The automotive industry wastewater treatment encompasses the management of complex wastewaters arising from multiple surface processing stages of modern automobile production. An automotive factory's wastewater comes from the stamping shop, welding, phosphating (Bonderite), cathodic electrodeposition (E-coat), primer and topcoat painting, engine assembly, and testing stages.
Automotive wastewaters have COD levels of 800-3,500 mg/L, oil-grease levels of 50-500 mg/L, phosphate levels of 50-300 mg/L, and heavy metals (Zn, Ni, Cr, Mn) levels of 5-50 mg/L. The wastewater from each stage has different pH and composition, fluctuating between pH 2 (phosphating) and pH 11 (alkaline oil removal).
Arsistek automotive sector solutions include a combination of flow separation, oil separator (API/CPI/DAF), heavy metal precipitation, biological treatment, and UF/RO recovery. Modern automotive factories aim for 70-90% water recovery.
Structure of Automotive Production Wastewater
In modern automobile manufacturing, there are 7-12 surface treatment stages. Degreasing (alkaline), phosphating (Bonderite acidic), passivation, cataphoresis (E-coat), primer paint, color paint, varnish. Washing waters come from each stage.
These multiple surface treatment wastewater contain zinc, iron, manganese, and nickel along with phosphates. In the cataphoresis stage, epoxy resin residues elevate KOİ. VOC residues pass through from the paint lines.
Test (engine test, air conditioning) and service wastewaters produce a different profile — oil-grease is high, and organic load is at a medium level. Therefore, flow separation + flow-specific pre-treatment is essential.
Oil Separation Systems
High oil-grease content wastewater (service, testing, machine washing) first passes through the API (American Petroleum Institute) separator — free oil is separated.
Then, emulsified oil is separated with the CPI (Corrugated Plate Interceptor). Chemical breaking + DAF is used for the remaining stable emulsion. Total oil removal is %95+.
Heavy Metal Precipitation
Alkaline precipitation (pH 9-10) is applied for zinc, iron, and nickel in surface treatment wastewater. They precipitate in hydroxide form.
For stricter limits, sulfide precipitation or ion exchange is used. The sludge is dewatered by belt-press and sent for licensed disposal.
Water Reuse and Zero Discharge
The automotive sector is a pioneer in the zero liquid discharge (ZLD) goal. Many premium automotive factories in Turkey and around the world have achieved over 95% water reuse.
The standard treatment flow is passed through UF (ultrafiltration) + RO (reverse osmosis) after treatment. RO permeate reduces conductivity to below 1,000 µS/cm and is returned to washing lines, cooling towers, and cathodic dip coating dilution.
RO concentrate (very high salinity) is converted into solid salt form using evaporator + crystallizer — the final link of ZLD. This ensures that no liquid waste is discharged.
Advantages of Solutions in the Automotive Sector
Automotive Industry Reference Projects
8 visuals will be added soon — stay tuned for our reference projects and facility photos.
Frequently Asked Questions
Acidic phosphating (pH 2), alkaline oil removal (pH 11), oil-grease heavy service, and neutral paint flows have very different compositions. If mixed, chemical interaction, corrosion, and inefficiency occur. They are collected separately, and specific pre-treatment is applied to each.
Yes. Many factories of premium brands such as Mercedes, BMW, and Toyota operate with ZLD. The CAPEX is high (2-3 times the standard), but it pays off with tender points, sustainability credits, and long-term water cost savings.
Phosphate is reduced to below 2 mg/L level through a combination of chemical precipitation (calcium or aluminum salts) and biological phosphorus removal (bio-P).
Preferably separate. Paint wastewater contains VOC, pigment, and resin residues. After specific pre-treatment with the combination of Ultrafiltration + GAC + Fenton, it is sent to a common biological stage.
The capacity of the facility varies according to the water reuse target and ZLD level. A detailed cost analysis is conducted through a facility-specific engineering study.
We have multiple wastewater treatment projects for large automotive investments and Tier-1 suppliers in Turkey focused on surface treatment. References will be shared with relevant clients under confidentiality agreements.