| Biogas is a kind of high-quality clean energy. H2S is typically the main pollutant in biogas which imposes restrictions onwidely use of biogas. Dry desulfurization is very common in our country, but it hashigh cost, complicated operation and seconda-ry pollution. Biological methods are efficientand environmentally friendly, which can be promoted. Developing pilot-scale desulfurization reactor needs cost-effective, safe desulfurization process, so in this research, we study and optimizethe effect of process parameters on the desulfurization efficiency, screen high-performancestrain, designpilotdevice, in order to ensure high-efficiency and low-cost of the process, promote engineering application. Major reserch results are as follows:1) The performance of the layered chemical-biological biogas desulfurization processand operation conditionswere investigated.①The labbioreactor was started quickly.When sulfide inlet concentration was 490±5 mg/L, aeration rate was 40～50 L/min, HRTwas 3 h,sulfideremoval efficien-cy was over 99%, elimination capacitywas 4.24 kg S m-3d-1.②Effect of absorbing liquid alkali concentration and the amount of absorbing liquid spray on H2S removal rate by absorption tower was discovered. When H2S inlet concentration was 1500 ppm, absorbing liquid alkali concentration was 2 g/L, the amount of absorbing liquid spray was 27.8 L/h, H2S removal efficiency was 94.74%, while which was over 98% under the amount of absorbing liquid spray was 60.0 L/h and over 99% under the amount of absorbing liquid spray was 83.4 L/h③ The layered chemical-biological joint process operation parameters were determined. When packing material was raschig ring, the amount of absorbing liquid spray was 8.33 L/h,absorbing liquid alkali concentration was 5.5 g/L, H2S removal efficiency was 95% and H2S outlet concentration was 12 ppm.2) The time-dependent variation of microbial community of SOB sludge and the microbial features of the biogasdesulphurization process were also studied.① The dominant microorganism was identified. Thiobacillus, one of known SOB, dominated the resulting enrichment that was obtained by feeding sulfite sodium. The abundance of Thiobacillus was 75.04%in the enrichment, but only 0.038% in the inoculum.② SOB was isolated from the enrichment. Two strains of SOB (strain C and strain D) were isolated from the biogas desulfurizer. Strains C and D were identified as Pseudomonas and Agrobacterium, respectively, by 16S rRNA sequencing and morphological observation. Moreover, strain C was more versatile tocarbon sources than strain D.③The effects of pH and temperature on the SOB enrichment and the isolated strain C were investigated. The optimal conditions of strain C were pH 9.18 and 26.5℃, whereas those of the enrichment were pH 8.84 and 29.8℃. The highest activity of sulfide oxidation was 116.18 mgSL-1h-1 in the strain C, but 98.33mgSL-h-1 in the enrichment.3) A layered chemical-biological biogas desulfurizer was designed and run in a pilot plant.①The pilot device was started quickly. The performance decreased slightly when the biogas loading rate increased from 10m3/h to 45m3/h, but the removal rate of sulfide could be back to>90% quickly, maybe because of the fast growth of SOB.②The pilot device was run steadily. Under the steady conditions, the averageflow rate of the biogas was 30m3/h(ca.720m3/d) and the average content of sulfide was 1508ppm. About 70% sulfide was converted into elemental sulfur under those conditions.③The novel biogas desulphurization process was economical. The cost of the pilot device was 0.07 yuan·m-3 biogas or 4.4 yuan·(kg-S)-1, which was 70%-off than the traditional chemical desulfurization. |
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