Biomedical subjects

Qitang Wu

Publications and source records attributed to Qitang Wu.

8 recordsLinked to original sources

PubMed2006

Photodegradation of orange I in the heterogeneous iron oxide-oxalate complex system under UVA irradiation.

To understand the photodegradation of azo dyes in natural aquatic environment, a novel photo-Fenton-like system, the heterogeneous iron oxide-oxalate complex system was set up with the existence of iron oxides and oxalate. Five iron oxides, including gamma-FeOOH, IO-250, IO-320, IO-420 and IO-520, were prepared and their adsorption capacity was investigated in the dark. The results showed that the saturated adsorption amount (gamma(max)) was ranked the order of IO-250 > IO-320 > gamma-FeOOH > IO-420 > IO-520 and the adsorption equilibrium constant (Ka) followed the order of IO-250 > IO-520 > gamma-FeOOH > IO-420 > IO-320. The effect of initial pH value, the initial concentrations of oxalate and orange I on the photodegradation of orange I were also investigated in different iron oxide-oxalate systems. The results showed that the photodegradation of orange I under UVA irradiation could be enhanced greatly in the presence of oxalate. And the optimal oxalate concentrations (C(ox)0) for gamma-FeOOH, IO-250, IO-320, IO-420 and IO-520 were 1.8, 1.6, 3.5, 3.0 and 0.8 mM, respectively. The photodegradation of orange I in the presence of optimal C(ox)0 was ranked as the order of gamma-FeOOH > IO-250 > IO-320 > IO-420 > IO-520. The optimal range of initial pH was at about 3-4. The first-order kinetic constant for the degradation of orange I decreased with the increase in the initial concentration of orange I. Furthermore, the variation of pH, the concentrations of Fe3+ and Fe2+ during the photoreaction were also strongly dependent on the C(ox)0 and iron oxides.

Azo Compounds↗

PubMed2005

Effect of simultaneous establishment of Sedum alfredii and Zea mays on heavy metal accumulation in plants.

Land application of biosolids to improve agricultural productivity is a cost-effective approach for resource recovery. Unfortunately, municipal biosolids often contain high concentrations of heavy metals, including zinc and copper. In this study, a co-cropping technique was investigated using a known zinc hyperaccumulator, Sedum alfredii with a grain crop, Zea mays. After a 3-mo growth trial, the results indicate that when Z. mays is co-cropped with S. alfredii, heavy metals accumulated in the grains were significantly reduced when compared to monoculture cropping. Co-cropping improved the growth of both plant species. In addition, the biosolids maintained stable pH, N-P-K concentrations, germination potential, and water content after the plant treatment, regardless of the plant species used in the trial. In conclusion, co-cropping with hyperaccumulators may be an effective approach to reducing the risk of contaminant uptake in edible crops.

Agriculture↗

PubMed2003

[Physicochemical changes and maturity evaluation of solid organic waste compost].

Composting is one of the most effective ways for recycling of organic solid waste. Various characteristics of different kinds of organic solid waste cause various physicochemical changes during composting, as well as the different composting conditions. Stability and maturity evaluation are the measurement for compost quality and the safe guarantee for its agricultural utilization. Stability evaluation of compost focuses on the impacts to environment after its agricultural utilization, while maturity evaluation pays attention on the phytotoxicity to plant. Stability and maturity of compost are affected by several factors, such as the characteristics of raw materials, the composting condition, and so on. Stability could be assessed by compost temperature, color, evolution rate of CO2, consumption rate of O2, content of NO3(-)-N and quantities of pathogen, etc. Temperature was suggested to be one of the most convenient parameters for stability evaluation. Maturity could be assessed by various parameters, including the chemical, biological, and phytotoxical parameters. Seed germination index, as the phytotoxical parameter, was recommended to be one of the most convenient and reliable parameters of maturity evaluation.

Conservation of Natural Resources↗

PubMed2003

[PAEs in composts of municipal sludge and rice straw].

Four composting treatments for municipal sludge and rice straw were carried out, which included turning composting, inoculation-turning composting, continuous aeration, and intermittent aeration. GC/MS determination of phthalic acid esters (PAEs) in different composted composts showed that the total contents of six PAE compounds (sigma PAEs) ranged from 0.980-17.832 mg.kg-1, decreasing in the order of turning composting (17.832 mg.kg-1) > inoculation-turning composting (13.927 mg.kg-1) > intermittent aeration (10.765 mg.kg-1) > continuous aeration (9.815 mg.kg-1). DnOP was dominated in the composts. The degradation rate of sigma PAEs after composting was 1.37-45.71% (mean 27.63%), and that of diethyl phthalate (DEP), di-n-butyl phthalate (DnBP) and butylbenzyl phthalate (BBP) was 95.76-98.68%, 79.56-99.46% and 87.42-98.42%, respectively. The concentration of di-n-octyl phthalate (DnOP) was increased in the composts. Aeration-composting, and continuous aeration composting in particular, was more efficient than other treatments to degrade PAEs in municipal sludge.

