The Research On The Start-up Of Anammox Based On Inactivation And Electromagnetic Strategy

The anaerobic ammonia oxidation(anammox)process is a new nitrogen removal process based on anammox bacteria which could oxidize NH4-N to N2 using NO2-N as an electron acceptor.The process does not need the addition of carbon source and aeration,does not produce greenhouse gas,and has a simple reaction process,so it has a wide range of application prospects.However,due to anammox bacteria generally have a long doubling cycle,and the requirements of temperature,dissolved oxygen,pH,and other environmental conditions are demanding,the application of anammox technology cannot be rapidly developed for a long time.The concept of resource recycling of wastewater treatment is increasingly valued.Anammox process,as a new generation of low-energy denitrification process,has been regarded as an important development direction for wastewater treatment since its discovery in the sewage treatment process for the first time in the 1990s.Researchers in the field of water treatment have conducted in-depth and extensive discussions from the basic theory and practical applications of anammox.In view of the long doubling time of anammox bacteria,some studies have been conducted to optimize the growth and metabolism environment of microorganisms using physical means such as electric and magnetic fields to accelerate the enrichment of anammox bacteria and reduce process start-up time,another researches have been conducted to optimize the competition environment of anammox by reducing the activity of coexisting microorganisms in the inoculated sludge to accelerate the enrichment of anammox bacteria.This study continues the research ideas of above two aspects and intends to conduct anammox process enhancement researches by reducing the activity of coexisting microorganisms and promoting the activity of anammox bacteria.On the one hand,Starting up anammox process using anaerobic granular sludge inactivated by high-pressure steam as inoculum sludge,on the other hand,enhancing the start-up of anammox process by irradiation of specific electromagnetic waves(EMFs).The main research results are as follows.(1)Continuous experiments indicated that reactor with inactivated sludge(R2)could shorten the start-up period from 72 days to 63 days.The first 50 days anammox population specific growth rates(?)of R1(the control)and R2 were determined to be 0.014 d-1 and 0.045 d-1 using q-PCR assays.Analysis of coefficient of variations of nitrogen removal performance during days 96-225 indicated that R2 was more stable than R1.The Illumina MiSeq sequencing showed that autoclaving could decrease microbial diversity of sludge and enhance the abundance of anammox bacteria.Furthermore,PICRUSt community functions forecast and c-di-GMP measure illuminated the result of higher stability in R2.(2)The EMFs can increase the activity of anammox bacteria in a short term.The results of batch test showed that the spectific anammox activity(SAA)was increased by 76%with impact of the EMFs and the anammox bacteria was directly effected by EMFs rather than effected by irradiated water.(3)Long-term effect of the EMFs on anammox was studied in upflow column reactors.The results demonstrated that the positive effect of EMFs on anammox process could be testified through shorter start-time(37%saved),hihger nitrogen removal efficiency(17.7%enhanced)and higher anammox bacteria growth rate.The result of high-throughput test showed that the existence of EMFs did not increase the abundance of anammox bacteria family,while an obvious niche partitioning phenomenon of anammox bacteria was detected under genus level.The community functions evaluation based on KEGG and c-di-GMP measure illuminated that the EMFs could supply a better environment for anammox bacteria.