Font Size: a A A

Study On Characteristic And Removal Efficiency Of DOM In Leachate

Posted on:2008-08-03Degree:MasterType:Thesis
Country:ChinaCandidate:G Q LiuFull Text:PDF
GTID:2121360242971276Subject:Municipal engineering
Abstract/Summary:PDF Full Text Request
Because of the complexity, serious pollution and variability of leachate, most of leachate treatment process in china could not operate well. However, the water quality of leachate was mainly characterized by conventional parameters, which was difficult to reflect the real characteristic of leachate and the difference of different leachates. Therefore, the water quality and seasonal variation of leachaes from Chongqing Chang Shengqiao landfill site and Tongxing incineration plant were investigated, and the farther study on the physico-chemical characteristics of DOM of the two leachates was done. The removal efficiency of leachate DOM adsorbed by activated sludge was studied as well.â‘ Conventional water quality of leachates from Chongqing Chang Shengqiao municipal solid waste landfill and Tongxing incineration plant were tested. The leachate DOM was separate into humic acid (HA), fulvic acid (FA) and hydrophilic organic matter (HyI), and the content and seasonal variation of isolated fractions from the two leachates was tested. The results were shown as following.The Chang Shengqiao landfill leachate, which contained high NH3-N and pH value, low COD and VFA, and poor biodegradability (BOD5/COD=0.21), was very different from Tongxing incineration leachate, which had good biodegradability (BOD5/COD=0.52). The COD,TOC,BOD5,BOD5/COD and VFA values of the summer landfill leachate were higher than those of other seasons leachates, and which were the lowest in winter leachate, while there were no distinct difference of NH3 content and pH value among different seasons. However, there was little seasonal variation of conventional water quality in incineration leachate.The average percentages of HA, FA and HyI in the DOC of landfill leachate were 10.8%,49.2% and 40.3% respectively, and which were 1.6%,55.3% and 44.9% in incineration leachate. There was little seasonal variation of DOM composing for incineration leachate, but distinct seasonal difference for landfill leachate.â‘¡All the isolated fractions (HA, FA and HyI) and C-HA were characterized using acid-base titration,UV-VIS (ultraviolet-visible)and FT/IR (infrared)spectroscopic methods, and the molecular weight distribution of all samples were also determined, The results were shown as following.The result of Acid-base titration indicated that the total organic acidity of HA,FA and HyI in landfill leachate were 3.7,3.9 and 5.8mmol/g, which were 4.4,5.3 and 7.0mmol/g in incineration leachate. Element analyse showed that the content of N in leachate humic substance was higher than that in standard humic substance, and humic substance in landill leachate had higher aromatic content than incineration leachate, while lower than standard humic substance and commercial humic acid.UV-VIS spectrum indicated the HA and FA in landfill leachate had more chromophores. The result of SUVA254 and E280 showed HA, FA and HyI in landfill leachate had higher aromaticity degree than those in incineration leachate, but the aromaticity of humic acid in leachate was much lower than commercial humic acid.FT/IR spectrum analysis indicated that, in the leachate, HA had more aromaticity than FA, while FA had more acidity group, and HyI had more nitrification compound and fatty acid. Molecular size distribution result indicated that the large molecules (>10kDA) percentage of HA was more than 60%, but the molecules of FA and HyI were mainly distributed in the small range (<2kDA), and the molecular size of HA and FA increased with the enhancement of humification. The SUVA254 values of all fractions in different molecule weight rangs were not the same, meaning the matter in different molecule weight rang did not have the accordant aromaticity degree.â‘¢Removal efficiency of aqueous commercial humic acids by activated sludge cultivated by accessional nutriment was studied. Using the same way to cultivate activated sludge, treatment efficiency of leachate effluent after biologic process by activated sludge was studied too. Adsorbed removal efficiency of HA isolated from leachate by activated sludge was tested, and the impact factors on removal efficiency, such as reaction time and sludge concentration, were taken into account. The results were shown as following.The removal efficiency of commercial aqueous humic acids by activated sludge process was studied using synthetic wastewater. In single-stage activated sludge process, the removal efficiency of aqueous humic acids was keep between 67%~84%, decreasing with the enhancement of humic acids content in the influent, and the different content of humic acids in the influent would not affect the removal efficiency of biodegradable organic matter. In the two-stage activated sludge process, the removal efficiency of humic acids in the first stage was 71.3%,better than that(60.1%) in second stage, and the removal efficiency of larger molecular humic acids was better than the smaller. Mechanism study indicated that humic acids was very difficult to be used by microorganism as carbon source, and removed by excess sludge discharge through adsorbed by activated sludge.The effluent leachate after biological process was treated by activated sludge cultivated with accessional nutriment, and removal efficiency of COD, SCOD,UV254 and NH3 were about 43.4%,37.7%,27.6% and 71.6% respectively. The result of sorption experiment indicated that sorption happened mainly before 0.5h, and sorption removal efficiency of HA, FA and HyI followed: HA>FA>HyI. The sludge concentration was the main factor for the sorption of HA, and sorption removal efficiency of HA increased with the increase of sludge concentration.Through this study, the water quality and seasonal variation of incineration plant and landfill leachate was further understood, and it was found that the activated sludge had certain adsorption removal efficiency for refractory organic matter in leachate, which could provide technical information for development or improvement of leachate treatment Process.
Keywords/Search Tags:Leachate, Dissolved organic matter, Characteristic, Activated sludge, Adsorption removal
PDF Full Text Request
Related items