Ontario resort upgrades its
wastewater treatment facility

By Colin Kent, P.Eng., President, Ainley Group

Fern Resort wastewater treatment plant.

Fern Resort, established in 1895 and owned and operated by the Downing family, is a quaint year round getaway, located on the south eastern shoreline of Lake Couchiching, on Rama Road, four kilometres north of Atherley, Orillia.

The resort, has 102 rooms and suites, which can accommodate approximately 300 guests with a staff complement of approximately 60. The guest units and other buildings including the main inn and kitchen, the recreational centre and the laundry facility were originally serviced by individual septic systems.

In 1975, a large communal septic tank and tile field were installed, but after a few years of operation, the tile field failed, and it was decided to build a single cell, facultative lagoon. The 1980 Certificate of Approval for the lagoon required seasonal discharge with effluent phosphorus concentrations of less than 1.0 mg/L. A requirement also existed that a second cell be provided, if the existing tile field could not handle the temporary flows of sewage, when the lagoon was being emptied.

In the mid 1980s, Fern applied to the MOE for an expansion of the lagoon, to service up to 600 persons. The MOE responded to the application, noting that effluent requirements of 10 mg/L BOD₅ 15 mg/L TSS & 0.3 mg/L TP, would be imposed, with any expansion. In addition, the use of the tile bed system was to be discontinued.

The project was put on hold until the mid 1990s, when the lack of an alternative treatment or storage facility, that could be used when the lagoon is being discharged, became an issue. Expansion alternatives were again considered, including optimization of the lagoon, conversion to a mechanical plant with disinfection and continuous effluent discharge, and a spray irrigation system. Again the project was shelved until December 1998, when a proposal was discussed with the MOE to provide a new treatment technology, that being a membrane bio-reactor utilizing the patented ZenoGem process.

The project proceeded on that basis, with the plant being designed for an Average Daily Flow of 163 m³/d, to accommodate the sewage flow from approximately 500 persons at 325 L/c/d.

The project includes an upgrade of the existing pump station, located at the resort and the provision of the new membrane treatment facility located in a small building, near the lagoon. The pump station upgrade includes the provision of two Myers constant speed grinder pumps which also provide fine screening, a necessity for the membrane process.

The membrane bio-reactor which is housed in a single storey building approximately 8 m x 10 m, consists of a poured concrete anoxic chamber, three aerobic chambers and a soak tank for cleaning the membranes. The largest aerobic chamber contains three membrane cassettes, each holding three modules initially but capable of holding four modules. Two permeate pumps, maintain the bio-reactor mixed liquor level, about 0.5 m above the membranes.

Peak flows can be retained in the bio-reactor, utilizing vertical equalization volumes. However, the permeate pumps can be adjusted, such that flows up to 2.5 x ADF can be drawn through the membranes, for short periods of time. Effluent is discharged continuously, as resort flows permit, through an in-line, enclosed Trojan UV disinfection device to Lake Couchiching, via Sucker Creek. About 20% of the permeate flow, is taken off to be used as backwash for the membranes. Backpulsing is carried outautomatically at a rate of 30 secs every 15-30 mins. In addition, air is constantly bubbled up through the membranes, to assist cleaning. Positive displacement aeration blowers and compressors are housed in a separate room of the building along with the alum and chemical buffering equipment.

The plant was started up in June 2000, and is believed to be the first permitted membrane wastewater plant in Ontario.

Mixed liquor was wasted from the membrane bio-reactor after approximately four months when the MLSS concentration reached approximately 19,000 mg/L, and was disposed of at a local municipal treatment plant.

The membranes have had to be cleaned once in the first three months, but it was later determined that the loss of permeate suction was due to clogged membrane module air headers. This was concluded to have happened after the cleaning air had been turned off inadvertently, during the early start-up days.

Certificate of Approval requirements in respect of the plant effluent, are all being met at the present time.

The plant was built by Aknor Construction of Orillia at an approximate cost of $650,000.

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