Chen Yingxu

Characterization and control of odorous gases at a landfill site: A case study in Hangzhou, China

Municipal solid waste (MSW) landfills are one of the major sources of offensive odors potentially creating annoyance in adjacent communities. At the end of May 2007, an odor pollution incident occurred at the Tianziling landfill site, Hangzhou, China, where the residents lodged complaints about the intense odor from the landfill, which drew a significant attention from the government. In this study, ambient air monitoring was conducted at the Tianziling landfill site. The main odor composition of the gas samples collected on June 1st 2007 and the reduction of various odorous gases from the samples collected on June 1st 2009 due to the applied odor control techniques were determined using gas chromatography-mass spectrometry (GC-MS). In addition, variations of primary odorous gaseous (NH(3) and H(2)S) concentrations at different locations in the landfill site from July 2007 to June 2009 were also investigated by using classical spectrophotometric methods. Results showed that a total of 68 volatile compounds were identified among which H(2)S (56.58-579.84 μg/m(3)) and NH(3) (520-4460 μg/m(3)) were the notable odor components contributing to 4.47-10.92% and 83.91-93.94% of total concentrations, respectively. Similar spatial and temporal shifts of H(2)S and NH(3) concentrations were observed and were significantly affected by environmental factors including temperature, air pressure and wind direction. Odor pollution was worse when high temperature, high humidity, low air pressure, and southeast, northeast or east wind appeared. Moreover, the environmental sampling points of the dumping area and the leachate treatment plant were found to be the main odor sources at the Tianziling landfill site. The odor control technologies used in this project had a good mitigating effect on the primary odorous compounds. This study provides long-term valuable information concerning the characteristics and control of odors at landfill sites in a long run.

Particle-facilitated lead and arsenic transport in abandoned mine sites soil influenced by simulated acid rain

The role of acid rain in affecting Pb and As transport from mine tailings was investigated by pumping simulated acid rain at a infiltration rate of 10.2 cm/h through soil columns. Simulated acid rain with pH of 3.0, 4.5 and 5.6 were used as leaching solutions. Results showed that 86.9-95.9% of Pb and 90-91.8% of As eluted from the columns were adsorbed by particles in the leachates. Scanning electron microscopy (SEM) analysis showed that particles released from the columns were mainly composed of flocculated aggregates and plate or rod shaped discrete grains. Transmission electron microscopy (TEM) coupled with energy dispersive X-ray analysis (EDX) showed that these particles were predominantly silicate minerals. Results from our experiments demonstrated that when rapid infiltration conditions or a rainstorm exist, particle-facilitated transport of contaminants is likely to the dominant metal transport pathway influenced by acid rain.

Environmental damage costs from fossil electricity generation in China, 2000~2003 *

Electricity consumption increases rapidly with the rapid development of China. The environmental damage costs of electricity generation are very important for both policy analysis and the proper management of the environment. A method was developed in this work to estimate gross environmental damage costs according to emission inventory and environmental cost factors, and to extend the costs from provincial to national level with population density. In this paper, sulfur dioxide (SO2), nitrogen oxides (NOx), particulate matter less than 10 μm in diameter (PM10), and carbon dioxide (CO2) from fossil fired power plants over 6000 kW were selected as index pollutants to quantify the environmental costs of damages on human health and global warming. With the new developed method, environmental damage costs, caused by 3 types of fired power plants in 30 provinces and 6 economic sectors during the years 2000 to 2003, were evaluated and analyzed. It can be seen that the calculated total national environmental damage costs of electricity have rapidly increased from 94930.87 × 106 USD in 2000 to about 141041.39 × 106 USD in 2003, with an average annual growth rate of 14.11%. Environmental damage costs of SO2, NOx, PM10, and CO2 are 69475.69 × 106, 30079.29 × 106, 28931.84 × 106, and 12554.57 × 106 USD and account for 49.26%, 21.33%, 20.51%, and 8.90% of total environmental costs in fossil electricity generation, respectively. With regard to regional distribution, external costs caused by fossil electricity generation are mainly concentrated in the more populated and industrialized areas of China, i.e., the Eastern Central and Southeastern areas.

Effect of Dissolved Oxygen on Removal of Nitrate in Laboratory Columns Packed with Solid Organic Carbon

Effect of dissolved oxygen (DO) on removal of nitrate from groundwater was studied in laboratory columns packed with solid organic carbon. DO was measured at different height in the column to clarify that there were conditions, aerobic and anoxic, in the column. The paper reactor was not more sensitive than the cotton reactor in the DO effect. the cotton denitrification rate was 0.5181 mgN/(L¡¤h) and the paper denitrification rate was 2.2333 mgN/(L¡¤h) in 0-8 cm of the column with the influent DO 5 mg/L, and the cotton denitrification rate was 5.7823 mg N/(L¡¤h)and the paper denitrification rate was 8.4135 mg N/(L¡¤h) in 0-8cm of the column with the influent DO 1 mg/L. The effect of DO on the rate of denitrification was studied in a column that was maintained at the HRT 9.0h, influent nitrate concentrations 22.6mg N/L in the cotton reactor and influent nitrate concentrations 45.2mg N/L in the paper reactor and DO 0~8 mg/L. The total N removal rate of the two reactors was 100% and had not nitrite.