氮杂环化合物吡啶在不同条件下的降解及共代谢研究

通过摇瓶试验研究了氮杂环化合物吡啶在曝气吹脱、好氧、缺氧和厌氧条件下的降解规律以及吡啶与喹啉、2-甲基吡啶、苯胺、茚和萘共代谢条件下在A2/O工艺中的去除规律。研究结果表明:经过24h曝气,吡啶去除率达到了26.9%,曝气吹脱对吡啶的去除作用明显;150mg/L吡啶在缺氧、好氧和厌氧条件下分别需经过3h、6h和24h达到较低浓度水平,在不同条件下的去除速率分别为缺氧>好氧>厌氧。共代谢条件下在A2/O工艺中吡啶的去除受到其他共代谢物质的抑制,在HRT=30h的A2/O工艺中,吡啶去除率仅为41%。     

A2/O2工艺处理氮肥废水短程硝化动力学研究

在中试装置中以A2/O2工艺(缺氧-厌氧-微氧-好氧)处理氮肥废水,通过控制运行条件实现稳定的亚硝酸氮积累后,采用间歇试验的方法,以微氧池中富含亚硝化菌的活性污泥为试验对象,研究了该工艺在常温下处理氮肥废水的短程硝化动力学特性,分别考察了氨氮的降解特征以及MLSS与MLVSS之间的关系,并分析了SVI、ORP对氨氮去除的影响,建立了短程硝化动力学方程.     

AAOBR处理屠宰废水实验研究

采用厌氧-缺氧-好氧折流生物反应器(AAOBR)处理屠宰废水,在不同流量下均取得了较好的处理效果.其中低流量下COD去除率为96.3%,ABR段SS去除率为90%;较高流量下COD去除率为93.8%,ABR段SS去除率为80.6%.同时探讨了AAOBR处理屠宰废水中COD、SS的去除规律.实验表明,AAOBR适宜处理屠...     

厌氧-好氧法污水处理厂优化运行数值模拟研究

利用FCASM3-Hydro耦合模型分别模拟研究了氧传递系数(K_(La))、污泥停留时间(SRT)、缺氧池与好氧池HRT比对杭州某厌氧-好氧法(A/O)污水处理厂营养物质去除效果的影响.结果表明,曝气量大小是影响A/O脱氮除磷效果的主要因素,在低曝气量(<2g·m~(-3))水平下,氨氮去除率将随着好氧池内曝气量的增加而提高;好氧池内曝气量过低(<0.3 g·m~(-3))或过高(>2 g·m~(-3)),都不利于磷酸盐的去除.通过对比分析模拟结果得到了该A/O污水处理厂的最佳运行工况为:K_(La)=250D~(-1)、SRT=10d,缺氧池与好氧池HRT比为1:8.     

A2/O-BAF反硝化脱氮除磷双污泥系统的二次启动特性

采用A~2/O-BAF双污泥系统,考察池容比(V_(厌氧):V_(缺氧):V_(好氧))分别为3:5:2和1:3:1时对搁置2个月的活性污泥去除污染物性能的恢复情况。结果表明,2种池容比对COD和NH_4~+-N的去除性能恢复影响较小。V_(厌氧):V_(缺氧):V_(好氧)=3:5:2更有利于TN和PO_4~(3-)P的去除性能恢复,其出水TN和PO_4~(3-)-P在第7天和第4天分别达到14.20 mg/L和0.42 mg/L,TN、PO_4~(3-)-P去除率分别为80.47%、92.02%。拟合方程分析厌氧释磷和缺/好氧吸磷的小试结果表明:V_(厌氧):V_(缺氧):V_(好氧)=3:5:2的厌氧释磷量和缺氧吸磷量更高,且吸磷速率更快。即V_(厌氧):V_(缺氧):V_(好氧)=3:5:2更有利于A~2/OBAF系统的二次启动。     

倒置A~2/O池容比对猪场消化液脱氮除磷的影响

利用倒置A~2/O工艺处理猪场废水厌氧消化液,研究了该工艺缺氧、厌氧、好氧池容比对低C/N猪场废水厌氧消化液脱氮除磷的影响。在总水力停留时间相同的前提下,实验设定工况1～工况4缺氧、厌氧、好氧池容比分别为(3:2:4)、(3:1:4)、(1:3:4)和(1:1:4)。结果表明,在处理低C/N猪场废水厌氧消化液时,池容比对厌氧消化液中COD、NH4+-N、TN和TP等污染物去除效果差异明显。在好氧段充分硝化的条件下,选择合适缺氧、厌氧池容比,能够提高倒置A~2/O工艺系统对低C/N厌氧消化液的脱氮除磷效率。工况1对污染物总体去除效果最好,该运行工况下COD、NH_4~+-N、TN和TP的平均去除率分别达到了88.75%、80.12%、65.33%和62.53%。     

