SBR法短程硝化及过程控制研究

考察采用SBR法处理氨氮浓度较高的化工废水时供氧方式对硝化过程中溶解氧(DO)质量浓度、氧化还原电位(ORP)和pH变化规律的影响.试验结果表明,在曝气流量恒定的条件下,可以硝化过程中DO质量浓度和pH升高速率的不同表征反应的进行程度,即当氨氮浓度接近零时,DO质量浓度和pH升高速率或变化幅度加大,二者可以作为SBR硝化反应时间的控制参数在DO质量浓度恒定的情况下,pH在整个硝化反应过程中都是缓慢下降或趋于稳定的,当硝化反应结束时突然升高,因此pH也可作为SBR硝化反应时间较好的控制参数.     

氢自养还原菌去除地下水中硫酸盐的影响因素研究

采用批式试验研究了以氢气为电子供体的氢自养还原茵对SO42-的还原及其影响因素.结果表明,氢自养还原菌还原SO42-的适宜温度为30～35℃;在pH为7.5～8.0时SO42-还原效果最好,当pH高于9.0时还原菌活性受到影响;提高SO42-负荷,还原速率随之升高,但SO42-去除率降低;NO3-对SO42-还原具有抑制作用,表现为SO42-去除率随NO3-负荷的升高而显著降低.     

SBR法短程硝化及过程控制研究

考察采用SBR法处理氨氮浓度较高的化工废水时供氧方式对硝化过程中溶解氧(DO)质量浓度、氧化还原电位(ORP)和pH变化规律的影响。试验结果表明,在曝气流量恒定的条件下,可以硝化过程中DO质量浓度和pH升高速率的不同表征反应的进行程度,即当氨氮浓度接近零时,DO质量浓度和pH升高速率或变化幅度加大,二者可以作为SBR硝化反应时间的控制参数在DO质量浓度恒定的情况下,pH在整个硝化反应过程中都是缓慢下降或趋于稳定的,当硝化反应结束时突然升高,因此pH也可作为SBR硝化反应时间较好的控制参数。     

FA与FNA对两级UASB-A/O处理垃圾渗滤液短程硝化的影响

采用两级UASB-A/O组合工艺处理实际高氨氮城市生活垃圾渗滤液,在获得稳定的有机物与氮同步去除的前提下,重点考察游离氨(FA)与游离亚硝酸(FNA)对短程硝化稳定性的影响。在UASB1中进行反硝化同时产甲烷以去除部分TN和部分COD,在UASB2通过产甲烷进一步去除COD,在A/O反应器中主要实现高氨氮的短程去除和剩余COD的降解。试验共进行104 d,历经短程硝化稳定、破坏和恢复3个阶段。结果表明,当最小FA浓度控制在3.1 mg.L-1以上时,系统可维持稳定的短程硝化,NH+4-N去除率、NO-2-N积累率、TN去除率分别可达到99%、95%和86%。当FA浓度小于0.6 mg.L-1时,在原水碱度充足且过曝气的条件下,仅依靠FA对NOB的抑制作用,难于维持短程硝化,NO-2-N积累率下降到29%。前两阶段的FNA浓度均低于0.011 mg.L-1,没有对NOB起到抑制作用,而在第3阶段,FA浓度仍维持在较低浓度,但系统FNA浓度通过降低pH值而大幅度提高(最大值为0.414 mg.L-1),从而利用FA和FNA的协同抑制作用迅速恢复并维持短程硝化,NO-2-N积累率升高到92%。可见FA与FNA是实现并维持城市生活垃圾渗滤液短程硝化的重要影响因素。     

超声作用下碘化钾溶液生成碘速率的影响因素研究

研究了在19.6 kHz的超声场作用下影响碘化钾溶液生成碘单质生成速率的因素.探讨了催化剂钼酸铵、超声输入功率、溶液主体温度及碘化钾初始浓度对碘的生成速率的影响.研究结果表明,当其他条件一定时,碘的生成量随时间线性增加,加入催化剂钼酸铵后碘的生成速率是没有加钼酸铵时碘的生成速率的2倍左右.碘的生成速率vi2(mol·L-1·s-1)随着超声输入电流Iin(A)增加呈线性增加,在温度为35℃、KI水溶液的初始浓度为0.1 mol·L-1、超声输入电流为0.47A～0.87A的声场作用下,有、无催化剂钼酸铵存在时,vI2和Iin的关系分别为:VI2=3.18×10-8Iin和vI2=1.48×10-8Iin.碘的生成速率随着溶液主体温度的升高而下降,温度从15℃升到55℃,在无钼酸铵存在时,碘的生成速率vI2从1.55×10-8降至4.6×10-9 mol·L-1·s-1;有钼酸铵时,v12从2.73×10-8降至1.49×10-8 mol·L-1·s-1.碘化钾初始浓度增加,碘的生成速率增大,但当其增加至一定的浓度后,碘的生成速率趋于恒定.     

