2/2/2024 0 Comments Aluminum reactivity![]() But unlike hydrogen, in an MSW landfill, the gas collection system is design to handle methane gas which is a green house gas generated during the anaerobic decomposition of MSW. Like hydrogen, methane is an explosive gas and care must be taken if salt cake reacts with liquids. Apart from being a fire hazard when mixed with CH 4, landfill gas collection systems are not designed to handle H 2 since MSW landfill gas generally consists of CH 4 and CO 2 at ~ 50/50 ratio. Hydrogen is even of greater concern if generated in MSW landfills. Hydrogen is an explosive gas and can potentially cause fires. At elevated temperatures encountered in MSW landfills, elevated levels of H 2 gas may be generated as a result of salt cake reactivity and will be of concern. While the heat generation potential per gram of salt cake sample is a sample specific parameter, the results presented herein suggest that higher environmental temperatures tend to intensify the salt cake reaction. Even outside of MSW landfills, once a salt cake reaction starts, it may self-propagate and increase the rate at which the reaction occurs. Furthermore, elevated temperatures can increase the rate of the salt cake reaction which further propagate the salt cake reaction. The elevated temperatures present in most MSW landfills can be conducive and could initiate salt cake reactions that otherwise may not take place. The MSW decomposition process is exothermic and as a result MSW landfill temperatures are typically greater than 37 oC and may reach 50 oC or greater. Also, care should be taken not to size reduce it after disposal by compacting it with heavy bulldozers. From the end-of-life management perspective, data presented here suggest that salt cake should not be size reduced before disposal. Results presented in this document are of particular importance when trying to understand concerns associated with the disposal of salt cake in MSW landfills. The analysis only showed a few aluminum species present in salt cake which does not exclude the presence of other crystalline species especially in light of the variability observed in the samples. The relative abundance of various aluminum species was evaluated but it is noted that the method used is a semi-quantitative method and as a result there is a limitation for the data use. The mineral phase analysis showed that various species of aluminum are present in the salt cake samples with a large degree of variability. As a result, salt cake should always be managed at facilities that utilize synthetic liner systems with leachate collection (the salt content of the leachate will increase the hydraulic conductivity of clay liners within a few years of installation). Results suggest that while the percent metal leached from the salt cake was relatively low, the leachable metal content may still pose a contamination concern and potential human and ecological exposure if uncontrollably released to the environment. The facilities were identified by the Aluminum Association to cover a wide range of processes. Thirty-nine salt cake samples were collected from 10 SAP facilities across the U.S.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |