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391.
Aquatic plant debris improve phosphorus sorption into sediment under anoxic condition 总被引:1,自引:0,他引:1
Chong-Wei Jin Shao-Ting Du Wu-Yuan Dong Jue-Hua Wang Cheng Shen Yong-Song Zhang 《Environmental science and pollution research international》2013,20(11):8237-8244
The effects of plant debris on phosphorus sorption by anoxic sediment were investigated. Addition of plant debris significantly enhanced the decrease of soluble relative phosphorus (SRP) in overlying water at both 10 and 30 °C during the 30-day investigation. Both cellulose and glucose, two typical plant components, also clearly enhanced the SRP decrease in anoxic overlying water. The measurement of phosphorus (P) fractions in sediment revealed that the levels of unstable P forms were decreased by plant debris addition, whereas the opposites were true for stable P forms. However, under sterilized condition, plant debris/glucose addition has no effect on the SRP decrease in overlying water. Overall, our results suggested that plant debris improve P sorption into sediment under anoxic condition through a microorganism-mediated mechanism. 相似文献
392.
以浮萍优势品种青萍(Lemna minor)为研究对象,开展受污染河水修复。分析了青萍在不同营养盐浓度条件下的生长特征,探讨了青萍对受污染河水的修复效果。在表面积为0.0095 m2的限制空间条件下,青萍在1、2和5 mg总氮(TN)/L营养液中的生长特征都能较好地服从Logistic生长模型,受制约的临界鲜重(FW)分别为1.20、1.36和1.36 g;青萍对受污染河水中氮磷污染物具有较好的去除效果,氨氮(NH+4-N)的平均去除率、平均去除量和平均去除速率分别为56.87%、1.22 mg/d和0.0466 mg/(g FW·h),正磷酸盐(PO3-4-P)的平均去除率、平均去除量和平均去除速率分别为66.95%、0.25 mg/d和0.0088 mg/(g FW·h)。根据相关性分析,进水NH+4-N和PO3-4-P浓度与其对应去除量之间极显著相关;青萍FW与NH+4-N去除速率之间显著负相关,但与PO3-4-P去除速率之间不存在显著相关性;NH+4-N进水浓度与去除速率相关性不显著,但PO3-4-P进水浓度与去除速率显著正相关。 相似文献
393.
Yingzhe Du Shengyong Lu Zheng Peng Xiaodong Li Jianhua Yan 《Journal of the Air & Waste Management Association (1995)》2013,63(2):230-236
Over the past decades in China, the number of medical waste incinerators (MWIs) has been rising rapidly, causing emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). In this study, samples of fly ash, ash deposits, and bottom ash from typical MWIs were analyzed for PCDD/Fs and their distribution characteristics. Results showed international toxic equivalent (I-TEQ) values in the range of 6.9–67 ng I-TEQ/g in fly ash and ash deposits, whereas the concentration in bottom ash was extremely low (only 1.33 pg I-TEQ/g), yet the generation of PCDD/Fs was mostly de novo synthesis in fly ash and ash deposits according to the ratio of PCDFs to PCDDs; the major distribution differences of PCDD/Fs in fly ash was manifested by the content of toxic furan 2,3,7,8-TCDF, but other toxic PCDD/Fs showed similar distribution. Other findings are that 2,3,4,7,8-PeCDF had the most contribution to TEQ concentration, and that the most abundant toxic furan congener is 1,2,3,4,6,7,8-HpCDF. Correlation analysis showed that there was no significant correlation between PCDD/Fs concentration and several other physical and chemical parameters.
Implications: This paper is of interest because it presents the emission performances of PCDD/Fs in ash from medical waste incineration in China. PCDD/F contents in fly ash and ash deposits vary between 6.9 and 67.3 ng I-TEQ/g. However, the concentration in bottom ash was extremely low (only 1.33?×?10?3 ng I-TEQ/g). The fingerprints of PCDD/Fs in fly ash are almost similar, except for 2,3,7,8-TCDF. There is no marked correlation between PCDD/Fs and other physicochemical properties. Supplemental Materials: Supplemental materials are available for this paper. Go to the publisher's online edition of the Journal of the Air & Waste Management Association. 相似文献
394.
