Nelson Environmental - Lagoon Aeration - Nitrification - Wastewater Treatment - Canada - United States

Project Information

Project Name: Municipality of Southwest Middlesex WWTP Upgrade

Location: Glencoe, Ontario (Canada)

Project Type: Municipal Wastewater Treatment

Completion Date: March 2011

Treatment Objectives

  • Flow capacity increase from 946 m3/day to 1742 m3/day (0.25 MGD to 0.46 MGD))
  • Effluent Quality: < 1.0/< 3.0 mg/L Summer/Winter TAN, <10 mg/L BOD5, <10 mg/L TSS & 0.3 mg/L TP

Municipality of Southwest Middlesex WWTP Upgrade

Municipality of Southwest Middlesex WWTP Upgrade

Project Background/Challenges

Southwest Middlesex's WWTP consisted two facultative (parallel) wastewater treatment lagoons were in operation since 1974-75. The lagoons were designed for seasonal discharge (early spring and late fall) with a maximum of 946 m3/day average daily flow. As of 2005, the facility was already operating at maximum hydraulic loading. An upgrade was required to meet current and future demand. In order to attain the capacity increase without constructing additional lagoons the process was to be converted from seasonal to continuous discharge. This required the effluent quality meet permit requirements on a year round basis.

NEI's Solution

Nelson Environmental Inc.'s (NEI) OPTAER® wastewater treatment with a SAGR® for nitrification was implemented as an upgrade to the facility. With a design flow capacity of 1742 m3/day the upgraded system has nearly twice the maximum hydraulic capacity of the previous design. The capacity increase will meet future demands based on a 30 year design life. The added capacity also creates room for surrounding communities to tie into the system, including the Hamlets of Appin and Melbourne.

Of the two previous facultative treatment lagoons, only one is in operation. The eastern facultative cell was taken offline, leaving it for use as a storage facility when needed (e.g. maintenance or bypass of the western treatment cell). The western cell was divided into three cells using geo-membrane floating baffle curtains to divert flow and effectively maximize the hydraulic retention time by preventing short circuiting. OPTAER® Fine Bubble diffused aeration was implemented in the partitioned cells to achieve improved year-round BOD5 and TSS removal through bacterial degradation and solids settling.

Lagoon based treatment systems provide some ammonia removal (nitrification) during the summer months, but are generally incapable of meeting low ammonia limits during prolonged periods of low water temperatures. The SAGR® (Submerged Attached Growth Reactor) tertiary treatment system with FBA® LINEAR Aeration was developed to address this issue. The Glencoe treatment facility consists of two SAGR® beds. The SAGR® process is followed by disc filters with chemical addition for phosphorus removal.

Upgraded System Performance

Glencoe's OPTAER® based wastewater treatment (with a SAGR®) is able to consistently meet ammonia effluent limits of <1.0 mg/L in summer, and <3.0 mg/L in winter with water temperatures as low as 0.5°C. As an added benefit, the SAGR® process provides BOD5 and TSS polishing to < 10/10 mg/L on consistent basis.

In addition to increased capacity and improved effluent quality, the overall footprint of the facility was approximately decreased in half which allows for future expansion without a footprint increase.

The components and design approach for the Glencoe wastewater water treatment process demonstrates the ability to increase hydraulic capacity and provide nutrient removal in a lagoon based process. The current design also maximizing the use of existing lagoon infrastructure and maintains low operation and maintenance costs.

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