Your reliable partner for cleaning agents in industrial water systems

Acidic cleaners are the first choice when mineral or oxidic deposits are present in water systems due to precipitation from the circulating water or corrosion reactions.

Typical deposits:

• Calcium carbonate (lime) from hard feed water or CO₂ degassing

• Calcium sulphate (gypsum), often in industrial cooling circuits with a high sulphate load

• Iron oxides (rust, magnetite) due to oxygen corrosion or start-up processes

• Silicates from silicic acid in raw water

• Mixed coatings of lime, iron and organic materials

Principle of action:
Acids such as phosphoric acid, citric acid, sulphamic acid or special mixtures dissolve these deposits by reacting with the minerals and converting them into water-soluble salts.

Practical example:
In an evaporative cooling tower with a high lime content, acid cleaning can improve heat transfer by up to 20 % and at the same time prevent biofilm formation, as the mineral base of the biofilm is removed.

Alkaline cleaners are used when organic or greasy soiling dominates in the system - often in the food, beverage or paper industry, but also in membrane systems.

Typical organic coatings:

• Biofilms (bacteria, algae, fungi) with organic matrix

• Greases, oils and lubricants from production processes

• Protein or starch deposits from food processing

• Polymer residues from flocculants or production auxiliaries

Principle of action:
Alkaline cleaners often contain sodium hydroxide or potassium hydroxide combined with surfactants and complexing agents to break up organic structures, saponify grease and disperse particles.

Practical example:
In a paper mill, the use of a special alkaline CIP cleaner reduced the pressure loss in heat exchangers by 30 % and extended the service life of the system by several weeks.

Oxidative cleaners are the most effective choice when microbiological contamination or highly cross-linked organic deposits that are resistant to purely acidic or alkaline agents need to be removed.

Typical applications:

• Elimination of legionella biofilms in cooling water systems

• Disinfection of RO/membrane systems after microbial contamination

• Cleaning wet separators in exhaust air systems

• Hygienization of district heating networks after a long standstill

Principle of action:
Oxidizing agents such as sodium hypochlorite, peracetic acid or hydrogen peroxide attack the organic matrix, destroy cell walls and disinfect at the same time.

Practical example:
The permeate performance of an RO system in the beverage industry was increased by 25 % and microbiological contamination was completely eliminated by means of combined oxidative pre-treatment and acidic post-cleaning.

A typical cleaning process includes:

1. Analysis: Water sample and, if necessary, coating sample to determine the type of coating

2. Choice of cleaning agent: Acidic, alkaline or oxidative variant depending on the coating and material

3. Dosing & circulation: In a closed circuit (CIP) or offline with external pump

4. Contact time: Between 30 minutes and several hours, depending on the thickness of the coating

5. Rinsing: With demineralized water or dechlorinated water until residual chemicals are removed

6. Neutralization: If necessary, before discharge into waste water

7. Post-treatment: e.g. with corrosion inhibitors or biocides

The cleaning intervals depend heavily on the type of system, water quality, load and standard specifications.
Proactive cleaning is more cost-efficient than reacting to total failures.

Recommended intervals:

• Cooling circuits: at least 1-2 × per year or if ΔT loss >2 K or pressure increase by >0.5 bar

• Boiler systems: for scale formation >0.5 mm or sludge containing magnetite >200 mg/l

• RO/membrane systems: with SDI >5 or ΔP increase of >15 %

• District heating systems: with iron values >1 mg/l or visible sludge load

• Food/pharmaceutical plants: according to HACCP/GMP plan, often weekly to monthly

Tip: The cleaning frequency can be optimized by online monitoring of differential pressure, temperature difference and bacterial count.

Chemical cleaning in water systems must comply with legal, technical and industry-specific regulations:

• VDI 2047 / 42nd BImSchV: Hygiene in evaporative cooling systems - biofilm and legionella must be checked

• VDI 2035: Boiler and hot-water systems - freedom from deposits is essential for energy efficiency

• PED (Pressure Equipment Directive): Chemical treatment must not damage pressure equipment

• WHG / TA Luft: Discharge of rinse water only after neutralization and approval

• Food and pharmaceutical industry: HACCP, GMP, use FDA-compliant cleaners

• Membrane systems: Observe manufacturer's approvals to obtain warranty

The protection of system materials is a key issue in dry cleaning. ALMA AQUA therefore takes this into account:

1. Material analysis - Which metals, plastics or coatings are used?

2. Temperaturverträglichkeit – Viele Werkstoffe haben Temperaturgrenzen, z. B. Aluminium <60 °C bei Säurereinigung.

3. pH range tolerance - materials such as copper or brass react sensitively to strongly acidic or alkaline environments.

