Car Wash Water Reclaim Systems

Ozone is used in car wash water treatment systems to disinfect, oxidize contaminants, and control odors, enabling efficient water recycling while meeting environmental and quality standards. Its advantages include powerful disinfection, no chemical residues, and vehicle-safe treatment, making it ideal for eco-conscious car washes. However, high costs, maintenance needs, and safety considerations require careful system design and operation. For car wash operators, ozone offers a sustainable solution to reduce water usage, comply with regulations, and appeal to environmentally conscious customers.

Ozone is used in car wash water treatment systems primarily for its powerful disinfecting and oxidizing properties, which help treat and recycle wastewater effectively. 

How Ozone is Used in Car Wash Water Treatment Systems:

Ozone Generation:

- Ozone (O₃) is generated on-site using an ozone generator, typically through corona discharge using oxygen as a feed-gas.

Water Treatment Process:

• Disinfection: Ozone is introduced into the wastewater to kill bacteria, viruses, fungi, and other microbiological pathogens.  Ozone also helps coagulate minerals and metals for more efficient filtration from water or to settle out as solids in settling tanks.
• Oxidation of Contaminants: Ozone oxidizes organic and inorganic compounds, such as oils, detergents, waxes, and other pollutants found in car wash wastewater. This breaks down complex molecules into simpler, less harmful substances that can be filtered out or biodegraded.
• Odor and Color Removal: Ozone neutralizes odor-causing compounds and can help remove discoloration in reclaimed water, improving its quality for reuse.
• Integration with Other Systems: Ozone treatment is often combined with filtration (e.g., activated carbon or multi-media filters), coagulation, flocculation, or UV disinfection to create a comprehensive water reclamation system. For example, after ozone treatment, water may pass through filters to remove oxidized particles like rust or organic debris.

Recycling and Reuse:

- After treatment, the water is stored in tanks and reused for various car wash functions, such as pre-soaking, washing, or rinsing. Ozone’s rapid breakdown into oxygen ensures no chemical residues remain in the recycled water, making it safe for reuse without affecting vehicle surfaces like paint or chrome.

Advantages of Ozone use in Car Wash Water Treatment Systems:

Effective Disinfection:

- Ozone is a powerful oxidant, killing microorganisms 3,000 times faster than chlorine. It ensures that recycled water is free from pathogens, which is essential for maintaining hygiene and preventing issues like biofouling in wash equipment.

Environmental Benefits:

- Unlike chlorine, ozone does not produce harmful disinfection by-products (e.g., trihalomethanes) that can contaminate water or harm the environment. It breaks down into oxygen, leaving no chemical residues. This aligns with eco-friendly practices and helps car washes comply with environmental regulations like the Clean Water Act.

Water Conservation:

- Car washes use significant amounts of water, and recycling is increasingly important due to rising water costs and environmental concerns. Ozone enables efficient water reuse by treating wastewater to a quality suitable for wash processes, reducing fresh water consumption by up to 50% in some systems.

No Damage to Vehicles:

- Ozone is safe for use in car wash systems as it does not negatively affect vehicle paint, chrome, or other surfaces, unlike chlorine-based treatments that may cause corrosion or discoloration over time.

Odor and Aesthetic Control:

- Ozone effectively eliminates odors caused by organic matter or chemicals in wastewater, ensuring the recycled water smells fresh. It also helps remove color from water, improving its appearance for customer satisfaction.

Cost-Effectiveness Over Time:

- While ozone systems have higher upfront costs due to equipment and maintenance, they can reduce long-term expenses by minimizing the need for chemical disinfectants, lowering sewer discharge fees, and reducing fresh water usage. This makes them cost-effective for high-volume car washes.

Summary:

Ozone is used in car wash water treatment systems to disinfect, oxidize contaminants, and control odors, enabling efficient water recycling while meeting environmental and quality standards. Its advantages include powerful disinfection, no chemical residues, and vehicle-safe treatment, making it ideal for eco-conscious car washes. For car wash operators, ozone offers a sustainable solution to reduce water usage, comply with regulations, and appeal to environmentally conscious customers.

