Research On Characteristics Of Bioaugmentation Anaerobic Acidogenesis Of Excess Activated Sludge Fermentation Broth

At present, there is a serious problem in sewage treatment plants of our country,that is the excessive emphasis on sewage treatment but ignoring the sludge treatment.However, with the attention for environmental protection,the problem of urbansludge treatment has been one of the focused issues of the researchers. As one of themost promising ways for sludge treatment, sludge fermentation for volatile fattyacid (VFAs) meets the requirements of our country, that is energy conservation andemission reduction,as well as the recycling of waste resources.In this study, we attached importance to the influence of bioaugmentation onanaerobic acidogenesis of waste activated sludge(WAS) fermentation broth. Withthe alkaline pretreatment, the WAS was fermented for24h, then a centrifuge can letus get excess activated sludge fermentation broth. After changing the initial pH, theratio of protein and polyscchrides (Pro/G),or flora environment, we should add acertain amount of sulfate reducting bacteria(SRB) in fermentation broth, whichwould be fermented under anaerobic conditions. By determining the concentrationchange of protein, polyscchrides,NH4+-N and PO43--P, we can seek out the optimumcondition for the producing of VFAs, at the same time, we can explore themechanism and form of the bioaugmentation on sludge anaerobicacidogenesis.Atthe same time we will build the kinetic model for the hydrolyticacidification process.Ceteris paribus, the experiment was carried out at pH=4.0,5.0,7.0,8.0,9.0and1.0respectively, the results show that the accumulation of VFAs is increasingwith the rise of pH. When the initial pH is4.0, the accumulation of VFAs is the least.The best pH for VFAs production is10.0, and the highest accumulation of VFAs is901.92mg/L, which is7.8times over the same period of pH=4.0, under other pHconditions, the results are similar. Controlling pH5.0and7.0, the fermentation wascarried out at Pro/G=0.1,0.5,1.0,5.0and10.0,respectively, the results show thatwhen Pro/G is0.5, the maximum accumulation of VFAs is exceed1600mg/L.When the excess activated sludge fermentation broth was not added SRB orwas radiosterilized,then added SRB, the accumulation of VFAs is not significant,which indicates only SRB cannot improve VFAs productivity,and the synergybetween SRB and acid-forming bacteria play an important role.When the concentration of polyscchrides is higher, its utilization rate will bebetter than protein, Under other conditions, the results are on the contrary.But,anyway, the dissolution rate of NH4+-N is higher than PO43--P.The change of pH is small for the fermentation type, acetic acid is the main composition, other types are not obvious.And the Pro/G has a significant influencefor the fermentation type. At the condition of Pro/G=0.2, there was butyric acid typefermentation and at Pro/G=0.5and1.0, propionic acid type fermentation wasappeared.yet at the condition of Pro/G=5.0and10.0, acetic acid fermentation type isthe main type.In this study, we adopt Logistic model to fit the hydrolytic process andacidization. And the results display that the regression coefficient is great, whichdemonstates Logistic model is appropriate for the change of substrate, and it alsomanifests the effect of bioaugmentation on anaerobic acidogenesis of excessactivated sludge fermentation broth is significant.