Wastewater treating is process by which waste water, water that is not suitable for clean use, is turned into an effluent that can be returned to the water cycle or  reused. Wastewater or sewage comes from flushing the toilet, bathing, laundry  and drains into a city sewage pipe, which transports it into a treatment center.

The process is broken into 4 key stages.

1. Preliminary Treatment
This stage is where the coarse solids are removed. Typically coarse screening, grit removal and other large objects are removed. In grit chambers, the velocity of the water through the chamber is high or flow turbulence is created to prevent the settling of the organic solid.

2. Primary Treatment
The objective of this stage is to remove the settle able organic and inorganic solids by sedimentation and skimming organic material by skimming. 50 t0 70% of suspended solids and 65% of oil and grease are removed during this treatment. Effluent from primary sedimentation is referred to as primary effluent.

3. Secondary Treatment
This stage removes biodegradable, dissolved and colloidal organic matter using aerobic biological treatment. The activated sludge process is an aeration tank containing a suspension of wastewater and micro organisms. These content are  mixed with aeration devices which supply oxygen to the biological suspension. A portion of the biological sludge is recycled to the aeration basin and the remainder  is removed from the process. Effluent from this stage can be disinfected from  chlorine before being discharged into rivers or streams.

4. Final Treatment
The last stage is where the wastewater is passed through a settlement tank and  has the ability to remove up to 99 percent of the impurities of wastewater. This stage is known as effluent polishing where there is removal of ammonia nitrogen and sand filtration for additional removal of suspended solids.

Project Snapshot

Waste Water Treatment

City of Calgary – Bonnybrook Treatment Facilities

Odour Control Fans

Environmental & Abrasiveness Conditions


To find an HVAC solution that would with stand moisture and help with odour control. There are many different methods to control odour and the first step is in identifying the sources. Some plants use deodorizing misting systems to hit the odour compounds in the air where as others add chemicals to the water that would react with the odour causing compounds. You can always cover the tank as well whereby you seal the source of the odour.

Easton Solution

EIA worked in conjunction with Aerovent to provide the capture and treat technology. This process captures the odours by containing them within a certain location then withdrawing and treating the foul air. The air is conveyed in a duct-work system and can be treated with different technologies such as a bio-filter, wet scrubber, or carbon filter.

In the Biofiltration system the odour contaminants are solubilized from a vapour and go into a liquid phase. The odorous air is collected and treated in a packaged biofilter.  The City of Calgary was provided with our custom designed backward curved industrial fibreglass fan for this process. This fan is specifically used for handling particulate free, corrosive or caustic air in high pressure applications where conventional steel and stainless steel fans are not suitable.  Four different industrial fans were provided. The Foul Air fan set was put in place in the process where they capture contaminated air and preventing odour leakage. The odour Control Fans were placed on the clean side of the air process and prevents leakage in to a clean environment.