| This thesis is done on the basics of study results that had been gained both at home and abroad, to get more new study results and technical references for drinking water de-nitrification. The ion exchange membrane bioreactor is applied in removing nitrate from drinking water. The seed bacterial sludge was got from WWTP Qingdao before anaerobic digestion, and cultured under the experimental environment before starting IEMBR operation in the lab. By setting different technical parameters and operation conditions, this thesis studies the mechanism of the ion exchange membrane bioreactor for removing nitrate from drinking water and the treating effects. The following results have been obtained in this research:Two ion exchange membrane bioreactors with different sectional shape are used to optimize the effects of influent nitrate concentration at the same operation conditions. The study finds that with nitrate inflow concentration grows from 47mg/L to 193 mg/L, the nitrate outflow concentration is among 0.2~47.4mg/L and 0.1~71.0mg/L respectively, with the highest removing efficient of 99.84% and the lowest one of 55.36%. But the net amount of nitrate removed increase along with the growing of inflow nitrate concentration, and this amount reaches 8.56 g NO3-/(m2·d) and 9.24g NO3-/(m2·d) respectively when the two settings end operation after 81days. The de-nitrification rate fluctuates with the change of biomass and their activities, but the reactors represent abilities to endure input nitrate concentration strike. The pH values both in the water and bio compartments are steady, the conductivities in outflow grow along with the rising of nitrate inflow concentrations, while the ones in bio-compartment decrease. And the figure of the IEMBR section has no obvious impact on the nitrate removal effects.Study through adjusting the driving factor value proves that the nitrate transport amount shows direct proportion to the driving factor, but it does not give remarkably change under the conditions set in this study with the driving factor range from 0.626 to 0.993. With the shortening of hydraulic retention time in the water compartment, the nitrate concentration outflow increases obviously, and the removal rate decreases, but the nitrate transport amount through the anion exchange membrane increases instead of decreasing when the hydraulic retention time (HRT) decreases, according to which we can change the amount of water treated without exceeding the recommended water qualities. In the trials on driving factor and hydraulic retention time, no relation between the conditions changed and de-nitrification rate but the intimate relation between the de-nitrification rate and activity of microbe as well as the biomass was observed.By the scanning electron microscope technique the anaerobic de-nitrification microbes are observed and the results show that there are many kinds of microbes in the seeding sludge and the microbe mixture in bio-compartment, such as bacillus, coccus, filamentous fungus, streptococcus and vibrio. The process of microbe community change among the operation is obviously observed, which is a relatively complicated and immense process indicating that at different phrases there are different microbes communities for de-nitrification. The PCR-DGGE study on microbe sample in the 1#IEMBR reflects the diversity in the IEMBR bio compartment is quite good, and the lane comparison etc. shows that there happened a huge change in the system. From the phylogenetic tree the complexity can be known for the microbes at different time derives from the same strain, which also proved by the comparability.
|
PDF Full Text Request