| Two different types of trickling filters were adopted to investigate H2S removalperformances by biological method. The vertical bio-trickling filter after starvationoperation could be re-started with bioaugmentation method. The optimaltechnological condition and H2S removal performance of immobilized beads havebeen conducted by adopting the dominant microfloras in the bio-trickling filter asbacteria source. Micro eco-structures in bio-trickling filters were tested using PCR-DGGE technology. Biodegradation dynamic model, which considered the cumulativeeffect of H2S in bio-trickling filter, has been constructed and verified.The overall start up period of the traditional vertical bio-trickling filter was only3days by adopting the "stimulate biofilm growth by high concentration of nutrientsand improve degradation ability by competition" method. The vertical bio-tricklingfilter could achieve high removal efficiency more than90%when the empty bedresident time was longer than15s, the optimal trickling rate was6L·h-1. In theprocess of elimination capacity test, the best volumetric elimination capacity was89.15g·(m3·h)-1, and the maximum value was135g·(m3·h)-1.Running parameters of grading bio-trickling filter in which gas and liquid werecontacted with a cross flow pattern. The immobilization period was still3days.Compared with the vertical one, the liquid trickling amount was lower, about3L·h-1.Elimination capacity of grading bio-trickling filter has been improved. The bestelimination capacity was171g·(m3·h)-1, and the maximum value was216g·(m3·h)-1.Pressure loss was not more than200Pa in the whole experimental period.The application of bioaugmentation to re-start up the vertical bio-trickling filterafter it was shut down for some days was conducted. Results showed that significantremoval performance was achieved: indigenous microorganisms and immobilizedmicroorganisms could exist in the same reactor; the removal efficiency was more than85%at starting stage. The best elimination capacity was improved from110g·(m3·h)-1to129g·(m3·h)-1, while the maximum elimination capacity increased up to170g·(m3·h)-1. Biofilm structures have not been changed when the ceramic pellets wereobserved by SEM.In the microorganisms' immobilization test, active carbon was chosen as additiveto improve immobilized beads' intensity. The sequences of factors influencingoptimum medium for immobilized beads production was obtained according toorthogonal experiments and the result was: microbe amount> sodium alginate>additive amount>CaCl2. The optimal preparation parameters was sodium alginate5%,CaCl22.5%, active carbon0.3%, and immobilized time12h. The optimal growth conditions of immobilized beads was S2-concentration4550mg·L-1, pH6, optimaltemperature5-30℃, rotation speed120r·min-1. Bio-trickling filter packed withimmobilized beads coud start up quickly, with removal efficiency more than90%.The optimal empty bed resident time was11s at inlet H2S concentration rangebetween50200mg·m3.Micro eco-structures in two bio-trickling filters were compared by PCR-DGGEtechnology. There were6same DGGE bands in the two reactors. The coexistencemicrobial species had different dominant position in their respective ecosystem. TheShannon-Weaver index of the vertical bio-trickling filter was2.12±0.08. That of thegrading bio-trickling filter was2.85±0.13. Microbial diversity of grading bio-trickling filter was higher than the vertical one.On the basis of the above data, biodegradation dynamic model was established,which considered the cumulative effect of H2S in bio-trickling filter. The microscopicmodel could predict H2S concentration in the biofilm. For the biodegradation processwas controlled by biochemical reaction, macroscopic model was established on thebasis of Michaelis-Menten equation. The model had a good relevance withexperimental data after modified.
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