Process water refers to industrially used water that is used in various processes such as production, cooling, cleaning or transportation. In contrast to drinking water or wastewater, process water is specially adapted to the requirements of the respective application. Its quality directly influences the efficiency and cost-effectiveness of industrial processes as well as the service life of systems.
Table of contents
Definition and properties
What is process water?
Process water is water that is specifically treated and used for industrial or technical applications. It is obtained from various sources such as drinking water, river water, groundwater or treated wastewater. Depending on the application, process water can have different physical, chemical and biological properties.
Typical requirements
The specific requirements for process water vary depending on the industry and application:
- Clarity and purity:
- No suspended solids, particles or organic impurities.
- Degree of hardness:
- Adjusted calcium and magnesium content to prevent scaling (limescale deposits).
- Ion content:
- Minimization of dissolved salts, especially for sensitive applications such as steam generators.
- Biological stability:
- No microbiological contamination that could lead to biofouling.
Areas of application for process water
Process water is an indispensable component of numerous industrial applications. It is specially treated to meet the requirements of the respective process in order to prevent deposits, corrosion, contamination and process disruptions. The following areas of use illustrate the variety of applications and the different water quality requirements.
1. cooling water
Application
Cooling water is used to dissipate heat in industrial processes and plays a central role in cooling towers, heat exchangers and closed circuits. It ensures that machines and systems do not overheat and can work at optimum efficiency.
Requirements
- Low solids and salt content:
- Solids can settle and lead to scaling (limescale deposits), while dissolved salts promote corrosion.
- Substances such as calcium and magnesium ions, which are found in hard water, are particularly problematic.
2. cleansing water
Application
Cleaning water is used in numerous industries, including the food and beverage industry, automotive production and electronics manufacturing. It is used to remove impurities from production facilities, products and workpieces, with the quality of the water playing a key role in determining the efficiency and success of the cleaning process.
Requirements
- Free from organic residues:
- Organic compounds could contaminate surfaces and impair cleaning effectiveness.
- Free from salts and solid particles:
- Dissolved salts could lead to staining, especially on sensitive materials such as glass or electronic components.
- Suspended particles can increase mechanical friction and damage sensitive surfaces.
- Use of demineralized water:
- Fully demineralized water (demineralized water) is required for sensitive applications such as cleaning semiconductor components or pharmaceutical systems.
- Deionized water prevents residues that could be caused by the evaporation of water containing minerals.
3. production water
Application
Production water is used directly in chemical reactions, manufacturing processes and in the production of semi-finished products. It is used as a medium for reaction, dilution, heat transfer or as a component of the end product.
Requirements
- Chemically stable composition:
- Fluctuations in the water composition can disrupt chemical reactions and impair the quality of the end product.
- Dissolved substances such as salts, metals or organic compounds must be reduced to a minimum in order to prevent side reactions.
- Specially adapted water treatment:
- In the chemical industry: Removal of impurities that could inhibit catalyst activity.
- In metal processing: control of water hardness to ensure optimum process conditions.
4. steam generator and boiler water
Use
In power plants, process industries and other applications that require steam production, process water is used as boiler water. Steam drives turbines, transfers heat or is used in chemical processes.
Requirements
- Extremely low salt content:
- Dissolved salts lead to scaling in boilers and deposits in steam turbines, which reduces efficiency and shortens the service life of the systems.
- Chlorides, sulphates and carbonates can lead to corrosion.
- Corrosion protection:
- Oxygen, carbon dioxide and aggressive ions must be removed to minimize corrosion.
- Degassing (thermal or chemical) and the use of oxygen binders such as sodium sulphite or hydrazine are necessary.
- Use of demineralized water or ultrapure water:
- Boiler water often has to be completely desalinated, especially in high-pressure steam boilers.
- Ultrapure water is used for steam generation in nuclear power plants or pharmaceutical production facilities.
Treatment processes in process water treatment
1. CP systems for river water and water recycling
CP plants (chemical-physical plants) are precipitation and flocculation plants that have been specially developed for the removal of impurities such as heavy metals, AOX, hydrocarbons or suspended solids. They are particularly flexible and are ideal for the treatment of river water and for water recycling applications.
- Use in river water treatment:
- Removal of metals such as iron, manganese or heavy metals.
- Separation of organic substances and solids by precipitation and flocculation.
- Use of chemical reagents for pH adjustment and precipitation.
- Use for water recycling:
- Treatment of highly contaminated process water in batch or continuous processes.
- Combination with flotation systems or sedimentation stages for solids separation.
- Adaptation to specific wastewater properties through modular extensions.
Advantages:
- High flexibility and scalability.
- Adaptation to variable inlet qualities.
- Low operating costs with constant efficiency.
