Characterisation by image analysis of anaerobic sludge under shock conditions

In the present work the characterisation by image analysis of anaerobic biomass under organic and hydraulic shocks was performed. The digester was fed with a synthetic substrate, containing 50% oleic acid (as COD). Organic and hydraulic shocks were performed by stepwise increasing the substrate concentration or by reducing the hydraulic retention time. In both cases the organic loading rate changed from 6 to 30 kg COD/m 3 .d. Hydraulic shock induced a fast decrease in the number of free filaments and in total filament length, which attained a minimum value 51 hours after beginning the shock. The initial filament values were not recovered 340 hours after the hydraulic shock. In the organic shock, the minimum values of these parameters were detected 200 hours after beginning the shock and initial values were recovered 840 hours after. During the hydraulic shock the methanogenic acetoclastic activity was directly correlated to the number and length of free filaments. This result suggests that filaments are predominantly acetoclastic bacteria, probably Methanosaeta .

[1]  W Verstraete,et al.  Contact angle measurement and cell hydrophobicity of granular sludge from upflow anaerobic sludge bed reactors , 1995, Applied and environmental microbiology.

[2]  N. Roche,et al.  Analyse des flocs bactériens et de la microfaune des boues activées para analyse d'Image , 1999 .

[3]  Gatze Lettinga,et al.  The selection pressure as a driving force behind the granulation of anaerobic sludge. , 1988 .

[4]  P. A. L. N. S. Sam-Soon,et al.  A long-chain fatty acid, oleate, as sole substrate in upflow anaerobic sludge bed (UASB) reactor systems , 1991 .

[5]  Rolando Chamy,et al.  Novel technique for measuring the size distribution of granules from anaerobic reactors for wastewater treatment , 1998 .

[6]  T. Golden,et al.  Use of Methanogenic Activity Tests to Characterize Anaerobic Sludges, Screen for Anaerobic Biodegradability and Determine Toxicity Thresholds against Individual Anaerobic Trophic Groups and Species , 1992 .

[7]  Freda R. Hawkes,et al.  Comparative performance of anaerobic digesters operating on ice-cream wastewater , 1995 .

[8]  Manuel Mota,et al.  FLOCS VS GRANULES: DIFFERENTIATION BY FRACTAL DIMENSION , 1997 .

[9]  W. Gujer,et al.  Conversion processes in anaerobic digestion , 1983 .

[10]  Gatze Lettinga,et al.  Comparative toxicity of long-chain fatty acid to anaerobic sludges from various origins , 1996 .

[11]  E. Colleran,et al.  Activity test system for determining the toxicity of xenobiotic chemicals to the methanogenic process , 1994 .

[12]  R. Kapuscinski,et al.  On performing experimental studies on transient states of continuous‐flow methanogenic reactors , 1990, Biotechnology and bioengineering.