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301.
Emission of volatile organic sulfur compounds (VOSCs) during aerobic decomposition of food wastes 总被引:1,自引:0,他引:1
Ting Wu Xinming Wang Dejun Li Zhigang Yi 《Atmospheric environment (Oxford, England : 1994)》2010,44(39):5065-5071
Food wastes collected from typical urban residential communities were investigated for the emission of volatile organic sulfur compounds (VOSCs) during laboratory-controlled aerobic decomposition in an incubator for a period of 41 days. Emission of VOSCs from the food wastes totaled 409.9 mg kg?1 (dry weight), and dimethyl disulfide (DMDS), dimethyl sulfide (DMS), methyl 2-propenyl disulfide, carbonyl sulfide and methyl 1-propenyl sulfide were the five most abundant VOSCs, with shares of 75.5%, 13.5%, 4.8%, 2.2% and 1.3% in total 15 VOSCs released, respectively. The emission fluxes of major VOSCs were very low at the beginning (day 0). They peaked at days 2–4 and then decreased sharply until they leveled off after 10 days of incubation. For most VOSCs, over 95% of their emission occurred in the first 10 days. The time series of VOSC emission fluxes, as well as their significant correlation with internal food waste temperature (p < 0.05) during incubation, suggested that production of VOSC species was induced mainly by microbial activities during the aerobic decomposition instead of as inherited. Released VOSCs accounted for 5.3% of sulfur content in the food wastes, implying that during aerobic decomposition considerable portion of sulfur in food wastes would be released into the atmosphere as VOSCs, primarily as DMDS, which is very short-lived in the atmosphere and thus usually less considered in the sources and sinks of reduced sulfur gases. 相似文献
302.
CPB改性沸石对磷酸盐的吸附-解吸性能研究 总被引:2,自引:1,他引:1
采用溴化十六烷基吡啶(CPB)对天然沸石进行改性,并考察了CPB改性沸石对磷酸盐的吸附-解吸性能。结果表明,CPB改性沸石对磷酸盐具备一定的吸附能力,且吸附行为满足Langmuir等温吸附模型;粒径、改性剂投加量、反应温度、pH值及共存阴离子等因素均会影响CPB改性沸石对磷酸盐的吸附能力;减小粒径和降低反应温度均有利于CPB改性沸石对磷酸盐的吸附去除;粒径≤0.18 mm CPB改性沸石吸附磷酸盐较优的改性剂投加量为250 mmol/kg;当溶液的初始pH值位于4~10之间时CPB改性沸石对磷酸盐的吸附能力随pH值的增加而增强;SO42-的存在会明显降低CPB改性沸石对磷酸盐的吸附效率,而提高溶液的pH值有助于消除SO42-存在对CPB改性沸石吸附磷酸盐的负面影响;HCO3-的存在会一定程度上抑制CPB改性沸石对磷酸盐的吸附去除,而提高溶液的pH值无法消除HCO3-存在对CPB改性沸石吸附磷酸盐的负面影响;CPB改性沸石吸附磷酸盐后一定条件下可以重新解吸出来,且随着解吸液SO42-浓度的增加解吸率明显增大。 相似文献
303.
石膏浆液旋流器的分离性能实验研究 总被引:1,自引:1,他引:0
通过理论分析及工程经验对石灰石/石膏法烟气脱硫工艺中石膏浆液脱水系统的旋流器进行优化设计,在与工业实际相近的操作条件下,优选出了一根综合性能较好的旋流器。考察了该旋流器的压力、流量与分离效率之间相互关系,与常规石膏浆液旋流器的分级效率进行了比较,确定了最佳操作条件。结果表明,旋流器的进口流量随着进出口压力差的增大而增大,分离效率随着流量增加先上升后下降。在进口硫石膏颗粒平均粒径为24μm,流量为11.8~14.8 m3/h时,分离效率在85%以上,底流出口10μm、15μm以下的颗粒分别占底流出口颗粒总体积的1%、10%左右,起到了很明显的分级浓缩作用,分离性能也优于常规使用的石膏浆液旋流器。 相似文献
304.
305.
306.
ACF电极电解处理含NaCl结晶紫染料废水的研究 总被引:3,自引:1,他引:2
以吸附结晶紫达到饱和的活性炭纤维为阳极,在NaCl介质中对初始浓度为100 mg/L的结晶紫染料废水进行了电解脱色处理。实验考察了NaCl浓度、pH值和电流密度等对溶液脱色率的影响,测定了电解时溶液中生成的游离氯浓度及不同电解时间后溶液的紫外-可见吸收光谱曲线,并对不同电解时间后溶液的归一化吸光度比值进行了计算。结果发现,溶液中所产生的游离氯的浓度随电解时间的增加快速上升,20 min时就几乎达到了最大值;在活性氯的作用下,结晶紫分子中的大π共轭体系被破坏,溶液迅速脱色;电解液中所含的NaCl浓度、电解液的pH值和电流密度等都对脱色率有影响;在一定实验条件下,初始浓度为100 mg/L的结晶紫染料废水在电解60 min后脱色率可高达99.3%。 相似文献
307.
