Denitrification Performance Of Aerobic Denitrifier Using Organic Matter Of Different Type And Molecular Weight As Carbon Source:Effects And Mechanisms

Nitrogen pollution has been a common problem faced by lots of drinking water reservoirs,excessive nitrogen will expose water bodies to the risk of eutrophication.Algae in the water bodies will grow excessively,resulting in a significant increase in water smell and organic matter,destroying the ecological health of the water body,and increasing the difficulty and cost of subsequent water treatment.However,the traditional denitrification will be inhibited in the presence of oxygen,and the aerobic denitrification biological technology can use oxygen and nitrate as electron acceptors,providing new ideas for the removal of nitrogen from natural water bodies.In drinking water reservoirs,the pollutants of sediment will be released in anoxic conditions,leading to repeated deterioration of water quality,and the growth of microorganism will be inhibited due to the lack of N or carbon source.Therefore,the application of aerobic denitrification technology in oligotrophic drinking water reservoirs should be a critical technology to solve the nitrogen pollution of oligotrophic reservoirs.Regarding nitrogen pollution control in drinking water reservoirs as the breakthrough point,and combining the actual organic matter derived from the reservoir,this paper aims to investigate(1)the nitrogen removal performance and nitrogen/carbon balance of four strain of oligotrophic aerobic denitrifiers;(2)the effects of different molecular weight(MW)of natural organic matter or algae organic matter on nitrogen removal ability of aerobic denitrifier;(3)the effects of water sources or organic matter from sediments on nitrogen removal characteristic of aerobic denitrifier.The main conclusions were shown as follows:(1)The nitrogen removal performance and nitrogen/carbon balance of four strain of oligotrophic aerobic denitrifiers were anglyzed.The results showed that the four strain of oligotrophic aerobic denitrifiers of WGX-9,ZHF3,ZMF5 and ZMF7 were identified as: Acinetobacter junii.,Acinetobacter junii.,Acinetobacter junii.,and Sphingomonas sp..The four strains of oligotrophic aerobic denitrifiers can efficiently remove the ammonium,nitrate,and nitrite,to obtain higher removal efficiency.The four aerobic denitrifiers showed effective nitrogen removal efficiency when cultural conditions were in low C/N,low temperature,p H of 5-11,and different oxygen content.The eco-recombination strategy was used to construct a denitrifying functional bacteria groups JQ-4(WGX-9,ZHF3,and ZMF5)that has a good denitrification performance in an oligotrophic environment,with nitrate removal efficiency of 27.50% and TOC removal efficiency of 36.40%).The denitrification pathways and electron transfer pathways of the strains during denitrification indicated that the type of carbon source can change the denitrification pathways of the strains and regulate the transfer of electrons to the nitrate respiratory chain.(2)The effects of different molecular weight(MW)of natural organic matter or algae organic matter on nitrogen removal ability of aerobic denitrifier were clarified.The results showed that the nitrogen removal performance was relatively higher when the extracellular algal organic matter(EOM)be used as the carbon source,followed by the intracellular algal organic matter(IOM),whereas when the nature organic matter(NOM),the nitrogen removal performance was relatively lower.Their MW distributions followed the order: NOM > IOM > EOM.Compared with the higher MW organic matter,the lower MW organic matter can promote the nitrogen removal of strain WGX-9.This might dut to that the lower MW organic matter can promote the growth of strain WGX-9,facilite the utilization performance of organic matter,and contain less aromatic substances and more tryptophan/tyrosine proteins that are easily used by microorganisms.(3)The effects of source water and organic matter in sediments as carbon source on nitrogen removal ability of aerobic denitrifier were studied.The study showed that the MW distribution of water source was relatively homogeneous,and the relative MW was lower,and it changed less at different periods.The nitrogen and carbon removal performance of strain WGX-9 with the actual high-density algae water as the carbon source was higher than that with actual low-density algae water as the carbon source.The distribution of organic matter in sediments was changed less at different periods.The findings can elucidate than the nitrogen removal performance(39.58%?59.03%)of the strain WGX-9 with the organic matter in sediment as the carbon source was relatively higher than that with the water source as the carbon source.The results indicated than the aerobic denitrification performance of the strain WGX-9 can be significantly promoted when the organic matter in sediments as a carbon source,compared with EOM,IOM,NOM,and actual water of drinking water reservoir,which shown better nitrate removal performance.