负载型燃烧催化剂La_(0.8)Ce_(0.2)CoO_3/Ce_(0.8)Zr_(0.2)O_2制备及性能研究

以复合氧化物La0.8Ce0.2CoO3为活性组分,Ce0.8Zr0.2O2固溶体为载体,采用柠檬酸络合法制备出负载型燃烧催化剂La0.8Ce0.2CoO3/Ce0.8Zr0.2O2。用XRD、BET和SEM对其进行表征,考察了焙烧温度、反应时间、反应温度及H2S存在对催化剂活性的影响。结果表明,载体表面形成了均一的钙钛矿相;该负载型催化剂对二甲苯完全氧化反应具有较高的催化活性,有良好的热稳定性、操作稳定性和强的抗H2S毒化能力。这可能是载体与负载组分之间密切的协同作用所导致。     

Fe3O4@SiO2-NH2磁性复合材料对水中单宁酸的吸附性能研究

通过简单方法制备出Fe3O4@SiO2-NH2磁性复合材料,并利用XRD、FT-IR、VSM和SEM等手段对其物理化学性质进行了表征,最后对水中单宁酸进行了吸附性能研究.结果表明,所制备复合材料上的氨基基团(N—H的特征吸收峰出现在1549.53cm-1)能够与单宁酸上的酚羟基反应,使—NH2质子化形成NH+3,并利用良好的磁性(42.5emu.g-1)使单宁酸从水中分离去除;对单宁酸的吸附符合Langmuir吸附模型和拟二级吸附动力学方程;在pH=6时,基于氢键和静电吸附的协同作用,吸附能力达到最强,为85.18mg.g-1(吸附温度为25℃,吸附时间为60min).研究证实,Fe3O4@SiO2-NH2磁性复合材料与Fe3O4@SiO2和SiO2相比,对单宁酸有更好的吸附性能,同时通过外磁场可以达到固液分离的效果.     

厌氧水解酸化-好氧氧化A1/A2/O工艺剩余污泥减量

在碱减量印染废水A₁/A₂/O生物处理系统,通过污泥回流、把剩余污泥回流到A₁段,利用A段污泥的水解、酸化和O段微生物的好氧氧化作用可有效实现对回流剩余污泥的减量,同时O段好氧污泥的表观产率系数下降,系统产生的剩余污泥量减少.厌氧水解酸化-好氧氧化A₁/A₂/O工艺实现污泥减量由3段共同完成:A₁段实现回流剩余污泥的“液化”和惰性化;A₂段对系统污泥减量起到了强化作用;而O段微生物的合成作用在逐渐减弱.6个月连续运行的动态试验表明,在A₁段的容积负荷(COD_Cr)为2.54 kg·(m³·d)^-1、水力停留时间为7.56h条件下,A₁段利用水解酸化作用对回流剩余污泥的减量达到67.87%,系统O段好氧污泥的表观产率系数也下降到试验初始时的45.5%.在A₁/A₂/O污泥减量系统中,各段污泥性状发生了变化,A₁段污泥[MLVSS/MLSS]值从试验开始时的0.718 2下降到0.592 2,A₂段污泥[MLVSS/MLSS]值从0.667 3下降到0.526 7,剩余污泥的减量是活性污泥逐渐惰性化过程,污泥的粒度分析也证明了这一点.     

Emissions of SO2, NO and N2O in a circulating fluidized bed combustor during co-firing coal and biomass

This paper presents the experimental investigations of the emissions of SO2, NO and N2O in a bench scale circulating fluidized bed combustor for coal combustion and co-firing coal and biomass. The thermal capacity of the combustor is 30 kW. The setup is electrically heated during startup. The influence of the excess air, the degree of the air staging, the biomass share and the feeding position of the fuels on the emissions of SO2, NO and N2O were studied. The results showed that an increase in the biomass shares resulted in an increase of the CO concentration in the flue gas, probably due to the high volatile content of the biomass. In co-firing, the emission of SO2 increased with increasing biomass share slightly, however, non-linear increase relationship between SO2 emission and fuel sulfur content was observed. Air staging significantly decreased the NO emission without raising the SO2 level. Although the change of the fuel feeding position from riser to downer resulted in a decrease in the NO emission level, no obvious change was observed for the SO2 level. Taking the coal feeding position R as a reference, the relative NO emission could significantly decrease during co-firing coal and biomass when feeding fuel at position D and keeping the first stage stoichiometry greater than 0.95. The possible mechanisms of the sulfur and nitrogen chemistry at these conditions were discussed and the ways of simultaneous reduction of SO2, NO and N2O were proposed.     

污泥基生物炭提升活性污泥系统处理性能

对污泥基生物炭提升活性污泥系统处理性能进行探讨,将活性炭和污泥基生物炭分别投入A²O工艺厌氧池活性污泥,发现其对COD削减率最高分别为72.9%和41.1%,均能有效削减,生物炭对TN削减率最高为74.1%,优于活性炭.表征显示污泥基生物炭上更易附着活性污泥且比表面积更大.在A²O小试厌氧池中以"1次/污泥龄"为频率投加活性炭、污泥基生物炭和脱脂污泥基生物炭,结果发现:投加污泥基生物炭对COD、TN、TP的削减均优于活性炭,投加脱脂污泥基生物炭对COD、TN的削减与投加活性炭相当,对TP平均削减率高达85.6%,优于活性炭,表明生物炭处理(BT)工艺比粉末活性炭处理(PACT)工艺处理生活污水能力更强,脱脂污泥基生物炭作为污泥脂质提取后的副产品更经济.     

