Aerobic sludge digestion under low dissolved oxygen concentrations.

Low dissolved oxygen (DO) concentrations occur commonly in aerobic digesters treating thickened sludge, with benefits of smaller digester size, much reduced aeration cost, and higher digestion temperature (especially important for plants in colder areas). The effects of low DO concentrations on digestion kinetics were studied using the sludge from municipal wastewater treatment plants in Akron, Ohio, and Los Lunas, New Mexico. The experiments were conducted in both batch digestion and a mixed mode of continuous, fed-batch, and batch operations. The low DO condition was clearly advantageous in eliminating the need for pH control because of the simultaneous occurrence of nitrification and denitrification. However, when compared with fully aerobic (high DO) systems under constant pH control (rare in full-scale plants), low DO concentrations and a higher solids loading had a negative effect on the specific volatile solids (VS) digestion kinetics. Nonetheless, the overall (volumetric) digestion performance depends not only on the specific digestion kinetics, but also the solids concentration, pH, and digester temperature. All of the latter factors favor the low DO digestion of thickened sludge. The significant effect of temperature on low DO digestion was confirmed in the mixed-mode study with the Akron sludge. When compared with the well-known empirical correlation between VS reduction and the product (temperature x solids retention time), the experimental data followed the same trend, but were lower than the correlation predictions. The latter was attributed to the lower digestible VS in the Akron sludge, the slower digestion at low DO concentrations, or both. Through model simulation, the first-order decay constant (kd) was estimated as 0.004 h(-1) in the mixed-mode operations, much lower than those (0.011 to 0.029 h(-1)) obtained in batch digestion. The findings suggested that the interactions among sludges with different treatment ages may have a substantially negative effect on digestion kinetics. The use of multistage digesters, especially with small front-end reactors, may be advantageous in both "process" kinetics and "biological reaction" kinetics for sludge digestion.     

催化铁与生物法耦合除磷工艺特性

为了研究催化铁与生物耦合后对生物除磷特性的影响,实验采用人工配水用厌氧／好氧间歇流式富集培养聚磷微生物。对比发现,催化铁与生物耦合组中厌氧末段ORP降低了约60mV,pH值小幅度的上升（≤0．3）,整个培养过程中铁离子的浓度开始快速增加,之后趋于稳定（约40mgFe／gMLSS）。对好氧末段污泥SVI值比较发现,耦合工艺污泥沉降性能得到改善。除磷曲线比较发现,耦合组中厌氧末段磷的释放量下降,而好氧阶段磷的吸收速率增加;胞内聚合物提取表明,耦合组厌氧末段聚磷菌细胞内PHA含量有提高,好氧末段糖原含量有下降。磷形态提取分析表明,耦合组好氧末段污泥中无机态PO3 4-- P含量更高。低浓度铁离子可以起到与生物耦合同步除磷的目的,本工艺长期运行未发现耦合体系中催化铁对除磷的抑制作用。     

金属铁铝对混凝强化初沉污泥中温厌氧消化的影响简

选取FeCl₃和AlCl₃·6H₂O作为混凝剂对城市污水进行一级强化混凝处理,降低二级生物处理的进水负荷,减少污水生物处理系统的能量消耗。主要研究混凝过程投加的金属盐对一级强化混凝产生的初沉污泥中温厌氧消化的影响。和剩余污泥相比,初沉污泥更适合厌氧消化处理,污泥降解性能和产气性能更高。当采用城市污水一级强化混凝处理时,污泥中的金属和金属盐水解引起的pH降低,使混凝强化初沉污泥的厌氧消化受到一定抑制。随着污泥中铝含量的降低和铁含量的增加,厌氧消化的COD降解率和挥发性固体（VS）降解率逐渐升高,生物气产量逐渐增大,产气速率加快。当混凝强化初沉污泥只含有铁时（铁含量为10.16 mg/L）,混凝强化初沉污泥厌氧消化效果最好,产气稳定,而且产气速率高,生物气产量为237 mL,生物气甲烷含量为55.5%,降解单位VS产气量为0.80 L/g,均高于其他含铝的混凝强化初沉污泥。污泥中的铁对初沉污泥厌氧消化的抑制作用远远小于铝的作用,说明铁盐适合用于城市污水的一级强化混凝处理。     

