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Löhnen waterworks, Dinslaken municipal utility: Drinking water treatment with state-of-the-art technology – Germany’s largest nanofiltration plant

The construction of this facility was required to preemptively counteract changes in the flow conditions of the groundwater wells that are expected to occur due to the decline in coal mining development. Trace substances from the Rhine bank filtrate could enter the groundwater wells that may not be safely removed using conventional treatment technology. The newly installed treatment system ensures the removal of ions and particles in the nanometer range by means of pressure-driven membrane modules. Description of the plant: The raw water from the existing water extraction is stored in 2 raw water chambers of 600m each. From here, the raw water is fed to the suction side of the 11 FEED pumps, which in turn convey the raw water via 11 membrane module lines, with the addition of an antiscalant to prevent scaling on the membrane modules. The water passed through the nanofiltration lines is called PERMEAT. After the membrane passage it is buffered in 2 permeate tanks of 300m3 each. From here, a permeate pumping station transfers the water to the pump receiver of the conventional treatment plant. The operation of a nanofiltration plant is very complex and requires numerous auxiliary systems for its function. These include:

• Antiscalant, (copmplex binder) supply and dosing system
• Preservative, (e.g.NaHSO3) storage and dosing system
• Acid, (e.g.H2SO4)- storage and dosing system
• Lye, (e.g. NaOH)- storage and dosing system
• Flushing and cleaning pumping stations
• Neutralization tank with periphery
• Conveying, monitoring and discharge of the concentrate

ENNI – Drinking water softening plant in Moers

Drinking water softening plant with downstream turbidity filtration. The softening plant serves to reduce the degree of hardness in the raw water from approx. 21°dH to the hardness range 12-14° dH. and thus supplies water in a moderate hardness range. The total treatment capacity is about 24,000m3/d. The plant consists of:

• 2 pieces of fast decarbonization reactors with a treatment capacity of 10.800m3/d each
• 4 pieces turbidity filter Ø 4.500 mm
• Fully automatic supply of the softening process with quartz sand as seed grain
• Drainage, storage and disposal facilities for the residues from the softening process
• Fully automatic quicklime slaking plant for the production of the lime-milk suspension required for the process, including metering technology
• Peripheral storage and dosing systems for phosphate (PO4), caustic soda NaOH) flocculants (FHM) and carbon dioxide (CO2)

Waterworks in Coesfeld

Via the wells of the existing raw water extraction, the water is led through the newly installed physical deacidification plant (2 pieces of Riesler with 6,600m3/d each ) and reaches two intermediate storage tanks. From these, the water is pumped via a controlled intermediate pumping station to the 2 softening reactors, treatment capacity per reactor max. 6,600m2/d fed, with the aim of softening to 10°dH. This is followed by a 2-stream filtration stage consisting of 4 steel pressure filters for turbidity filtration, each with a capacity of 3,000m3/d. After that, the water enters two clean water chambers with a capacity of 350 m3 each. The network pumping station consists of 3 pieces of vertical, frequency-controlled high-pressure pumps with a capacity of 6,600m3/d each. They take over the distribution of water into the supply network. Numerous ancillary plants have been installed for the treatment of the raw water to drinking water in accordance with the TVO specifications, as well as for the post-treatment of the rinsing wastewater:

• Flushing water pumping station
• Complete lime milk preparation and dosing plant for the production of lime milk from white fine lime.
• Fully automatic supply of the softening process with quartz sand as seed grain
• Drainage, storage and disposal facilities for the residues from the softening process
• CO2 storage and metering system for volume-proportional metering of carbon dioxide into the reactor discharge line. (for the adjustment of the lime-carbonic acid balance).
• Neutralization plant for the neutralization of rinsing wastewater from softening
• Chlorine gas, control and dosing system
• Sludge pumping station and sludge treatment of the residues from filtration, including a flocculant dosing system.
• Compressed air supply systems for the control of fittings and aggregates in the treatment process