Industrial wastewater treatment with P-recovery in Doruchów
Doruchów commune in Poland is the operator of a municipal wastewater treatment plant built in 2000. The treatment plant treats 465 m3 of wastewater daily, out of which 65 m3 is industrial wastewater from meat processing industry. The phosphorus content of the industrial wastewater is very high, even though the industrial wastewater is pretreated to some extent at the industrial plants in the process of flotation. Since the capacity of the old municipal treatment plant was not sufficient to treat the amount of wastewater arriving to the plant, a new line for mechanical and biological treatment of industrial effluents for 1100 PE was built in 2020, including tertiary treatment for phosphorus recovery using calcium-silicate filter media. With the new treatment line and filter media Doruchow is able to reduce the phosphorus content of the water from 40 mg/l in the influent to 3 mg/l in the effluent. The calcium-silicate filter media also makes it possible to reuse the recovered phosphorus in agriculture.
Components installed in the solution
The phosphorus filtration system is based on a unique and entirely innovative approach to remove and recover phosphorus from the wastewater without the use of chemical agents. The filtering media applied in the treatment process is in a form of highly porous calcium silicate material. A material called Rockfos® with a particle size of 2–6 mm is used in the process. P present in wastewater flowing through the filter is absorbed. This technology has the potential to significantly reduce the use of chemicals used for P precipitations, thus saving costs is expected. P loaded filter media can be used as a fertilizer facilitating P recycling. In addition, this rock filter media with a high pH and content of calcium (Ca) and amorphous silica (Si), may be a potential soil conditioner, which can be particularly beneficial for acid soils.
As part of the construction of the new mechanical and biological treatment line for industrial wastewater, the following facilities with a footprint area of 252.95 m2 were installed:
- delivered sewage disposal point
- equalisation tank
- biological reactor
- secondary sedimentation tank
- dolomite bed tanks with a pH correction station
- monitoring well
- bed stacking yard
- blower station
The construction scope also covers hardening of the area and construction of paved paths and cover slabs with an area of 702.40 m2. It also includes construction of process pipelines (sewage, water, sludge and air pipelines with necessary fittings) as well as electrical, lighting and ICA systems.
After the mechanical and biological treatment, the water is directed to the secondary sedimentation tank where the sludge is separated from the treated wastewater. The water is then directed through a drain to dolomite bed tanks. In those tanks, wastewater flows through a filtration bed, where phosphorus is absorbed. Bark is used to lower the pH. The treated wastewater is directed to the flow meter chamber and discharged into the “Struga spod Zalesia” water body. The estimated durability of the filter material is 604 days. After this time, the bed should be replaced. The bed is located in crates transported by an overhead crane.
The opening of the new line will result in significant improvement of the quality of wastewater discharged to the nearby Zalesianka stream.