H2O2对循环半干法烟气脱硫效率的影响分析

通过循环半干法烟气脱硫技术在某热电厂130t／h机组上的应用,分析了H2O2对循环半干法烟气脱硫效率的影响。结果表明：对于循环半干法烟气脱硫,在脱硫剂中添加少量的氧化性物质H2O2,控制H2O2水溶液浓度为1％左右增湿脱硫剂,在合适的运行条件下．当Ca／S（mol／m01）=1．1左右时,可以达到90％以上的脱硫效率。     

载2,4-DCP粉末活性炭微波再生的影响因素

2,4-DCP(2,4-二氯苯酚)是一种具有代表性的氯酚类化合物,在我国和欧美等国的饮用水水质标准中,氯酚类化合物都被列为优先控制污染物。实验以2,4-DCP溶液作为给水中难降解有机物的模拟水样,使用粉末活性炭(PAC)对其吸附至饱和后进行微波辐照再生,探讨了影响活性炭再生效果的诸多因素。以N2为载气的正交实验结果表明:在微波功率为800 W,再生时间为3 min,载气流量为0.6 L/min的控制条件下可得到最佳的再生效果;另选CO2为载气对活性炭再生进行比照实验,结果表明CO2载气的再生效果略优于N2,具有活化作用。     

Selective removal of 2,4-dichlorophenoxyacetic acid from water by molecularly-imprinted amino-functionalized silica gel sorbent

A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid(2,4-D) was prepared by a surface imprinting technique in combination with a sol-gel process.The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR,nitrogen adsorption and static adsorption experiments.The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol(2,4-DCP) mixture or using an aqueous 2...     

Catalytic performance of Fe3O4-CoO/Al2O3 catalyst in ozonation of 2-(2,4-dichlorophenoxy)propionic acid, nitrobenzene and oxalic acid in water

Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe(NO3) 3·9H2O and Co(NO3) 2·6H2O as the precursors,and its catalytic performance was investigated in ozonation of 2-(2,4-dichlorophenoxy) propionic acid(2,4-DP) ,nitrobenzene and oxalic acid.The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation eciency during the degradation of each organic pollutant,and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism.The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance.In the catalytic ozonation of 2,4-DP,the apparent reaction rate constants(k) were determined to be 1.456×10-2 min-1 for ozonation alone and 4.740×10-2 min-1 for O3/Fe3O4-CoO/Al2O3.And O3/Fe3O4-CoO/Al2O3 had a larger Rct(6.614×10-9) calculated by the relative method than O3 did(1.800×10-9) ,showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical.Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid.The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree.     

Iron-doped Mn-Ce/TiO2 catalyst for low temperature selective catalytic reduction of NO with NH3

The catalysts of iron-doped Mn-Ce/TiO 2(Fe-Mn-Ce/TiO 2) prepared by sol-gel method were investigated for low temperature selective catalytic reduction(SCR) of NO with NH 3.It was found that the NO conversion over Fe-Mn-Ce/TiO 2 was obviously improved after iron doping compared with that over Mn-Ce/TiO 2.Fe-Mn-Ce/TiO 2 with the molar ratio of Fe/Ti = 0.1 exhibited the highest activity.The results showed that 96.8% NO conversion was obtained over Fe(0.1)-Mn-Ce/TiO 2 at 180°C at a space velocity of 50,000 hr 1.Fe-Mn-Ce/TiO 2 exhibited much higher resistance to H 2 O and SO 2 than that of Mn-Ce/TiO 2.The properties of the catalysts were characterized using X-ray diffraction(XRD),N 2 adsorption,temperature programmed desorption(NH 3-TPD and NOx-TPD),and Xray photoelectron spectroscopy(XPS) techniques.BET,NH3-TPD and NOx-TPD results showed that the specific surface area and NH3 and NOx adsorption capacity of the catalysts increased with iron doping.It was known from XPS analysis that iron valence state on the surface of the catalysts were in Fe3+ state.The doping of iron enhanced the dispersion and oxidation state of Mn and Ce on the surface of the catalysts.The oxygen concentrations on the surface of the catalysts were found to increase after iron doping.Fe-Mn-Ce/TiO2 represented a promising catalyst for low temperature SCR of NO with NH3 in the presence of H2 O and SO2.     

Cover crop effects on nitrous oxide emission from a manure-treated Mollisol

Agriculture contributes 40–60% of the total annual N₂O emissions to the atmosphere. Development of management practices to reduce these emissions would have a significant impact on greenhouse gas levels. Non-leguminous cover crops are efficient scavengers of residual soil NO₃, thereby reducing leaching losses. However, the effect of a grass cover crop on N₂O emissions from soil receiving liquid swine manure has not been evaluated. This study investigated: (i) the temporal patterns of N₂O emissions following addition of swine manure slurry in a laboratory setting under fluctuating soil moisture regimes; (ii) assessed the potential of a rye (Secale cereale L.) cover crop to decrease N₂O emissions under these conditions; and (iii) quantified field N₂O emissions in response to either spring applied urea ammonium nitrate (UAN) or different rates of fall-applied liquid swine manure, in the presence or absence of a rye/oat winter cover crop. Laboratory experiments investigating cover crop effects N₂O emissions were performed in a controlled environment chamber programmed for a 14 h light period, 18 °C day temperature, and 15 °C night temperature. Treatments with or without a living rye cover crop were treated with either: (i) no manure; (ii) a phosphorus-based manure application rate (low manure): or (iii) a nitrogen-based manure application rate (high manure). We observed a significant reduction in N₂O emissions in the presence of the rye cover crop. Field experiments were performed on a fine-loamy soil in Central Iowa from October 12, 2005 to October 2, 2006. We observed no significant effect of the cover crop on cumulative N₂O emissions in the field. The primary factor influencing N₂O emission was N application rate, regardless of form or timing. The response of N₂O emission to N additions was non-linear, with progressively more N₂O emitted with increasing N application. These results indicate that while cover crops have the potential to reduce N₂O emissions, N application rate may be the overriding factor.     

