The production wastewater of ternary cathode factory is usually divided into washing water, workshop mop water, bathing water, laboratory testing wastewater, water curtain dust removal wastewater and other wastewater, in which the washing water volume is large, the lithium content is high and the heavy metal content is high; However, the content of heavy metals and COD in workshop mop water, bath water and laboratory test wastewater is high, and the benefit of recovering lithium is low. Therefore, we propose zero discharge of washing water.