Sustainable Wastewater Treatment Solutions for the Semiconductor Industry
DAS Environmental Experts offers customised, sustainable wastewater solutions and recycling concepts for the semiconductor industry. With high quality standards and individual project management for wastewater treatment plants, we are your reliable partner for efficient water utilisation in chip production.
Water management for semiconductor factories is of crucial importance in view of the global water shortage. Only just under three per cent of the world’s water reserves are fresh water, large parts of which are affected by pollution and overuse. As a major water consumer, the semiconductor industry faces the challenge of optimising its water requirements. Innovative wastewater treatment technologies and environmentally friendly water treatment plants for semiconductor factories are crucial to reducing the burden on freshwater resources.
DAS Environmental Experts develops sustainable water treatment systems that address the increasing demand for clean water in industry and at the same time help to conserve the world’s water resources. By using innovative water recycling technologies in semiconductor production, companies can significantly reduce their fresh water consumption. Our solutions for industrial wastewater treatment help to close the water cycle in semiconductor factories and ensure the sustainable use of this vital resource.
Water in the Semiconductor Industry
The production of microprocessors on silicon wafers is a resource-intensive process in semiconductor industry. Microchip production consumes large amounts of energy, water, chemicals and gases. The high water consumption in particular poses major challenges for sustainability in the semiconductor industry. In the course of chip production, the silicon wafers pass through over 1000 individual process steps in the clean room, which require regular cleaning processes. Ultrapure water (UPW), which is also used in etching processes, is used for this purpose. The use of UPW is a critical factor for resource efficiency in semiconductor production.
The environmental impact of microelectronics is particularly evident in the generation of hazardous waste such as heavy metals, acids and solvents. These can cause considerable environmental damage if disposed of improperly. During the various production steps, the water is contaminated by chemicals such as nitric acid, sulphuric acid, hydrogen fluoride, ammonia, hydrogen peroxide and isopropanol, as well as by particles from the various stages of chip production. Effective wastewater treatment is therefore crucial for chip fabs. Optimising these processes is essential to improving sustainability in microchip production and reducing the environmental footprint of the semiconductor industry.
Three Decades of Experience in Industrial Wastewater and Waste Gas Treatment
With over 30 years of experience in industrial wastewater and waste gas treatment, DAS Environmental Experts epitomises German precision engineering and quality manufacturing. Our proven and scalable solutions provide reliable wastewater treatment for the specific requirements of high-tech manufacturing as well as numerous other industries such as food and beverage, chemical, pharmaceutical and cosmetics.
Our project approach encompasses the individual requirements of our customers, from wastewater volume and composition to specific requirements for energy and chemical use, footprint and other design requirements, as well as effluent quality for recycling, indirect and direct discharge. By prefabricating the plant components in Dresden, we guarantee the highest quality and efficiency.
One stop solutions
Our comprehensive range of services covers all areas: from consulting (including laboratory and pilot tests) to planning, plant construction, commissioning, optimization and maintenance of wastewater treatment plants. Our wide range of biological, mechanical and chemical-physical processes enables us to reduce the specific pollutants in our customers’ process, industrial and waste water to acceptable levels for discharge or recycling.
This includes:
- Removal of organic contaminants
- Removal of heavy metals or other toxic compounds
- Treatment of chemical-mechanical polishing/planarisation waste water (CMP)
- Treatment of grinding residues
- Treatment of waste water containing fluoride and arsenic
- Treatment of isopropanol (IPA) or other volatile organic compounds (VOCs)
- Reuse of treated waste water (water recycling)
- Recovery and recycling of valuable metals from waste water
Use of Biological Wastewater Treatment in the Semiconductor Industry using the example of the Moving Bed Biofilm Reactor (MBBR)
A Moving Bed Biofilm Reactor (MBBR) is a biological reactor that is capable of removing a wide range of organic contaminants from industrial wastewater due to its flexibility and efficiency. It offers good performance in the removal of nitrogen and phosphorus compounds as well as in the removal of organic compounds represented as COD/BOD/TOC. The process is robust, user-friendly, easily scalable and can therefore be adapted very well to specific customer requirements. The use of carrier material and the associated very high sludge age is ideal for adapting to a wide range of organic substances, including those that are difficult to degrade. As it is not activated sludge, less excess sludge is also formed, which reduces operating costs.