碳源类型对A~2O系统脱氮除磷的影响

采用52.5 L的A2O反应器,以乙酸和丙酸分别作为进水唯一碳源,系统研究了进水碳源类型对脱氮除磷和代谢过程的影响.结果表明,在进水COD为250 mg/L左右,NH+4-N为52 mg/L左右的条件下,原水碳源类型对TN的去除影响不大,系统TN去除率均在65%左右.进水碳源类型对TP的去除及相应污泥中PHA的类型、含量和代谢及糖原的变化影响较大.乙酸为唯一碳源时,厌氧区放磷浓度较高,污泥中PHA的成分主要为PHB和PHV,两者在厌氧区的合成量差别不大,PHB在随后的反应过程中变化较大,对除磷代谢过程起主要作用,而PHV的变化较小.丙酸作为进水唯一碳源时,厌氧区的放磷浓度偏低,主要合成PHV,几乎不含PHB,PHV在随后吸磷过程中浓度变化较大,对除磷代谢起主要作用,而且出水TP浓度偏低.碳源类型对污泥中糖原的代谢也有影响,乙酸为碳源时糖原的含量高,变化范围也较大,丙酸为碳源时糖原的变化幅度较小.在同步脱氮除磷系统中,与乙酸相比,丙酸是一种更合适的碳源.     

基于不同土壤数据单元法的DNDC模型对太湖地区水稻土CH4排放模拟研究

利用农业土壤痕量气体排放模型DNDC(DeNitrification-DeComposition),以整个太湖地区37个县234万hm2水稻土为例,分析了3种不同土壤数据单元法对CH4排放模拟的影响.其中,1∶5万图斑单元法土壤属性来自1∶5万土壤数据库,图斑为最小模拟单元;1∶5万"县级"单元法土壤属性也取自1∶5万土壤数据库,"县"为最小模拟单元;1∶1 400万"县级"单元法土壤属性取自国内同类研究使用最多的1∶1 400万土壤图和《中国土种志》,"县"为最小模拟单元.结果表明,虽然1∶5万图斑单元法大多数县的CH4排放量都在1∶5万"县级"单元法最大与最小值范围之间,但整个地区总排放量(以C计,下同)相差达到1 680 Gg;而1∶1 400万"县级"单元法CH4排放量与1∶5万图斑单元法相比,尽管整个地区总排放量只相差180 Gg,但各"县级"单元之间的估算差异却很大,这一方面说明了土壤数据的详细程度是保证地球生物化学模型模拟精度的重要因子,另一方面也说明在区域CH4排放量估算模拟中使用更详细的土壤资料是非常必要的.     

流量分配对分段进水A/O工艺脱氮性能的影响

采用分段进水A/O中试脱氮系统处理实际生活污水,为充分利用原水碳源,采用流量分配系数法对进水流量进行分配.在高、低负荷,进水COD/TKN分别为3、 5、 7、 9、 11、 13下,研究流量分配比对分段进水A/O工艺脱氮性能的影响.结果表明,在高负荷、低C/N(COD/TKN＜5)下,按流量分配系数分配流量,会造成系统硝化容量浪费,导致氨氮去除效果下降.而在高负荷、高C/N(COD/TKN＞9),由于首端氨氮负荷过高,氨氮不能完全氧化,导致后段反硝化电子受体不 足,造成系统碳源浪费,结果随C/N提高,总氮(TN)去除率却逐渐降低.而低负荷下,由于不存在硝化限制,系统TN去除率随进水C/N升高而升高,当C/N为13时,出水TN<2 mg/Ｌ,最高TN去除率可达976%.高、低负荷,不同C/N下的试验结果证明,高C/N污水(C/N＞α),采用流量分配系数分配流量,可充分利用原水碳源,提高TN去除效率,但需保证各段硝化完全.而低C/N污水(C/N＜α),C/N是决定TN去除率的关键因素,从保证硝化效果、利于硝化菌生长的角度考虑,不宜采用流量分配系数法分配流量,各段等负荷分配流量是一个可能的选择.     

质粒pJP4水平转移介导生物膜系统强化降解2,4-D效应

以携带质粒pJP4[其上含编码2,4-二氯苯氧基乙酸(2,4-dichlorophenoxyacetic acid,2,4-D)降解功能的基因簇(tfd)]的基因工程菌Pseudomonas putida SM1443::gfp2x(pJP4::dsRed)为供体菌,以生物膜系统为对象,通过半连续流实验研究了质粒pJP4水平转移介导基因强化降解2,4-D效应,考察了目标基因在系统中存在状况及基因强化对系统菌群结构的影响.结果表明,以2,4-D(初始浓度为170 mg/L±10 mg/L)为唯一碳源,向生物膜系统加入携pJP4质粒的基因工程菌对2,4-D的降解具有促进作用,运行初期,促进作用较弱,随着半连续流反应的进行,促进作用显著增强,基因强化系统较对照系统对2,4-D的平均降解速率之差达13.3 mg/(L.h).通过对基因强化系统功能基因片段tfdB基因及报告基因gfp的跟踪检测,证实了在pJP4质粒介导下生物膜系统基因水平转移的发生.PCR-DGGE结果表明基因强化的生物膜系统较对照系统在受到2,4-D冲击条件下保持了相对更加稳定的菌群结构.