活性污泥呼吸抑制试验的微生物接种物研究

研究了污泥接种物中微生物活性差异对活性污泥呼吸抑制试验结果的影响。用17组不同来源、批次及相同干重质量浓度的污泥作为接种物进行3 h活性污泥呼吸抑制试验,根据满足EC_(50)值5～30 mg/L质控要求的数据组拟合呼吸速率-EC_(50)值曲线;对不同来源、批次及不同干重的20组活性污泥悬液中的活细菌数量及其3 h后的呼吸速率进行测定,建立了活细菌数量与呼吸速率间的函数关系。根据活细菌数-呼吸速率的拟合方程,结合呼吸抑制试验结果,认为在呼吸抑制试验中应控制每升污泥接种悬液中的活菌数在10^(10)数量级以上,推荐将每批污泥中微生物接种物用量控制在每升污泥悬液1.50×10^(10)-2.53×10^(10)个活细胞之间,以进一步保证试验结果间的可比性及化学品安全评估研究的标准化。

Turning, Microbial Inoculation and Use of Eisenia foetida in Household Organic Waste Composting

On site composting of organic household wastes is an economical and environmentally tiiendly way to manage municipal wastes. In this manuscript authors evaluated the importance of turning the wastes and of inoculating microorganisms and worms in order to unprove the composting process at domestic scale. Four treatments （Control without turning- C-, Control with Turning- CT- inoculated Mountain Microorganism with turning- MM- and Worms without turning- W-） were tested in a random experiment with tour replicates. Sixteen composting bins were fed with 300 kg of organic wastes from a local street market. The process of compostnig lasted 13 weeks after which all the composts were sifted and submitted to a range of chemical, physical and biological analysis. According to the results MM slightly increased the initial temperature and enzymatic activiry. This investigation outcome don＇t provide of sufficient grounds for a precise recommendation about worms inoculation in compost bins. A decrease between 75% and 80% in the fresh weight of the organic waste was found in the first thirteen weeks after starting the composting process in all the treatments. The quality level of the compost was acceptable, with very low heavy metal content. Turn over helps to keep the product hygienic especially after the inoculation with MM microbial starts. In conclusion and according to the results of this investigation, the use of 320 L compost bins for the organic waste management is strongly advisable.

The Impact of Inoculum-Substrate Ratios on Microbial Levels during Psychrophilic Anaerobic Digestion

The study evaluated impact of psychrophilic anaerobic digestion on levels of viable populations of fecal indicator bacteria using various inoculum-to-substrate ratios （I：S）. Laboratory-scale batch reactors were maintained at 10 ℃ and 20 ℃ for 25 days with dairy manure substrate. Five treatments included inoculum （control inoculum; inoculum only [CI]）, manure （control manure; substrate only [CM]）, and 3I：1S, II：IS, and 1I：3S. E. coli decreased in all treatments, while Enterococci decreased in only a few treatments. Treatment 1 I： 1S achieved highest E. coli decrease at 20 ℃ （3.11 log）; CM showed highest E. coli decrease at 10 ℃ （2.33 log）. The 1I：3 Streatment showed highest decrease of Enterococci at 20 ℃ （1.82 log）, whereas CM had highest, but less substantial, decrease at 10 ℃ （0.49 log）. These decreases may be the result of environmental conditions, namely substrate limitation for E. coli, and, increased VFA （volatile fatty acid） levels for Enterococci. Lower I：S showed higher levels of indicator organisms; less stable conditions with more acidic pH, higher VFAs, and lower biogas production. Results suggest II：IS is ideal for starting a digester at 20 ℃, whereas 3I：1S appears optimal for 10 ℃, Overall, I：S influenced chemical parameters and fecal indicators during batch psychrophilic anaerobic digestion of manure.

Effect of Rhizobacterium Rhodopseudomonas palustris Inoculation on Stevia rebaudiana Plant Growth and Soil Microbial Community

There is an increasing concern that the continuous use of chemical fertilizers might lead to harmful effects on soil ecosystem.Accordingly, a biocompatible approach involving inoculation of beneficial microorganisms is presented to promote plant growth and simultaneously minimize the negative effect of chemical fertilizers. In this study, Rhodopseudomonas palustris, a plant growth-promoting rhizobacterium(PGPR), was inoculated into both fertilized and unfertilized soils to assess its influence on Stevia rebaudiana plant growth and microbial community in rhizosphere soils in a 122-d field experiment. Soil enzyme assays(dehydrogenase, urease, invertase, and phosphomonoesterase), real-time quantitative polymerase chain reaction(RT-_qPCR), and a high-throughput sequencing technique were employed to determine the microbial activity and characterize the bacterial community. Results showed that the R.palustris inoculation did not significantly influence Stevia yields and root biomass in either the fertilized or unfertilized soil. Chemical fertilization had strong negative effects on soil bacterial community properties, especially on dehydrogenase and urease activities.However, R. palustris inoculation counteracted the effect of chemical fertilizer on dehydrogenase and urease activities, and increased the abundances of some bacterial lineages(including Bacteroidia, Nitrospirae, Planctomycetacia, Myxococcales, and Legionellales). In contrast, inoculation into the unfertilized soil did not significantly change the soil enzyme activities or the soil bacterial community structure. For both the fertilized and unfertilized soils, R. palustris inoculation decreased the relative abundances of some bacterial lineages possessing photosynthetic ability, such as Cyanobacteria, Rhodobacter, Sphingomonadales, and Burkholderiales. Taken together, our observations stress the potential utilization of R. palustris as PGPR in agriculture, which might further ameliorate the soil microbial properties in the long run.

Improved Biodegradation of 1,2,4-Trichlorobenzene by Adapted Microorganisms in Agricultural Soil and in Soil Suspension Cultures

Inoculating soil with an adapted microbial community is a more effective bioaugmentation approach than inoculation with pure strains in bioremediation.However,information on the potential of different inocula from sites with varying contamination levels and pollution histories in soil remediation is lacking.The objective of the study was to investigate the potential of adapted microorganisms in soil inocula,with different contamination levels and pollution histories,to degrade 1,2,4-trichlorobenzene (1,2,4-TCB).Three different soils from chlorobenzene-contaminated sites were inoculated into agricultural soils and soil suspension cultures spiked with 1,2,4-TCB.The results showed that 36.52% of the initially applied 1,2,4-TCB was present in the non-inoculated soil,whereas about 19.00% of 1,2,4-TCB was present in the agricultural soils inoculated with contaminated soils after 28 days of incubation.The soils inoculated with adapted microbial biomass (in the soil inocula) showed higher respiration and lower 1,2,4-TCB volatilization than the non-inoculated soils,suggesting the existence of 1,2,4-TCB adapted degraders in the contaminated soils used for inoculation.It was further confirmed in the contaminated soil suspension cultures that the concentration of inorganic chloride ions increased continuously over the entire experimental period.Higher contamination of the inocula led not only to higher degradation potential but also to higher residue formation.However,even inocula of low-level contamination were effective in enhancing the degradation of 1,2,4-TCB.Therefore,applying adapted microorganisms in the form of soil inocula,especially with lower contamination levels,could be an effective and environment-friendly strategy for soil remediation.