双氰胺对冬闲稻田和油菜地N2O排放的影响

冬季的温室气体排放往往被忽视,而最新的研究结果表明,冬闲稻田和冬季油菜地N_2O排放仍较大,研究相应的减排措施及减排机制对于减少农田土壤N_2O排放有重要意义.在中国科学院桃源农业生态试验站选择冬闲稻田和油菜地两种不同土地利用方式,并设置添加和不添加双氰胺(DCD)处理,采用静态箱采集和气相色谱法结合监测N_2O排放动态,利用分子生物学手段分析氨氧化古菌(AOA)和氨氧化细菌(AOB)的群落结构和丰度变化.结果表明,添加DCD后明显抑制了冬闲稻田和油菜地N_2O排放,分别减少了36.7%和23.6%.DCD施入抑制了冬闲稻田AOA和AOB的丰度但只改变AOA的群落结构,DCD使AOA和AOB丰度分别减少了59.3%和73.7%.与此相反,添加DCD只改变油菜地AOB的群落结构同时只抑制了AOB的丰度.本研究表明,施加DCD能有效减少冬闲稻田和冬季油菜地N_2O排放,但减排机制不一致.     

Promoting effect of vanadium on catalytic activity of Pt/Ce–Zr–O diesel oxidation catalysts

A series of Pt–V/Ce–Zr–O diesel oxidation catalysts was prepared using the impregnation method. The catalytic activity and sulfur resistance of Pt–V/Ce–Zr–O were investigated in the presence of simulated diesel exhaust. The effect of vanadium on the structure and redox properties of the catalysts was also investigated using the Brunauer–Emmett–Teller method,X-ray diffraction, H2temperature-programmed reduction, CO temperature-programmed desorption, X-ray photoelectron spectroscopy, and Energy Dispersive Spectroscopy. Results showed that the Pt particles were well dispersed on the Ce–Zr–O carrier through the vanadium isolation effect, which significantly improved the oxidation activity toward CO and hydrocarbons. An electron-withdrawing phenomenon occurred from V to Pt, resulting in an increase in the metallic nature of platinum, which was beneficial to hydrocarbon molecular activation.     

Anoxic phosphorus removal in a pilot scale anaerobic-anoxic oxidation ditch process

The anaerobic-anoxic oxidation ditch (A²/O OD) process is popularly used to eliminate nutrients from domestic wastewater. In order to identify the existence of denitrifying phosphorus removing bacteria (DPB), evaluate the contribution of DPB to biological nutrient removal, and enhance the denitrifying phosphorus removal in the A²/O OD process, a pilot-scale A²/O OD plant (375 L) was conducted. At the same time batch tests using sequence batch reactors (12 L and 4 L) were operated to reveal the significance of anoxic phosphorus removal. The results indicated that: The average removal efficiency of COD, NH₄⁺, PO₄³⁻, and TN were 88.2%, 92.6%, 87.8%, and 73.1%, respectively, when the steady state of the pilotscale A²/O OD plant was reached during 31–73 d, demonstrating a good denitrifying phosphorus removal performance. Phosphorus uptake took place in the anoxic zone by poly-phosphorus accumulating organisms NO₂⁻ could be used as electron receptors in denitrifying phosphorus removal, and the phosphorus uptake rate with NO₂⁻ as the electron receptor was higher than that with NO₃⁻ when the initial concentration of either NO₂⁻ or NO₃⁻ was 40 mg/L.     

官厅水库入库水生物接触A/O工艺低温试验研究

试验表明,生物接触A/O工艺可以在低温下稳定运行,对官厅水库入库水中NH₄⁺-N有较好的去除效果,对COD、TN均有一定的去除效果.当温度大幅下降时,在温度下降初期NH₄⁺-N去除率明显下降,但经过一段时间后,NH₄⁺-N去除率逐渐回升,并稳定在较高的去除率水平.在本试验条件下,0～5℃时,进水N₄⁺-N为10mg/L左右,NH₄⁺-N去除率最终稳定在95%以上,出水NH₄⁺-N稳定＜0.5mg/L.另外,温度变化对COD去除效果的影响不明显.镜检结果表明,在0～5℃条件下生物膜中的微生物仍具有较好的活性.     

低溶解氧污泥微膨胀节能方法在A/O中的试验验证

采用实际的生活污水,在A/O系统中验证了低溶解氧污泥微膨胀节能理论与方法.结果表明,A/O系统在微膨胀运行期间SVI值能稳定维持在150～230 mL/g之间,单纯低溶解氧不会造成污泥沉降性能的严重恶化.相对于高溶解氧、污泥沉降性能良好时的运行情况,微膨胀期间COD和总氮去除率略有升高,分别为86%和63%,氨氮去除率略有下降,平均为70%,且约有10%～25%的氮可通过同步硝化反硝化去除.丝状菌的网捕作用使出水的SS浓度明显减低,出水浊度低于3 NTU.维持DO=0.5 mg/L所需的理论供气量相对DO=2.0 mg/L时可节约17%,对实际的小试结果比较发现可节约57%的曝气量.