Yang J.,Shanghai Academy of Environmental science |
Yu K.,Shanghai Academy of Environmental science |
Liu C.,CAS Nanjing Institute of Soil Science
Journal of Hazardous Materials | Year: 2017
The potential risk of heavy metal in soil can be reduced by stabilization techniques. Stabilizing amendments, montmorillonites modified with tetramethylammonium (TMA) and hexadecyltrimethylammonium (HDTMA) at different loadings were prepared, characterized and assayed for remediation of hexavalent chromium contaminated soil. Characterization results demonstrated that TMA modification resulted in increased surface area and pore volume, whereas HDTMA modification resulted in decreased surface area and pore volume. For HDTMA modified montmorillonites (H-Monts), the arrangement model of surfactant molecules and the structural characteristics strongly depended on the surfactant loading density. Less pronounced packing density dependence was observed for TMA modified montmorillonites (T-Monts). Modified toxicity characteristic leaching procedure (TCLP) was utilized to evaluate the chromium immobilizing capacity of the prepared organo-montmorillonites, and the results revealed that both T-Monts and H-Monts can be reasonably effective in chromium stabilization under different leaching condition. The comparison of chromium leaching behavior manifested by T-Monts and H-Monts suggested that mechanisms for chromium immobilization by organo-montmorillonites amendment proceeded via two adsorption approaches. Each approach involves different functional groups, depending on the leaching pH and surfactant loading concentration. In addition, the effect of HDTMA loading concentration, amendment dosage, initial chromium concentration and incubation time on the immobilizing efficiency of H-Monts was investigated. © 2016 Elsevier B.V.
Ye J.,Shanghai Academy of Environmental science |
Wang L.,CAS Shanghai Advanced Research Institute |
Li D.,Shanghai Academy of Environmental science |
Han W.,Hohai University |
Ye C.,Hohai University
Ecological Engineering | Year: 2012
To improve nitrogen removal performance in vertical-flow constructed wetlands (VFCWs) and promote their application in domestic wastewater treatment in China, it is important to identify the reoxygenation sources, their contribution weightings and the oxygen distribution profiles in the VFCW substrates. This study indicated that dissolved oxygen (DO) levels rise at first and then drop in the VFCWs vertically from top to bottom in the VFCWs treating domestic wastewater. There were other sources of oxygen supply to the wastewater in the VFCWs, especially in the upper portion of the VFCWs. In treating domestic wastewater, atmospheric reoxygenation is the main oxygen source for the VFCWs, contributing more than 99.9% of the total oxygen supply. Approximately 50% of atmospheric reoxygenation is supplied to 0-10. cm below the wastewater distribution system in the VFCWs. Over 99.8% of the oxygen consumed is used for organics degradation and nitrification. In this study, oxygen was mainly consumed in organics degradation in the upper 0-40. cm of the VFCWs and nitrification was dominant in the lower part. © 2012.
Xu J.,North Carolina State University |
Shen G.,Shanghai Academy of Environmental science
Bioresource Technology | Year: 2011
Spirodela oligorrhiza, a promising duckweed identified in previous studies, was examined under different cropping conditions for nutrient recovery from swine wastewater and biomass production. To prevent algae bloom during the start-up of a duckweed system, inoculating 60% of the water surface with duckweed fronds was required. In the growing season, the duckweed system was capable of removing 83.7% and 89.4% of total nitrogen (TN) and total phosphorus (TP) respectively from 6% swine lagoon water in eight weeks at a harvest frequency of twice a week. The total biomass harvested was 5.30 times that of the starting amount. In winter, nutrients could still be substantially removed in spite of the limited duckweed growth, which was probably attributed to the improved protein accumulation of duckweed plants and the nutrient uptake by the attached biofilm (algae and bacteria) on duckweed and walls of the system. © 2010 Elsevier Ltd.
Xu J.,North Carolina State University |
Shen G.,Shanghai Academy of Environmental science
Water Environment Research | Year: 2011
Harvest regime and water depth were investigated to determine their effects on nutrient recovery from swine wastewater by a Spirodela oligorrhiza system. The results show that harvesting less duckweed at shorter intervals favored nutrient removal and total biomass production. Harvesting 20% of duckweed twice a week led to 66.3 and 109.4% higher total nitrogen and total phosphorus removals, respectively, and a duckweed production of 20.0 g fresh biomass/m 2·d-39.6% higher than that of harvesting 80% of duckweed once every 4 weeks. The water depth of duckweed system was of great importance to total nutrient removal. At the water depth of 40 cm, total nitrogen and total phosphorus removals were 2.05 and 2.16 times higher, respectively, than those at the water depth of 10 cm. However, because of the larger amount of nutrients in a deeper system, it took a longer time for the nutrient concentrations to decrease.
Zhang G.,Shanghai Academy of Environmental science
Chinese Journal of Environmental Engineering | Year: 2016
Based on a comprehensive literature review, this article addresses various aspects of leak detection and repair (LDAR) technologies and corresponding applications. Firstly, this article summarizes the implementation statuses and experiences from developped countries such as the United States and those from the European Union. Next, it discusses the domestic policy, providing a comparison of national criteria in China with those of the other countries and regions. Lastly, it analyzes the current implementation challenges based on case studies, and provides suggestions from different aspects including supportive policies, third-party participation, information management, and examination and supervision for implementation and promotion of LDAR. © 2016, Science Press. All right reserved.