Case Studies and White Papers:

Below are specific case studies and research showcasing the use of ozone in car was reclaim and water treatment systems.

Catalytic Ozonation Combined with Conventional Treatment Technologies for the Recycling of Automobile Serivce Station Wastewater

The ample increase in water scarcity and depletion of natural resources due to their overconsumption and the contamination of water sources becomes more challenging day by day. This challenging situation has pushed the scientific community to cope with it by providing alternative solutions. Therefore, it is indeed important to conduct a sustainable study on recycling wastewater for a particular purpose. Taking this into account, an effort was made to develop a novel hybrid treatment system that applied both conventional and advanced oxidation treatment processes. In this sustainable study, an integrated system was designed for the effective treatment followed by the recycling of automobile service station wastewater (ASSWW) which comprised sedimentation (sed), catalytic ozonation, adsorption, and filtration. In the current investigation, two catalysts/adsorbents, the granular activated carbon (GAC) and rice husk (RH) were employed individually and in combination for the first time in the studied hybrid process and their performance was compared and evaluated. The obtained results revealed that the hybrid system combination-I (Sed–O₃/GAC) was more efficient than combination-II (Sed–O₃/RH); the maximum removal efficiency of COD was 100% and 80%, respectively. In addition, the hybrid system combination-III (Sed–O₃/RH + GAC) was more economical and efficient than others by employing 35% of each absorbent in the adsorption column. Moreover, this efficient Sed–O₃/RH + GAC system has a maximum removal efficiency 99%, 100%, 99%, 100%, (89%, 99%, 100%) and 100% for turbidity, COD, BOD₅, fecal coliform, potentially toxic metals (Cd, Pb, As), oil and grease, respectively, at optimized conditions (O₃ = 82.5 mg/L; contact time = 18 min and catalyst dose of GAC and RH = 200 g each). Furthermore, the treated water sample complied with the WWF-recommended Irrigation Water Quality Guidelines (IWQGs) for class D. The increase in biodegradability (BOD₅/COD ratio) was observed from 0.41 to 0.83. Therefore, the proposed efficacious hybrid system may be employed for the recycling of ASSWW for irrigation purposes.

Summary of the Paper

The paper, published in Water 2023, 15, 171, addresses the global challenge of water scarcity and the need for sustainable wastewater treatment by developing a novel hybrid system for treating and recycling automobile service station wastewater (ASSWW) for irrigation. The system integrates conventional treatment technologies (CTTs) like sedimentation with advanced treatment technologies (ATTs) such as catalytic ozonation, adsorption, and filtration. Two catalysts/adsorbents—granular activated carbon (GAC) and rice husk (RH)—were used in three treatment combinations: Sed–O3/GAC, Sed–O3/RH, and Sed–O3/RH + GAC. The study evaluates their performance in removing contaminants like turbidity, COD, BOD5, fecal coliform, toxic metals (Cd, Pb, As), and oil and grease.

The most effective and economical combination was Sed–O3/RH + GAC, using 200 g of each catalyst, achieving removal efficiencies of 99% (turbidity), 100% (COD), 99% (BOD5), 100% (fecal coliform), 89–100% (toxic metals), and 100% (oil and grease) at optimized conditions (ozone dose: 82.5 mg/L, contact time: 18 min). This outperformed Sed–O3/GAC (100% COD removal but higher cost) and Sed–O3/RH (80% COD removal). The treated water met WWF Irrigation Water Quality Guidelines (IWQGs) for Class D, with an improved BOD5/COD ratio (0.41 to 0.83), indicating enhanced biodegradability. The study supports UN Sustainable Development Goals (SDGs) 3, 6, and 11 by promoting sustainable water management.

