生物滴滤塔降解甲苯废气长期运行生物膜相特性研究

分析生物滴滤(BTF)长期运行过程生物量积累和分布规律、生物膜相特性变化,旨在探讨生物膜相特性变化与体系运行性能恶化的相关作用效应.结果表明,生物滴滤塔运行130 d后呈现出降解性能恶化的趋势,生物膜厚度和床层压降逐渐增加,且生物膜呈现出非均匀性分布,填料层上、下半段孔隙率已从启动期的85%和82%分别降低至65%和40%,表征生物膜平均代谢活性的AWCD值也明显降低,表明生物膜出现老化现象.生物膜胞外多聚物(EPS)总分泌量和蛋白质含量运行后期分别约为前期的2倍.蛋白质与多糖比值(PN/PS)逐渐从0.3增至0.95;生物膜表面疏水性与PN/PS值呈正相关,也相应从33%增为73%;EPS的平均分子量呈现减小的趋势;FTIR分析结果进一步表明,EPS的主要化学成分发生了变化.EPS分泌量和主要成分的变化可能是导致反应体系运行性能恶化的本质原因之一.上述结果可为从本质上解决生物滴滤体系长期运行面临的填料层堵塞和运行性能恶化等共性技术难题奠定基础.

Characteristics of Biofilm Phase During the Long-term Degradation of a Toluene-contaminated Gas Stream Using BTF

This study analyzes the accumulation and distribution of biomass and changes in properties of biofilm in a long-term biotrickling filter (BTF) system in order to investigate the correlation between the biofilm phase properties and the performance. After a long-term operation of 130 days, the BTF showed a deterioration in degradation performance and an increase in pressure drop with a gradual increase of biofilm thickness and uneven distribution of biomass. Meanwhile, the porosity of the upper and lower layers decreased from 85% and 82% in the start-up period to 65% and 40%, respectively, as a result of the excessive accumulation of biomass and its non-uniform distribution. The AWCD values showed a decreasing trend indicating that the biological activity decreased with the aging of biofilm in the long-term BTF. The contents of total extracellular polymeric substances (EPS) and protein in the later period were twice as much as those in the start-up period. The value of protein to polysaccharide (PN/PS) ratio increased from 0.3 to 0.95, and showed positive correlation with the surface hydrophobicity of the biofilm, which increased from 33% to 73% accordingly. The mean molecular weight of EPS decreased during the operation of BTF. The result of FTIR further showed that the main chemical composition of EPS changed in the long-term BTF accordingly, possibly resulting in the deterioration of performance in the long-term BTF. The above experimental results could be very helpful for reducing the clogging and performance deterioration in long-term BTF.