Tannery Wastewater Treatment Plant

We need to ​implement a ​compact waste ​water treatment ​plant for a ​tannery. ​

It needs to ​have low CAPEX ​and OPEX and ​the treated ​effluent should ​meet the ​standards of ​pretreated ​sewage to be ​discharged into ​the municipal ​sewage network.​  ​

How do I ​remove chrome ​and other ​residues of the ​industrial ​process of ​tanneries? ​

I will ​appreciate any ​information and ​experiences ​with ​designing such ​a plant and ​treatment ​technologies.​  ​