MBBR Plant
for Multi-Stage Biological Treatment of Wastewater from Etching Processes
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Carrier material
The MBBR contains loosely packed plastic carrier material, which serves as a surface for the colonisation of specialised microorganisms. These free-floating carrier materials have a large surface area to enable a high biomass concentration. The microorganisms are responsible for the degradation of both organic wastewater constituents and nitrogen compounds and, due to the very long residence time in the wastewater and the resulting selective specialisation as well as the protected space in the growth bodies, ensure that the MBBR process is significantly more stable and adaptive than other biological treatment technologies.
Oxygenation and mixing
Air is blown into the reactor to provide oxygen and supply the microorganisms with nutrients. Due to the lower solids content compared to activated sludge processes, the oxygen input is very efficient. At the same time, aeration ensures mixing of the wastewater and the carrier materials in the reactor.
Biofilm growth
Microorganisms in the wastewater, such as bacteria, attach themselves to the surface of the carrier materials and form a biofilm. This biofilm contains a variety of organisms that can break down organic compounds in the wastewater.
Degradation of pollutants
The microorganisms in the biofilm break down organic compounds and other pollutants in the wastewater by using them as a food source. This degradation takes place through biochemical processes such as aerobic and anaerobic respiration and denitrification.
Purification
After the microorganisms have broken down the pollutants, the purified water flows out of the reactor. Most of the biomass remains in the reactor and can be used for the biological degradation of further pollutants. As the biomass is not present as activated sludge, there is also less excess sludge at the end.
DAS EE has many Years of Experience with MBBR in various Industries.
For the utilization of this technology in the semiconductor industry, we recommend the following technological process combination as an example:
- One mixing and balancing tank for buffering & conditioning (pH adjustment, addition of necessary nutrients, H2O2 catalysis)
- Two aerobic MBBRs for COD degradation and nitrification
- One anoxic (dissolved oxygen-free) MBBR for nitrate degradation
- Flotation for solids separation
- Sludge presses for sludge dewatering
Membrane Bio Reactor (MBR)
Another wastewater treatment method that can be used in the semiconductor industry is the Membrane Bio Reactor (MBR). Here, the activated sludge process is combined with membrane filtration to retain particles and activated sludge before the biologically treated wastewater is discharged.
The wastewater is first fed into a biological reactor containing micro-organisms. These organisms play a key role in the degradation of organic contaminants in the wastewater and, unlike the MBBR, are not present as a biofilm but as activated sludge and therefore in the form of flocs suspended in the wastewater. Anaerobic, anoxic and aerobic tanks or zones are also used to exploit the characteristics of different micro-organisms in the biocenosis. However, unlike MBBR, these pass through all stages rather than remaining in one zone.
To maintain the activity of the aerobic organisms, air is injected into the reactor, allowing their aerobic growth and accelerating the degradation of pollutants. Anaerobic or anoxic zones are mixed without the introduction of air. The treated wastewater then passes through membrane filtration in the MBR system. Special membranes are used to effectively retain particles and activated sludge.
Periodic backwashing of the membranes is required to remove deposits and blockages, usually by reversing the water flow or using chemical cleaning methods. Depending on the level of fouling, alkalis, acids or even enzymatic cleaners and chlorine-based hypochlorite are used. The activated sludge is recirculated to the upstream parts of the plant to avoid a critical concentration in the membrane chamber. The excess sludge produced during the process is also removed from this recirculation. Finally, depending on the application, the purified water can be reused or discharged to the central sewerage system.
