August 18, 2022
Categories: Project News
Meeting Effluent Requirements Through Membrane Bioreactor Technologies
Nick Romero, P.Eng., M.Eng.
Design Engineer, Municipal Engineering
Overcoming uncertainties and navigating tricky design constraints are the challenges that our team thrives on.
When we were hired to complete the detailed design of a wastewater treatment plant to service a new warehouse, we saw an opportunity to not only meet the client’s strict effluent requirements with membrane bioreactor technology, but to also develop a solution that would streamline operations and mitigate risks.
Our client’s warehouse is being developed on a site that was previously home to a vehicle manufacturing and assembling facility. While the property is located within St. Thomas, it sits outside of the wastewater service area of all the surrounding towns.
The former manufacturing facility did operate on a private onsite wastewater treatment plant, however the plant was decommissioned and demolished as part of the facility’s closure. This is where our team comes in! We were retained to design a brand new wastewater treatment plant for the proposed development and acquire the necessary approvals to operate the system.
Wastewater Treatment System Criteria
Since our client’s plans for the site involved a new warehouse that would not generate any process water streams, the new plant would only need to treat domestic sewage that is typically generated from toilets, sinks and general housekeeping originating from the facility. Similar to the former plant on the site, the treated effluent would be discharged to Dodd Creek.
Our team identified some criteria for the wastewater treatment system and set up a competitive RFP process for suppliers. We were looking at:
- Costs (capital/operations/maintenance)
- Ability to meet stringent “dry-ditch” effluent requirements
- Tolerance to fluctuations of flows
- Flexibility for expanding the system
- Ease of constructability and installation
Working within Constraints
The warehouse expects around 1,220 employees per day, but could go up to over 3,000 employees per day depending on seasonal demands. Designing the system to meet the Ontario Building Code flow rates and the guidelines set out by the Ministry of the Environment, Conservation and Parks (MECP), we determined the day-to-day fluctuations in flows throughout the year, from 32 to 232 m³/day, while flows during commissioning of the system are expected to be as low as 10 m³/day. Since the wastewater treatment plant will have a capacity greater than 10 m3/day, we were required to obtain Environmental Compliance Approval (ECA).
In order to streamline the ECA approval process, our team was proactive in setting up preliminary discussions with the MECP to discuss the proposed development, wastewater treatment plant concept, and discharge location, as well as to request that ‘dry-ditch’ criteria be followed for the effluent requirements.
Noting that that the effluent requirements for the previous plant were less stringent than the dry-ditch criteria requirements proposed, and that the discharge flows would be significantly lower than the former plant, the MECP accepted the existing Assimilative Capacity study on Dodd Creek to establish the effluent criteria. Our team was able to obtain ECA approval for the system within three months of submitting our application.
Membrane Bioreactor Treatment System
In designing the wastewater treatment plant, we decided to incorporate a membrane bioreactor treatment system, supplied by Newterra.
Newterra was ultimately chosen as the preferred supplier, as their membrane bioreactor technology not only met the design requirements and constrains of the project, but also provided additional value and benefits.
Membrane bioreactor systems are a combination of an activated sludge biological treatment process with membrane filtration. This system was chosen for its ability to meet stringent effluent requirements, its tolerance to fluctuation of flows, flexibility for expanding the system with modular units, and ease of constructability and installation. The wastewater treatment plant is sized to accommodate the maximum daily design flow of 232 m3/day, while also being equipped to handle a variation of flows as low as 32 m3/day.
Our plant design consists of the following processes:
- Lift Station and Flow-equalization
- Fine Screening
- Biological Treatment
- pH Correction and Alkalinity Addition
- Phosphorous Reduction
- Membrane Filtration
- Effluent Disinfection
- Waste Activated Sludge (WAS) Handling
Taking a Value-Added Approach
From an operations perspective, we developed a strategy to identify redundancy requirements within the plant. Working with the client, we identified components within the system that would benefit from additional redundancy. This included spare aeration blowers (EQ and aeration tanks), spare pumps (aeration and EQ tanks), and fine screening spare parts. Spare equipment will be stored in a heated sea container, easily accessible by operations staff.
To facilitate the transition from construction to operations, our client has retained a licensed operator, along with the equipment supplier, to assist with the commissioning of the system, as well as manage operations for the first three months. Due to the low flows anticipated during the first six to nine months of the start-up of the system, continuous monitoring and operational adjustments are anticipated. After the first three months’ post start-up, our client will look to secure an Operating Authority for the system.
Due to the COVID-19 pandemic, uncertainties surrounding supply chains led us to identify long-lead items that would significantly impact the schedule of the project. As a result, equipment with long delivery times, including pumps and blowers, were ordered and approved 20 weeks in advance from the proposed construction date to ensure there would be no delays.
Ultimately, our use of a membrane bioreactor, taking careful consideration to redundancy, procurement and a turn-key approach, allowed us to not only solve some of the constraints our client would typically face with a standard package plant, but it also provided further benefits by streamlining operations and mitigating risks associated with maintenance and regulatory requirements.
Construction of the system began in May 2022, while the commissioning and start-up began in August.Back to All News Stories