ANC Effluent Treatment
The effluent treatment system designed for ANC includes removal of coarse solids, primary clarification, an equalization basin, dump pond, activated sludge basin, secondary clarification and a polishing pond. Follow this link for an overall schematic. The steps are described as follows:
Coarse Screening - Effluent from the trenches passes through a rotating bar screen for removal of coarse solids such as rags, wood, etc.
Primary Clarification -The screened effluent flows to atop feed 30.5 meter diameter Einico reactor clarifier with design removal efficiency of 90% on settleable solids.
Dump Pond - The dump pond has a capacity of 7500 cubic metres or 12 hours retention. It is intended for use to catch emergency spills. The basin is concrete lined, effluent can be neutralized within the pond and later processed through the effluent treatment system.
Equalization Basin - Clear filtrate from the primary clarifier feeds the equalization basin. The 12 hour basin serves to avoid effluent shocks in pH, temperature, BOD, etc. from reaching the major microbiological population within the activated sludge basin. A spray cooler in this basin cools the temperature when required. Initial mixing and aeration occurs within this basin.
Activated Sludge Basin - Effluent flows from the equalization basin to the activated sludge basin. This 2.5 day basin serves as the major holding pond for a bacterial population to consume wood sugars and resins contained within the effluent. This virtually eliminates the oxygen demand the effluent would otherwise have on the river, which might have effected aquatic life.
Secondary Clarifier - Effluent flows from the activated sludge basin to the secondary clarifier. This 45.7 meter diameter clarifier serves to separate solids (largely microorganisms) from the water. The secondary clarified water goes to the polishing basin. The solids are reused in the activated sludge pond and a portion wasted to sludge dewatering. This controls the age of our microorganism population.
Polishing Basin - Under normal operation the feed to the polishing basin is clean enough to discharge to the river. To ensure a non-toxic effluent and to handle plant upsets a 2.5 day polishing basin was included to provide further aeration, prior to river discharge.
The design of the waste treatment plant includes a level of conservation, equipment selection and redundancy in critical areas which provides reliable performance and comply with the stringent standards applied by Alberta Environment.