Specific Advantages of Ozone Highlighted

High Contaminant Removal Efficiency:

- Ozone, through catalytic ozonation, enabled near-complete removal of key pollutants: 100% COD, 100% fecal coliform, 100% oil and grease, and 89–100% toxic metals (Cd, Pb, As). This outperforms conventional methods like coagulation or biological treatment, which achieved lower removal rates (e.g., 79% turbidity removal via aerobic biological treatment).

No Harmful Byproducts:

- Unlike chlorination, ozonation does not produce chlorinated byproducts, odors, or trihalomethanes, making it environmentally friendly and safer for irrigation reuse.

Enhanced Biodegradability:

- Ozone increased the BOD5/COD ratio from 0.41 to 0.83, improving the biodegradability of the wastewater, which facilitates further natural degradation if needed.

Efficient Organic Compound Mineralization:

- Ozone effectively mineralized organic compounds (e.g., detergents, oils) in ASSWW, contributing to 100% COD and oil/grease removal, surpassing methods like reverse osmosis (96% COD removal with higher costs and sludge production).

Rapid Reaction Time:

- The system achieved high removal efficiencies in just 18 minutes of contact time, compared to other methods like integrated flocculation/ozonation, which required 60 minutes for 84.76% BOD5 removal.

Versatility in Complex Wastewater:

- Ozone’s ability to degrade complex pollutants (e.g., in ASSWW with high COD, BOD5, and toxic metals) makes it more effective than conventional treatments, as noted in comparisons with textile wastewater treatment (98% color removal, 89% COD).

Economic Efficiency with Catalysts:

- When combined with GAC and RH, ozone reduced the required catalyst quantity (200 g each vs. 400 g GAC alone), lowering costs while maintaining high efficiency (97–100% COD removal), making the process more economical than GAC-only systems.

This hybrid system, leveraging ozone’s oxidative power, offers a sustainable, efficient, and cost-effective solution for Auto Wash Reclaim Water.

Read the full study here.

Application of Flocculation-Flotation Followed by Ozoneation in Vehicle Wash Wastewater Treatment/Disinfection and Water Reclamation

This article provides the results of flocculation–flotation followed by sand filtration and ozonation (FFO), applied for the treatment of car wash wastewater in a water reclamation system in Brazil. The assessment of the efficiency of the process in enhancing reclaimed water quality, especially aesthetic, microbiological, and chemical issues is reported. The FFO process provided disinfected (Escherichia coli < 1.8 CFU 100 mL−1 ) and clarified water (10 NTU), minor foaming (residual surfactants = 1.30 mg L−1 MBAS), and no odor-related problems from reclaimed water. Comparative studies were carried out at bench scale; ozone (AOP) and chlorine were applied separately as oxidation procedures and a mass balance was assessed as a function of the number of water cycles. Results revealed that besides higher oxidation of organics and water clarification, both conductivity and dissolved solids concentrations for the ozone-treated water were lower than those obtained with the chlorinated water. A cost–benefit analysis performed for two different Brazilian scenarios showed that the payback period of the FFO equipment might be as short as one year, depending on water prices and daily wash demand. Thus, it appears that the FFO process has a great potential to be gradually introduced in sustainable vehicle wash water reclamation systems both in Brazil and worldwide.

Summary of the Paper

The paper, published in Desalination and Water Treatment 56 (2015), investigates the application of flocculation–flotation followed by sand filtration and ozonation (FFO) for treating and reclaiming vehicle wash wastewater in Porto Alegre, Brazil. The study aims to enhance water quality for reuse by addressing aesthetic, microbiological, and chemical challenges in a car wash recycling system with a 70% reclamation rate. The FFO process was implemented at a full-scale car wash (40–50 cars/day) over five weeks, reducing turbidity to 10 NTU, disinfecting water (E. coli < 1.8 CFU/100 mL), minimizing foaming (surfactants at 1.3 mg/L MBAS), and eliminating odor. Bench-scale comparisons between ozonation and chlorination showed ozone’s superior performance in organic oxidation (COD reduced to 96 mg/L, BOD to 60 mg/L) and clarification without increasing conductivity or dissolved solids, unlike chlorine. A mass balance revealed lower TDS buildup with ozone (1,700 mg/L) compared to chlorine (2,800 mg/L), reducing corrosion risks. A cost–benefit analysis indicated FFO’s payback period could be as short as one year in high-water-price areas like São Paulo, despite higher energy costs than chlorination (FFC). The FFO process supports sustainable water reuse in vehicle wash systems globally.