4. Inhibitor addition - Our cleaners contain metal protection inhibitors that form a temporary passive layer during cleaning.

5. Neutralization step - After cleaning, the system is adjusted to a neutral pH to prevent post-corrosion.

Practical example:
When cleaning a plate heat exchanger with titanium plates, a special inhibitor-stabilized citric acid cleaner was used to remove both limescale and biofilm - without damaging titanium or gaskets.

Yes - this often makes sense.
Example: An alkaline cleaner with surfactants dissolves the biofilm, which is then treated with an oxidative biocide to kill any remaining germs.
For membrane systems, we also offer 2-in-1 products that enable cleaning and disinfection in one step.

Coating analysis is often the decisive factor between the success and failure of a cleaning.
Without analysis, a cleaning agent that is not optimal is often selected, which can lead to incomplete removal or material damage.

Benefits of pavement analysis:

• Identification of the type of covering: mineral, organic, biological or mixed covering

• Chemical optimization: selection of active ingredients, pH range and temperature

• Avoidance of faulty chemistry: e.g. use of acid on biofilm → no effect

• System optimization: Conclusions on water chemistry, dosing points and operating mode

Analytical methods:

• Microscopy (light and scanning electron microscopy)

• X-ray fluorescence analysis (XRF) for element determination

• Thermogravimetry (TGA) for organic/mineral separation

Practical example:
In a cooling circuit of a plastic extrusion, a coating analysis revealed a mixed calcium-phosphate coating. Instead of a standard acid cleaning, a targeted chelate cleaning was carried out - with 100% deposit removal and no material damage.

CIP cleaning (Cleaning in Place) is the standard process for restoring the performance of membrane systems such as reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF) or microfiltration (MF).

Target:

• Removal of fouling (organic, biological, mineral)

• Restoration of the permeate flow

• Reduction of the differential pressure (ΔP)

• Extension of the diaphragm service life

Optimal procedure:

1. Analysis of performance data (permeate flow, ΔP, salt retention) → Selection of the appropriate cleaning agent

2. Chemical selection according to coating type:

   • Acidic cleaners for limescale, metal oxides, silicates

   • Alkaline cleaners for organic fouling, biofilm, grease

   • Oxidation-free cleaners (for polyamide membranes, as chlorine causes damage)

3. Preparation: rinsing with permeate or deionized water, temperature control (usually 25-35 °C)

4. Circulation phase: 30-60 minutes per circuit, change flow direction to mechanically loosen deposits

5. Reaction phase: Leave solution at standstill for 30-60 minutes

6. Rinsing: With permeate or demineralized water until the conductivity in the rinse water is stable

7. Documentation: chemical consumption, measured values, cleaning effect

Tip:
Regular CIP cleaning before critical limit values are reached (e.g. ΔP increase >15%, flux loss >10%) significantly increases the service life of membranes and reduces biofouling in the long term.

Legionella are water-borne bacteria that colonize biofilms and can cause legionellosis when aerosols form (e.g. in cooling towers or wet separators).
Disinfection alone is often not sufficient, as biofilms act as a protective layer.

Sustainable approach:

1. Root cause analysis: water samples, bacterial count, biofilm measurement, flow analysis (identify dead zones)

2. Mechanical & chemical biofilm removal:

   • Alkaline cleaners with surfactants to break up the biofilm matrix

   • Subsequent oxidative disinfection (e.g. peracetic acid, chlorine, chlorine dioxide)

3. Shock disinfection planning:

   • Dosing in increased concentration for a limited time

   • Circulation and complete flow through all parts of the system

   • Compliance with the contact time in accordance with VDI 2047 / 42nd BImSchV

4. Follow-up check: bacterial count, Legionella-specific PCR analysis

5. Long-term prevention:

   • Continuous biocide dosing in low concentrations

   • Surface modifications, avoid dead zones

   • Regular plaque and biofilm analyses

Practical example:
In a cooling tower with recurring legionella infestation, a two-stage cleaning process (alkaline + oxidative) and subsequent continuous biocide program kept the bacterial load permanently below the limit values - documented in accordance with the specifications of VDI 2047 Sheet 2.