There are a  lot of literature concerning tannery waste water treatment. But you have to identify chemical or biological treatment? 

Dear sir, could you provide the literature on biological treatment of tannery wastewater.

please find the links and attachments below. 

http://www.ncbi.nlm.nih.gov/pubmed/12943317 

http://www.sciencedirect.com/science/article/pii/S0301479704000647

http://www.scialert.net/fulltext/?doi=jest.2011.1.17&org=11

www.doiserbia.nb.rs/ft.aspx?id=0352-51391100039H

www.microbialcellfactories.com/content/7/1/15

www.ijmer.com/papers/Vol3_Issue1/AT31119122.pdf

In the treatment of tannery industry effluent there are various oxidation and combined processes such as UV/H2O2/Hypochlorites, Fenton and Electro-oxidation, photo-chemical, photo-catalytic, electro-catalytic oxidation, wet air oxidation, ozonation, biological followed by ozone/UV/ H2O2, coagulation or electro-coagulation and catalytic treatments have been considered. The tannery wastewater with sulphide as main sources of pollutant, electro-coagulation is the best removal efficiency process among the other oxidation processes, whereas for chromium, photo catalytic oxidation process using nano-TiO2 and wet air oxidation in the presence of manganese  sulphate and activated carbon as a catalyst are more efficiency processes. The integrated combined processes described permit to meet disposal limits, health quality standards and the recovery of several chemicals utilized in the tanneries.

http://www.ijer.ir/article_320_21.html

Thank you sir....please add more response

Treatment of waste water depends on the parameters objectionable to human health and a lot of literature is available. However biosorption using the Mangifera indica, Syzigium cumini & Ficus racemosa barks have shown a remarkable adsorption efficiencies for Cr(VI) removal present in tannery polluted waters. You may opt it