Cultivation Of Aerobic Granular Sludge For Degrading Nitrobenzene In SBR And Its Characteristics Studying

Nitrobenzene(NB)is the basic substance which is widely used for producing chemical raw material.For example,it is mainly applied in such industries as agricultural chemical,dyestuff,medicine,and explosive,all of which have a lot of organic pollutants(e.g.,nitrobenzene and aniline)in their industrial wastewater.Nitrobenzene is a kind of high toxic substances and weak mutagenicity.Long term exposure will do great harm to human bodies and other animals or plants.The American Environmental Department have already put it in the list of the pollutants which require prior control.Hence,to seek effective method of controlling the Nitrobenzene pollution is quite urgent.This dissertation has developed the research of granulation of degradation NB aerobic sludge and its characteristics,taking the sequencing batch reactor(SBR)as the platform and taking the nitrobenzene as the model organic compound.It has gained research results as follows:1.Enhance the biont selection pressure of SBR reactor through gradient(increase the load of target contaminant gradually and shorten the sludge settling time).Under the condition that take NB as the only carbon energy,the load is 1.4 kg·m-3·d-1,the aeration speed is 0.3m3·h-1,the sludge settling time is 5?10min and HRT is 17.2 h,the granulation phenomenon appears in aerobic sludge.the grain diameter of mature granule is mainly between 0.25?0.75mm,and the degradation rate of NB can reach 0.52 g·gVSS-1·d-1.The settle ability of aerobic granular sludge is excellent,and the biomass is larger than that of ordinary sludge obviously.The microorganism community in the granule is abundant and the bioactivity is also better than that of ordinary sludge.2.To use particle sludge gained by domestication to study the influence different situations have on reaction system degradation rate.And to control the immutability of other variables,change the single variable and stabilize them for two periods.After adding the simulated wasted water sample in intervals,Monitor and analyze data.The result shows that different concentrations of the influent have very little effection on the degradation rate of the COD and NB in the system(within the maximum load),about 0.5 g·gVSS-1·d-1,but the time for complete degradation was prolonged relatively.The optimum pH is 7.Higher or lower pH will both decline degradation rate.The degradation rate raises with the increasing of aeration rate(The biggest aeration rate is 0.4 m 3·h-1).The bigger the concentration of sludge is,the quicker the NB degradation rate will become,which doesn't affected apparently.External carbon source has no influence on the degradation rate of NB.3?After relevant researches on the degradation characteristics of the reactor,the reactor was controlled to operate continuously for 5 cycles under the optimal condition,and to measure the water pollution monitoring indexes(total N,NH3-N,total P,pH,DO,COD,etc).By analyzing of the total N data,we found TN concentration decreased when it sediments and settled,then set up the experiment by prolonging the standing time to monitor the index N.Then compared with normal temperature,the experiment done in the experiment reactor under low temperature(8?)show that the degradation time delayed about 4 hours.Because NB is a kind of substance with a relatively low carbon-nitrogen ratio,and the reactor takes NB as the only C source and N source.N in the reactor also has the function of accumulation,which makes the sludge system operate under the situation of low carbon-nitrogen ratio for a long time.Besides,it also has a very good handling result for some liquid waste with a low carbon-nitrogen ratio,such as the pressed and filtered filtrate of livestock and poultry's feces.The research results of this thesis have certain guiding significance for taming the granular sludge in SBR and disposing liquid waste with low carbon nitrogen ratio.