Wastewater Treatment in Laundries: Processes, Water Recycling, and Safe Discharge
Sector overview
Industrial laundries generate large quantities of wastewater containing surfactants, organic substances, microfibers, and chemicals. Efficient treatment significantly reduces fresh water consumption, operating costs, and wastewater volumes. Simultaneously, it protects subsequent processes from contamination by solids, fats, and detergent residues.
On this page, you will find an overview of suitable processes and modular solutions for wastewater treatment in laundries based on our extensive experience in this sector. PPU has designed manufactured and installed complete modular, turnkey solutions for laundries providing complete wastewater treatment and reuse for clients in Europe.
Wastewater Treatment in Laundries: Processes, Water Recycling, and Safe Discharge
Sector overview
Contents
Laundries generate complex contaminated laundry wastewater daily, containing surfactants, chemicals, fibers, and organic substances. Through various process steps, the water can be treated to be suitable for reuse in operations or for indirect discharge into the sewer system or directly into the environment. Appropriate wastewater treatment in laundries reduces operating costs, protects plant components, and helps comply with legal requirements.
Sources of Laundry Wastewater
Industrial laundries require reliable wastewater treatment, as the contamination level varies greatly depending on the type of laundry. Hotel laundry, hospital laundry, and workwear/professional clothing from industry and commerce all introduce different pollutant loads into the wastewater. Therefore, the decision regarding process selection depends on wastewater volume, pollutant load, target effluent quality, and operating costs.
Laundry wastewater is not only generated during the main wash. Rather, every wet production step generates its own substance inputs, which must be considered when planning industrial wastewater treatment. A precise analysis of the partial flows therefore forms the basis for every plant design.
| Production step | Production component | Substances in the wastewater |
|---|---|---|
| Pre-wash | Washing machines, drums | Sand, dust, textile fibers, suspended solids, particles |
| Main wash | Detergents, surfactants, lyes | Surfactants, fats, oils, dissolved organic substances; elevated COD and BOD values |
| Bleaching | Hydrogen peroxide, peracetic acid, active chlorine | Oxidizing agents, residual chemicals; with active chlorine, additional chlorine residues and AOX risk |
| Disinfection | Peracetic acid, chemothermal disinfectants, possibly active chlorine | Disinfectant residues, peracetic acid, residual chemicals |
| Rinsing cycles | Fresh water, rinse zone | Dissolved salts, residual surfactants, residual alkalinity, and detergent residues |
| Special wash | Cleaning cloths, mats, workwear | Depending on origin: hydrocarbons, metals, fats, oils, particles, and production-specific residues |
Cleaning cloths, industrial mats, and workwear from metal, automotive, or chemical companies, however, generate significantly higher pollutant loads.
The most important difference lies in the type of laundry and the respective degree of contamination. Household laundry usually causes lower loads, as the materials washed are less contaminated. Cleaning cloths, industrial mats, and workwear from metal, automotive, or chemical companies, however, generate significantly higher pollutant loads. In addition, factors such as temperature, time, chemicals, and mechanical processing determine the washing result and influence chemical usage.
Composition of Wastewater in Laundries
The composition of laundry wastewater varies greatly. Washing program, textile type, chemicals, temperature, and degree of contamination influence the concentrations in the wastewater. Therefore, the following values serve only as a guide.
| Parameter | Documented Individual Values | Significance for Planning |
|---|---|---|
| COD | 875–4,155 mg/l | Organic load and plant size |
| COD, wide range | 1,200–20,000 mg/l | Heavily contaminated raw wastewater |
| BOD5 | 300–1,200 mg/l | Biodegradability |
| COD after pretreatment | 835 ± 176 mg/l | Residual load after physico-chemical treatment |
| BOD5 after pretreatment | 445 ± 114 mg/l | Indication of biodegradable residual load |
| Suspended solids | 80 mg/l | Fibers and particles |
| Phosphate | 94.65 mg/l on average | Nutrient load and precipitation |
| LAS surfactants | 12.24–1,023.7 mg/l | Foaming and toxicity |
| Iron | 0.037–0.72 mg/l | Metal contamination |
| Microplastics | 440,000–1,080,000 particles per 100 l | Fiber abrasion and fine particles |
The high COD and BOD values indicate a strong organic load. This load is primarily caused by surfactants, fats, oils, pollutants, and detergent residues. Surfactants also lead to foaming and complicate treatment.
Bleaching agents such as hydrogen peroxide or active chlorine further influence the chemical composition. Active chlorine increases the AOX risk and must be completely reduced before mixing with other wastewater.
