The Water Reclamation Facility collection system receives all wastewater from housing and dorm areas, as well as academic and auxiliary buildings on the three square miles of the University of Florida main campus.

During the pretreatment stage, heavy solids and fatty greases are separated and removed from the wastewater, beginning the treatment process. The first treatment step applied to the influent after entering the plant is passing it through a screen as well a grit and grease chamber.

The automated, self-cleaning mechanical bar screens remove roots, rags, sticks and other large debris which is hauled to a landfill. The Channel grinder is used for cutting material such as roots, cans, and sticks. The grit removal system removes sand and gravel, which is also taken to a landfill.

The wastewater is then directed into a splitter box where it is contacted with deterrent activated sludge from the secondary clarifiers and gently mixed with low-speed submersible mixers to promote the proliferation of microorganisms that are capable of storing and releasing soluble phosphorus.

The low-speed mixers provide a homogenous mixture of the activated sludge without the creation of any floc shear, or the formation of vortices. As the influent and return activated sludge are stressed under anaerobic conditions, bacteria begin releasing phosphorus into the mixed liquor, increasing the phosphorus concentration.

After passing through the three stages of the anaerobic selector, the influent flow is then directed to a distribution chamber. The mixed liquor is directed into the appropriate reactor, depending on the current phase of operation.

Each reactor is equipped with a maxi-rotor, or brush aerator, which provides the necessary oxygen for the process, as well as low-speed, low-horsepower submersible mixers to provide the necessary mixing. During the anoxic phases of operation, the low-speed submersible mixers are utilized to keep the mixed-liquor in suspension, as well as maintaining the required flow velocity within each reactor while a brush aerator is not operating.

Located at the end of each reactor is a motor-operated, adjustable, effluent weir. This weir insures a constant liquid level within the reactor at all times, as well as controlling the hydraulic gradient between the two reactors.
Generally the entire process is broken down into four separate phases of operation, which involve changes within the reactors from oxic to anoxic. Depending on the particular plant application, the number of phases can be increased or the duration times changed to provide the plant operator with a system that is capable of handling a one-quarter load just as efficiently as full flow. Throughout the entire duration of the hydraulic retention time, or HRT, this cycle of phases is repeated four complete times. This facilitates the dilution of both nitrogen and phosphorus over the entire HRT. (See BioDenipho Process Phases for more details on the phase cycle.)

The BioDenipho process takes full advantage of mechanical aerators as well as submersible mixers. The maxi-rotor is only operational during the oxic phases of the process, remaining dormant during the anoxic phases to promote conditions suitable for denitrification. The effluent weir plays a key role in reducing the energy requirements of the entire process. The BioDenipho process utilizes constant control of the liquid level within each reactor. The amount of oxygen produced per kilowatt-hour of operation is directly related to the submersion depth of the maxi rotor. It is for this reason that the effluent weir is utilized to adjust the liquid level, providing the maximum oxygen yield possible with the least amount of energy. Since aeration energy consumption usually represents 50 - 90% of the total energy demand of a treatment plant, the oxygen concentration is controlled during the oxic phases with the use of dissolved oxygen (DO), probe. This probe is self-cleaning and can be calibrated without the use of chemicals.

Conventional wastewater systems operate in such a way as to constantly provide a high enough dissolved oxygen concentration to meet the oxygen demands during peak loading periods. At less than peak loads, oxygen is wasted, resulting in lower efficiency. With the use of dissolved oxygen control, the amount of aeration is adjusted to adapt to the influent loading, therefore aeration is not wasted and energy costs are kept to a minimum. Online monitoring, in conjunction with a programmable-logic computer (PLC), is used to regulate the operation of the plant. Pre-programmed upper and lower dissolved oxygen limits are established and fed into the PLC to identify the operating range for the system to maintain.

When the dissolved oxygen level reaches the upper limit (2.0) within the oxic reactor, a maxi-rotor is shut down and the submersible mixers are started. Similarly, if the dissolved oxygen level falls below the predetermined minimum (1.5), a rotor will be started to reestablish the oxygen concentration. Generally, according to this principle of separate aeration and mixing, the energy savings achievable with dissolved oxygen control ranges between 25 - 40%. When all of these treatment elements are combined together the result is a highly effective, cost efficient treatment plant.