RO/NFUF

MBR

Chemicals

CASE STUDY

RO | UF | MBR | ANTISCALANT

Water Treatment Chemicals
Löhnen Dinslaken, Germany

Assessment of Using ROPUR RPI® Antiscalants Projects
Significant Savings
OVERVIEWIn 1961, Wasserwerke Dinslaken GmbH formed a private utility toservice the Lower Rhine region and today operates the Löhnen
drinking water plant. Nearby the plant is the City of Dinslaken, an
area where deep-shaft coal mining was active for nearly a century.
As a result, mining-induced subsidence of up to five meters
had occurred where the Löhnen waterworks have their supply
wells. As a result, the filtration depth from the surface to thegroundwater table became insufficient to warrant the removalof particles and pollutants from the surface. A way to augment
this problem was to operate large polder pumps and lower the
groundwater table by transferring vast amounts of water to thenearby Rhine River. However, with this method, simulations
revealed that groundwater intrusion from the river's undergroundside streams might occur. Densely populated cities situated near
the Rhine use the river as a discharge line for clarified wastewater.
The intrusion streams would carry increased concentrationsof anthropogenic substances, including pharmaceuticalresidues from painkillers and medication to treat cancer, x-ray
contrast chemicals, herbicides, pesticides, and other emerging
contaminants of industrial wastewater and surface runoff.

In 2006, the Dinslaken utility began feasibility studies with
the Rheinisch-Westfälische Institute for Water (IWW ) to findsolutions for the Löhne Waterworks to secure high-quality
drinking water for current and future communities. The feasibility
studies included rigorous pilot tests replicating worst-casescenarios of groundwater contamination. IWW selected Toray RO
membrane elements for a two-stage low-pressure membraneprocess as a viable solution for reducing impurities at low energy
consumption.
THE CHALLENGE
The membrane system design consisted of operating at 87%
recovery, a flux of 25 l/m²/hr, and transmembrane differential
pressure of around 5.5 bars. However, as hard minerals suchas calcium, magnesium, and carbonate ions are present in
the source water, operating at these conditions increased thelikelihood of premature scaling. Membrane experts from Toray
Membrane Europe AG (TMEU) further determined that operating
without antiscalants would lead to irreversible membrane
damage from crystal surface abrasion, triggering heavy routine
cleaning, increased labor, and membrane replacement costs.

Quick Facts — RO Specifications
Model

TMH20-430

Membrane typeLow-pressure

Nominal NaCl rejection*

99.3%

Operating pressure*0.69 MPa

System array

10:5

No. of elements per vessel

6

Design capacity

1,100 m³/h

Design flux

25 L/m²·h

Recovery87%

Selective membrane material

Polyamide*manufacturer's specifications
Figure 1: Low-pressure RO system at Löhnen drinking water plant

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CASE STUDY
RO | UF | MBR |Assessment of Using ROPUR RPI® Antiscalants Projects
Significant Savings

Figure 2: Annual OPEX at Löhnen plant

SIGNIFICANT SAVINGSTMEU used Toray's DS2 software to run membrane performanceprojections, ROPUR's RPI Calc for antiscalant dosing simulations, andevaluated other water treatment sites using Toray products. Details
from these evaluations helped identify the dosage structure andpotential savings by using an effective membrane and antiscalantcombination. As shown in Figure 2, using ROPUR RPI® Antiscalants
estimated the following results over 12-months:•Units: kEuros

Product XLess than half membrane replacements indicating extended
membrane lifetime;•75% less chemical demand, such as the use of biocides andclean-in-place (CIP) frequencies;•Four times more CIP's and the use of biocides in the absenceof RPI antiscalants;•Stabilized operating pressure through excellent control ofscaling leading to annual energy savings of €63,000;•An estimated gain of €263,000 in water revenue resulting
from less downtime and more water produced (Table 1); and•

Total annual savings of 34% representing €620,500.

Lastly, the high strength and purity of ROPUR RPI® Antiscalants
require a low dosage (2 mg/L at Löhnen), further contributing tooverall cost savings.

340

RPI

150

140
100
70
Antiscalants

Membranereplacements

8563

Divers*Energy costs***Chemicals, biocides, filters. Simulation is based on the required number ofweeks of CIP per year per antiscalant: 4 weeks for competitor and only 1 weekof CIP with RPI-4000A**Due to 10% pressure increase per train as a result of scaling/fouling. Estimatedcost to operate at higher pressure is 6300 Eur/train/year.

Table 1: Estimated loss of revenue caused by CIP downtime*

ROPUR ANTISCALANT TECHNOLOGY

Item

ROPUR RPI® ingredients are from the latest generation of polyphosphonate salts. They produce an efficiency several orders ofmagnitude higher than comparable products in the market, requiring
only low concentrations to be effective. ROPUR Antiscalants keep themembrane surface free of inorganic and organic components andstabilizes filtration flow through the membrane layer at optimum
rates by preventing or delaying the formation of CaCO3, CaSO4,Barium, Strontium Sulfate, Silicate, and metallic oxides. This functional
property of the antiscalants allows for a constant high flow rate at
stable pressures resulting in low-energy consumption and extended
membrane life. The daily operation at the Löhnen plant relies on
the fine-tuning of parameters like flow rates, hydraulic pressures,pH, and recovery rates, to name a few. The in-depth knowledge andevaluation of membrane processes and the availability of the RPI Calc
for producing dosage calculations helped facilitate energy-efficientand reliable protection of the membrane operations at Dinslaken.
For more information on ROPUR RPI® Antiscalants, please visit www.
ropur.com.

Competitor

ROPUR RPI®

Total downtime per year

4 weeks

1 weeks

Total volume of water not produced

700,000 m³

175,000 m³

Loss of revenue

350,000 euros

87,500 euros*Calculations based on price of water at 0.50 Eur/m³

TORAY MEMBRANE EUROPE AG (TMEU)
Grabenackerstrasse 8b, Muenchenstein 1 CH-4142, Switzerland

www.water.toray
info.tmeu.mb@mail.toray
LinkedIn

www.ropur.com+41 61 415 8710

www.csmfilter.com

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All information presented herein is believed reliable and in accordance with accepted engineering practices. Toray makes nowarranties as to the completeness of this information. Users are responsible for evaluating individual product suitability forspecific applications. Toray assumes no liability whatsoever for any special, indirect or consequential damages arising from thesale, resale or misuse of its products. © 2023 Toray Industries, Inc. Subject to change without notice.
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