Alberta Capital Region Wastewater Treatment Plant - Introduction

All Commission facilities and operations are regulated by Alberta Environment under Approval No. 486-02-00 that runs until May 31, 2015. This Approval requires the plant treatment processes to achieve ammonia-nitrogen concentration less than 10 mg/L during winter months and less than 5 mg/L during summer months, and total phosphorus less than 1.0 mg/L. Effluent disinfection is also required to reduce fecal coliforms to less than 200 counts/100 mL (change to E. Coli from November 2006). The old conventional activated sludge process was upgraded to a biological nutrient removal (BNR) process in 2004 in order to meet the new effluent requirements. The commissioning of process was carried out from October 2004 to May 2005; and the normal operation started from June, 2005. In addition, the plant expansion was completed in December 2005, which raised the plant secondary treatment capacity from 70,000 m3/d to 87,500 m3/d. From December 2005, the plant started to run at the new capacity. We have being showing excellence in running the biological nutrient removal process and UV facility and achieving very good effluent data. From June 2005 to December 2007, our effluent monthly average ammonia nitrogen for summer months (Jun ~ Nov) was 2.96 mg/L (Permit is 5) and for winter months (Dec ~ May) was 5.27 mg/L (Permit is 10), and monthly average total phosphorus was 0.59 mg/L (Permit is 1.0). Most of the time, alum was not added for the phosphorus removal. Monthly average fecal coliform/E. Coli was 20 counts/100 mL (Permit is 200). Please click here to read the detailed monthly average data of monitored parameters of treated effluent.

Biosolids (digested sludge) disposal is contracted to the City of Edmonton. The sludge is used either as a co-composting material or as agricultural fertilizer after solids/liquid separation in a sludge lagoon.

The annual average wastewater flow to the plant in 2007 was 80,010 m3/d. The service population in 2007 was estimated to be around 206,000.

• Operational Approval and Treatment requirements from Alberta Environment
• Plant Monthly Operation Data
• Annual Report
• Monthly average flowrates from 2002 to 2008; Historical flowrate data & service population
• Operation Manual
• BNR 101 and Quiz
• Bioreactor layout sketch and operating tips
• Modelling simulation of BNR operation by using BioWin
• Plant Tour
• Plant Hydraulic Profile

Plant Capacity & Process Components

Through the upgrade and expansion from 2003 to 2005, the Treatment Plant has a design capacity of 225,000 m3/d for the primary treatment, and a design average capacity of 87,500 m3/d and a peak capacity of 175,000 m3/d for the secondary treatment. The process consists of:

• Headworks
• Primary Clarifiers
• Fermenters
• Bioreactors (BNR)
• UV Disinfection
• Effluent Outfall
• DAF
• Sludge Digesters

Process Description

 Wastewater enters the treatment plant, it first goes through a fine screen with 6 mm spacing for the removal of coarse solids or debris to protect pumps and other equipment. In the following aerated grit chamber, sand and other small grits are removed. This will protect equipment from wear, reduce deposits in pipe, channels and digesters. Then, wastewater enters the primary clarifier for the removal of very small particles, and at the same time, some organic contaminants are also removed. The screenings and grit generated are trucked to outside for disposal. Sludge settled in the primary clarifier is called primary sludge and is sent to the fermenters and then to digesters.

After the primary treatment, wastewater flows into the Biological Nutrient Removal (BNR) bioreactors where organic matter, nitrogen and phosphorus are removed through the metabolism of numerous and natural microorganisms. The treated wastewater and microorganisms (activated sludge) are separated in the following secondary clarifier. The clear effluent flows into a Ultraviolet (UV) facility for the inactivation of pathogenic microorganisms. The effluent is discharged to the North Saskatchewan River. Settled activated sludge in the secondary clarifier is pumped back to the BNR bioreactor in order to maintain the amount of activated sludge required by the process.
 
In the biological removal of phosphorus, volatile fatty acids (VFAs) are required. They are generated through the fermentation of primary sludge in the fermenters.

Air from blowers is introduced into some cells of the BNR bioreactor for the biological oxidation of organic matter and oxidation of ammonia nitrogen to nitrate (i.e. nitrification process). Nitrates are subsequently biologically reduced to nitrogen gas (i.e. denitrification process).

Excess sludge (also called waste activated sludge or WAS) generated during the metabolism of microorganisms is pumped into the dissolved air flotation (DAF) unit for thickening.

Thickened WAS, along with scum and fermented primary sludge, are pumped to anaerobic digesters for digestion. During the process, a high percentage of the sludge is converted into biogas (a mixture of methane and carbon dioxide), which is utilized as a fuel for plant or process heating. Digested sludge (remaining sludge) after digestion is hauled by truck to Edmonton's Clovebar lagoons for settling and ultimate disposal by co-composting or land spreading in agricultural fields.

Process Diagram