The Pretreatment Of Rear Earth Wastewater By Uasb Reactor And The Identification Of Special Bacteria

Rare earth industry in Baotou ranks first in our country, but nitrogen of rare earth wastewater exceeded nearly 200 times of grade two set by the state.In order not to pollute drinking water and the water environment, rare earth wastewater was dealed with by biological that low cost and no secondary pollution. A new way was provided that the study of special bacteria for treatment high concentration nitrogen wastewater.This paper was about the serious problem of rare earth wastewater polluion, special bacterium was studied and rear earth wastewater was pretreated by UASB reactor.Temperature,pH,HRT,hardness and C/N for the influence of the removal of NH4~+-N and COD, which were studied by single factor experiments of this pretreatment,the best experiment conditions within reactor were that : temperature was 20-30℃, pH=7.0-8.0,C/N was 2-5.5,HRT was 10-12h,hardness the lower the better.The best experiment conditions were controlled in the UASB reactor, concentration of NH4~+-N in wastewater was increased gradually to 490mg/L, after operation of 65 days, the removal rate finally was able to reach 40%.During this period, Bacillus, Coccus and Inactive Protozoan were found first, then Coccus, Bacillus have increased dozens times, Protozoan were observed by acclimation, and a red bacterium was seen on the reactor wall. The feature and best experiment condition of special bacteria were further analyzed by beakers experiment, and was identified. Anaerobic stage, the best control conditions: concentration of inoculum was 15%, concentration of NH4~+-N in wastewater was 500-600mg/L, C/N was 3-5,temperature was 30-35℃,pH=8.0-8.5,HRT was 3-4h. The principal and subordinate factors affecting the bacterial growth were temperature>pH>HRT. This bacteria was light-sensitive bacteria, the removal rate of NH4~+-N decressed about 25%-40%. Aerobic stage, this bacterium was completely inhibited by DO, but this inhibition effect was reversible, This bacterium was coccus or irregular coccus, no flagella, there features were very similar to the characteristics and photos of anaerobic ammonia oxidizing bacteria on related data, therefore, this bacterium that was preliminary identified was anaerobic ammonia oxidizing bacteria.