Project Information
- Location: Doaktown, New Brunswick
- Project Type: Municipal Wastewater Treatment Plant Upgrade
- Completion Date: December 2010
Treatment Objectives
- Design Flow:
10 mg/L cBOD5 - Effluent Quality Requirements:
10 mg/L TSS
TSS: < 10 mg/L
1 mg/L Total Ammonia (Summer)
7 mg/L Total Ammonia (Winter)
PROJECT BACKGROUND & CHALLENGES
The town of Doaktown, New Brunswick can be found in Northumberland County on the shores of the Miramichi River. Once home to one of the largest Atlantic salmon populations in North America, water from the Miramichi River eventually makes its way to the Gulf of St Lawrence. Today, the Miramichi River not only continues to support a large fishery, but the river attracts recreational fly fisherman from all over the world. In order to preserve this industry, the New Brunswick Department of Natural Resources has implemented rules and regulations for fishing.
But in order to protect life within the river, stricter limits were also placed upon the wastewater effluent that is discharged into the river. The Canadian government’s Wastewater Systems Effluent Regulations (WSER) department introduced new and lowered nutrient limits for all Canadian wastewater treatment facilities. With only one facultative lagoon servicing the needs of the plant, this meant the wastewater treatment facility (WWTF) at Doaktown would no longer capable of maintaining compliance.
Historically, lagoon systems like Doaktown were designed to meet BOD and TSS limits but were not capable of producing non-toxic effluent throughout the year. The increased federal enforcement of toxicity requirements has resulted in a greater focus on effluent ammonia levels, and the first indication of an issue is a fish kill in the receiving stream or river. For these reasons, engineers for Doaktown sought a cost-effective and reliable solution.
The NEI Answer
In 2010, the existing wastewater treatment plant in Doaktown consisted of a single facultative lagoon. The proposed solution would utilize this existing lagoon as part of the overall upgrade, allowing the WWTF to realize cost savings in the construction, and long-term operation and maintenance of the system. The updated facility would consist of a new optAER® aerated lagoon for primary treatment, followed by the existing lagoon, which was divided into two treatment cells for secondary treatment, using a geomembrane floating baffle curtain to divert flow and effectively maximize the hydraulic retention time by preventing short-circuiting. Two SAGR® beds were then constructed to provide tertiary treatment before discharging into the Miramichi River.
Addition of a new aerated lagoon:
A brand-new lagoon was constructed west of the existing lagoon to serve as primary treatment, and aerated using our optAER lagoon-based wastewater treatment system. In comparison to mechanical treatment facilities, optAER process-enhanced sites can be implemented at a fraction of the cost but still maintain the simplicity of a lagoon. Aeration provides internal sludge digestion, resulting in minimal solids accumulation, and extending the life of the lagoon.
Installation of optAER aeration into the existing lagoon:
The existing facultative treatment lagoon at Doaktown was first drained for sludge removal, and then expanded. It was divided into two separate cells by a geomembrane floating baffle curtain,m used to divert flow and maximize hydraulic retention time. The optAER system was then added to the two cells individually to assist with improved year-round BOD and TSS removal through bacterial degradation and solids settling.
Implementation of the SAGRs:
At Doaktown, two SAGR beds were constructed after the lagoons for tertiary treatment, providing additional BOD and TSS polishing. The SAGR consists of an aerated submerged aggregate bed, with a horizontal flow distributing influent wastewater across the bed.
UPGRADED SYSTEM PERFORMANCE
Following the successful completion of system construction, the upgraded WTTF at Doaktown was commissioned in December 2010, with operator training on December 20th. Since commissioning, the Doaktown facility has exceeded all effluent requirements – consistently producing low effluent concentrations for BOD, TSS and TAN.
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