一株架桥细菌的共凝集能力及强化生物膜反应器效能的研究

测定了架桥细菌Bacillus cereus G5与活性污泥中分离得到的13株土著细菌及3株复杂有机物降解菌配对组合后的共凝集能力和成膜能力.结果表明:凝集2 h和20 h时的共凝集率分别达到40%~70%和55%~80%;架桥细菌与其中15株细菌混合培养时的生物膜形成量高于单菌培养时的生物膜量.这表明在废水处理系统外G5能与土著菌和降解菌发生较强程度的共凝集,并可促进多数菌株生物膜量的增加.进一步考察了G5与3,5-二硝基苯甲酸降解菌Comamonas testosterone A3投加到序批式生物膜反应器(SBBR)中的生物强化效果.32 d的运行结果表明,同时投加A3与G5菌株的反应器,24 h时出水中3,5-二硝基苯甲酸由100.0 mg·L-1降解至10.1 mg·L-1,降解最快;3,5-硝基苯甲酸负荷由100 mg·L-1增加到1000 mg·L-1的运行过程中,平均降解率稳定在65.0%~88.1%的范围内,表现出最强的抗冲击能力;生物膜量在1.4~2.0 mg·cm-2之间,比其他两组反应器同期时的生物膜量略高.表明在废水处理系统内Bacillus cereus G5亦可能通过其广泛的共凝集能力,促进反应器中生物膜的形成,并辅助降解菌以自固定化方式定殖于生物膜,从而表现出快速的生物强化作用和较强的抗冲击能力.

Co-aggregation ability of a bridge bacterium and its enhancement in the performance of the biofilm reactor

The ability of co-aggregation and biofilm formation of Bacillus cereus G5 co-cultured with 13 indigenous strains isolated from municipal sewage and 3 organic pollutants degrading bacteria was measured. Results showed that the co-aggregation percertages after 2 h and 20 h were 40%~70% and 55%~80%, respectively. Meanwhile, the biofilm biomass co-cultured with 15 bacteria was more than that of the single cultures. It was indicated that G5 had a strong ability of co-aggregation with indigenous bacteria and degrading bacteria out of the wastewater treatment system. We further studied the bio-augmentation of G5 and 3,5-Dinitrobenzoic acid-degraded bacterium Comamonas testosteroni A3 in sequencing batch biofilm reactors after processing 32 days. Results revealed that the concentration of 3,5-DNBA in effluent decreased from 100 mg·L^-1 to 10.1 mg·L^-1 after 24 h with the highest degradation rate. The degradation rate remained 65.0%~88.1% when the concentration of 3,5-Dinitrobenzoic acid in influent rising from 100 mg·L^-1 to 1000 mg·L^-1, which showed the strongest resistance to 3,5-DNBA shock loading. Additionally, the amount of biofilm varied from 1.4 mg·cm^-2 to 2.0 mg·cm^-2, higher than that of the other two reactors. The study demonstrated that Bacillus cereus G5 was likely to promote the biofilm formation by its extensive co-aggregation ability and to make degrading bacteria fixed in the biofilm in self-immobilized form, which indicated fast bio-augmentation and strong shock resistance.