| The organic load of tannery wastewater is high and fluctuating,while it is rich in various characteristic pollutants such as nitrogen,sulfur,chromium and neutral salt,etc.Its water treatment process is long with specificly large sludge volume,high anaerobic toxicity and aerobic energy consumption,which leads to a normal fact that the effluent is unstable in meeting the standards for refractory dissolved organic matter（DOM）,total nitrogen（TN）and total Cr（Ⅲ）.For a long time,the engineering and technical problems caused by mutual stress inhibition of different microbial functional populations in the process of decarbonization,denitrification and desulfurization of wastewater biochemical systems have not been solved,while the biological toxicity of the heavy metal Cr（Ⅲ）has aggravated the complexity of the water treatment process.Bioenhanced collaborative treatment technology based on multi target pollutants control and its functional microbial community regulation mechanism deserve in-depth research.Based on the recycling and emission reduction of sulphur-containing wastewater from tannery,this thesis constructs a "biochemical conditioning-upflow anaerobic sludge bed（UASB）-anaerobic oxic（AO）" whole process bioaugmentation model,and systematically investigates the bioreinforced synergistic organic matter mineralization,sulfide conversion,nitrification denitrification,acid and methanogenic activity,chromium adsorption by extracellular polymers（EPS）,and the succession pattern of functional microbial bacteria.The main research contents and conclusions are as follows:（1）Aiming at the problems of high organic nitrogen and high biological toxicity of sulfur-containing wastewater,the change trend of components such as sulfide（S2-）,calcium ion（Ca2+）,total organic carbon（TOC）,and total suspended solids（TSS）during the 30-day cycle of sulfur-containing wastewater was tracked.It was found that the disturbance of significant increases in soluble protein and TOC in the circulating liquid on the separation of effective components in the recycling process was the main reason restricting the cycle sustainability.The objective of effective circulation emission reduction and the treatment method of circulation liquid based on S2-,Ca2+,TSS,soluble TOC are put forward.（2）The interactions of multiple pollutants in a biochemically functioning conditioning tank were investigated,revealing that sulfide is the main obstacle factor causing the toxicity of nitrifying microorganisms,and suggesting that controlling sulfide concentration to achieve its adsorption and in situ reduction in activated sludge,together with gas blow-off,can significantly reduce biological toxicity,while rapid microbial EPS adsorption of Cr（Ⅲ）and biomineralization of chromium containing organic complexes can achieve effective destabilization and removal of chromium.16S rDNA High-throughput sequencing analysis showed that microbial populations in aerobic activated sludge were elevated by 13.9%and biodiversity by about 30%with the presence of highly loaded organic wastewater,and the expression of genes related to trans-cellular transport function was significantly enhanced in other functional groups,except for nitrifier whose activity was reduced due to their sensitivity.（3）In response to the problems of organic carbon metabolism and sulfide inhibition of nitrifying microorganisms in the biochemical process of high organic load,the community succession and metabolic function decay of functional bacterial agents in different biochemical units were explored based on the screening,activation and in situ dosing of different biofortification functional agents to analyze and evaluate the treatment effect after biofortification was carried out.The research results shoed that the chemical oxygen demand（CODCr）and ammonia nitrogen（NH3-N）could be synergistically removed by using a composite bacterial agent for enhancement.To improve the efficiency of nitrogen removal significantly and rapidly convert sulfides into sulfate radicals through reinforcing the exogenous bacterial rich in Pediococcus,Lactobacillus,and Bacillus,it is possible to activate the genera Thauera,Thiobacillus,and Xanthomonadales into dominant bacterial groups.The results of carbon metabolic fingerprint analysis showed that the metabolic capacity of amino acid carbon sources was significantly enhanced in the bioaugmented biochemical conditioning tank（O1）,the metabolic capacity of sugar carbon sources,organic acid carbon sources and amino acid carbon sources was significantly enhanced in the secondary anaerobic/aerobic（A2/02）,and the metabolic activity of microorganisms in activated sludge was increased.（4）The pilot study of the internal circulation anaerobic reactor（IC reactor）operation found that the anaerobic treatment process of tannery wastewater could be divided into four stages:the first stage of adaptation,the second stage of rapid increase in volatile fatty acids（VFA）with organic load（OLR）（CODCr removal rate reaching a stable period）,and the third stage of stable increase in VFA with OLR（CODCr removal rate unstable period）.The accumulation period of VFA（fluctuation and decline period of CODCr removal rate）during the fourth stage as OLR increases.It was shown that the key reason for the low methane production efficiency of the anaerobic process of tannery wastewater and the inability of the system to operate for a long period of time is the frequent,multi-mechanism fluctuations of many factors such as sulfur,calcium,organic matter type,and feed water pH in the hydrolysis acidification and hydrogen production methane production segments.（5）The effects of anaerobic granular sludge on the adsorption of S2-,the production of hydrogen sulfide（H2S）and the inhibition of methanogenic activity by Ca2+ were investigated by comparing the effects of IC operation under different sulfur-containing conditions.The relationships between the changes of VFA,alkalinity（ALK）and pH and the removal efficiency of OLR,NH3-N and methane yield were traced,and the changes of granular sludge traits and microbial ecological communities during the start-up and operation of the IC reactor were followed by 16S rDNA high-throughput sequencing.The results showed that the combined wastewater with and without sulfur showed completely different acidification characteristics and acid accumulation effects during the anaerobic process due to the reason that Ca2+ in sulfur-containing combined wastewater has a good acidification buffering effect.In the start-up and stable stage of anaerobic reactor,the CODcr/S was higher than 1.67,the sulfate reducing bacteria could not compete out methanogens,and the effect of S2’ on the operation of anaerobic reactor was minor.Compared with the original sludge,the proportion of Georgenia and Ruminococcus1 increased,which could promote organic hydrolysis and VAF production.The predominant archaea population of sulfur-containing wastewater were methane Microbacteria,indicating that methane production by acetic acid was the main way in this senario.Collectively,this study establishes a multi-pollutant whole-process bioenhanced synergistic treatment model for the engineering and technical challenges caused by high load,high fluctuation,and inhibition of microbial metabolic stress of multi-pollutants such as carbon,nitrogen,sulfur and chromium in integrated tannery wastewater.The sulfur-containing wastewater is recycled and directly fed into the integrated tannery wastewater treatment,and the acute toxic effects of sulfide and chromium on the microbial community in the activated sludge can be mitigated by bioaugmentation of exogenous bacterial agents,while S2-and Cr（Ⅲ）can be rapidly enriched by sludge adsorption,and the synergistic removal of CODcr,NH3-N,sulfur and total Cr can be achieved by the efficient oxidation and degradation of various types of desulfurization,decarbonization and denitrogenation functional flora. |