Photo: Our CP system ALMA CHEM MCW for the precipitation and flocculation of heavy metals, AOX, hydrocarbons and cyanides
2. biofiltration for water recycling
Biofiltration is a process that uses microbiological activity to remove organic residues. Biofiltration is an efficient and economical solution, especially for water recycling applications with low residual loads.
- Functionality:
- Microorganisms on filter materials (e.g. sand, activated carbon) break down organic substances.
- Oxygen supply optimizes the decomposition process.
- Use for water recycling:
- Removal of organic residues from wastewater streams, e.g. in the food industry (dairy wastewater, vapor condensates).
- Reduction of biofouling in downstream membrane systems (e.g. reverse osmosis).
Advantages:
- Sustainable process through biological reactions.
- Low operating costs with continuous operation.
- Improvement of the water quality for subsequent treatment stages.
Photo: Our ALMA BioFil Compact biofiltration system for removing residual organic contamination upstream of reverse osmosis systems
3. reverse osmosis (RO)
The reverse osmosis is a pressure-driven membrane process that effectively removes dissolved salts, organic compounds and other dissolved substances. It is one of the most frequently used processes in process water treatment.
For use in river water treatment:
- Removal of salts, heavy metals and suspended solids.
- Pre-treatment using CP systems, filtration or biofiltration often makes economic sense.
Use in water recycling:
- Recovery and treatment of wastewater streams for reuse.
- Removal of organic residues, salts and trace substances.
Use with demineralized water:
- Production of virtually salt-free water.
- Combination with ion exchanger systems to achieve higher purity.
Use with ultrapure water:
- Multi-stage reverse osmosis systems to reduce salts, organic substances and particles to a minimum.
Advantages:
- Very high retention of dissolved substances (up to 99 %).
- Suitable for different water qualities.
- Modular design for specific requirements.
Photo: Our ALMA OSMO reverse osmosis system for the production of deionized water and for water recycling applications
4. ion exchange
The ion exchange is a process for removing ions from water by exchanging cations and anions using resins. It is particularly efficient in the production of demineralized water and ultrapure water.
How it works:
- Cation exchange: Exchange of positive ions (e.g. calcium, magnesium) for hydrogen ions (H⁺).
- Anion exchange: Exchange of negative ions (e.g. chloride, sulphate) for hydroxide ions (OH-).
- Selective ion exchangers: remove specific ions such as heavy metals.
For use in river water treatment:
- Removal of hardness formers and heavy metals.
- Post-treatment after the reverse osmosis system to achieve higher water qualities.
Use in water recycling:
- Removal of interfering ions from treated wastewater.
- Support with cycle management in sensitive processes.
Use with demineralized water:
- Production of demineralized water by combining cation and anion exchangers.
- Use in thermal processes such as steam generators.
Use with ultrapure water:
- High-purity resins for the removal of trace substances.
- Combined processes with reverse osmosis for ultrapure applications.
Advantages:
- Very high water purity.
- Effective removal of specific ions.
- Long service life of the resins with correct regeneration.
Photo: Our ALMA ION ion exchanger system with upstream ALMA FIL AK activated carbon filter
Requirements for process water in various industries
The requirements for process water are heavily dependent on the specific circumstances of the respective industry. Each industry has its own standards and objectives relating to water quality, purity and availability. The following examples illustrate the key requirements and challenges in various industries.
1. chemical industry
Requirements:
- High chemical purity:
- Impurities such as dissolved salts, metals or organic substances can interfere with chemical reactions and impair product quality.
- Exact composition:
- Process water must be of a constant quality, as fluctuations can affect the effectiveness of catalysts or the stability of end products.
- Corrosion protection:
- Water for reactors and heat exchangers must be chemically stabilized to prevent corrosion.
Typical applications:
- Production of basic chemicals, polymers, solvents.
- Use of demineralized water (demineralized water) in reactors.
- Cooling water for heat exchanger and reaction control.
2. food and beverage industry
Requirements:
- Hygiene and microbiological safety:
- Process water must be free of microorganisms, biofilms and organic residues in order to avoid contamination of the products.
- Flavor neutrality:
- Water must not contain any foreign flavors or dissolved substances that affect the taste of the end product.
- Regulatory requirements:
- Compliance with strict standards such as Regulation (EC) No. 852/2004 for food hygiene.
Typical applications:
- Cleaning systems, bottles and containers with demineralized water.
- Production of beverages such as soft drinks, beer and water.
- Steam production for pasteurization or sterilization.
3. pharmaceutical industry
Requirements:
- Highest purity:
- Process water for pharmaceutical production must be virtually free of ions, particles and microorganisms. Water qualities such as ultrapure water (e.g. USP-Purified Water, WFI - Water for Injection) are standard here.
- Sterility:
- Special requirements for sterility and microbiological safety for processes such as injection production or sterilization.
