| The technology of organic wastewater biological hydrogen for hydrogen-methaneproduction has advantages of high energy recovery, good stability and water resource. Ithas becoming an important way to slove the current energy demand and environmentalissues. The key of realized industrialization of technology on organic wastewaterbiological hydrogen-methane is how to improve the capacity of hydrogen-methaneproduction of system and to reduce production costs. ABR combines the theory oforganic wastewater by anaerobic fermentation with ideology for staged multi-phaseanaerobic treatment. It has a significant acvantage for biological hydrogen-methaneproduction. At present, the report on study of ABR for hydrogen-methane production isless. Study for the hydraulic characteristics and running performance of ABR, which isto obtain higher microbial holdings and energy recovery, is of great significance for thepromotion of hydrogen-methane production coupled process.In this paper, an improved ABR was used to explore the hydrogen-methaneproduction coupled process. The flow characteristics in ABR and the startupcharacteristics of hydrogen-methane production coupling process were investigated.Further study the impact of organic loading on hydrogen-methane production couplingprocess operating performance. In addition, the succession rule of microbial communityin each compartment of ABR has been preliminary studied through the methods ofmolecular biology.The hydrodynamic characteristics of ABR directly affect the biomass and thedegree of mixing of micro-organisms with the substrate, influencing the operationperformance of the reactor. Traditional ABR has the disadvantages of uneven waterdistribution and weaken sludge retention. It was improved by increasing the baffle andimproving water distribution area. FLUENT was used to analyze the flow field in ABRwith two-phase (sludge and wastewater) model. The results showed that backmixingwithin the reactor significantly enhanced and it got higher sludge retention capacity tomaintain high microbial holdings, when the rising velocity was0.12m/h. In0.13～0.20m range of the reactor, the sludge phase volume fraction in improved ABR washigher than in tranditional ABR. In0.25～0.29m, the sludge phase volume fraction ofimproved ABR was significantly lower than traditional ABR. The other within the twotype ABR were of basic the same.The improved ABR startup strategy was explored with molasses wastewater as thesubstrate. Hydrogen phase was inoculated with aeration pretreatment of sludge. Methane phase inoculated with anaerobic sludge. While HRT was28h,(35±1)℃,volume organic loading (VOL) from1.71kg COD/(m~3·d) increased to5.13kgCOD/(m~3·d), the hydrogen-methane production coupled process complete the activationwithin85d. COD removal efficiency was around77.6%. Gas yield was134.74L/d. Inhydrogen production phase, COD removal rate was about24%, effluent pH of4.7to5.0,acetic acid and bulyric acid in the liquid end production were521.52mg/L and517.34mg/L, which were65.72%of the total. It was bulyric acid type fermentation. Gasproduction average was0.449m~3/(m~3·d),the hydrogen content was of34.6%. Inmethane phase, COD removal efficiency stabilized at50%to55%, the effluent pH wasabout7.0and the average gas production was2.4m~3/(m~3·d), including58.3%methane.Further study of operating characteristics of hydrogen-methane production coupledprocess was conducted. Study found that when the influent COD concentration was of7000to10000mg/L and the HRT shorted from32h to20h, the COD removal rate wasstabilized at81%to85%. The effluent pH and VFAs changed little. At the condition of7000mg/L influent concentration and24h HRT, the sludge concentration reached themaximum and the entire energy recovery got the best. The energy recovery rate ofhydrogen production phase, methane production phase and the total were3.24%,76.9%and80.14%.PCR-DGGE was used to analyze microbial species within the system andmicrobial community structure changes along the journey. The results showed that ererycompartment formed its own anvantages microbe population. Pseudomonas sp.Clostridium and butyricum strain were the advantages microbe population. Alphaproteobacterium, Uncultured bacterium clone, Uncultured Nitratireductor, andRoseomonas sp. were the advantages microbe population. |
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