The Computer Controlled Activated Sludge Process Unit "PPFAC" allows the natural breakdown of organic matter by biological metabolism and the separation of the solids and liquids by bio-flocculation and the natural force of gravity. The unit is mounted on a floor standing metallic frame and consists of two modules connected by a set of hoses (included). One module is a supply unit with a tank to store the raw water with dissolved organic substances (organic matter). It includes a tank with two computer controlled stirrers and a computer controlled pump to transfer the raw water from the tank to an aeration tank. The other module includes the aeration tank, a clarifier and the elements required to carry out the wastewater treatment. The raw water pH value can be modified by the pH system to study its influence in the activated sludge process. The raw water is pumped to the aeration tank, where it is combined with the activated sludge (aerobic microorganisms) to reduce organic matter in wastewater in the presence of oxygen. This tank is divided in two zones, separated by a partition wall: one zone is for the nitrification process (ammonium is oxidized to nitrate in the presence of oxygen) and the other zone is for the denitrification process (nitrate is reduced to nitrogen).
The nitrification zone includes two stirrers (computer controlled), an oxygen sensor and drain valves. In the de-nitrification zone there are a stirrer (computer controlled) and an oxygen sensor to measure the oxygen concentration in the treated water. The oxygen concentration and temperature of the treated water in the nitrification process can be modified by the aeration system and the heating system of the unit, respectively. The aeration tank includes a line to connect the nitrification zone with the denitrification zone, using a computer controlled pump. After spending a specified interval of time in the aeration tank, the treated water passes to the clarifier, where the activated sludge settles by sedimentation and is separated from the treated water. In this clarifier, a coagulant (the repulsive forces between the solid particles are cancelled out) and a flocculant (to generate larger flocs) can be added, by two computer controlled pumps. A portion of the activated sludge is returned to the aeration tank (return sludge). The treated water is stored in a tank. The following flow rates are adjustable: raw water, return sludge, internal recirculation for pre-denitrification and air. Several temperature, pH, oxygen concentration and flow sensors have been strategically located, allowing to study the process. In addition, the unit includes several sample collections at all relevant points. This Computer Controlled Unit is supplied with the EDIBON Computer Control System (SCADA), and includes: The unit itself + a Control Interface Box + a Data Acquisition Board + Computer Control, Data Acquisition and Data Management Software Packages, for controlling the process and all parameters involved in the process.