testing BAF Units (L -Biofor ; R - Biostyr ) Figure 2 illustrates the physical set up of the two BAF systems on site (housed in a temporary building to allow for environmental control). Table 1 summarizes the pilot testing operational conditions (specifically the hydraulic loading rates for the 2 systems, for a variety of operational conditions, i.e. average daily flow, peak daily flow, etc.). In parallel with the pilot testing activities, the laboratory testing was run over a shortened time period, and Figure 3 illustrates the laboratory BAF column setup, with Table 2 summarizing the investigated parameters in this phase of the work. 1050mm In. Dia:100mm 3120mm Backwash Pump Treated wastewater Mesh (Screen) and gasket 1070mm 900 (Media height) Biomass sampling port Wastewater sampling tap Air compressor Backwash Solids Disposal Feeding Pump Synthetic wastewater Figure 3: Laboratory BAF testing unit 870

7 Table 1: Pilot testing operational conditions Parameter Full-scale design flow (m 3 /d) Peak flow factor Equivalent flow to Biofor pilot (m 3 /h) Equivalent flow to Biostyr pilot (m 3 /h) Average flow 95, Maximum flow 167, Peak Hour flow 192, Table 2: Pilot testing operational conditions Hydraulic loading (m 3 /m 2.h) Flow rate (L/h) Process air rate (L/h) Ratio of process air to water flow Backwash rate Water rinse (L/m 2.s) Air scour (L/m 2.s) As noted previously this was a comprehensive evaluation of the BAF process at the field and laboratory scales, which allowed for a robust data set to be created to help with system selection (Biofor or Biostyr ), and allowed the Ravensview operators to work with the system before full implementation. As a result of this evaluation, the Biostyr BAF process was chosen for full design, for reasons of both process effectiveness and operational simplicity (specifically for ammonium nitrogen removal and excess biomass generation). Figure 4 summarizes typical pilot scale operating results for both systems, and Table 3 provides a parameter by parameter comparison of Biofor and Biostyr performance at the pilot scale level. 871

8 Effluent Concentration (mg/l) BOD 5, TSS Design Objective (15mg/L) Biostyr Biofor TSS BOD 5 TKN TN TP Overall Performance of Two BAF Systems Figure 4: Summarized pilot-scale BAF performance Table 3: Pilot testing results summary (average % removal) System BOD 5 TSS COD TN NH 3 -N TKN Biostyr Biofor Implementation of system upgrade at Ravensview Once the BAF process selection was made, the 3 year renovation of the Ravensview treatment plant began. When completed (including the one-year proof of performance period), the plant was officially opened on 09 October 2009 (see Figure 5 for construction photos). From the beginning of this project, it set excellent benchmarks for infrastructure renewal, in terms of both environmental and fiscal responsibility. The overall cost of the project came in at approximately CAN $13,000,000 less than budgeted, and the project was completed ahead of schedule, thanks in large part to the attention paid to the concept of team-building among the contractors, administrators and the City during construction. Many have commented that this project, while extremely complex, was also the best administered in their experience. The success of this project can also be seen in the early performance data for average effluent concentrations: cbod 5 8.7/25.0 mg/l; suspended solids 3.7/25.0; phosphorus 0.48/1.0 (achieved/moe compliance level). 872

9 Figure 5: BAF construction (top L blasting limestone; top R BAF basins; bottom hydraulic testing of BAF basins) Another component worth noting during the upgrade was the involvement and engagement of the citizens of Kingston, with a Public Liaison Committee (PLC) and a Construction Liaison Committee (CLC) struck at appropriate times during the project. These committees were very active in helping with the regular newsletter distributed across the City, ensuring that questions and concerns were addressed in a very timely manner, and they were also active in the planning and execution of all aspects of the project. Many of the committee members live in close proximity to the treatment plant, and were therefore the residents to be most impacted by the construction project; the general consensus among these members, however, was also that this project had very little impact on their daily lives, and the completed project had actually improved other aspects of the area (i.e. walking and cycling trails, wildlife corridors and natural landscaping). These committees helped to create a significant educational identity for Ravensview (as did the project website and real time web cam), which allowed the public at large to understand exactly what was happening, why it was happening, and why it was important from the perspective of source water protection in the Kingston region (in essence helping to generate a water stewardship mindset among the residents of Kingston). 3. RAVENSVIEW AS AN ENVIRONMENTAL CENTRE One of the anticipated outcomes of the Ravensview upgrade project for Utilities Kingston and the City of Kingston was the creation of an environmental centre, with wastewater management as only one important aspect of water stewardship, and with integration of other environmental aspects of the urban landscape into this site [5]. It is commonly stated that Ravensview directly produces three important products: clean water, high quality residual solids for agricultural use and clean energy from the solids stabilization process (which was also upgraded during the project). The entire upgrade project has demonstrated a high level of sustainability principles, starting with the selection of the BAF process (to reduce the overall footprint of the biological treatment system and thus minimize site disturbance), and continuing with reuse of most of the blasted rock on site and application for LEED certification for certain aspects of the upgrade (if successful, this would be one of the first such certifications, which would help raise the profile of wastewater servicing). 873

10 Ravensview will also now serve as a first-class facility for Queen s University researchers. There are already a number of projects on-going at Ravensview (e.g. integration of organic solid waste into the biosolids stabilization process for enhanced biogas generation; isolation of hydrogen from the biogas for use in solid oxide fuel cells), with other research project ideas in discussion including use of the high quality effluent for non-potable urban water uses like landscape irrigation, and investigation of the presence and risk posed by pharmaceuticals and personal care products in wastewater collection systems (with a longer term view to the mitigation measures that might be required by city officials). From these projects, a clearer idea is anticipated of the role of wastewater processing in the creation of sustainable, water smart cities of the future, where we can break away from the old design paradigm of excessive water use to generate flushing flows for wastewater collection systems, and where we can identify and recover materials of value in these formerly undervalued flows (e.g. phosphorus capture and recovery; green energy generation, etc.). In this light, the Ravensview upgrade has allowed this discussion to begin in earnest, and it is anticipated that this facility will continue to engage the citizens of Kingston, and serve as a template for the way forward for other Canadian (and international) cities wrestling with similar concerns. REFERENCES [1] Zimonjic, P. Poll: Albertans least worried about water quality, The Toronto Sun, April 4 (2010). [2] J.L. Richards and XCG Consultants Ltd. Technical Memorandum Biological Aerated Filter Technology Pilot Testing Program at the Ravensview WPCP, City of Kingston, Utilities Kingston (2004). [3] Tan, H. An Evaluation of Biological Aerated Filtration for Wastewater Treatment through Pilot and Laboratory Scale Experiments, M.Sc.(Eng.) thesis, Department of Civil Engineering, Queen s University (2007). [4] Zimonjic, P. and Burnett, T. Canada s dirty little secret, The Kingston Whig Standard, May 29 (2010). [5] Anderson, B.C. Sustainable infrastructure: Ravensview sewage treatment plant upgrade, in The Story of Brownfields Development and Smart Growth in Kingston, Ontario: From Contamination to Revitalization, Welbourn, P., Cleghorn, H., Davis, J., Rose, S. (eds)., Classroom Complete Press (2009), 325p. 874