低浓度含砷污酸处理工艺的比较研究 总被引:1,自引:0,他引:1
比较研究了石灰中和法和石灰-铁盐法对硫化后含低浓度砷(20~50 mg/L)污酸的处理效果。结果表明,单纯采用石灰法,废水难以达标排放;而两段石灰-铁盐(氯化铁)法满足达标排放的同时,一段及二段沉淀物的浸出液中砷、镉、铜、铅和锌含量均低于危险废物鉴别标准要求(GB 5085.3-2007);其最优工艺参数为一段终了pH=2,反应时间为2 h,二段终了pH=8、Fe/As=8、反应时间为60 min、氧化剂投加量(Ca(ClO)2/As)为6∶1;正交实验结果中各参数对铁盐除砷效果影响顺序为终了pH>反应时间>Fe/As>氧化剂投加量。 相似文献
395.
以甲醛、苯甲醛为交联剂,制备交联壳聚糖树脂,再与锆(Ⅳ)离子反应制备锆负载交联壳聚糖吸附剂。采用静态吸附法考察了该吸附剂对水中硫酸根离子(SO24-)的吸附性能。实验发现,吸附时间2 h,SO24-溶液初始浓度500 mg/L,pH值3.0,溶液温度35℃为较优的吸附条件;吸附过程符合Langmuir等温吸附模型,属于优惠吸附型,吸附容量可达78.65 mg/g;吸附过程较好地符合拟二级动力学模型;锆负载前后交联壳聚糖对硫酸根的吸附量提高了约4.5倍;该吸附剂具有良好的耐酸性和再生性能。 相似文献
396.
397.
398.
The colloid-associated plutonium-239, as the dominant species of Pu in natural environment, was formed through sorption of Pu onto in situ colloids. In case of chemical perturbations present in pore water, the fate and transport of Pu would be therefore impacted by changes in sorption affinity of Pu for the colloid surfaces. The present study reveals that colloidal 239Pu exhibited the kinetic stability in two respects. First, in situ colloids isolated from the vadose zone sediments at Lop Nor, when in contact with solutions of high ion concentrations or low pH, were significantly aggregated and then exhibited fast settling. Kinetics settling characteristics were described by the parameters, including settling index and characteristic time. Second, Pu dissociation from colloid surfaces occurred immediately after the introduction of Na+. However, the dissolved species was still unstable and had the potential for re-association with the fraction of colloids that had not settled out from the suspensions due to small size and then remained in suspension. This implies that Pu sorption sites on initial colloids were changed to the sites of suspended colloids. 相似文献
399.
天然沸石同步去除水中氨氮和磷酸盐 总被引:1,自引:0,他引:1
通过静态吸附实验考察了浙江缙云产天然沸石对溶液中氨氮和磷酸盐的同步去除能力及机制,结果表明,天然沸石对溶液中氨氮的吸附过程较好地满足拟二级动力学模型、Langmuir和Dubinin-Radushkevich等温吸附模型。天然沸石对磷酸盐的去除能力随溶液中初始氨氮浓度的增加而增加。当溶液pH由7.0增加到9.0时,天然沸石对氨氮的吸附能力随之增加,而当pH由9.0增加到10时,天然沸石对氨氮的吸附能力则下降。当溶液pH低于7.5时,天然沸石对溶液中的磷酸盐无去除能力,当溶液pH位于7.5~9.0时,天然沸石对磷酸盐的去除能力随pH的增加急剧增加,当溶液pH大于9.0时,天然沸石对磷酸盐的去除能力随pH的增加则呈下降趋势。天然沸石对溶液中氨氮和磷酸盐的同步去除过程是自发进行、吸热及熵增加的过程。天然沸石对溶液中氨氮的吸附机制为离子交换,对磷酸盐的去除机制则为化学沉淀作用。 相似文献
400.