The Study Of Kinetics And Hydrolysis And Acidogenisis In Anaerobic Digestion Of Kitchen Waste

Through the high performance liquid chromatography, detected the concentration offormic acid, acetic acid, lactic acid, propionic acid, butyric acid in sequencing batch kitchenwaste fermentation system, found the fermentation type in different pH value: pH <5.0, thelactic acid fermentation was primary; pH=5.0-6.0, the butyric acid fermentation was dominant;pH>6.0, the acetic acid fermentation was primary. Gas production rate and methane contentgrowed with the increasement of acetic acid concentration basically in the fermentation broth,when the acetate concentration reached45%, the two parameters were up to1.0L*L-1d-1and55%or more; VFA concentration reduced with the increasement of acetic acid concentration,when acetic acid concentration was below10%, VFA concentration were more than3000mg/L. while acetate concentration was40%or more, VFA concentration was below1000mg/L. While under the condition of pH<5.0, VFA concentration>3000mg/L, the contentof fruits and vegetables were more than30%in the kitchen waste, the anaerobic fermentationproned to acidification. In the single-phase anaerobic digestion, under the condition of samepH and unit volume, fruits and vegetables produced the most VFA concentration, followed bythe starches and celluloses, and the lipids and proteins produced the least VFA concentration.In batch anaerobic digestion of single-component and mixed kitchen waste, making thezero order and first order kinetics analysis about the hydrolysis and gas-production process,found that in single-component system, fitting results of the zero order kinetics and first orderkinetics model were close, relevance square were both over0.95, the relationship ofhydrolysis and gas-production speed was proteins>starches> celluloses> lipids, hydrolysisconstant k was correspondingly0.0366,0.0331,0.0215,0.0154d-1. Gas-production processhad some proportional relationship with hydrolysis process, but had no obvious relationshipwith acidogenesis process. For mixed kitchen waste, the first order kinetics model whichthought multiple components should hydrolyse respectively according to the different k hadthe best fitting effect, relevance square was over0.95；the zero order kinetics model and 1-component first order kinetics model which saw the mixture as a whole with a commonhydrolysis characteristics, and the2-component first order kinetics model which divided themixture into rapid hydrolysis matters and slow hydrolysis matters, the effect of three kineticsfitting were all not ideal. Particle size and solid concentration had little influence onhydrolysis constant k, but hydrolysis constant k would be restrained when pH<5.0, VFAconcentration>2500mg/L.