Phosphine Production And The Microbial Community Structure Analysis Under Controlling Reduction Potential Of Phosphorus

The wastewater treatment system is an important place for phosphorus sink and phosphine(PH3)release,which has been gradually recognized as a key role in participating in phosphorus cycling in natural enviroment.However,PH3 production in the traditional wastewater treatment system is less effective,and the formation mechanism of PH3 is still unclear.Phosphorus recovery by gasification in wastewater treatment still faces enormous challenges.Therefore,studies on the methods of improving PH3 production from wastewater treatment processes have important significance for the development of resource utilization of phosphorus in wastewater.In this study,we constructed a biocathode microbial electrolysis cell(MEC)based on mixture culture of pig manure and anaerobic sludge,and investigated the feasibility of promoting PH3 formation in synthetic wastewater treatment by MEC.In the meantime,different cathode potentials,phosphorus form(inorganic phosphorus(IP)and organic phosphorus(OP)),alkaline phosphatase activity(APA),dehydrogenase activity(DHA)and other running conditions(pH,HRT and temperature)on the effects on PH3 production had also been discussed.Illlumina MiSeq high-throughput sequencing was used to analyze the relationship between the change of microbial community and PH3 production.The main results of the present work are as follows:1.PH3 production was promoted in biocathode MEC under different potentials(125~500% higher than that of the control group),and the highest concentration of PH3(1103.10 ± 72.02 ng m-3)was obtained in IP-fed MEC operated at-0.6 V.However,this process was limited apparently by methanogens.Meanwhile,H2 levels was relatively low(<10%)and increased slightly accompanying PH3 formation.2.PH3 production in the IP-fed MEC was generally higher than that in OP-fed MEC,and exhibited similar change trends with APA and average current density.It reflected underlying response mechanisms between potential and PH3 production in MEC,and inorganic phosphorus is more likely to be an accessible source of PH3 formation.3.Extended the HRT could to some extent improve PH3 production,however,it is not conducive to the accumulation of PH3 when the HRT>4 d;The temperature range of mesophilic fermentation were favourable to the formation of PH3,and the optimum temperature is 35?;Neutral and acidic conditions were more conducive to the the formation of PH3,and high pH is easy to form phosphorus precipitation on the surface of zoogloea,which could affect the microbial activity and limit the production of PH3.4.Sequence analysis showed that the dominant bacterium group in MEC were Proteobacteria,followed by Bacteroidetes and Chloroflexi.The Betaproteobacteria and Deltaproteobacteria,belonging to Proteobacteria,increased apparently,which are responsible for the current generation.The known phosphate-reducing organisms(PROs)and phosphate-accumulating organisms(PAO),such as Clostridum and Dechloromonas,could also been riched in MEC.However,Kouleothrix,Gemmata and Thiothrix were inhibited apparently.And how the changes of the microorganism participated and controled the key step of PH3 production remains to be elucidated.