A study of the pig manure degradation and biofilm development under moderate psicrophilic conditions (20°C) was carried out on two pilot lab scale anaerobic fluidized bed reactors (AFBR), where biolite and activated coal were used as supports, respectively. The soluble total organic carbon (TOC) reduction in the treated waste was 40% for both reactors, working with a high organic loading rate (OLR) of 10 kg TOCnr'd'. The percentage of organic carbon removal rose until 90% when the organic loading rate decreased up to 3 kg TOCm'd1 (treating in this case only manure proceeding from the piglet room). The study shows imperceptible contents in acetic, propionic and butyric acids in the treated manure, whereas fatty acids of longer chain are detected. Microbial population developed inside reactors seems unable to degrade these long chain acids as fast as short chain ones because the biofilm is thinly populated by acidogenic bacteria. On the contrary, it seems to be large acetogenic and methanogenic population that carries out short chain fatty acid degradation. Kinetic studies reveal the existence of a remaining organic fraction in the anaerobic pig waste degradation caused by inhibition of hydrolysis step. Scanning Electron Microscopy shows a wide variety of microcolonies of different trophic populations which are located in crevices and other regions sheltered from hydraulic shear forces.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.