Biodegradation of Leather Solid Waste and Manipulation of Methanogens and Chromium-resistant Microorganisms

Abstract

The final solid wastes generated by tanneries are usuallyseparately disposed of in hazardous industrial landfills, whichare characterized as places of waste confinement where theresidues undergo undesired and uncontrolled biologicaltreatment. The storage and corresponding evolution of thesludge has not yet focalized the attention of the scientificcommunity. Apart from developing knowledge of the ecologyand function of the microbial community in anaerobic digestionprocesses, it is necessary to control this biological process. Themanipulation of strict anaerobic microorganisms is the limitingfactor in their isolation due to their high sensitivity to oxygen;therefore, cultivation under anaerobic conditions is essential.This work presents an evaluation of biogas generation andquality. In addition, microbial biodegradation is carried out inbench bioreactors containing two main solid wastes fromtanneries: wet-blue shavings and sludge from a tannerywastewater treatment plant (WWTP). We analyzed two storageconditions of the sludge: storage under ambient conditions andunder refrigeration. Sludge kept at ambient conditions showed asignificantly higher methane production; methane was onlydetected in vials containing high concentrations ofmicroorganisms. The manipulation of microorganisms did notinterrupt biodegradation. The isolation technique with vialsproved to be appropriate for the quantification of methanogenicmicroorganisms in biodegradation tests, although it was notfully elucidated for their isolation.