Storage and dosing system for flocculation agent and CONTINUFLOC solution and dosing systems
for phosphate elimination Alltech uses a storage and dosing system for iron chloride sulphate
Expansion of ARA Windisch required a new concept for phophate elimination
In the WWTP Windisch (Switzerland) waste water for 12 connected municipalities is treated. With the new municipalities of Turgi and Untersiggenthal, the plant in Windisch will now clean the waste water for a population of up to 90,000 equivalents. Alltech received the order to supply, install and commission the phosphate elimination system as part of the expansion of WWTP with additional biofiltration. The WWTP Windisch also uses three Alltech CONTINUFLOC solution and dosing systems in the sludge dewatering process.
Phosphate which is contained in the waste water is removed by chemical precipitation
The waste water is treated in 6 steps (bar screening, grit chamber, pre-treatment, biological treatment, phosphate elimination and secondary clarification) and is then discharged into the river Aare.
The expansion of ARA Windisch on biofiltration required a new concept for phosphate elimination. The tank filling, flocculation agent storage and dosing station were built in the new biofilter building with limited room height. Iron chloride sulphate is used as flocculation agent, but it is also possible to switch to other chemicals by means of two independent storage tanks.
Storage and dosing station according to the local regulations of water protection
In general, systems for fluids hazardous to water are subject to the Swiss regulation VWF (Verordnung über den Schutz der Gewässer vor wassergefährdenden Flüssigkeiten). This corresponds to the water protection regulations of the German Water Resources Act (WHG). By this the components had to comply with the relevant SUVA directives and the technical tank regulations (TTV Switzerland) as part of the project specifications.
The cylindrical storage tanks are designed according to VWF and have a net volume of 26 cubic meters.
The tanks are filled with the flocculation agent from the tank lorry by means of the automatic tank filling unit TABESY. Both storage tanks are equipped with continuous level control and overfill protection. The storage tanks were installed in a specially coated concrete collecting bund, which is equipped with leak detector.
The dosing station for flocculation agent consists of five dosing lines, which have been completely mounted on a PP wall mounting plate with collecting bund. The robust piston-diaphragm dosing pumps FKM with continuous and linear capacity adjustment, controllable drive motor and integrated safety valve are used here. The dosing pumps are operated by the proportional control TRIGGOMAT C2. The protection of the environment against chemical leaks is ensured by having a collecting bund with integrated leakage detector.
The dosage of precipitant is controlled separately for each dosing point, and for each application point a separate dosing pump is assigned.
Design of all components with regard to the efficiency of the whole plant
In addition to the long service life of all components and operational safety, the customer was particularly interested in optimising the design of every component with regard to the function of the entire plant. The fact that Alltech’s phosphate elimination systems meet these requirements has already been proved in the more than 15-year-old trouble-free operation of the first phosphate elimination system also supplied by Alltech.