Because of the growing tourism industry in British Columbia, the Cultus Country Resort, 60 miles east of Vancouver, was in need of wastewater treatment. For utilities, water systems and water products company Corix, an opportunity to build and operate a wastewater treatment plant (WWTP) in its native Canada was too good to turn down.
Since Eimco Water Technologies is also interested in the Canadian market, the two Canadian companies started talking. Some of the factors considered in the decision-making process included current and future permit compliance issues, fluctuating loading conditions and treatment capacity.
The system was selected for many reasons, said Corix engineer John Sainas.
“In [British Columbia], all developers must complete an environmental study. The environmental study mandates what treatment quality is required, Salinas said. “For this developer, the fact that there were water wells in the area was key in setting low effluent specs: biochemical oxygen demand [less than] 10 mg/L, total suspended solids [less than] 10 mg/L and fecal coliforms [less than] 2.2 CFU/100 ml. While there are other ways to achieve this, membranes are in vogue and their dependability is proven, enabling Corix to make a decision to go with membranes.”
Additionally, because Corix will operate the facility, Sainas added, “It was really our ability to work on an OEM basis with Eimco Water Technologies that was the key. It enables us to make a profit and add value to our delivery.”
The Process
Cultus Country Resort serves summer tourists to British Columbia’s beautiful Cultus Lake. The harsh Canadian winters minimize tourism during the cold season and consequently, the wastewater treatment system design for the resort would have to be flexible enough to handle a range of hydraulic demands.
Using the concept of biohydraulics, the Cultus Country MBR system was designed to exceed biological treatment objectives over the range of expected operating conditions. The resort's WWTP is comprised of two independent process trains that include one anoxic zone and one MBR zone and uses the Storm Master configuration, which offers a cost-effective means of handling storm events that can significantly reduce solids handling costs. With the configuration, the plant is capable of transforming into a sludge thickening system during the low-flow winter months. This capability minimizes hauling requirements and saves the plant thousands of dollars in hauling expenses.
The design is an important feature of the Cultus Country Resort WWTP because it further reduces overall plant operating costs by putting offline membrane capacity to beneficial use. During extremely low flows, one of the process trains is used to treat incoming wastewater while another is used to digest and thicken solids to 3% before further treatment. As flows increase, the plant computer brings all trains online to treat peak flows.
Using Kubota flat-plate submerged membrane units (SMUs), the MBR system is designed to handle average daily flows of approximately 53,000 gal per day (gpd) and can expand to approximately 80,000 gpd with the addition of two more Kubota ES-200s.
The ability to operate the plant manually during times of emergency provides another level of reliability. Unlike many membrane systems that require complex automation and constant adjustments, the plant can be run in a manual mode to protect against power surges, brownouts or a loss of network communications that may temporarily interrupt automation, even with necessary built-in redundancy.
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