Biomedical subjects

Guang-he Li

Publications and source records attributed to Guang-he Li.

4 recordsLinked to original sources

PubMed2006

[Relationships between loading rates and nitrogen removal effectiveness in subsurface constructed wetlands].

About forty kinds of nitrogen loading removal rate were studied in field in 15 months, inflow and outflow loading rules of reeds/Zizania caduciflora/mixing and no-plant bed were discussed in different inflow loading. The four kinds SFS inflow loading changed from 400 mg x (m2 x d)(-1) to 8 000 mg x (m2d)(-1), while outflow loading is less than 7,000 mg (m2 d)(-1). Results show that outflow loading increase with the increase of inflow loading, linear relation is obvious. Total nitrogen removal rate has the same trend at low inflow loading. But in high inflow loading TN removal rate has much variation. The system had better run between 2,000 mg x (m2 x d)(-1) and 4,000 mg x (m2 x d)( -1) inflow loading. Average removal rate in between 1062 mg x (m2 x d)(-1) and 2 007 mg x (m2 x d)(-1). Plant SFS removal rate is better than no-plant SFS. TN removal rate of reed and zizania caduciflora bed is 63 % and 27 % higher than no-plant bed. Plant harvesting is unimportant and contributes less than 5% of TN removal loading, plant can improve system microenviroment and hydrology condition which could increase TN removal rate. The results provided deep insight to SFS nitrogen removal and reference to SFS design.

Biodegradation, Environmental↗

PubMed2006

[Physical and chemical effects and plant growth suitability of substrates in subsurface flow wetland].

Substrate, which not only takes part in the pollutant-removing, but influences the plant growth, plays an important role in subsurface flow wetland. With X-ray fluorescence measurement and X-ray diffractometer, the elements and minerals in zeolite and shale were confirmed, and the removal mechanics of nitrogen, phosphate and hydrogen ion in substrates were explained respectively. The investigation show that the zeolite has abounded with micropores and mesopores, while the shale has only mesopores, which causes the NH4+ -N adsorption capability of the shale is less than zeolite. The PO4(3-) -P removal and hydrogen ion buffer capacity of shale are greater than those of zeolite because CaCO3 is one of the main contents of shale. In pilot-plant system to treat starch waste water, the reeds and acorus aclamuc were either planted in shale and zeolite, and the phytum's indexes in shale including relative green concentration, average plant height, root stem ratio were higher than those in zeolite. The root vitality of reeds and acorus aclamuc planted in shale were 3.7 and 1.6 times of those in zeolite respectively. Total nitrogen and phosphorus contents in the plant organization of acorus aclamuc in shale were 7.8 and 3.4 times of those in zeolite; total nitrogen and phosphorus contents in the plant organization of reeds in shale were 3.3 and 2.2 times of those in zeolite. The results indicate that shale provides a steady pH for the plant's root in the acid waste water and it is more suitable for plant growth than zeolite.

Biodegradation, Environmental↗

PubMed2005

[Effects of acid soils on the biodegradation of hydrocarbons].

Biodegradation efficiency of hydrocarbons and melioration of micro-ecosystem conditions in acid soils should be seriously concerned due to either occurrence of acid polluted soils or acidification during bioremediation process. The influence of acid situation on degrading microbes and the biodegradation rate were figured out by monitoring variations of biomass, microbial activities and petroleum contents with time in acid and alkaline polluted soils in laboratory. Injecting degrading microbes and meliorating micro-ecosystem conditions of acid soils were conducted. The results showed that acid soils (pH = 5.4-5.7) had extreme restraint on local microbe numbers and activities, and biodegradation rate almost reached zero. Injection of degrading microbes could not remarkably reduce the restriction of acid conditions. The microbe numbers quickly went down from 10(6) cells/g dried soil to zero in 14 days and the Fluorescein Diacetate (FDA) activities were only about 0.10 Abs/g dried soil. However, addition of bio-carriers could effectively improve micro-ecosystem conditions in acid soils, thus notably diminish the restraint to some extent. In 19 days, the amount of microorganisms decreased from 2 x 10(6) to 2.2 x 10(2) cells/g dried soil. And up to 49 days, about 13% hydrocarbons were removed from the polluted soils by microbes.

Acids↗

PubMed2004

[The relationship between abiotic factors and microbial activities of microbial eco-system in contaminated soil with petroleum hydrocarbons].

By means of the biostimulation and bioaugmentation in the micro-ecological environment of contaminated soil with petrochemical hydrocarbons, the biodegradation rates and mode of the contaminants were significantly improved. Based on the investigations carried out in some oilfields and petrochemical industrial area of Northern China, the relationship between the abiotic factors such as nutrient, pH, contaminants, water content, alkalinity, etc., and microbial activities was interpreted and identified in this paper. The results from the investigations and indoor and in-situ experiments conducted recent years indicated that the soils in the areas, to the extent, have been polluted by the different kinds of organic compounds composed of monoaromatic benzene, PAHs, chlorinated solvent, and alkanes, and the concentrations of the compounds mostly were elevated as compared to the background, with the highest 34,000 mg/kg dry soil. The column chromatography analysis results showed that the alkyl and aromatic compounds were accounted for more than 50% of the total hydrocarbon contents, which was readily degraded by degrading bacteria and improved the degrading microbe activities. The effective nitrogen and phosphorus encountered in the soil was less than 30 mg/kg dry soil and 10 mg/kg dry soil, only about 5% of total contents of them respectively. Based on the stoichiometric calculation and reasonable ratio of carbon to nutrient content regarding the biodegradation of organic compounds, the nutrient levels mainly composed of nitrogen and phosphorus in polluted soil as importantly limiting factors to degrading bacterial growth and activity were insufficient to the biodegradation of petrochemicals, and it is needed to add the nutrient for the bioremediation of contaminated soil. It is undoubted that the optimization of abiotic factors play significant role in increasing the microbial activity and improving the biodegradation rates.

Biodegradation, Environmental↗