Redmond, OR
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WWTP Virtual Tour
Updated on 03/06/2019 9:18 AM
Virtual tour of the wastewater treatment process.
After traveling through the City collection system, wastewater enters the plant at the headworks. The function of the headworks is to remove material larger than 1 mm from incoming wastewater. A large bar screen first removes large items before directing the water through a fine drum screen. The removed solids are transported to a receptacle via a conveyor belt and landfilled. Air from the headworks screening room is processed through an underground biofilter containing microbes and sand which removes odors from this process.
Next, the wastewater travels to the Orbal Aeration Basins. Bacterial organisms called microbes are introduced to the wastewater through the addition of activated sludge. The water travels through three channels as it is aerated. As the water moves from the outer to inner channel, it moves from an anoxic (oxygen deficient) to an aerobic (oxygen rich) zone. This biological process is engineered to ensure sufficient retention time for the microbes to remove targeted wastewater pollutants from the wastewater. Target pollutants that are removed in the aeration basins include Ammonia, Nitrate and Nitrite. Aerated water is then transferred from the center channel to the clarifier for settling and solids removal. The sludge is either recycled back to the beginning of the aeration basin or sent to the sludge holding tank for temporary storage, keeping the organism population at a constant.
From the aeration basins, the wastewater flows into the splitter boxes where it is divided and passed onto one of three clarifiers. Within these tanks, water and sludge are slowly separated. The sludge settles, and the water flows over the edge. From here, the sludge and water take different paths.
The water is sent to the effluent junction box and then onto the chlorine contact chamber. Here sodium Hypochlorite is added as a disinfectant to kill all bacteria present. The water then travels on to the irrigation site or the infiltration basin...
After leaving the clarifier, the sludge is pumped into a sludge holding tank, and then on to the solids building. There, polymer is added to the sludge for dewatering. It is then pressed and lime is added to prevent bacterial growth. The biosolids are then placed into a truck and hauled to the irrigation site...
Through the infiltration basin, the water is allowed to slowly soak back into the earth where it is eventually cleaned by natural means. Upon returning to the water table, the water is suitable for potable water and irrigation purposes.
The water is sent to an irrigation pond where water is stored until it is used on the city's fields. Hay is grown with the use of both this water, and the biosolids which are an end product of the sludge.