高分散性纳米级Fe0/BAC-cH2-t催化剂催化还原NO

以椰壳活性炭为载体,采用氢气还原法制备出高分散性纳米级零价铁催化剂,采用固定床反应器研究了其对NO催化还原能力。采用XRD、TEM、SEM、XPS等分析手段对催化剂的微纳结构进行表征,考察了催化剂制备过程中H2浓度及煅烧还原温度对催化剂分散性、催化还原NO性能影响,催化剂的再生以及CO对催化剂还原NO的影响,并对CO还原NO反应机理进行推测。结果表明,催化剂活性随着H2浓度的增加逐渐增强,随着煅烧还原温度的升高先升高后降低。当H2浓度为100%时,在700℃煅烧温度下制备出的催化剂,Fe0粒径达到9 nm且均匀分散在椰壳活性炭中。Fe0/BAC-100H2-700催化剂在325℃时,NO转化率可以达到100%,表现出了良好的NO脱除效果。还原NO过程中,Fe0逐渐被氧化成Fe3O4导致催化剂最终失活,失活后的催化剂经再生处理后可恢复活性。NO还原反应过程中CO的加入可以还原Fe3O4再次生成Fe0,提供活性位点,有效的延长催化剂的寿命,减缓催化剂失活的速率。     

啤酒废水同步脱氮除磷工艺影响因素研究

通过SBR短程硝化反硝化同步脱氮除磷工艺处理模拟啤酒生产综合废水,为达到稳定的COD、NH4+-N和TP的去除及NO2--N的积累,对该工艺的影响因素进行了研究.结果表明,工艺的稳定运行是由进水COD、pH、DO、温度和MLSS等因素共同作用的结果,其中控制较低的DO的质量浓度(＜0.5 mg·L-1)是实现NO2--N积累的关键因素之一;过低或过高的进水pH、COD均会影响该工艺的正常运行.温度及MLSS含量会影响氨氧化过程与反硝化过程的反应速率,但不是系统稳定运行的决定因素.当DO的质量浓度为0.3～0.5 mg·L-1、进水COD低于1 100 mg· L-1、pH为7.2～8.4,在12～25℃可获得稳定的NO2--N积累.     

低温镀铁层沉积速率的研究

研究了pH值、温度、电流密度以及主盐的质量浓度对低温镀铁层沉积速率的影响.结果表明:当pH值为1.0时,镀层的沉积速率最大;随着温度的升高,电流密度的增加或者镀液中主盐的质量浓度的增加,镀层的沉积速率增大.     

一株氢自养反硝化菌去除地下水硝酸盐的实验研究

从厌氧污泥中分离出一株氢自养反硝化细菌S1,通过模拟地下水环境,考察了硝酸盐浓度、碳源投加量、pH、温度、SO_4~(2-)浓度对该菌株脱氮性能的影响。结果表明,菌株S1为陶厄氏菌属,反硝化过程中最适碳源投加量为0.5 g/L。当NO_3~--N质量浓度100 mg/L,pH=6或SO42-质量浓度90 mg/L时,菌株对NO_3~--N的去除均受到抑制。pH在7～10范围内,随着pH升高,菌株反硝化速率增大;温度在10～30℃范围内,温度越高,菌株反硝化速率越快。     

唑螨酯的水解特性

通过实验室的模拟试验研究了唑螨酯在不同温度、pH值及不同水体条件下的水解动态,以及表面活性剂这一水体常见影响因素对唑螨酯水解的影响.结果表明:在25℃和45℃条件下,pH值的变化对水解速率的影响不大,即水解速率大致相同在5℃时,水解速率随pH值变化有所不同,呈明显负相关.在3种pH值条件下,唑螨酯在水中的降解规律表现为随着温度的升高,水解速率加快,半衰期缩短.唑螨酯在缓冲溶液中的水解速率与在自然河水中的水解速率相似.随着表面活性剂浓度的增大,对于唑螨酯水解的影响越小.当SDBS质量浓度为10 mg/L时的影响最为显著,质最浓度为30、50 mg/L时对唑螨酯水解的影响不大,且两者影响程度相当.     