Alternatively, it can be subjected to further purification processes to achieve higher levels of purity. The advantages of this process include the absence of solids in the effluent, potentially lower reactor volumes due to higher activated sludge concentrations, easy stepwise increase in filtration capacity and a smaller footprint for solids separation compared to gravity sedimentation.
Chemical-physical Wastewater Treatment in the Semiconductor Industry
Chemical-physical wastewater treatment is a combination of different processes to remove heavy metals, organic compounds, acids and bases as well as particles from the process water. Depending on customer requirements, our team of experts decides which of the processes to combine in order to achieve optimum results.
Solution for Chemical-Physical Wastewater Treatment
DAS EE offers the following Procedures:
Filtration
Filtration is a mechanical process for separating solids from liquids. Membrane filtration in the form of microfiltration, ultrafiltration, nanofiltration and reverse osmosis, which can retain particles and molecules of a defined size, is particularly suitable for use in the semiconductor industry. This process can also be used to remove colloidal substances and bacteria and desalinate the water.
Flotation
During flotation, dispersed or suspended substances are removed from liquids with the help of coagulants such as aluminium sulphate or ferric chloride as well as flocculants. The process effectively contributes to the removal of particulate impurities from other treatment steps such as activated sludge separation from the MBBR before the water is subjected to further purification processes.
Sedimentation
Sedimentation is used to separate solid particles by gravity in shallow, virtually flow-free tanks. The tanks are usually designed according to residence time. This means that the water must remain in the tank until the particles have sunk. The higher the sinking speed, the smaller the sediment. Depending on the particle size, sedimentation is a robust, low-energy and simple process for separating solids by utilising gravity. By using lamella clarifier, this can be further optimised in terms of space.
Oxidation/Reduction
Oxidation processes are used, among other things, to remove organic compounds that are difficult to biodegrade, particularly effectively through photochemical purification with hydroxyl radicals from hydrogen peroxide or ozone using UV light. These Advanced Oxidation Processes (AOP) reliably destroy trace substances. This process can also be used to break down so-called heavy metal complexes.
Adsorption and Chemisorption
Adsorption is the accumulation of substances on the surface of a solid body, typically through van der Waals forces. Chemisorption, in which substances are bound to the surface by chemical bonds, is often irreversible in contrast to adsorption. The adsorbent activated carbon has the ability to bind a variety of substances to its porous surface. As a result, organic compounds such as PFAS (per- and polyfluorinated alkyl substances) and other dissolved substances can be effectively bound from the wastewater. Doped activated carbon and iron hydroxide granules are used to remove arsenic and heavy metals by reacting with the pollutants.
Neutralization
Neutralization is used to adjust the pH value. Acids or bases are added as required, particularly after processes such as precipitation and flocculation. It can also be used before the biological process to set a neutral pH value so that the bacteria are not destroyed.
Precipitation
Precipitation is a chemical process for separating a previously soluble substance from a fluid. Heavy metals are typically precipitated by adding suitable substances to convert them into sparingly soluble metal hydroxides. Anions such as fluoride ions can be precipitated by reactions with calcium, iron or aluminium salts. Iron and aluminium salts can also be used for phosphate precipitation.
Flocculation
Flocculation removes the finest particles from the water, which are present in suspension or as colloidal solutions. Using suitable chemicals called flocculants and flocculation aids, these particles can be agglomerated to form macro-flocs that sediment. This improves the settling properties and dewatering of residues.
Ion Exchanger
Ion exchangers are materials that can replace ions in a solution with other ions. For example, calcium ions can be replaced by sodium ions. When the ion exchanger is exhausted, it must be regenerated. Ion exchangers are used for the targeted removal of heavy metals and ions, e.g. as a “police filter” after precipitation/flocculation. They are also used for softening, re-salination and demineralisation of water. In the semiconductor industry, they are crucial for the production of extremely pure, demineralised water (ultrapure water).
