Heavy metal-contaminated sediments posed a serious threat to both human beings and environment. A biosurfactant, rhamnolipid, was employed as the washing agent to remove heavy metals in river sediment. Batch experiments were conducted to test the removal capability. The effects of rhamnolipid concentration, washing time, solution pH, and liquid/solid ratio were investigated. The speciation of heavy metals before and after washing in sediment was also analyzed. Heavy metal washing was favored at high concentration, long washing time, and high pH. In addition, the efficiency of washing was closely related to the original speciation of heavy metals in sediment. Rhamnolipid mainly targeted metals in exchangeable, carbonate-bound or Fe-Mn oxide-bound fractions. Overall, rhamnolipid biosurfactant as a washing agent could effectively remove heavy metals from sediment.
Environmental Science and Pollution Research - Municipal solid waste incineration (MSWI) fly ash has been classified as hazardous waste and needs treatment in an environmentally safe manner.... 相似文献
Environmental Science and Pollution Research - Microbial fuel cell (MFC) is a sustainable technology to treat cattle manure slurry (CMS) for converting chemical energy to bioelectricity. In this... 相似文献
Fine particulate matter (PM2.5) levels, carbon dioxide (CO2) levels and particle-number concentrations (PNC) were monitored in train carriages on seven routes of the mass transit railway in Hong Kong between March and May 2014, using real-time monitoring instruments. The 8-h average PM2.5 levels in carriages on the seven routes ranged from 24.1 to 49.8 µg/m3, higher than levels in Finland and similar to those in New York, and in most cases exceeding the standard set by the World Health Organisation (25 µg/m3). The CO2 concentration ranged from 714 to 1801 ppm on four of the routes, generally exceeding indoor air quality guidelines (1000 ppm over 8 h) and reaching levels as high as those in Beijing. PNC ranged from 1506 to 11,570 particles/cm3, lower than readings in Sydney and higher than readings in Taipei. Correlation analysis indicated that the number of passengers in a given carriage did not affect the PM2.5 concentration or PNC in the carriage. However, a significant positive correlation (p < 0.001, R2 = 0.834) was observed between passenger numbers and CO2 levels, with each passenger contributing approximately 7.7–9.8 ppm of CO2. The real-time measurements of PM2.5 and PNC varied considerably, rising when carriage doors opened on arrival at a station and when passengers inside the carriage were more active. This suggests that air pollutants outside the train and passenger movements may contribute to PM2.5 levels and PNC. Assessment of the risk associated with PM2.5 exposure revealed that children are most severely affected by PM2.5 pollution, followed in order by juveniles, adults and the elderly. In addition, females were found to be more vulnerable to PM2.5 pollution than males (p < 0.001), and different subway lines were associated with different levels of risk. 相似文献
This paper aims to reveal the heat transfer mechanism of low-temperature phase change material (PCM) and design PCM heat storage device in building heating environment. Firstly, low-temperature binary PCMs of lauric acid and stearic acid are prepared, and their thermal properties are investigated by DSC. Then, shell and tube latent heat thermal energy storage units are conducted, and heat transfer experiments are carried out to analyze the heat transfer mechanism of PCM. The results demonstrate that natural convection plays an important role in heat transfer process, and the heat storage efficiency of PCMs can be significantly enhanced by increasing the fin width and improving the inlet heat transfer fluid (HTF) temperature. Furthermore, some proposals are put forward to guide the design of PCM storage device in building heating environment. 相似文献