- Constant water quality:
- Fluctuations in water quality can affect the chemical stability of active ingredients.
Typical applications:
- Ultrapure water for the production of pharmaceuticals and vaccines.
- Steam for sterilization and cleaning.
- Water for cleaning and rinsing containers and instruments.
4. energy and power plant industry
Requirements:
- Desalinated water:
- Water for steam boilers and turbines must have extremely low conductivity and salt content to prevent corrosion and scaling.
- Degassing:
- Oxygen and carbon dioxide must be removed to prevent corrosion in high-pressure systems.
- High thermal stability:
- Water must remain chemically stable at high temperatures.
Typical applications:
- Demineralized water for steam boilers and turbines.
- Cooling water for thermal power plants.
- Water for condensate return and feed water treatment.
5th automotive industry
Requirements:
- Hardness-free water:
- Process water for painting lines and washing processes must be free of hardening agents to prevent streaking.
- Corrosion protection:
- Cooling water in production plants and test facilities must be stabilized against corrosion.
- Sustainability:
- Water recycling is increasingly important in order to meet environmental regulations and sustainability targets.
Typical applications:
- Deionized water for painting systems and surface treatment.
- Cooling water for machines and test benches.
- Water recycling from process wastewater.
6. semiconductor and electronics industry
Requirements:
- Ultrapure water (UPW):
- Water must be extremely pure, as even the slightest impurities can impair the function of electronic components.
- Free from organic and inorganic residues:
- Avoid particles, metals or organic substances that could damage conductors or components.
- Strict purity requirements:
- Compliance with standards such as ASTM D5127 for ultrapure water.
Typical applications:
- Ultrapure water for wafer cleaning and semiconductor production.
- Cooling water for test equipment.
- Process water for etching and coating processes.
7. metal processing
Requirements:
- Hardness control:
- Water must have specific degrees of hardness to ensure optimum lubrication and cooling properties in machine tools.
- Corrosion protection:
- Additives in the process water prevent corrosion on workpieces and machines.
- Particle-free water:
- Avoidance of particle residues that could impair the processing quality.
Typical applications:
- Cooling and lubricating water for machine tools.
- Deionized water for electrochemical processes such as electroplating.
- Water for cleaning and rinsing workpieces.
8. paper industry
The paper industry is one of the most water-intensive sectors, as water plays a central role in almost all production steps. From pulp production to surface finishing, the quality of the process water is crucial for product quality and economic efficiency.
Requirements:
- Free from suspended solids and organic compounds:
- Contamination can impair the paper structure and cause blockages in machines.
- Adjusted hardness and ion content:
- Water with suitable calcium and magnesium concentrations prevents deposits and corrosion.
- Sustainability through water recycling:
- Closed circuits to reduce fresh water consumption and minimize the volume of waste water.
Typical applications:
- Process water for pulp preparation and paper machine systems.
- Cooling water for the machines and drying systems.
- Water for surface treatment, such as coating and coloring paper.
9. paint and varnish industry
The paint and coatings industry uses process water both in production and in the cleaning of systems. The demands placed on the water are high, as impurities can impair the chemical reactions and the quality of the products.
Requirements:
- High chemical purity:
- Avoidance of ions that affect the stability of color pigments or binders.
- Particle-free water:
- No suspended solids that could impair the homogeneity of the mixtures.
- Efficient wastewater treatment:
- Treatment of heavily contaminated wastewater with high concentrations of organic substances, pigments and solvents.
Typical applications:
- Production of color dispersions, binders and solvent mixtures.
- Water for cleaning processes in mixing and filling systems.
- Steam and cooling water for production processes.
10. plastic recycling
In plastic recycling, water is used intensively for cleaning, sorting and processing plastic waste. The quality of the process water is crucial in order to effectively remove residues of dirt, adhesives and additives.
Requirements:
- Efficient particle removal:
- Water must be able to bind and remove foreign substances such as paper fibers, adhesive residues or organic impurities.
- Circulation with minimal fresh water consumption:
- Reuse of treated water to reduce operating costs and environmental impact.
- Robust processing technologies:
- Systems must be resistant to high solids and grease loads.
Typical applications:
- Washing processes for plastic flakes (e.g. PET, HDPE).
- Cooling water for extruders and granulators.
- Water for separation processes such as flotation, in which plastic types are separated by differences in density.
Conclusion
Process water is an indispensable component of many industrial processes and its treatment places the highest demands on technology and expertise. From river water treatment and water recycling to the production of demineralized and ultrapure water, advanced technologies such as reverse osmosis, ion exchange, CP systems and biofiltration are essential to meet the required quality standards. Customized process water treatment not only ensures compliance with environmental and quality requirements, but also the efficiency and longevity of industrial plants.
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