Wastewater treatment process in production of nickel cobalt hydroxide

A wastewater treatment process in the production of associated with nickel cobalt hydroxide production, comprising the following steps:

• S1 subjecting a laterite nickel ore acid-leaching solution successively to iron-aluminum removal and nickel-cobalt precipitation to obtain wastewater;
• S2 subjecting the wastewater successively to chromium ions, manganese ions, and silicon ion removal treatments to obtain a suspension;
• and
• S3 reusing a portion of the suspension and continuing iron-aluminum removal;
• subjecting the remaining suspension successively to homogenizing, alkali adjusting, standing still, CCD counter-current washing, and solid-liquid separation to obtain a supernatant and a residue phase, collecting the residue phase, and discharging the supernatant after neutralization;
• wherein the steps of chromium ion removal are as follows:
• adding a reducing agent to the wastewater to perform a reduction reaction, followed by precipitation and separation to obtain a primary liquid;
• the reducing agent is a biomass straw hydrolysate;
• the preparation method of the biomass straw hydrolysate is as follows:
• grinding biomass straw into powder, and then adding concentrated sulfuric acid for hydrolysis.