| Anaerobic digestion of sludge not only decreases the mass/volume of sludge,but also increases the production of energy-rich biogas?sulfate in the waste stream causes the biogas contain H2 S.Biotrickling filter is an environmental-friendly and costeffective alternative for biogas treatment?This work aimed to investigate the interactive effects of empty bed retention time(EBRT),H2 S concentration(c)and oxygen to sulfide ratio(O/S)to remove H2 S in neutral biotrickling filter.Response surface methodology was employed that gave the H2 S removal relationship model.A model sensitivity analysis indicated the influence of the process variables on the bioreactor performance.Process optimisation was undertaken on a H2 S removal efficiency basis,while maintaining a target H2 S loading rate,depending on the desired quality for the biogas use and the technological requirements.This experiment also investigated the oxidation of biosulfur particle which accumulated in the packed bed.And the effects of sulfur accumulation on H2 S removal efficiency,sulfate produced ratio and porosity of packed bed.Halothiobacillus sp.?Stenotrophomonas sp.and Acidithiobacillus sp.predominance in the consortia of this condition was confirmed by high throughput sequencing.(1)When the S2-concentration exceeded 220 mg / L inhibited the sulfur-oxidizing bacteria.The mass transfer process is the rate-limiting step of the desulfurization process.When the oxygen and sulfur is relatively low,not only the proportion of sulfate generation is very low,but also affect the hydrogen sulfide removal efficiency.(2)The second order equation of hydrogen sulfide removal rate was obtained by fitting the data of response surface method: ER = 98.35-2.85 × CH2 S + 5.86 × EBRT +1.57×O/S + 2.07 × CH2S×EBRT +1.10× CH2 S ×O/S-1.32 × EBRT × O/S-5.00 × EBRT2.The sensitivity analysis of the model showed that the effect of EBRT on the removal rate was significantly higher than that of H2 S concentration and oxygen and sulfur ratio under the same load change.Reducing the EBRT ratio had a greater effect on the hydrogen sulfide treatment efficiency than increasing the hydrogen sulfide concentration.The reduction in EBRT has a greater impact on the desulfurization efficiency of gases with larger concentrations.Increasing the oxygen and sulfur ratio can effectively improve the efficiency of hydrogen sulfide treatment,and when H2 S concentration is bigger,EBRT shorter treatment efficiency is more obvious.The second-order equation of sulfate generation ratio was obtained by fitting the response surface test data:S-SO42-/S-H2Sremoved=30.61-0.039×CH2S +11.28×EBRT +19.36×O/S +6.78×EBRT×O/S +3.27×CH2S 2.Through the sensitivity analysis of the model,it was found that the ratio of oxygen to sulfur and EBRT had a great effect on the sulfate generation ratio.The interaction shows that the interaction between EBRT and oxygen / sulfur ratio is stronger,the greater the EBRT,the greater the effect of increasing the ratio of sulfur to sulfur on the sulfate generation ratio.(3)The experiment was carried out for the desulfurization process by double standard optimization,while maximizing the desulfurization efficiency,while maintaining a certain load.(4)High-throughput sequencing analysis showed that the dominant sulfuroxidizing bacteria were Halothiobacillus(59.3%),Stenotrophomonas(11.62%),Acidithiobacillus(8.49%)and Thiomonas(3.99%).(5)The accumulation of bio-sulfur element causes a slight decrease in the porosity of the packed bed and a decrease in the proportion of sulfate generation,which has little effect on the removal efficiency of hydrogen sulfide.When the H2 S gas was used to treat the H2 S gas(1000 ppmv EBRT = 150 s O2 / H2 S = 16),the S0 particle was produced at a rate of 15.69 mg S-S0 h-1 L-1,The maximum generation rate is 83.83 mg S-SO42-h-1 L-1.Indicating that after the stop air only through the pure air method can effectively alleviate the biological drip tank caused by sulfur element accumulation problem. |
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