Research On Isolation And Application Of High-efficient Ammonia Nitrogen Removal Strains For Slow-flow Water Bodies

For slow-flow water bodies,the removal rate of ammonia nitrogen was low,in allusion to this issue,improved medium and modern microorganism separation techniqueswas used in this paper,and efficient removal of ammonia nitrogen strains were screened out.Inoculant was produced,the influence factors on removal rate of ammonia nitrogen for inoculants was analyzedthrough the orthogonal test.The effcet on inoculants applied to slow-flow water bodies was studied.Based on other scholars research,nitrosation bacteria concentration in culture medium was improved,ammonia nitrogen was controlled strictly,brown sugar was added in order to enrich the content of carbon and trace elements.Modern microorganism separation technology was used,26 strains was isolatedfrom sludge and sewagenearby sewage treatment plants and domestic waste treatment plants which had a higher removal rate of ammonia nitrogen.Among them,16 strains which using NH4+ as a nitrogen source and denoted byX1-X16,10 strains which usingNO₂^-as nitrogen source and denoted byX17-X26.The growth rate of all strains were researched,X1,X3,X4,X6,X17,X18,X19 were screened out because of their rapid growth.Their denitrification efficiency were analyzed and the results showed that when hybridstrains X1 and X18 were used,the removal rate of ammonia nitrogenwas highest,up to 90.0%.With brown sugar as the main raw material for fermentation,the hybrid strains was cultivated,inoculant was produced,and enterprise standards about inoculant was drafted.According to composition of slow-flow water bodies,initial concentration of ammonia nitrogen,pH,temperature,time,adding amount,dissolved oxygen were selected,5 levels were seted with every factor.The influence factors on removal rate of ammonia nitrogen for inoculants was analyzed in the process and the best condition was determined.Orthogonal test showed that the order of six factors was temperature,initial concentration of ammonia nitrogen,dissolved oxygen,bacterium agent content,pH,time.Whentemperature was25℃,initial concentration of ammonia nitrogen was 40 mg/L,dissolved oxygen was 2mg/L,bacterium agent content was 0.3%,pH was 8 and when time went to120 h,removal rate of ammonia nitrogen was highest,up to 94.7%.When the microbial agents was applied to black smelly slow-flow water bodies,the conclusion was obtained that the removal rate of ammonia nitrogen was82.6% and 85.0% after 120 h,the olfactory threshold of water samples significantly decreased;compared to removal rate of ammonia nitrogen that microbial agentsapplied tosynthetic wastewaterin laboratory,which declined by 13.0%.The main reason may be that The composition of actual slow-flow water bodies was relatively complicated,the growth of the microbial agents could be inhibited because of other microbial communities or harmful substances,so the effect was not ideal.Further research is being carried out to see the different natures between synthetic wastewaterin laboratory with black smelly slow-flow water bodies,to improve the removal rate of ammonia nitrogen.