Biomedical subjects

Bei-dou Xi

Publications and source records attributed to Bei-dou Xi.

6 recordsLinked to original sources

PubMed2006

[Inoculating microbes on municipal solid wastes composting affects organic acids and maturity].

Inoculating microbes (Meishang compound microbes, MS; Zhongjia fermentation microbes, ZJ) on municipal solid wastes composting which adopted industrialized technology was studied. The dynamic changes of low molecule weight organic acid and high molecule weight humic substance were discussed. The results show that inoculating microbes on municipal solid wastes composting could increase the content of organic acid at initial stage of composting, and decrease that at final stage. But humic substance and humic acid decline at the initial stage, then increase at the final stage of composting. The dynamic changes of organic acid and humification index indicate that inoculating microbes on municipal solid wastes can obviously increase the maturity of composting, and order as follow: MS+ ZJ>ZJ > MS>CK.

Acids↗

PubMed2006

[Relationship between the nitrogen removal and oxygen demand in constructed wetlands].

A simplified model of sequential N transformations and sink was applied to investigate the relationship between the nitrogen removal and oxygen demand to verify the validity of full nitrification-denitrification mechanism in a newly-built multi-stages constructed wetlands. Average net rates of N mineralization ranged from 0.01 to 0.28 g x (m2 x d)(-1), nitrification from 0.50 to 1.54 g x (m2 x d)(-1), denitrification from 0.41 to 1.13 g x (m2 x d)(-1)(3.4% approximately 35.4% of measured N removal in different stage) and plant assimilation from 0.07 to 0.26 g x (m2 x d)(-1) in the five tanks. Nitrification and denitrification occurred concurrently with BOD removal, even in the first stage receiving the higher-strength wastewater. Surprisingly, net areal nitrification rates, was correlated with BOD removal rates positively. Nitrification rates were also correlated linearly with average NH4+-N concentrations in the cascade tanks. The nitrogenous oxygen demand (NOD) required to support full nitrification of ammonia and mineralized Org-N in the wetland was in the upper range of that expected to be able to be supplied through surface and plant-mediated oxygen transfer. Some potential alternative nitrogen removal pathways with reduced overall oxygen requirements that have relevance to constructed wetlands were discussed.

Environmental Monitoring↗

PubMed2005

[Characteristics of melting and solidification process of fly ash from refuse incinerator].

This study was conducted to investigate the migration patterns of main compositions of the fly ash from refuse incinerator during melting and solidification process. The experiment was performed in a high temperature melting furnace with temperature controlled. X-ray fluorescence spectroscopy (XRF) and X-ray diffractometer (XRD) were used to analyzed the fly ash treated. The parameters investigated included main compositional contents, phase constituents, alkalinity, vaporation rate, volume reduction rate. The results show: (1) During the melting and solidification process, the contents of CaO, Al2O3, and SiO2 in fly ash increased as the temperature went up, but element Cl and S decreased from initial 20.59%, 10.74% to final 0.15%, 0.22%, respectively. This suggests that higher amount of Cl and S in original fly ash could lead to more vaporation in the form of chloride and calcium salfate in the process, which was further verified by XRD analyzing result. (2) The alkalinity decreased as melting temperature increased, but tended to be stable and maintained around 0.95 after temperature reached flowing temperature. (3) The decomposition and vaporation of the salts in the fly ash mainly occurred in the temperatures between 1150 degrees C and 1260 degrees C, which was approximately 100 degrees C lower than melting temperature.

Air Pollutants↗

PubMed2005

Fluorescence characteristic changes of dissolved organic matter during municipal solid waste composting.

Dissolved organic matter(DOM) of municipal solid waste (MSW) consists of minerals, water, ash and humic substances, and is known to enhance plant growth. In this study, inoculating microbes (ZJ, MS) were used in municipal solid wastes composting, and composting implemented a industrialized technology. During composting, dissolved organic matter was extracted from the compost and purified. The spectral characteristics of dissolved organic matter was determined by fluorescence emission, excitation, and synchronous spectroscopy. Fluorescence emission, excitation, and synchronous spectra characterized by different relative fluorescent intensities and peaks over time. Fluorescence spectra were similar to that of fulvic acid in sewage sludge, indicating the presence of dissolved organic matter with aromatic structures and a high degree of molecular polymerization. Compared with the controls with no microbial inoculation, the microbe-inoculated treatments exhibited the increase of aromatic polycondensation, in the following order: MS + ZJ > ZJ > MS > CK.

Bacteria, Aerobic↗

PubMed2004

Two stages kinetics of municipal solid waste inoculation composting processes.

In order to understand the key mechanisms of the composting processes, the municipal solid waste (MSW) composting processes were divided into two stages, and the characteristics of typical experimental scenarios from the viewpoint of microbial kinetics was analyzed. Through experimentation with advanced composting reactor under controlled composting conditions, several equations were worked out to simulate the degradation rate of the substrate. The equations showed that the degradation rate was controlled by concentration of microbes in the first stage. The degradation rates of substrates of inoculation Run A, B, C and Control composting systems were 13.61 g/(kg x h), 13.08 g/(kg x h), 15.671 g/(kg x h), and 10.5 g/(kg x h), respectively. The value of Run C is around 1.5 times higher than that of Control system. The decomposition rate of the second stage is controlled by concentration of substrate. Although the organic matter degradation rates were similar to all Runs, inoculation could reduce the values of the half velocity coefficient Km and could be more efficient to make the composting stable. Particularly, for Run C, the degradation rate is high in the first stage, and Km is low in the second stage. The results indicated that the inoculation was efficient for the composting processes.

Bacteria↗

PubMed2002

Composting MSW and sewage sludge with effective complex microorganisms.

The effects of complex microorganisms in composting process of the municipal solid waste (MSW) and sludge were examined through inspecting biomass, temperature, oxygen consumption, organic mater, and C/N (the ratio of carbon and nitrogen). The experimental results shows: complex microorganisms are effective to compose organic matter and speedup composting change into humus.

Biomass↗