[Dual-Perspective Analysis of the Warming Effect of the Methane Emissions from Animal Husbandry in China].

Accurate quantitative evaluation of the greenhouse effects of methane(CH4) is the foundation for developing effective mitigation strategies. This study was the first to quantitatively evaluate the warming effects of the CH4 emissions from animal husbandry in China using the recently proposed climate metric GWP-star(GWP*), which is designed for short-lived climate pollutants(SLCP), and to compare the results with the commonly used climate metric global warming potential(GWP). The results showed:CH4emissions from animal husbandry in China decreased from 957.0×105 t in 2000 to 764.0×105 t. The GWP results showed that the greenhouse effect of CH4 emissions from animal husbandry in China was increasing between 2015 and 2019, and the GWP* results showed that it decreased compared to that 20 years ago. The amount of reduction was equivalent to removing the warming of 2.1×108 t of carbon dioxide. Under the GWP evaluation system, achieving carbon neutrality in the livestock industry in China requires eliminating or offsetting stable annual CH4 emissions from increased carbon sinks. Instead, under the GWP* evaluation system, China's livestock industry could achieve its carbon neutrality in the short term by effectively reducing CH4 emissions by only 0.3% per year. In the case that the livestock industry in China continues to take effective emission reduction measures, the reduction target under the GWP* metric will be reached earlier than that under GWP. Still, the choice of GWP or GWP* requires careful consideration of the objectives of evaluation, the time scale of assessment, and practical operability.

[Study on quantification assessment and odor fingerprint of volatile aromatic hydrocarbons from sewage treatment plant].

The malodorous volatile organic compounds (MVOCs) from a typical municipal sewage treatment plant in Guangzhou were detected and analyzed using thermal-desorption/GC-MS and electronic nose, respectively. The results showed that: (1) Aromatic hydrocarbons were the main malodorous volatile organic compounds of the sewage treatment plant, with concentrations ranging from 96.61 microg x m(-3) to 818.03 microg x m(-3), accounting for more than 50% of the total MVOCs, much higher than other MVOCs species. (2) Volatile aromatic hydrocarbons (VAH) in municipal sewage treatment plant were mainly from domestic wastewater, and the sludge treatment process played an important part in release of these pollutants. The total concentration of aromatic hydrocarbons emitted from each processing unit in a descending order was: the sludge dehydration room > sludge thickener > aeration tank > grille > biochemical pool> grit chamber. (3) rincipal component analysis (PCA) was able to distinguish the characteristic of odor emission from each processing unit, with the recognition index reaching 71% , and the PCA recognition index of simulated gases which simulated the VAH levels of different processes reached 94% , indicating that there was big difference among the srmll of the VAH emitted from different processes. (4) The comparison of the original odor fingerprint and simulated odor fingerprint measured by the sensor T70/2 showed that the original odor fingerprint was greater than the simulated odor fingerprint, and the correlation analysis indicated that the VAH had a great contribution to the odor fingerprint of each unit, and the contribution of VAH odor of the aeration tank tq the original odor fingerprint reached 0. 98.

[Source emission characteristics and impact factors of volatile halogenated organic compounds from wastewater treatment plant].

A low enrichment method of using Tenax as absorbent and liquid nitrogen as refrigerant has been established to sample the volatile halogenated organic compounds in Guangzhou Liede municipal wastewater treatment plant as well as its ambient air. The composition and concentration of target halogenated hydrocarbons were analyzed by combined thermal desorption/GC-MS to explore its sources profile and impact factors. The result showed that 19 halogenated organic compounds were detected, including 11 halogenated alkanets, 3 halogenated alkenes, 3 halogenated aromatic hydrocarbons and 2 haloesters, with their total concentrations ranged from 34.91 microg x m(-3) to 127.74 microg x m(-3) and mean concentrations ranged from n.d. to 33.39 microg x m(-3). Main pollutants of the studied plant were CH2Cl2, CHCl3, CFC-12, C2H4Cl2, CFC-11, C2HCl3 and C2Cl4, they came from the wastewater by volatilization. Among the six processing units, the dehydration room showed the highest level of halogenated organic compounds, followed by pumping station, while the sludge thickener was the lowest. The emissions from pumping station, aeration tank and biochemical pool were significantly affected by temperature and humidity of environment.

[Quantification assessment of the relationship between chemical and olfactory concentrations for malodorous volatile organic compounds].

Using self-made cold-traps and gas bags, the odor samples were collected from 6 sewage treatment workshops of a typical municipal sewage treatment plant in Guangzhou City. The chemical composition and olfactory concentrations of these samples were respectively analyzed by thermal-desorption/GC-MS and triangle odor bag method. Finally, a mathematical equation was built for assessing the relationship between principal organic odorants and the olfactory concentrations. The result showing that: (1) More than 70 volatile organic compounds were detected in municipal sewage treatment plant, among which were 30 malodorous volatile organic compounds (MVOCs), ranging from 0.37 to 1 872.24 microg x m(-3) and appearing in sludge dewatering, thickening and aeration tank with the highest concentrations. (2) Principle component analysis was used to group the target MVOCs into 5 categories: benzenes, halohydrocarbons, aldehydes, hydrocarbons and S, N-containing organic compounds. (3) Multiple lineal regression analysis was used to build a quantified relationship between chemical and olfactory concentrations of MVOCs. The result indicated that 25% of the odor problem of sewage treatment unit was due to MVOCs. The predicted values were fitting well with measured values. The sensitivity of mathematical equation for measuring odor concentration was higher than that of human olfactory system.