氢气还原针铁矿去除水中的亚硝酸盐

采用氢气还原天然针铁矿和合成针铁矿制备铁粉,研究了反应时间、反应pH值、初始亚硝酸盐浓度等对两种还原铁粉去除亚硝酸盐的影响。结果表明：反应3 h、低亚硝酸盐初始浓度（〈16 mg/L）、低铁粉与亚硝酸盐质量比（〈33：1）情况下,由合成针铁矿制备的还原铁粉对亚硝酸盐的去除率均高于由天然针铁矿制备出的铁粉,但随着反应时间的延长（〉3 h）、亚硝酸盐初始浓度的增加（〉16 mg/L）、铁粉与亚硝酸盐质量比的增加（〉33：1）,由天然针铁矿制备的还原铁粉对亚硝酸盐的去除率均高于由合成针铁矿制备出的铁粉。Al部分替代天然针铁矿中Fe阻碍了铁粉表面钝化膜的形成,从而增加了还原铁粉还原亚硝酸盐的稳定性,提高了亚硝酸盐的去除率。     

亚硫酸盐去除硝基氧化剂废水中的亚硝酸盐

研究了用亚硫酸盐将亚硝酸盐还原为氮气 ,消除了污染 ,并探索了 p H<3、p H=6～ 7、p H>1 2条件下亚硝酸盐降解率的变化及不同亚硝酸盐与亚硫酸盐的初始浓度比对降解率的影响 ,得出了最佳反应条件为 p H=2 ,亚硫酸盐与亚硝酸盐的最佳投料比为 1 .5 :1 ,使用该法处理硝基氧化剂废水的初始浓度最好在 80 0 mg/L 以下     

好氧聚磷污泥反硝化除磷特性研究

以培养成功的好氧聚磷污泥为研究对象,考察其在硝酸盐或亚硝酸盐存在下的反硝化除磷特性。结果表明,好氧聚磷污泥在在未经厌氧/缺氧驯化条件下已具有良好反硝化聚磷特性。好氧聚磷污泥可利用硝酸盐作为电子受体进行脱氮除磷,在硝酸盐耗尽后停止聚磷,在一定的浓度范围内聚磷量与硝酸盐消耗量具有线性关系。在以亚硝酸盐作为电子受体的条件下,好氧聚磷污泥与反硝化聚磷污泥具有相似特点:在初始亚硝酸盐浓度较低情况下可少量聚磷,在其浓度较高时聚磷受到抑制。亚硝酸盐有可能为解偶联剂,在其还原的过程中并不耦合发生聚磷。反硝化速率随着其硝酸盐或亚硝酸盐初始浓度的升高而降低。     

Nitrate and Nitrite Removal Using a Continuous Heterotrophic Denitrifying Granular Sludge Bioreactor

The denitrification potential of a continuous denitrifying granular‐sludge bioreactor for concentrated nitrate/nitrite wastes was investigated. Granules were cultivated using nitrite as sole electron acceptor. Complete denitrification could be achieved at nitrite, nitrate, and nitrate‐nitrite mixture (50:50) loading rates up to 2.7, 3 and 3 g N L^–1d^–1, respectively. The maximum nitrite and nitrate reduction capacities were limited by the biomass concentration. Removal of nitrate and nitrite was studied with constant biomass concentration at different pH values. A lower pH value resulted in a considerable increase of inhibitory effects of both nitrite and nitrate whereby nitrate exhibited the more significant impact.     

Kinetics of Sulfite Oxidation in the Simultaneous Desulfurization and Denitrification of the Oxidation‐Absorption Process

The kinetics of sulfite oxidation in the simultaneous desulfurization and denitrification of the oxidation‐absorption process was investigated with a bubbling apparatus under the conditions of varying pH, sulfite concentration, nitrite concentration, temperature, and air flow. The results indicate that the oxidation of sulfite is promoted dramatically by mixing with nitrite, due to the decline of the apparent energy of activation and the initiation of nitric dioxide decomposition by nitrite. An increase of the nitrite concentration, the air flow, the reaction temperature, or the pH supports the decomposition of nitrite and the production of nitric dioxide, thus leading to an enhancement of the sulfite oxidation rate. A kinetic model is established according to the experimental results. A satisfactory agreement between the calculated and the experimental values is obtained.     

甲醇为碳源时C/N对反硝化过程中亚硝酸盐积累的影响

如何获得稳定的NO2--N作为厌氧氨氧化细菌的电子受体是城镇污水通过厌氧氨氧化途径脱氮的瓶颈问题。为此考虑利用反硝化途径获取稳定的NO2--N。以甲醇为碳源,采用小试装置的SBR反应器,通过控制进水C/N(COD与NO3--N质量浓度比)的策略,研究了反硝化过程中的NO2--N积累的状况。试验结果表明以甲醇为碳源且投加量不足时(C/N3.2),反硝化过程中和反硝化结束后会产生稳定的NO2--N积累;在C/N不足的前提下,NO2--N积累量随甲醇投加量的增加而增加;进水C/N为2.4～3.2时,可获得约25%的NO2--N积累率;进水C/N为0.8时,NO2--N积累率仅为5.6%;C/N1时,NO2--N与NO3--N的还原速率随着COD浓度的增加而增加;C/N≥1时,COD浓度不再影响NO2--N与NO3--N的还原速率。     

