The Inhibition And Control Stratega Of Copper(Ⅱ)and Oxytetracvcline On Anammox Performance

Anaerobic ammonium oxidation(anammox)process has a broad application prospect in the field of biological nitrogen removal due to its advantages of higher nitrogen removal efficiency and energy-saving characteristics.However,the heavy metals and antibiotics contained in the real wastewater,e.g.livestock and poultry breeding wastewater,inevitably inhibited the activity of the functional bacteria and impaired the operation performance of anammox process.Therefore,the inhibitory impact of the heavy metal copper(Ⅱ)and oxytetracycline(OTC)on the anammox performance was explored,and the inhibition and recovery mechanism was revealled by analyzing the response of variation of microbial community,key functional genes and antibiotics resistance gene(ARGs).During the performance recovery,the self-recovery mechanism and the bio-augmentation mechanism of bio-augmentation modes on anammox process suffering OTC inhibition were assessed.On this basis,the secondary stress characteristics of copper(Ⅱ)on the anammox process after acclimatization of OTC,and the inhibition and recovery mechanism of copper(Ⅱ)inhibition were further studied.The main results of this experiment are presented as follows:1)The inhibition of Cu(Ⅱ)and OTC on anammox performance with its self-recovery process was studied.The individual and combined impacts of Cu(Ⅱ)and OTC on anammox performance,microbial flora,functional genes and ARGs were investigated.Experimental results showed that the anammox performance and the activity of Ca.Kuenenia were inhibited by 1.0 mg L-1 OTC,Cu(Ⅱ)and OTC +Cu(Ⅱ).The inhibited performance could be recovered by self-regulation with the recovery time of respectively for 25,3 and 3 d.The abundance of nirS was significantly increased at 2.0 mg L-1 Cu(Ⅱ)and OTC+Cu(Ⅱ).In the tested reactors,Xanthomonadaceae was found as the second dominant families.This fact suggested that the potential resistant species were progressively induced after Cu(Ⅱ)inhibition.The effect of efflux pump genes were one of the resistance mechanism of anammox bacteria to the Cu(Ⅱ)inhibition.2)The remission of OTC inhibition on anammox process by different bio-augmentation modes was explored.The feasibility of two bio-augmentation modes to remit the inhibited anammox performance was studied by analyzing the responses of anammox performance,microbiota flora distribution,anammox activity,functional genes and ARGs.Experimental results showed that bio-augmentation was in favour of recovery of anammox performance after OTC inhibition,and bio-augmentation-exchange mode was superior to that of bio-augmentation-addition mode.Ca.Kuenenia is the potential antibiotic resistance specie,but the increasing of Ca.Kuenenia abundance was not the key factors for the recovery of anammox performance.Complex interrelationships of metabolic activity,heme c and mRNA level of functional genes were found in the whole inhibition and recovery process.Bio-augmentation regulates the changes in the structure and content of extracellular polymeric substance(EPS),enabling it to construct the defense mechanism of anammox mixture against OTC stress.And the key of bio-augmentation lie in the selection of bio-augmentation bacterial sources and the appropriate bio-augmentation mode.3)The secondary stress of copper(Ⅱ)on the anammox process after acclimatization of OTC was revealed.The secondary stress characteristics of Cu(Ⅱ)on anammox performance was studied by the analysis of response of anammox performance,microbiota flora distribution,anammox activity,functional genes and ARGs.Experimental results showed that the suppressed anammox performance could be recovery from Cu(Ⅱ)inhibition.The inhibition mode of gradually increasing Cu(Ⅲ)from 0.1 to 2.0 mg L-1 is more beneficial for the improvement of anammox performance under Cu(Ⅱ)inhibition comparing with that of higher level of Cu(Ⅱ)(1.0 and 2.0 mg L-1 Cu(Ⅱ)with inhibition time lasting 60 d each).The dominant genus Ca.Kuenenia and Ca.Anammoxoglobus was succession(from 0.09%increased to 36%)in anammox process under Cu(Ⅱ)stress.For the resistance of Cu(Ⅱ)stress,the abundance of nirS was significant increased in anammox systems.The recovery mechanism of anammox suffering Cu(Ⅱ)inhibition was the induce of the Cu(Ⅱ)resistant speciess and enrichment of sludge resistomes.