金属铁铝对混凝强化初沉污泥中温厌氧消化的影响

选取FeCl3和AlCl2·6H2O作为混凝剂对城市污水进行一级强化混凝处理,降低二级生物处理的进水负荷,减少污水生物处理系统的能量消耗。主要研究混凝过程投加的金属盐对一级强化混凝产生的初沉污泥中温厌氧消化的影响。和剩余污泥相比,初沉污泥更适合厌氧消化处理,污泥降解性能和产气性能更高。当采用城市污水一级强化混凝处理时,污泥中的金属和金属盐水解引起的pH降低,使混凝强化初沉污泥的厌氧消化受到一定抑制。随着污泥中铝含量的降低和铁含量的增加,厌氧消化的COD降解率和挥发性固体（Vs）降解率逐渐升高,生物气产量逐渐增大,产气速率加快。当混凝强化初沉污泥只含有铁时（铁含量为10．16mg／L）,混凝强化初沉污泥厌氧消化效果最好,产气稳定,而且产气速率高,生物气产量为237mL,生物气甲烷含量为55．5％,降解单位Vs产气量为0．80L／g,均高于其他含铝的混凝强化初沉污泥。污泥中的铁对初沉污泥厌氧消化的抑制作用远远小于铝的作用,说明铁盐适合用于城市污水的一级强化混凝处理。     

高效聚磷菌的选育及其特性研究

从鱼塘底部污泥中分离驯化得到一株高效聚磷菌株P5,采用厌氧/好氧(A/O)方式培养,在厌氧阶段3 h的最大释磷量为17 mg/L;在好氧条件下培养16 h后,P5对总磷(PO43--P)浓度为10~30 mg/L的模拟废水的除磷率均可保持在90%,COD的去除率达到82.1%。染色实验表明,P5是革兰氏阴性球杆菌,菌体内含有异染颗粒。     

ICSTD反应器处理污泥的启动试验研究

新型内循环污泥浓缩消化反应器（ICSTD）处理污泥的启动运行试验采用某污水处理厂二沉池好氧活性污泥进行驯化培养,使反应器正常启动运行。在日处理量为50 L/d,进泥含水率为99.23％～99.46％,进泥VS/TS为0.65～0.73,进泥COD为4 115～5 780 mg/L,反应器容积负荷为1.31 kg COD/(m³·d)时,排泥含水率在96.2％～97.3％,排泥VS/TS为0.48～0.57,COD去除率在95％以上,出水pH在6.6～7.1,且上清液澄清。试验结果表明： ICSTD反应器处理污泥的启动试验,采用直接培养污泥启动的方式培养厌氧污泥历时66 d,能较快地培养厌氧污泥且运行稳定,对污泥的浓缩消化起到较好的作用,同时对反应器后续运行的消化效果提供了一个良好的条件。     

非稳定状态下除磷过程的特点研究

为了研究非稳定状态下生物除磷的特点,采用序批式间歇反应器(SBR),通过不同的进水方式(连续进水和瞬时进水),系统地考察了进水体积、NOX-N、限制曝气等因素对除磷过程的影响。结果表明,在温度为(23±0.5)℃、pH为7.0～8.0时,厌氧搅拌期连续进水的比释磷量(单位质量污泥(以MLSS计)的释磷量(以PO43-P计))比瞬时进水时高出42.11%。在运行条件相似的情况下,厌氧搅拌期的比释磷量与每周期进水体积无关。相对于连续进水,瞬时进水更有助于促进微生物利用有机底物进行自身的生长。限制曝气对连续进水和瞬时进水的释磷过程都存在明显的影响,在DO小于0.1mg/L的情况下,2者的比释磷量相对非限制曝气时分别降低了57.14%和55.56%。在连续进水时,NOX-N的反硝化结束伴随着释磷速率的突然升高。利用贮存作用并不能每次都成功地抑制丝状菌污泥膨胀。     

好氧/缺氧消化降解污泥特征分析

为考察好氧/缺氧消化过程中污泥降解的特征,利用2个反应器进行对比试验,研究好氧/缺氧和好氧消化2个过程中VS的去除,pH和碱度变化,消化上清液中COD和氮元素变化等情况。试验结果表明:好氧/缺氧消化能够满足污泥稳定的要求,在常温条件下,消化16 d VS去除率即可达到38.2%,同时比好氧消化节约曝气能耗。好氧/缺氧消化对污泥中总氮的去除率高于传统的好氧消化,达到了36.4%,而且能够降低消化污泥上清液中的氨氮和硝态氮浓度。     

Combined anaerobic/aerobic digestion: effect of aerobic retention time on nitrogen and solids removal

A combined anaerobic/aerobic sludge digestion system was studied to determine the effect of aerobic solids retention time (SRT) on its solids and nitrogen removal efficiencies. After the anaerobic digester reached steady state, effluent from the anaerobic digester was fed to aerobic digesters that were operated at 2- to 5-day SRTs. The anaerobic system was fed with a mixture of primary and secondary sludge from a local municipal wastewater treatment plant. Both systems were fed once per a day. The aerobic reactor was continuously aerated with ambient air, maintaining dissolved oxygen level at 1.1 +/- 0.3 mg/L. At a 4-day or longer SRT, more than 11% additional volatile solids and 90% or greater ammonia were removed in the aerobic digester, while 32.8 mg-N/L or more nitrite/nitrate also was measured. Most total Kjeldahl nitrogen removal was via ammonia removal, while little organic nitrogen was removed in the aerobic digester.     

