As per definition, waste water is water that has polluted by its use, and therefore cannot be used any longer for its original purpose. Waste water contains several pollutants, solid waste particles as well as many dissolved components such as carbon- and nitrogen compounds and phosphates. These pollutants can also be described as “nutrients”, since smaller lifeforms, such as bacteria or protozea, can feed on them. The digestion and absorption of these compounds, with the help of suspended bacteria (“the activated sludge”) and with the provision of oxygen is the base of the activated sludge process (ASP), which is the underlying principle for the aerobic biological waste water treatment.
The BIOWORKS®-process is a variant of the ASP, which commonly is known as “low loaded, extended aeration” process. In combination with submerged floating fine bubble aeration with self propelled movement by the OXIWORKS®-aeration system and its other important feature, the integrated secondary clarifier at the end of the biological treatment step, we have created the BIOWORKS® process.
The BIOWORKS®-process starts with the (optional) Bio-P zone (1). Waste water and return sludge (bacteria resp. activated sludge) enter this Bio-P zone. In this “selector basin” and under an anaerobic environment, the bacteria are driven to absorb more phosphates than usually in the following activated sludge stage. Submerged mixers ensure good contact between the activated sludge and the waste water. Effluent values of total P < 1 mg/l without chemical dosage are possible under the condition, that the inflow phosphate levels do not exceed common values.
The next treatment step is conducted in the Activated sludge basin (2), where the aerobic digestion of carbon- and nitrogen compounds takes place. In this section of the basin, waste water with its pollutants is digested by the rich biocenosis of bacteria living in this basin. The aeration system OXIWORKS® enables the bacteria to do their work, because the floating fine bubble aeration provides oxygen to all parts of the basin. Because of its unique self propelled movement, the OXIWORKS® aeration system is able to mix even the largest of tanks without additional mixing devices.
For purpose of enhanced N-removal, BIOWORKS® utilizes the process of simultaneous denitrification process. Selected control of the air supply will result in anoxic zones within the Activated sludge basin. Oxygen which is normally bound to the nitrate will be utilized by certain bacteria (Denitrificant) in that zones in order to oxidize carbon compounds. The nitrogen is released as gas to the atmosphere (3).
In the next treatment step, the activated sludge/water mixture flows into the Clarifier (4). In this sedimentation tank, as the water body is calm and unstirred, the activated sludge separate from the water, will settle to the bottom by gravity, while the cleaned water is accumulating at the top and is flowing out of the treatment by an overflow (5). Typically the system is able to achieve removal rates of > 95 % for BOD/TSS/COD, 99% for NH4-N and > 80 % for TN. Coliforms are typically reduced by log 3. Further treatment steps such as filtration or disinfection can follow.