Secondary batteries, a core component of electric vehicles, have their cost and performance largely determined by cathode materials. The process of producing precursors, essential for manufacturing cathode materials, uses large amounts of water and chemicals, generating substantial volumes of high-concentration saline wastewater. Producing one ton of precursor generates approximately 20 to 30 tons of saline wastewater, which contains heavy metals such as nickel—a serious ecological toxin—along with large quantities of sulfates and sodium salts. Despite nickel being a toxic heavy metal that can severely damage aquatic ecosystems, the lack of technology to completely purify this high-concentration saline wastewater has posed significant environmental and economic problems.
This serious saline wastewater issue, lying behind the growth of the secondary battery industry, is a challenge that must be resolved. Most companies generating saline wastewater treat it using Multi-Effect Vapor Recompression (MVR) equipment, a conventional industrial wastewater treatment technology based on evaporative concentration. This method separates water and byproducts by evaporating the wastewater. While the evaporated steam can be collected and reused as industrial water, the sludge byproduct remaining after evaporation contains large amounts of heavy metals such as nickel, requiring additional treatment costs for landfill disposal as industrial waste.
Sludge byproducts amount to about 10% of the saline wastewater volume, which is cited as a major problem undermining the sustainability of the electric vehicle industry that promotes itself as carbon-reducing and eco-friendly. Therefore, a high-value-added circular economy system is needed that treats saline wastewater while converting 100% of byproducts into resources. Beyond simply purifying wastewater, the revenue-generating substances and byproducts contained in the wastewater must be upcycled into high-value-added products.
First, heavy metals and salts in saline wastewater must be removed to lower the toxicity unit (TU) index to a clean water level of 1 or below. This would allow the saline wastewater to be safely discharged or reused as industrial water. This approach can significantly reduce environmental pollution compared with conventional marine discharge treatment methods.
Second, high-value-added resources must be produced through technology that crystallizes the salts (sulfates, sodium salts) contained in saline wastewater into high-purity sodium sulfate. High-purity sodium sulfate is used in various industries, including as a raw material for colonoscopy pharmaceuticals and as an ingredient in bath products and other cosmetics.
Third, diverse applied products must be developed to maximize the resource recovery from saline wastewater. A desalting agent made by combining high-purity sodium sulfate with functional ingredients removes salinity from reclaimed land soil and, when applied at food waste treatment facilities, helps reduce equipment corrosion. A deodorizer eliminates odors from livestock barns, while an ammonia-nitrogen removal agent is being used to purify water in shrimp farms and similar facilities. The material is also used as an additive in detergents and as a hardening agent additive for construction cement, among many other applications.
Kari has demonstrated, through a demonstration plant with a processing capacity of 20 tons per day at its factory in Hwaseong, Gyeonggi Province, that the precursor saline wastewater problem can be solved. The core of this technology lies in a process that removes 100% of heavy metals and then combines sulfates and sodium salts to crystallize them into high-purity sodium sulfate decahydrate. Kim Pan-chae, co-founder of Kari, developed this technology. After studying in Japan, he founded the Korean Crystallographic Society in Korea. Over the past two years, he conducted thousands of experiments, compiled the optimized technology into data, and completed a patent registration last year. Using this technology, the total electricity consumption across the entire process can be cut to about half that of existing technologies. Kari has also completed market testing of its solid and liquid byproduct products and plans to review applications for reclaimed land improvement, desalting and deodorizing at food waste treatment facilities, deodorizing in the livestock industry, and water purification in pharmaceutical and cosmetic production processes. Kari recently received occupancy approval from the Saemangeum Development and Investment Agency and plans to complete a 10,000-pyeong (about 33,000 square meters) commercial plant in Saemangeum next year.
Ultimately, this creates a cross-value-chain circular economy system in which the waste of one industry is used as raw material for another. For the electric vehicle market to move beyond the chasm—a phenomenon of stagnant demand before a new technology becomes widespread—and achieve broad mainstream adoption, the environmental problems generated during production must be resolved. Deep-tech startups need to pay greater attention to their role in protecting the environment within the electric vehicle value chain, supporting the success of Korea's EV industry.