Biodegradation, Environmental↗

PubMed2003

[Effect of municipal sludge and chemical fertilizers on phthalic acid esters (PAEs) contents in Ipomoea aquatica grown on paddy soils].

GC/MS determinations on six phthalic acid esters (PAEs) in Ipomoea aquatic grown on potted paddy soil fertilized with municipal sludge and chemical fertilizers showed that the total contents of PAEs (sigma PAEs) in Ipomoea aquatic aboveground parts ranged from 2.129 mg.kg-1 to 7.111 mg.kg-1, decreasing in order of Guangzhou sludge + fertilizers (7.111 mg.kg-1) > Guangzhou sludge (4.767 mg.kg-1) > Foshan sludge (3.569 mg.kg-1) > Foshan sludge + fertilizers (3.305 mg.kg-1) > fertilizers (2.638 mg.kg-1) > control (2.129 mg.kg-1), indicating that compared with control, fertilization increased sigma PAEs in Ipomoea aquatica to a different extent. Only certain compounds of PAEs in different treatments of Ipomoea aquatica were dominant, e.g., butylbenzyl phthalate (BBP) in control, chemical fertilizers, Foshan sludge, and Guangzhou sludge accounted for 40% to 80% of sigma PAEs, di-n-butyl phthalate(DnBP) in foshan sludge + chemical fertilizers accounted for 56%, while di-n-octyl phthalate(DnOP), di(2-ethylhexyl)phthalate(DEHP) and BBP in Guangzhou sludge + chemical fertilizers accounted for approximately 30%. sigma PAEs and the contents of its most compounds were higher in the plants of Ipomoea aquatica than in its roots to a different extent.

Fertilizers↗

PubMed2002

[Changes of chemical and biological properties during composting sewage sludge by using forced aerated static pile model].

Municipal sewage sludge was composted for 53 days with Chinese medical herb residues as bulking agent through forced aerated static pile model. The temperature of the pile could quickly rise to more than 55 degrees C after the second day after composting. Furthermore, the temperature of more than 55 degrees C maintained as long as 8 days, which was helpful in inactivation of pathogens in compost. The cress seed germination index (GI) and the ratio of water-soluble organic carbon to organic nitrogen (soluble C/N-organic), used as indicators of phytotoxicity and maturation of compost, exhibited that the sludge compost was almost stabilized and matured near the 40th day of composting, when 80% of GI and 6.4 of soluble C/N-organic were obtained. The content of total N, P, Cu, Zn and Cd in compost increased as the composting time elapsed, while volatile solids, solid and water soluble organic carbons, pH, and NH4(+)-N decreased. F. coli, as a common indicator of pathogens in sludge, was reduced greatly from 1.41 x 10(5) to 2.32 x 10(1) in the final examination of the compost.

Aerobiosis↗

PubMed2002

[Effect of sewage sludge and its composts on the accumulation of organic pollutants in Ipomoea aquatic grown in paddy soil].

Eight kinds of organic pollutants including 44 compounds in Ipomoea aquatic grown in paddy soil fertilized with sewage sludge and its composts were systematically determined by GC/MS. The results showed that twenty eight compounds consisting mainly of phthalic acid esters, nitrobenzenes, and polycyclic aromatic hydrocarbons were deteced in Ipomoea aquatic. Only individual or very few compounds for each kind of organic pollutants in Ipomoea aquatic were predominant, while others were trace or not detected. Compared with control, compounds detected in Ipomoea aquatic fertilized with sludge were commonly higher to a different extent, but those detected in Ipomoea aquatic fertilized with different sludge composts were commonly lower and even not detected, especially for Ipomoea aquatic fertilized with sludge + rice straw composts was detected only one compound. It was therefore concluded that direct use of sewage sludge as organic fertilizer could result in bioaccumulation of organic pollutants in crops, but sludge compost application would be safe if proper compost treatment for sludge was conducted.

Fertilizers↗

PubMed2002

[On nitrogen transformations and maturity during composting of pig manure].

The contents of T-N, the ratios of soluble NO3-N/soluble T-N and soluble organic-N/soluble T-N increased after co-composting for 63 days of pig manure and sawdust with or without additional leaves, while the ratios of soluble NH4-N/soluble T-N decreased. In this study, addition of leaves was beneficial for maturation of pig manure composting, and it could shorten the composting time from 42 d to 35 d. The ratios of soluble NH4-N/soluble T-N, soluble NO3-N/soluble T-N and soluble organic N/soluble T-N correlated with seed germination index (GI) significantly, and it could be used for maturity evaluation.

Animals↗