Design Of New-style Biofilm Reactor And Study On Removal Of Nitrogen In Wastewater

This thesis focuses on the design of new-style biofilm reactor-rice-husk biofilm reactor and studied its characteristic of nitrogen removal in waste water treatment.The nitrifying and denitrifying bacteria biomembrane was cultivated using rice husk as a carrier. The culture conditions of the biomembrane were investigated and its microbiological inspection was also made. The results showed that the rice-husk biomembrane of denitrifying bacteria has advantage of resisting capacity of acid or alkali and can tolerate low temperature. In culture process,the nitrate degradation rate is quickened with the increase of nitrate initial concentration at the range of 0-100mg/L. The optimum culture range of pH is 6.5-8.0 .The optimum pH and preferred temperature are 7 30. The optimum culture conditions of nitrifying bacteria are pH 7.0-8.5,DO 2-4mg/L,using 2000mg/L NaHCO3 and 2000mg/L glucose as a carbon source under room temperature. In rice-husk biomembrane,the nitrifying bacteria is mainly G" coccus or long bacillus,but the denitrifying bacteria is mainly G" short bacillus.In addition,through the experiment of wastewater containing nitrogen,the characteristic of nitrogen removal of rice-husk biofilm reactor was studied. It showed that the reactor can remove nitrogen efficiently and quickly. Simultaneous nitrification and denitrification can be realized in it. The reactor can tolerate changes of environmental factors. It operate easily and its cost is cheaper than that of other treatment methods. The removal rates of ammonia nitrogen and nitrate nitrogen are 1.7andl.9 times as fast as that of activated sludge process under the equal conditions. Under the influent concentration of NH4+-N NO3--N and NO2--N are 75.9mg/L96mg/L and 45mg/L,the effluent concentration of NH4+-N NO3--N NO2--N are 11.8mg/L,8.7mg/L,1.7mg/L and their removal rate are 84.5% 90.9% 96.2%,respectively. The removal rate of COD is 86.6%. In experiment of cooling waste water of diesel locomotive,the removal rate of NO2--N NO3--N COD are 94.1%,92.1% 66.2%,respectively. This method provides a new way for the improvement of the removal rate of nitrogen in wastewater treatment.