Anaerobic digestion of winery wastewaters derived from different wine making processes

Anaerobic digestion of winery effluents derived from two different wine making processes was compared in a laboratory scale upflow filter. White winery effluents (WWE) were more easily degradable (average soluble COD removal = 92%) than red winery effluents (RWE) (average soluble COD removal = 85%). Differences in the reactor microbial populations for the two effluents were also observed. Both aceticlastic and hydrogenotrophic methanogens in the circulating fractions were significantly higher during the treatment of WWE than during that of RWE. With both wastewaters, the reactor promptly reacted to volumetric organic load (Bv) stress (tripling from 4 to 12 g COD L^-1 d^-1). Following the Bv perturbation, COD removal decreased to 50%. However, after two weeks the COD removal values were as before perturbation. Volatile fatty acids, especially total VFAs and butyrate measured on the second day after the imposed Bv perturbation, were good indicators of process imbalance. Coenzyme F₄₂₀ determination and scanning electron microscopy revealed the presence of Methanosaeta like cells embedded to extracellular polymers in a uniform slime matrix in the biofilm. The main methanogens observed in the effluents were Methanosarcina and Methanobrevibacter cells.