Study On Nitrification Mechanism Of Ferric Enzymatic Activated Sludge Based On The Analysis Of Energy Metabolism

During the past years, as the phenomenon of water pollution and eutrophication becomeworse, biological nitrogen and phosphorus removal technology obtain important position inwaste water treatment. As the technology use activated sludge to treat waste water, existingthe problems that bad operating stability, low removal efficiency of nitrogen and phosphorusand nitration under low temperature condition become a challenge. So the development ofeconomic and efficient wastewater biological denitrification and phosphorus removaltechnology has important practical significance for solving the existing problems of sewagetreatment technology and fundamentally solving the problem of eutrophication.The technology of composite ferric enzyme enhanced activated sludge was proposed byUrban Aqua Environmental Pollution Control Research Team Qingdao TechnologicalUniversity. It is a new and high efficiency way to treat waste water as it solving the problemsfundamentally which conventional activated sludge faced. Iron ion was added to the treatmentsystem to affect the biochemical reaction and energy metabolism process in microorganism.As the role that Iron ion played in the progress of electron transport and enzymatic reactionprocess is enhanced, the microbial activity is promoted and so is the nitrogen and phosphorusremoval efficiency.The sequencing batch reactor was chosen as research object in this study. Under differentwater quality, research was made on activated sludge with different content of iron. Thedifference between activated sludge with different iron content and conventional activatedsludge was investigated at12℃，20℃respectively, which contained the efficiency of nitrogenand phosphorus removal, microbial activity, enzymatic reaction, removal rate of CODcr, andelectron transfer system activity. Focused research was made on the recovery capability ofsystems after been disrupted. Maximum specific growth rate and nitrifying activity ofnitrobacteria were investigated to make sure the nitrification mechanism of composite ferricenzyme enhanced activated sludge.The results showed that:（1）On the experimental study of artificial water distribution, the composite ferricenzyme enhanced activated sludge performed better in nitrogen and phosphorus removalefficiency and CODcr removal rate. What’s more, the best result was reached when the ironmass fraction was5%.When the iron content more than5%, promoting effect will decline.Comparing with conventional activated sludge, the dehydrogenase activity of the activated sludge with iron mass fraction5%was respectively increased by33.2%,31.2%,34.1%,17.3%, the level of ATP, electron transport system and nitrifying activity of nitrobacteria atnormal temperature and40.1%,33.5%,44.3%,35.2%respectively at low temperature.（2）Systems recovery research: the composite ferric enzyme enhanced activated sludgerecovered faster than conventional activated sludge systems and the system with iron massfraction5%done better. In the first day of recovery phase, the nitrogen and phosphorusremoval rate was increased by15.2%,18.7%respectively, dehydrogenase activity in theaerobic phase by73.3%, and electron transport system activity by41.8%. In recovery phase,nitrogen and phosphorus removal rate was increased by9.4%、11.4%respectivelly, thedehydrogenase activity in the aerobic phase and electron transport system activity increasedby45.0%and37.0%. The activated sludge with iron mass fraction1%,3%,7%worked wellthan conventional activated sludge but not activated sludge with iron mass fraction5%. Withthe effect of storage condition, microorganism in anaerobic and anoxic phase had shorterrecovery phase than in aerobic phase. It could denitrified as usual after5days and the abilityto remove phosphorus recovered3days later, so we can came the conclusion that foractivated sludge, anaerobic and low temperature have more impact on Its denitrificationability than phosphorus removal ability.（3）On the experimental study of domestic sewage, the composite ferric enzymeenhanced activated sludge system in denitrification and phosphorus removal efficiency andremoval rate of CODCrwere superior to the common activated sludge system under thecondition of normal temperature and low temperature, and when iron content was5%, theeffect was the most best. The removal rate of phosphate,ammonia nitrogen and CODCrof ironcontent5%composite ferric enzyme enhanced activated sludge system were increased by7.3%and10.9%,7.3%and13.4%,6.5%and8.4%, and its dehydrogenase activity, ATP leveland electron transport system were increased by36.2%and37.2%,36.2%and37.6%,28.4%and29.8%than the ordinary activated sludge. Under the temperature of16℃,20℃,12℃and8℃, the maximum specific growth rate and ratio of activated sludge system nitrificationrate of the iron content of1%,3%,5%,7%composite ferric enzyme enhanced activatedsludge system were higher than ordinary actived sludge. The maximum specific growth rateand specific nitrification rate of5%composite ferric enzyme enhanced activated sludge werethe largest when the temperature were16℃,20℃,12℃and8℃, and were respectivelyincreased by19.4%and11.6%、28.9%and12.0%、35.3%and17.5%、37.0%and38.2% compared with the conventional activated sludge.