The strong fluctuation of values represents a central challenge. Therefore, a wastewater treatment plant for laundry wastewater must be designed for variable loads. A detailed analysis of the wastewater forms the basis for a stable design. ClearFox offers wastewater analyses as a service for this purpose.
Why should Laundries implement wastewater treatment solutions?
Wastewater treatment primarily serves to comply with legal requirements. For laundries, the Wastewater Ordinance and local drainage statutes are relevant. These requirements differ depending on whether it is a direct discharge or an indirect discharge into the sewer system.
Furthermore, economic efficiency plays a central role. Internal wastewater treatment reduces fresh water demand and, in the long term, lowers water and wastewater costs. This becomes particularly interesting when treated process water is reused in pre-washing, rinsing processes, or technical circuits.
Another advantage lies in operational reliability. Surfactants, oils, fibers, and suspended solids burden pumps, pipes, and biological processes. Appropriate pretreatment protects subsequent plant components, reduces malfunctions, and stabilizes effluent quality.
Options for Wastewater Treatment in Laundries
Treatment takes place in several coordinated stages. The goal is the removal of solids, organic load, and dissolved pollutants.
Mechanical pre-treatment
The problem often lies in fibers, lint, sand, and other solids in laundry wastewater. These substances cause deposits, burden pumps, and disrupt subsequent processes.
Mechanical pretreatment reliably removes these components. Screens reduce the solid load at the beginning of the process chain, thereby improving the efficiency of further wastewater treatment.
The ClearFox® Screen is suitable for this step. The system automatically separates solids from the wastewater stream, dewaters them, and reduces the solid volume. This reduces the load on subsequent treatment stages. A range of screens and filters are available to ensure effective project specific pretreatment.
Chemical-Physical Treatment
Dissolved pollutants such as phosphates, surfactants, and heavy metals remain in the water after the mechanical stage. These substances can often be specifically reduced through chemical-physical wastewater treatment.
Treatment occurs via precipitation and flocculation. Dissolved substances are converted into solid particles. Subsequently, microbubbles transport the formed flocs to the surface, where they are skimmed off as flotation sludge.
The ClearFox® DAF thus removes solids, oils, hydrocarbons, dissolved metals, and organic compounds that increase COD. This makes dissolved air flotation particularly suitable for laundry wastewater containing fats, oils, and fine particles.
Aerobic Biological Treatment
After pretreatment, a relevant organic residual load remains in the water. This residual load is evident in elevated COD and BOD5 values and requires stable biological wastewater purification.
The ClearFox® FBR System operates as an aerobic fixed-bed reactor with solid carrier materials. Microorganisms settle on them and ensure stable purification performance. The biofilm supports reliable COD reduction and is particularly suitable for fluctuating influent conditions in industrial laundries.
Secondary Clarification and Solid Separation
After biological treatment, the water still contains sludge flocs. These solids must be reliably separated before discharge or reuse.
The ClearFox® Lamella Clarifier separates solid particles by sedimentation. Inclined lamellas increase the settling area and significantly reduce space requirements. This efficiently separates even fine particles.
Advanced Treatment for Persistent Substances
For reuse in operations, dissolved substances may also need to be reduced, depending on the application area. These substances affect washing processes, odor, salinity, and the quality of the recycled process water.
Various methods can be used for this, such as a glass bead filter, ultrafiltration, reverse osmosis, and UV disinfection. A glass bead filter first removes remaining suspended solids and fine particles from the biologically treated wastewater. Ultrafiltration primarily removes the finest particles, while reverse osmosis also significantly reduces dissolved components. For hygienic safeguarding of the treated water, UV disinfection can be applied if necessary, which reduces microorganisms and further improves water quality.
Subsequently, ultrafiltration reduces colloids, microorganisms, and the finest particles. The membrane forms an important protective stage for reverse osmosis and stabilizes water quality under fluctuating loads. Reverse osmosis then removes dissolved salts, trace substances, and other dissolved components, producing high-quality process water for reuse in operations.
The combination of several processes enables water reuse. This creates a multi-stage solution for water recycling in laundries, saving fresh water and reducing wastewater volume.
Modular Complete System
For combining different treatment stages, ClearFox offers modular containerized wastewater treatment plants. ClearFox® container systems combine mechanical, chemical-physical, and biological processes in pre-assembled shipping containers. This allows individual process steps to be flexibly combined and adapted to different requirements. They treat 7.5 to 3,000 m³ of wastewater per day and can be customized to specific needs.
