Oil Removal from New Energy Industry Wastewater: A Comprehensive Analysis of Industry Pain Points and Technical Solutions

Abstract

The rapid growth of the new energy industry—lithium-ion battery manufacturing, photovoltaic production, and EV assembly—generates significant oily wastewater containing surfactants, mineral oils, phosphates, and heavy metals, with highly fluctuating quality. This wastewater is toxic, hard to biochemically treat, and causes pollution and resource loss if mishandled. Mature oil-water separation technologies offer a solution for compliance and resource recovery.

A flexible, multi-stage suite has been developed: pretreatment uses DAF (micro-bubbles capture oil and SS, achieving effluent oil <20 mg/L and >90% SS removal) and CPI coalescing separators (removing >95% free oil and >70% dispersed oil without chemicals, effluent oil as low as 10 ppm). Advanced treatment employs fouling-resistant membranes and coalescing filter cartridges to capture residual micro-droplets and emulsified oils, enabling water reuse.

Real-world applications in lithium battery precursor production—treating emulsified oil, mineral oil, organic solvents, and metal impurities—use a combined process of "hydrocyclone + DAF" and "anti-fouling membranes + coalescing cartridges." This consistently meets discharge limits, achieves 70–90% water recovery, and recovers low-water waste oil with direct economic benefits, supporting cleaner production and resource recycling.

I. The Challenge: Complex and Toxic Oily Wastewater in New Energy Production

Driven by "dual carbon" goals, the new energy industry is expanding at an unprecedented pace; however, it is less widely known that processes such as lithium-ion battery manufacturing, photovoltaic production, and new energy vehicle assembly generate significant volumes of oily wastewater. Characterized by complex composition, high toxicity, and resistance to direct biochemical treatment, this type of wastewater has become a critical bottleneck hindering the industry’s green development. Research indicates that wastewater from the new energy vehicle industry contains pollutants such as surfactants, mineral oils, phosphates, and heavy metals; furthermore, the wastewater quality fluctuates significantly, making treatment extremely challenging. Improper handling not only causes severe water and soil pollution but also leads to the loss of valuable oils and organic solvents, thereby increasing operational costs. Conversely, efficient and mature oil-water separation technologies have emerged as a key solution to this challenge, enabling new energy enterprises to achieve the dual objectives of environmental compliance and resource recycling.

II. A Flexible Multi-Stage Oil-Water Separation Solution

Pre-Treatment Stage: DAF and CPI Coalescing Separators

A mature and efficient suite of oil-water separation solutions has been developed for the oily wastewater generated by the new energy industry; these solutions can be flexibly combined and applied based on the specific characteristics of the wastewater source. At the pre-treatment stage, dissolved air flotation (DAF) technology—which utilizes a multitude of micro-bubbles to capture oil droplets and suspended solids—consistently maintains effluent oil content below 20 mg/L and achieves a suspended solids removal rate exceeding 90%. Meanwhile, CPI (Corrugated Plate Interceptor) coalescing separators utilize gravity and fluid dynamics to remove over 95% of free oil and more than 70% of dispersed oil without the need for chemical additives, resulting in an effluent oil concentration as low as 10 ppm and minimal operating costs.

Advanced Treatment Stage: Membranes and Coalescing Filter Cartridges

During the advanced treatment phase, fouling-resistant membrane separation technologies (such as coalescing filter cartridges for deep oil removal and nano-ceramic membrane filtration) further capture residual micro-droplets and impurities. Notably, coalescing filter cartridges employ specially designed media to force micro-droplets to collide and coalesce into larger droplets that rapidly rise to the surface; this highly efficient process can effectively handle partially emulsified oils, facilitating resource recovery and reuse. This multi-stage process combination—spanning from pre-treatment to advanced treatment—not only significantly enhances treatment efficiency but also establishes a robust technical foundation for wastewater reuse and resource recovery.

III. Verified Results in New Energy Applications

Real-world applications demonstrate that these technologies have already yielded significant results within the new energy industry. Wastewater from the production of lithium battery precursors contains emulsified oil, mineral oil, organic solvents, and trace metal impurities—contaminants that are difficult to separate thoroughly using conventional methods. By employing a combined process of "high-efficiency pretreatment (hydrocyclone separation + dissolved air flotation)" and "advanced purification (anti-fouling membranes + coalescing filter elements)," the concentration of petroleum-related substances in the effluent can be consistently kept within regulatory limits, and water recovery rates reach 70% to 90%; furthermore, the process yields effective waste oil recovery with low water content, generating direct economic benefits.

The large-scale application of demulsifiers in lithium battery wastewater treatment has helped enterprises effectively resolve challenges associated with treating oily wastewater—such as cleaning wastewater—thereby enhancing cleaner production while aligning with the industry’s strategic direction toward resource recycling and reuse.