Coagulant Dosing System DOSY-F

Especially for smaller wastewater treatment plants (< 2,000 PE), legal and municipal requirements for phosphate elimination vary greatly from region to region. While large treatment plants (GK4/GK5) are subject to clear limit values of < 1 mg/l or < 0.5 mg/l phosphate, binding specifications are often lacking for smaller facilities – a situation that has been further intensified regionally since 2026 by K.A.R.L. The wastewater charge notice issued by water management authorities and district offices is based on the strength of pollutants in the effluent. Operators who significantly reduce their phosphate discharge through targeted coagulation can actively work toward lowering their charge notice.

According to a study by the Bavarian State Office for the Environment (2018), the investment costs for phosphate elimination at a treatment plant with 2,750 PE – approximately €22,500 – are amortized within just 4 years. Thereafter, the measure enables annual savings on wastewater charges of about €2,500. With the DOSY-F from ETL Verfahrenstechnik, the operator can introduce a suitable coagulant in a targeted manner – depending on the coagulant and optimal dosing, the phosphate level in the outlet can be reduced by up to two-thirds compared to the level without coagulation.

A diaphragm pump conveys the coagulant directly from the DOSY-F's integrated storage tank into the dosing line, where it is introduced evenly at the designated dosing point. The storage tank (DOSY-F F60: 60 l / DOSY-F F1000: 1,000 l IBC) can be conveniently filled using the integrated auxiliary pump or transfer device, and emptied again for cleaning purposes. The system is designed for use with common coagulants, including iron chlorides (FeCl₂, FeCl₃), iron chloride sulfate (FeClSO₄), iron(II) sulfate/copperas (FeSO₄), aluminum sulfate (Al₂(SO₄)₃), sodium aluminates (NaAl(OH)₄), and lime milk (Ca(OH)₂).