Filters Reduce TSS & NTU For Process Water

July 5, 2019

About the author:

Aqua-Aerobic Systems Inc. can be reached at or 815.654.2501. 


Shepard Energy Centre is located in Calgary, AB, Canada. Operations began March 2015 and the center can generate more than 800 MW of electricity to Alberta residents using natural gas. The facility utilizes two combustion turbines featuring a combined cycle technology to generate electricity. In addition, it processes waste heat through a steam turbine to produce even more electricity. 

This electricity generation process makes Shepard approximately 30% more efficient than coal-fired plants, which reduces overall fuel costs. Not only is the plant more efficient, but it also emits less than half of the CO2 emissions per MW hour compared to a coal generated facility. Sulphur dioxide and nitrogen dioxide emissions also are reduced.

The facility uses up to 7.7 million gal per day (mgd) of reclaimed wastewater from the city of Calgary’s Bonnybrook Wastewater Treatment Plant (WWTP). This is the first application of reclaimed water for power production in Alberta. The majority of this water is used for cooling tower water and boiler feedwater.

Enmax and Capital Power installed three eight-disk AquaDisk cloth media filter units to aid this process. Effluent from the Bonnybrook WWTP is pumped through a 9-mile pipe to the Shepard Energy Centre. Water then passes through the AquaDisk cloth media filters before being sent to the cooling tower. Filtration is critical to prevent solids accumulation in the cooling tower.

AquaDisk Filter Process

Water from the Bonnybrook WWTP enters the filters and flows by gravity through the cloth media of the stationary hollow disks. The filtrate exits through the hollow shaft, which supports the individual disks, and flows to the effluent channel. As solids accumulate on the surface of the media, the water level surrounding the disks rises. 

Once a predetermined level is reached, the disks rotate and the media surface automatically is vacuum backwashed clean. Heavier solids settle to the bottom of the tank and then are removed using a solids manifold. Both backwash and solids wastewater are sent back to the wastewater treatment plant.

The AquaDisk filters remove total suspended solids and reduce turbidity to protect the heat exchangers from clogging. This reduces energy consumption, and in severe cases, prevents plant shutdown. Shepard Energy Centre now is Alberta’s largest gas-fueled electricity generation facility.