A modular wastewater treatment plant for laundries offers advantages when partial flows, available space, and effluent targets need to be considered individually. This creates a flexible solution for indirect discharge, water recycling, or future expansions.
Use of residual materials from wastewater treatment
Wastewater treatment generates various residues. Their treatment and disposal are an integral part of the overall concept of an industrial wastewater treatment plant.
A central residue is the sewage or flotation sludge. It is dewatered and then disposed of or thermally utilized. The ClearFox® Sludge Screw Press mechanically reduces sludge volume and dewaters biological sludges as well as flotation sludges.
In addition, concentrates from membrane processes or distillation are produced. These residues contain concentrated components and must be disposed of properly according to analysis.
However, the greatest benefit lies in the treated water. Depending on the treatment quality, the purified water can be reused in the washing process, thereby reducing fresh water demand.
Planning and Purchasing a Wastewater Treatment Plant for a Laundry
The planning of a wastewater treatment plant begins with a detailed analysis. This includes recording wastewater volumes, peak loads, COD, BOD5, surfactants, solids, fats, oils, and potential heavy metals. This is followed by defining the objectives. A laundry decides between indirect discharge into the sewer system and reuse in operations.
The following points are crucial for purchase:
- Wastewater volume per day and per hour
- Proportion of household laundry, hospital laundry, and heavily soiled laundry
- Desired effluent quality for sewer discharge or reuse
- Available footprint in the facility
- Chemical consumption and sludge volume
- Automation, maintenance, and remote monitoring
ClearFox offers modular process chains consisting of screening, DAF, FBR, lamella clarification, and sludge treatment. This combination is suitable for fluctuating loads in laundries and forms a flexible basis for industrial wastewater treatment.
Conclusion
Wastewater treatment in laundries represents a technical and economic necessity. The combination of mechanical, chemical, and biological processes enables stable compliance with limit values.
Modern systems, such as ClearFox solutions, offer flexible and efficient implementation. They can be designed for discharge into the sewer system, reuse in operations, or future plant expansion.
Your benefits at a glance
With integrated solutions and clearly defined process guarantees, ClearFox® is one of the leading providers of industrial wastewater treatment in Europe. We flexibly adapt our modular, container-based systems to your requirements. This creates an economical and individually tailored solution for every application.
Your Advantages
Compact design for minimal space requirements
Fully automatic operation with optional remote monitoring
Low operating costs due to energy-efficient processes
Easy integration into existing plants and processes
Practical solutions for complex requirements
Economical planning without compromising quality
Personal support and customer-oriented service
Reliable technology with clear results
Our fixed-bed process (FBR) has been independently tested and certified by PIA GmbH.
This means you benefit from:
particularly low operating costs
modular and scalable systems
flexible leasing options for pilot or short-term projects
We understand the requirements of laundries
Every laundry has its own unique wastewater profile. That is why it is crucial to work with a partner who has a thorough understanding of the industry’s processes and challenges.
We have already carried out numerous projects in laundries and developed treatment systems that are precisely tailored to the specific operating conditions in terms of technical, economic and regulatory requirements.
Global support, local expertise
The international ClearFox® service team supports you throughout the entire project – from planning to well beyond commissioning. This ensures reliable and smooth plant operation.
Start Your Project
Would you like to learn more? We would be happy to prepare a non-binding site analysis including a preliminary design for you. We evaluate loads, general conditions, and effluent targets to develop the appropriate solution for your operation and provide an initial cost estimate.
FAQs
Can existing laundries install wastewater treatment systems retrospectively?
Yes, existing laundries can often be retrofitted. Modular systems allow integration into existing operations without rebuilding the entire infrastructure.
What advantages does a modular containerized wastewater treatment plant offer for laundries?
Modular containerized wastewater treatment plants save space, shorten installation time, and can be flexibly expanded. This makes them particularly suitable for growing laundry businesses or fluctuating wastewater volumes.
Can treated laundry wastewater be reused?
Yes, treated laundry wastewater can be reused in the washing process, depending on its quality. Pre-washing and technical processes are particularly suitable for water recycling.
What does a DAF system remove from laundry wastewater?
A DAF system removes fats, oils, suspended solids, and fine particles from wastewater. Microbubbles transport the substances to the surface, where they are skimmed off.
What is the process for a wastewater treatment project in a laundry?
A project usually begins with an analysis of the wastewater and operational data. This is followed by the selection of suitable processes and the design of the plant based on wastewater volume, pollutant load, and desired effluent quality.
Reference projects
- 40,000+ treatment systems
- Installed in over 50 countries
- Treating 25 million litres daily
