Study On The Flocculation Ability By Using Fermentation Liquid Of Straw Under Different Conditions

With the increasing demand of biological flocculant industry production and application, the expensive culture medium becomes the key factor that limits the development of biological flocculant, it's necessary to seek the cheap alternative medium. In this topic, the performance of aerobic saccharification reactor and the anaerobic fermentation reactor which takes cow dung biogas slurry as inoculum and taken rice straw as substrate were discussed. According to the varieties of parameters during the reactor operating and the flocculation effect of fermentation liquid, a kind of straw decomposition method that closing to the natural can be found, and ti is easier to promote the complex industrial scale bio-flocculant Preparation.The mixture of cow dung and biogas slurry was taken as inoculum for aerobic pretreatment, according to the analysis of microorganism communities, it can be found that the advantage bacterium in the system are cellulose degradation bacterium and Clostridia sp.. In addition, it is speculated that a new species appeared in that system. The fresh rice straw and the broth that including enriched and domesticated cellulose degradation were added in the aerobic saccharification reactor. In the early stage, TOC increased gradually, after adding the biogas slurry TOC decreased sharply, TN also increased with fermatation time. pH reached 9.2 finally, C/N remained at around 20:1, the reactor operated stably, and degraded rice straw effectively.The mixture of cow dung and biogas slurry was taken as inoculum and the rice straw was taken as substrate for the anaerobic fermentation reactor, the reactor operated stably by the mode of inner loop. The pH decreased rapidly at the initial fermatation, then rised slowly after 30d. Dry anaerobic fermentation reactor did not appear the phenomenon of acid accumulation, and the fermentation type is butyric acid type fermentation. TOC increased with time while TN decreased with time, C/N reached 15:1 finally. The hemicellulose and cellulose degradated effectively, lignin degraded slightly, and the intramolecular hydrogen bond destroyed, the structure changed significantly. It is speculated that the advantage bacterium are Firmicutes, Proteobacteria, Bacteroidetes.Then, we took the different fermentation liquids and the traditional flocculation culture medium mixture under different ratio as compound flocculation culture medium. The optimal ratio of aerobic saccharification liquid with traditional flocculation culture medium is 1:3, the aerobic saccharification liquid of the 67d and the 109d compound with the traditional flocculation culture medium under optimal ratio reached the highest flocculation efficiency. While the optimal ratio of anaerobic fermentation liquid with traditional flocculation culture medium is 1:1, the anaerobic fermentation liquid of the 100d compound with the traditional flocculation culture medium under optimal ratio reached the highest flocculation efficiency, the flocculation efficiency is 92.45%, which higher than the traditional flocculation culture medium. The compound flocculation culture medium mixed with dry fermented liquid with tradiondal flocculation culture medium achieved excellent flocculation efficiency, the result attributed to two accounts: the complex components of anaerobic fermentation liquid offers the richer substrate species for the floc bacteria; the straw fractions have not been degraded exsited in the anaerobic fermentation liquid promote the process of the formation of flocs.