Precipitation of wastewater

I need suggestion about treatment with chemical precipitation. I have a sample of electroplating wastewater contained of:

ppm
Cr 7,09
Cu 37,500
Fe 13,200
Mn 41,6

Can you suggest me what is the best way to precipitate them all? I think I have to reduce the chromium first then doing cyanide destruction and precipitate them all. Can you suggest me the best precipitant? and the best chemical to destruct the cyanide?

Firstly I think, I have to destruct the cyanide content with sodium hypochlorite and reduce the Cr(VI) to Cr(III)with sodium bisulfite. Then I'll precipitate them with pH variation with lime or caustic soda. Anyone have any comment about the chemical that I'll use? Anyone know the pH of minimum solubility for Mn? Do you have any idea of the best stirring velocity (? rpm) and how long is the time to settling down?

Thanks,

It is best if these two things are done separately.
The most common process for cyanide destruction is alkaline chlorination. ORP and pH controls are key to this process. Isolate the cyanide stream first. Alkaline chlorination is a 2 step process. First raise the pH to above 10.5, introduce sodium hypochlorite to see a positive 550 or higher OPR, and maintain this with additions of sodium hydroxide and sodium hypochlorite for 30minutes to 1 hour. This step produces cyanogen chloride which then converts to cyanate. Second, lower the pH to 8.5-9. At this pH the cyanate is hydrolyzed to carbon dioxide and ammonia fairly quickly. If you try to maintain the higher pH from the first stage you may see this step take several hours to complete. From there the solids that are formed should be removed and a cyanide test ran to determine how effective the destruction process was.
Hex-chrome reduction is completed at a pH of 2.5 or lower. An addition of a reducing agent such as sodium metabisulfite to see the ORP hit a positive 250 or lower, while maintaining the 2.5 or lower pH is needed. This will show a color change, but the process should take 30 minutes or less to complete.
Hydroxide precipitation is the most common for of metal removal in the industry now. There are solubility curve charts you can download to show you the optimal pH for each metal you want to remove.