Specific Advantages of Ozone Highlighted

Effective Disinfection:

- Ozone achieved complete E. coli destruction (<1.8 CFU/100 mL) within 10 minutes, meeting the safe microbiological limit of 200 CFU/100 mL for reclaimed water, outperforming chlorination, which required 30 mg/L Cl₂ for similar results.

Superior Organic Oxidation:

- Ozone reduced COD by 52% (to 96 mg/L) and BOD by 47% (to 60 mg/L) at bench scale, more effectively oxidizing organic matter (e.g., detergents, wax) than chlorine, which showed minimal COD reduction even at 60 mg/L Cl₂.

Enhanced Water Clarification:

- Ozone improved aesthetic quality, reducing turbidity to 1 NTU after 60 minutes at bench scale, compared to chlorination, which showed no clarification (turbidity remained at 5.4 NTU). Full-scale FFO achieved 10 NTU, enhancing reclaimed water quality.

No Harmful Byproducts or Conductivity Increase:

- Unlike chlorination, which increased conductivity (up to 1,422 μS/cm) and TDS (2,800 mg/L), ozone maintained lower conductivity (around 859 μS/cm) and TDS (1,700 mg/L), reducing corrosion risks in vehicles.

Odor and Foaming Control:

- Ozone eliminated odor by reducing sulfides (to 0.6 mg/L S²⁻) and other sulfur compounds (e.g., mercaptans), and minimized foaming by lowering surfactants to 0.2 mg/L MBAS at bench scale (1.3 mg/L full scale), compared to chlorination’s 3 mg/L MBAS.

Rapid Action and Efficiency:

- Ozone’s disinfection and oxidation were rapid, achieving significant results within 10–60 minutes, making it efficient for continuous reclamation systems compared to chlorination’s slower process and higher chemical demand.

Support for Sustainability:

- By avoiding salt buildup and providing high-quality reclaimed water, ozone supports sustainable water reuse, aligning with policies restricting drinking water use in car washes (e.g., 60–70 L/car) and promoting recycling ratios of 70–80%.

Read the full study here.

Assessment of Carwash Wastewater Reclamation Potential Based on Household Water Treatment Technologies

This paper assesses a bench-scale carwash wastewater treatment system's removal efficiency based on coagulation-flocculation and a household-type activated carbon filter and water ozonator. For the experiment, the wastewater that went through an oil/water separator (OWS) from a medium-sized carwash facility located in a dense commercial area in Barranquilla, Colombia, was collected. The study evaluates the following parameters: water quality indicators recommended by the U.S. Environmental Protection Agency and literature related to carwash water reclamation. The treatment results are compared to related regional studies in Latin America and Colombian legislation in force. Experimental results evidence that reclaimed water's characteristics are similar to those of a groundwater source for most analyzed variables, and the system was able to reduce organic matter concentrations considerably. Regarding the organoleptic characteristics, the system eliminated foaming and generated a transparent and odorless product. The coliform test showed that reclaimed water has an average total coliform count of around 5800 MPN/100 ml, which is above the proposed health risk limit per most international standards for water reuse; but as it complies with industrial wastewater and non-food irrigation purposes in Colombia, additional disinfection is recommended depending on the reuse purpose. The results from this research may assist future carwash wastewater reclamation regulations in Colombia and the Latin American region.

Read the full study here.