Testing aerobic degredation of the protein portion of filter cake afeter filtration of chrome tanned waste

An example of utilizing tanning waste as a secondary raw material is enzymatic hydrolysis of chrome shavings, the result of which is collagen hydrolysate (commercially applicable ) and filter cake containing hydrated Cr 2 O 3 contaminated with collagen residues. With a view to further potential utilisation of chrome cake, the content of collagen portion has to be reduced to a minimum. A possible solution, the subject of this presented work, is removal of the collagen portion through aerobic biological degradation in an aqueous or soil environment. This process was examined by means of biochemical oxygen consumption (standard CSN EN ISO 9408) and carbon dioxide production expressed as a percentage of theoretical production (standard ASTM 5209-92). The source of micro organisms was the commercially produced soil substrate and a soil extract prepared there from for inoculating aqueous environment. Using the described conditions, it was found that the collagen portion is removed from aqueous environment by 83% and from the soil by 58% (in approximately 80 hours). Due to its insolubility, chromic oxide does not exhibit toxic influence.