亚硝酸盐的光催化氧化

利用半导体光催化剂Bi2O3 对含亚硝酸盐废水的处理进行了研究，并讨论了影响亚硝酸盐氧化率的主要因素，实验结果表明：选择活性较高的Bi2O3作为光催化剂，当其用量为0.050g，试液PH=3.70,NO2^--N起始浓度为400.0mg/L，光照1h时，亚硝酸盐的氧化率达到97.0%。     

Electrocatalytic reduction of nitrite using ferricyanide; Application for its simple and selective determination

The electrocatalytic reduction of nitrite has been studied by ferricyanide at the surface of carbon paste electrode. Cyclic voltammetry and chronoamperometry techniques were used to investigate the suitability of ferricyanide as a mediator for the electrocatalytic nitrite reduction in aqueous solution with various pH. Results showed that pH 0.00 is the most suitable for this purpose. In the optimum pH, the electrocatalytic ability about 700 mV can be seen and the homogeneous second-order rate constant (k_s) for nitrite coupled catalytically to ferricyanide was calculated 2.75 × 10³ M⁻¹ s⁻¹ by Nicholson-Shain method. Also, electron transfer coefficients (α) for ferricyanide was determined by using various electrochemical approaches such as Tafel plot in the absence and presence of nitrite 0.556 and 0.760, respectively. The catalytic reduction peak current was linearly dependent on the nitrite concentration and the linearity range obtained was 5.00 × 10⁻⁵ to 1.00 × 10⁻³ M. Detection limit has been found to be 2.63 × 10⁻⁵ M (2σ). This method has been applied as a selective, simple and precise method for determination of nitrite in real sample.     

Process Control of an Alternating Aerobic‐Anoxic Sequencing Batch Reactor for Nitrogen Removal via Nitrite

Nitrogen removal via nitrite is a novel technology and is becoming popular for engineering applications since it results in a saving of the aeration energy required for nitritation and external carbon sources for denitritation. An alternating aerobic‐anoxic (AAA) operational pattern was applied in a sequencing batch reactor (SBR) process to improve the nitrogen removal efficiency and achieve partial nitrification via nitrite from industrial wastewater with influent alkalinity deficiencies. The results showed that the online monitoring of the pH‐time variations during nitrification could indicate if the alkalinity was sufficient and when the ammonia nitrogen was completely oxidized. Under conditions of deficient influent alkalinity, the AAA process reduced the external alkalinity and the carbon sources addition and improved the effluent quality with ammonia nitrogen concentration below the detection limits. Half of the alkalinity previously consumed during aerobic nitrification could be recovered during the subsequent anoxic denitrification period. If the cycles of alternating aerobic/anoxic were repeated more than twice, the first nitrification cycle was stopped when the pH decreased by 0.4–0.5. The middle nitrification was terminated when the pH decreased by 0.8–1.0, and the final nitrification duration was controlled by the dissolved oxygen (DO) breakpoint and ammonia valley on the pH profile. Each anoxic time‐scale for denitrification was determined by the nitrate knee on the oxidation‐reduction potential (ORP) profile and the nitrate apex on the pH profiles. In comparison to the conventional SBR process, the AAA process with a real‐time control strategy resulted in an improved nitrogen removal efficiency of greater than 97 % under conditions of deficient influent alkalinity. Moreover, nitrogen removal via nitrite was achieved with a nitrite accumulation rate above 95 %.     

亚硝酸盐对厌氧产酸耦合反硝化工艺的影响

以木薯酒精废水为碳源,通过批次实验研究了亚硝酸盐对厌氧产酸耦合反硝化系统的影响。结果表明,投加600 mg·L^-1 后的最终产酸量与空白反应器相差不大,但是投加相同浓度亚硝酸盐后产酸受到严重抑 制,最终产酸量仅为空白反应器的1.8%。而硝酸盐还原过程中厌氧产酸受到抑制可能是由于反硝化中间产物亚硝酸盐的存在,低投加量的亚硝酸盐即可对厌氧产酸产生强烈的抑制作用并具有持续性,且对各产酸组分的影响作用：正丁酸>丙酸>乙酸。随着 的降低,亚硝酸盐的还原率由74.9%降低至22.2%。当游离亚硝酸（free nitrous acid, FNA）浓度为0.05 mg·L^-1以上时,亚硝酸盐还原几乎被完全抑制（90%以上）。此外,随着 的增加,反硝化所占的比例逐渐减小,而DNRA过程（dissimilatory nitrate reduction to ammonium,异化硝酸盐还原为铵）逐渐占优势。