Luo Q.,Shanghai Academy of Environmental Science
Frontiers of Environmental Science and Engineering | Year: 2014
The oxidation of aqueous monochlorobenzene (MCB) solutions using thermally-activated persulfate has been investigated. The influence of reaction temperature on the kinetics of MCB oxidation was examined, and the Arrenhius Equation rate constants at 20°C, 30°C, 40°C, 50°C, and 60°C for MCB oxidation performance were calculated as 0, 0.001, 0.002, 0.015, 0.057 min-1, which indicates that elevated temperature accelerated the rate. The most efficient molar ratio of persulfate/MCB for MCB oxidation was determined to be 200 to 1 and an increase in the rate constants suggests that the oxidation process proceeded more rapidly with increasing persulfate/MCB molar ratios. In addition, the reactivity of persulfate in contaminated water is partly influenced by the presence of background ions such as Cl-, HCO3 -, SO4 2-, and NO3 -. Importantly, a scavenging effect in rate constant was observed for both Cl- and CO3 2- but not for other ions. The effective thermally activated persulfate oxidation of MCB in groundwater from a real contaminated site was achieved using both elevated reaction temperature and increased persulfate/MCB molar ratio. © 2014 Higher Education Press and Springer-Verlag Berlin Heidelberg.
Sha C.-y.,Shanghai Academy of Environmental science
Chinese Journal of Ecology | Year: 2011
In November 2008-October 2009, a field research by the method of static chambergas chromatography was conducted on the spatiotemporal pattern of methane (CH4) emission from two riparian wetlands (constructed and natural) in the Wilma H. Schiermeier Olentangy River Wetland Research Park in Columbus, Ohio, USA, with the effects of soil temperature, carbon content, hydrological condition, and vegetation on the CH4 emission approached. Both of the wetlands had an obvious seasonal variation of CH4 flux, and the CH4 emission from natural wetland was significantly higher than that from constructed wetland (P<0.05), being 114 and 68 g CH4-C • m-2 • a-1, respectively, possibly due to the higher cumulative productivity in natural wetland. For the two wetlands, the CH4 emission was higher in deep water zone than in transition zone, and the median value (average) was 4.7 (59.9 mg • m-2 • h-1) and 0.09 (1.17 mg • m-2 • h-1), respectively (P<0.01). Intermittent flooded area produced lesser methane than permanently inundated area, and soil temperature and organic carbon content had definite effects on the CH4 emission. It was suggested that to configure proper vegetation and proper hydrological conditions in riparian wetland and to implement proper management could effectively reduce the CH4 emission from the wetland.
Wang X.,Shanghai Academy of Environmental science
Advanced Materials Research | Year: 2012
During the commissioning (alternate unipolar and bipolar operation) of ±800KV DC transmission grounding electrode, the average grounding current is much greater than that of the steady bipolar operation, which might cause undesirable impacts on the edatope. In this study, the soil physicochemical property variations of the plant root zone (depth 0.5 m) and the soil temperature during the commissioning of the grounding electrode were monitored and analyzed. And the influence of the commissioning on plant growth was evaluated. © (2012) Trans Tech Publications, Switzerland.
Bai Y.,Shanghai Academy of Environmental science
Chinese Journal of Applied Ecology | Year: 2012
Through the evaluation of the gains and losses of the key functions of regional ecological system under different management modes, various ecosystems functions and their spatial distribution patterns in Wanquan Town were analyzed. Based on different development needs, various scenarios were established and weighed. In 2009, the support function value supplied by the ecosystems in the Town was 58 million RMB, among which, oxygen release function ranked first(37 million RMB), and the regulation function value provided by the ecosystems was 1238 million RMB, among which, climate regulation ranked first(1127 million RMB). The total ecosystem services value was 1297 million RMB, being 1. 46 times of the local GDP(888 million RMB) in the same year. Compared with that in 2002, the service function value of the ecosystems declined in 2009, with the largest decrements in climate regulation and water yield. Under policy scenario and protection scenario, the variation trends of the values of various ecosystems functions were basically the same. Except that the values of the functions oxygen release and nutrient cycling decreased, the values of the others increased obviously. Under protection scenario, the total ecosystem services value had a higher increment than that under policy scenario, especially for the water yield and carbon sequestration functions. It was suggested that protection scenario could be the optimal land use management mode for the socio-economic sustainable development of the Town.
Wu J.-Q.,Shanghai Academy of Environmental science
Shuikexue Jinzhan/Advances in Water Science | Year: 2011
Using the constructed buffer strip experimental site and the hydrometric devices in the Dongfeng Port of Shanghai, a quantitative study is conducted to investigate the damping effect of buffer strips with different slopes on runoff and the pollutant removal efficiency of nitrogen (N) and phosphorous (P) from agricultural lands. The result shows that for a similar configuration of vegetation structure, the gentler the slope gradient is in relation to the damping effect of buffer strips, the slower the runoff moves, and the greater the hydraulic permeability is. For example, on a 19-m long buffer strip with a 2% slope, there will be a delay of 7.3 minutes for runoff starting to flow out of the strip compared to that with a 5% slope. The two slope configurations can lead to a ratio of 1:1.74 with respect to the seepage water. The improvement in the pollutant removal efficiency of N and P would be more significant in comparison with the damping effect on runoff when the slope gradient increases. For instances, on the buffer strips with 2%, 3%, 4% and 5% slopes, the improvement ratio of the two elements are 2.32, 2.15, 1.82 and 1.64, respectively. The gentler the slope gradient is in relation to the pollutant removal efficiency of N and P, the greater the total efficiency and unit area improvements will be. For example, on the buffer strips with 2% and 5% slopes, the two improvement ratios are found to be 1.56 and 1.66, respectively. The buffer strip with a 2% slope would have the highest pollutant removal efficiency of total nitrogen (TN), ammonia nitrogen (NH3-N) and total phosphorous (TP), which are 0.661, 0.672 and 0.044 g/m2, respectively.