In recent years, people’s environmental awareness has increased. The high density of the urban population has caused a considerable increase in the demand for car washing services, which has created large quantities of car wash wastewater. The main pollutants in car wash wastewater are detergents, dirt, oil, and grease. Untreated wastewater released into rainwater sewer systems or other water bodies may pollute the water and generate excessive bubble foams, which negatively affects urban appearance. Car washes are divided into mechanical car washes and manual or self-service car washes. In general, car washes have a small operation and scale, occupy limited land, and cannot afford wastewater treatment costs. Therefore, most car washes are not equipped with wastewater treatment facilities. Consequently, the discharge of wastewater from car washes negatively affects the water quality in the surrounding environment and results in wasteful use of water resources. This study reviewed 68 research papers on the quality, treatment techniques, treatment costs, and treatment effectiveness of car wash wastewater to provide a reference for car wash operators to contribute to the preservation of water resources. We found that there is a higher chance of recycling car wash wastewater when combing two different techniques for car wash wastewater treatment.

With the increase in transportation demand and facilities in this era and the significant improvement in people’s living standards, the annual production and sales of vehicles are steadily increasing. With this, the issues of car wash wastewater treatment and water pollution are becoming more and more serious. Car wash wastewater mainly comprises fine sand, slick oil, suspended solids (SS), and surfactants, and can be quantified as chemical oxygen demand (COD) on a normative basis. This study examines the use of cyclo-flow filtration with high filtrate flux to treat car wash wastewater to solve issue of limited space in metropolitan areas and increase the willingness of the industry to invest in car wash equipment to recover water resources. The average removal rates of SS and COD are about 81% and 43%, respectively. Compared with current technology, the price of recycled water can compensate for operating costs, requiring minimal operating space owing to the single-unit cyclo-flow filtration system.