The Study Of The Effect Of Salinity And Megatic Field On Anammox-related Processes

With the advanced technology and the rapid development of industries,more and more nitrogen compounds were discharged into the environment,causing a series of problems.Accourding to the Environmental Quality Bulletin of China 2016,the nitrogen pollution in Chinese rivers and groundwater is very serious,which threats the drinking water safety and should be solved quickly.Anammox is a novel process,and its realted processes have a bright future compared with traditional processes due to their many advantages such as the short process flow,low sludge yield and N2O release,a little oxygen and external carbon supply and low cost,which deserves more investigation.Nitrite is absent from ammonia-rich wastewaters,as the electronic acceptor for anammox process,which hinderes the anammox process for the treatment of wastewaters.Simultaneous partial nitrification and anammox process could solve this problem by producing nitrite for anammox via limited aeration.The compositions of wastewaters are complex,especially for the wastewaters from seafoods processing plants,tanneries and textile mills.These wastewaters not only contains ammonium but also comprises salinity,which has a potential inhibition on organisms.From now on,no information about the effect of high salinity and hypersaline wastewater on SNAP process is found and related work is worthy to progress.It is worthy to note that in SNAP process,nitrate(about 11%)is formed and accumulates gradually in effluent,which needs further treatments to reach the standards for nitrogen discharge to the environment.Simultaneous partial nitrification-anammox and denitrification process(SNAD)could solve this problem.In the SNAD process,the residual nitrate can be reduced to nitrogen gas via denitrification and the consumed ammonium can be wholly transformed into nitrogen gas in theory.Many parameters such as the concentrations of organic matters,the dissolved oxygen and aeration could impact the stability and nitrogen removal performance of SNAD process.However,there is no information of the effect of magnetic field on SNAD process,which deserves further investigation.The main research results are as follows:(1)Low-middle salinity had a little effect on SNAP process.The salinity(0.5%-2.0%)had slight inhibition on AOB while severe inhibition on NOB,resulting to a lower ammonium removal efficiency and equally TN removal efficiency.(2)High salinity(3.0%)had a big influence on SNAP process.While the inhibition of salinity(3.0%)on anammox was reversible through long time training.The inhibition of salinity on AOB could be relieved and the activity of AOB even be enhanced by the elevated aeration,which was different from NOB.And better ammonium and TN removal efficiencies could be attained via the elevated aeration under high salinity.(3)Hypersalinity(5.0%)also had a big influence on SNAP process.Both the activities of AOB and anammox were inhibited under hypersalinity and the SNAP process could not be operated stablely.(4)The stratified community structure in MBR contributed to protect the anammox and denitrifiers from the suffering of oxygen,which was in favour of the stable state of SNAD process.(5)The magnetic field(3.5 mT)could destroy the stratified community structure in MBR by stimulating the growth of NOB and heterotrophic anaerobes(genus Caldithrix).The rise of NOB could compete oxygen with AOB and compete nitrite with anammox,and the rise of genus Caldithrix could compete the limited organic carbon source with denitrifiers,resulting to the activities of AOB,anammox and denitrifiers were inhibited.(6)The magnetic field had a big influence on the microbial community of SNAD process.The dominated phylum was changed from previous Proteobacteria(25.6%)to Deferribacteres(10.7%),and all the abundance of functional genera were decreased significantly under the magnetic filed.