Water Reclamation Facility
The Water Reclamation Facility (WRF) is designed to treat up to 3.6 million gallons of wastewater a day. The facility is designed to remove the following from its discharge:
Critical equipment is monitored 24 hours a day with a computerized data acquisition system. The facility is also equipped with 3 standby generators.
The Town of Apex Water Reclamation Division is dedicated to protecting public health and the environment by providing high quality wastewater treatment in an economically and ethically responsible manner to maintain the quality of life in Apex while exceeding all federal and state regulations.
Every house, apartment, business, factory, and commercial business in the Town produces wastewater from:
- Industrial processes
- Laundry equipment
- Other processes
This wastewater flows through a series of pipes and pump stations which delivers the wastewater to the plant’s headworks or the intake point.
At the headworks, preliminary treatment takes place as wastewater is passed through bar screens to remove paper, sticks and other debris for safe operation of the machinery in the plant. The next area is the grit removal units. These units remove sand, grit and rocks.
Secondary Treatment (Oxidation Ditches)
After the preliminary treatment is accomplished, the wastewater is pumped to the secondary treatment process, where three Oxidation ditches provide the necessary detention time to grow microorganisms. The primary functions of the bugs are the removal of organic material and ammonia. The bugs convert organic matter into other compounds, such as carbon dioxide and water. The secondary role of the bugs is to assist in flocculation and settlement of the solids in the system. The bugs require a specific type of environment to survive and carry out the process. In order to maintain this environment, many things must be monitored: pH, temperature, dissolved oxygen, and available food or organic matter.
These organisms also reduce the available nitrogen and phosphorous, thereby protecting the stream from excessive nutrient loading. Mixers are provided in these tanks as an air supply and for keeping the organisms and solids in suspension. The mixture of solids and organisms are referred to as activated sludge.
Secondary Treatment - Continued (Clarifiers)
After leaving the oxidation ditches, the water continues to the second stage of secondary treatment; clarifying stage. The four circular concrete tanks provide the detention time necessary for solids to settle from the water. This allows the solids to be easily removed and recycled or wasted. In order to maintain a good concentration of bugs, much of the sludge removed from the secondary clarifiers is recycled back to the aeration Ditches. This sludge is referred to as return activated sludge (RAS). There are also times some sludge must be wasted. This sludge is called waste activated sludge (WAS). Some wasting is required in order to maintain a healthy concentration of bugs. The clarified water continues to the next process for additional treatment.
Tertiary Treatment (Disc Filters)
Effluent polishing occurs during this process. Tertiary treatment adds a more advanced level of treatment. Tertiary treatment can achieve levels of water purification that make the water safe for reuse in water-intensive processes. Gravity pushes wastewater from the drum into the filters in an inside-out flow pattern. Then, media mounted on each side of the discs separate solid particles from the liquid. Clean water flows into a collection tank, and backwash water cleans the media once they become saturated with particles. The inlet water level is measured and controlled automatically to initiate backwash cycles. These solids collected during the backwash are returned to the secondary process. The filtered water then continues on to the final phase of treatment; UV disinfection.
Ultraviolet high intensity lamps are used for disinfection. Disease carrying organisms are eliminated during this process. The UV light disinfects by penetrating microorganisms and destroying their DNA. DNA plays an important role in organisms’ functions and reproduction, hence destroying the DNA prevents the organism from being active and multiplying. This level of treatment makes the water once again safe and ready for future use. An additional benefit of ultraviolet disinfection is that no dangerous chemicals, such as chlorine, are needed. This protects the aquatic life in the receiving stream.
Dissolved oxygen is needed in the receiving stream for the aquatic life to flourish. At this stage, it is added by simply allowing the reclaimed water to cascade down concrete steps into the stream. After nearly 30 hours of intensive treatment, the water can be safely returned to the environment.
If you’d like to tour our facility, please call (919) 387-3078 to set up a time.