生物膜法A~2/O~2焦化废水处理系统缺氧反应器工艺特性

以焦化厂废水处理系统气浮设备出水为试验废水水源,在中试规模上研究了生物膜法A2/O2(厌氧/缺氧/好氧/好氧)系统中缺氧反应器的工艺特性和效果。缺氧反应器为以陶粒作填料的上流式滤池。研究结果表明,缺氧反硝化对去除焦化废水中COD有重要作用。反硝化菌可利用一些好氧微生物和厌氧微生物都难以降解的焦化废水中的有机物作碳源,反硝化反应器可去除进水中40%的COD。缺氧反硝化反应器进水碳氮质量比在5以上就可基本满足焦化废水反硝化对碳源的需求。稳定运行状况下的NO3--N容积负荷不大于0.24 kg/(m3.d)。缺氧反应器的水力停留时间不小于24 h。系统进水COD、NH3-N的质量浓度分别在1 000～2 200、200～400 mg/L范围内,对系统进水不进行稀释的条件下,水解酸化反应器HRT为20 h,缺氧反应器HRT为24 h,一级好氧反应器和二级好氧反应器HRT均为48 h,二级好氧反应器硝化液回流比为3时,生物膜法A2/O2系统处理出水的COD和NH3-N可以同时达到《污水综合排放标准》(GB8978-1996)中的一级排放标准。     

分段进水一体化工艺同步硝化反硝化脱氮影响因素研究

以考察分段进水一体化工艺脱氮的影响因素及脱氮能力为目的,研究了进水流量比(厌氧区∶缺氧区)、好氧区溶解氧(DO)浓度、水力停留时间(HRT)(固定厌氧区和缺氧区进水流量比为3∶1)对工艺的同步硝化反硝化(SND)的影响,同时运用动力学模型对工艺的脱氮能力进行了模拟分析。试验结果表明:厌氧区和缺氧区进水量比为3∶1时,总氮去除率最高,平均去除率在86%以上;好氧区DO质量浓度约为2.0 mg/L时,总氮去除率最高,平均去除率在85%以上;保持厌氧区和缺氧区进水流量比为3∶1, HRT为12 h时,总氮去除率最高,平均去除率在86%左右;对脱氮动力学进行了研究,反硝化速率方程为R=-1.87×10-3X,总氮降解常数为1.87×10-3 h-1。     

染料分散大红S-BWFL生物降解特性研究

在好氧、厌氧、厌氧/好氧条件下,采用活性污泥法降解染料分散大红S-BWFL。实验结果表明分散大红S-BWFL在厌氧条件下降解效率最高,厌氧/好氧交替条件次之,好氧条件下降解效率最低。进水染料浓度100 mg/L时,染料12 h去除率最高为94.45%;随着染料浓度的增加,微生物对染料的降解效率逐渐下降,进水染料浓度500 mg/L时,染料12 h去除率最高为75.03%;分散大红S-BWFL降解最佳初始p H为8。GC-MS测得分散大红S-BWFL生物降解中间产物有对硝基苯胺、邻苯二甲酸单(2-乙基己基)酯和对硝基苯甲醚。     

生物转鼓过滤器反硝化去除NO的模型研究和实验验证

在厌氧条件下,对利用生物转鼓过滤器(Rotating Drum Biofilter,简称RDB)反硝化净化一氧化氮(NO)废气的过程进行了理论模型探讨,并用实验结果进行了验证.在分析NO在RDB内的传质-反应过程基础上,建立了滤料微单元内NO在气相、液相内的质量守恒方程,结合生物膜内NO的传质方程和厌氧条件下的Monod微生物反应动力学方程,最终得到了NO在RDB中的浓度分布方程及NO去除效率方程.模型计算值与实验结果比较表明,两者去除效率的变化趋势互为一致,模型能够较好地描述RDB对低浓度(<600 mg·m-3)NO的去除过程,但因模型未考虑RDB内营养液对NO的吸收作用等因素,模型计算值比实验结果约低10%.     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.