The aim of this study was to investigate the mechanism of cadmium (Cd) adsorbed by microalgae Chlamydomonas reinhardtii (C.reinhardtii). The kinetic and adsorption isotherm of the process could be well described by mathematical models. Chemical modification experiments and Fourier transform infrared spectra indicated that carboxyl and amine groups were the important functional groups for adsorption of Cd. The maximum contribution of physical adsorption in the overall adsorption process was evaluated as 5.5%... 相似文献
308.
以坡耕地柑桔园为研究对象,地表覆盖方式采用对照、秸秆覆盖和地膜覆盖3个处理,实验采用完全方案。结果表明,在本实验条件下,坡地地膜覆盖处理一定程度增加了径流量,而秸秆覆盖处理与对照每次降雨径流量基本相当;各处理土壤氮磷养分均有一定程度的流失,以氮素流失量较高,磷素流失量相对较低;在地膜覆盖条件下,柑桔园地表径流中N、P流失量较高,其总氮和总磷流失系数分别达0054%和0064%,而秸秆覆盖总氮和总磷流失系数最低;对不同地表覆盖方式柑桔园地表径流水体氮素形态特征分析表明,可溶性氮素占总氮的比例较高,可溶性氮素中又以NO-3 N为主,而NH+4 N所占的比重较低。以上结果说明,在丹江口库区,氮素污染风险要高于磷,防控的主要矛盾是氮,而秸秆覆盖是减少坡耕地养分流失较好的管理措施 相似文献
309.
Xuefeng Li Qixing Zhou Yi Luo Guang Yang Tong Zhou 《Environmental science and pollution research international》2013,20(2):957-966
Aquatic ecosystems are vulnerable to the exposure with petrochemicals such as toluene, ethylbenzene, and xylene (o-, m-, and p-xylene) (TEX) and their adverse effects. Considering the widespread use, occurrence, and high toxicity of TEX, the aim of this work was to investigate the differential toxicity of TEX against midge (Chironomus plumosus) larvae and reveal the joint action of binary and ternary mixtures of TEX using the predictive concentration addition model. More importantly, this research can afford the basic toxicity data and scientific reference for the establishment of water quality criteria or benchmark, water pollution control, and aquatic risk assessment. Single and joint toxic effects of TEX on C. plumosus larvae were investigated using a semi-static bioassay, and the type of joint effects of TEX was ascertained. In the single toxicant experiments, the toxicity of the three pollutants could be sequenced as ethylbenzene > xylene > toluene. Specifically, LC50s of T, E, and X after a 48-h exposure were 64.9, 37.8, and 42.0 mg/L, respectively. In the binary mixture experiments, the interaction between toluene and ethylbenzene, ethylbenzene and xylene, and toluene and xylene was largely in conformity with partial additive or additive effect as determined by isobologram representation and toxic unit models. In the ternary mixture experiments, the interaction was basically dependent on the use of additive index and mixture toxicity index methods. However, the antagonistic and synergistic actions were not significant. Thus, the tertiary mixture interaction could be regarded as additive action. The concentration addition model could successfully predict the joint action of TEX mixtures on C. plumosus larvae. Particularly, the additive action of TEX on C. plumosus larvae can be further recommended to evaluate water quality criteria of TEX. 相似文献
310.
Gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate bound mercury (PBM) were measured on the University of Mississippi campus from July 2011 to June 2012. It is believed to be the first time that concentrations of atmospheric mercury species have been documented in northern Mississippi, and at a location with relatively large and sudden swings in population. The mean concentration (±1SD) of GEM was 1.54 ± 0.32 ng m−3; levels were lower and generally more stable during the winter (1.48 ± 0.22) and spring (1.46 ± 0.27) compared with the summer (1.56 ± 0.32) and fall (1.63 ± 0.42). Mean concentrations for GOM and PBM were 3.87 pg m−3 and 4.58 pg m−3, respectively; levels tended to be highest in the afternoon and lowest in the early morning hours. During the fall and spring academic semesters concentrations and variability of GOM and PBM both increased, possibly from vehicle exhaust. There were moderate negative correlations with wind speed (all species) and humidity (GOM and PBM). Backward air mass trajectory modeling for the ten highest peaks for each mercury species revealed that the majority of these events occurred from air masses that passed through the northern continental US region. Overall, this study illustrates the complexity of temporal fluctuations of airborne mercury species, even in a small town environment. 相似文献