Biological phosphate uptake and release: effect of pH and magnesium ions.

Enhanced biological phosphorus removal (EBPR) is based on poly-phosphate accumulating organisms' (PAOs) unique features of "luxury" phosphate uptake during aerobic conditions and phosphate release in anaerobic conditions. It is believed that poly-phosphate accumulation is accompanied by the uptake and accumulation of potassium ions (K+) and magnesium ions (Mg2+). The release of phosphate under anaerobic conditions is also accompanied by the release of both cations. The objective of this research was to evaluate the effect of pH and Mg2+ on the biological phosphate uptake and release behavior of activated sludge mixed liquor during aeration and sedimentation. Research results indicate that Mg2+, supplied either by magnesium chloride (MgCl2) or magnesium hydroxide [Mg(OH)2], stimulated phosphate uptake during the aeration period, while pH increase, caused by the application of Mg(OH)2, enhanced phosphate release during the sedimentation period. It is also noted in our experiments with MgCl2 that Mg2+ slightly inhibited anaerobic phosphate release.     

变频控制DO下SBR硝化反应控制参数及节能的中试研究

根据微生物好氧反应的需氧量调节曝气量在当今能源紧缺的形势下具有十分重要的意义.为了研究曝气量大小对SBR实时控制参数pH、DO的影响,采用变频器调节曝气量以控制系统不同的DO浓度,以60 m3中试SBR反应器处理北京市北小河污水处理厂城市污水,考察了硝化过程中pH值、DO与有机物去除及硝化过程的相关性,并引入了新的控制参数--变频频率f.试验结果表明,控制溶解氧浓度较低时,pH值不能作为硝化结束的控制参数,但可根据变频频率f的特征点判断硝化反应的结束;控制溶解氧为3.0 mg/L和4.0 mg/L时,DO、pH值、变频频率f都可作为硝化结束的控制参数,同时,变频控制可有效降低单位时间内风机的能耗.     

污水生物除磷若干影响因素分析

在系统阐述污水生物除磷机理的基础上,深入分析了微生物群体平衡、城市污水水质、环境因子以及工艺运行参数和运行方式等方面对生物除磷效果的影响.分析结果表明:生物除磷系统的溶解氧浓度不宜太高,一般好氧区DO＜2 mg/L,厌氧区DO＜0.2 mg/L;厌氧段存在硝酸盐对生物释磷有负面影响,缺氧段存在一定浓度的硝酸盐有利于生物聚磷;碳源必须充分、易降解;TKN/COD＜0.1的城市污水有利于生物除磷;pH偏碱性可提高生物除磷效率;低温对生物除磷效果影响不明显.     

Contrast of volatile fatty acid driven and inorganic acid or base driven phosphorus release and uptake in enhanced biological phosphorus removal

Addition of an inorganic acid or base was detrimental to net phosphorus removals in short-term batch experiments, suggesting there might be system upset when pH changes. In contrast, addition of volatile fatty acids (VFAs) increased anaerobic phosphorus release and aerobic phosphorus uptake while maintaining or improving net phosphorus removals. The effect of pH change differed if the acid or base added was inorganic versus organic. Volatile fatty acids that resulted in poly-3-hydroxy-butyrate rather than poly-3-hydroxy-valerate resulted in greater net phosphorus removals, and this corresponded to differences in consumption of reducing equivalents. Acetic acid resulted in improved net phosphorus removal compared to sodium acetate, suggesting that acid forms of VFAs might be superior as supplemental VFAs. It is hypothesized that anaerobic phosphorus release following addition of inorganic acid is primarily a result of phosphorus and proton (H+) symport (excretion from the cell) for pH homeostasis, whereas addition of VFAs results in phosphorus and H+ release to maintain the proton motive force.     

离子交换法选择性回收污泥厌氧消化液中的磷

为探讨高效选择性回收污泥厌氧消化液中磷的离子交换方法,采用静态实验和动态实验研究了4种阴离子交换树脂（D213、D202、D301和DSQ）的磷回收性能,筛选了适合富磷污泥厌氧消化液选择性磷回收的高交换容量树脂。实验结果表明,D213、D202、D301和DSQ 4种树脂对正磷浓度为70 mg/L的厌氧消化液进行动态处理时,其最大穿透体积分别为3、7、17和90 BV;DSQ树脂磷交换容量远高于其他3种树脂,达到6 860 mg P/L湿树脂,是目前报道的高磷交换容量树脂的3~4倍;DSQ树脂能有效地抵抗厌氧消化液中有机质和硫酸根等阴离子的干扰;用NaOH溶液再生DSQ树脂并回收磷,磷洗脱率超过96%,洗脱液是高浓度含磷液,可作为磷矿石的优质替代品。研究表明,DSQ树脂是一种高效选择性分离磷的树脂,适用于污泥厌氧消化液的磷回收。     

耐酸厌氧消化污泥处理餐厨垃圾

采用耐酸驯化的厌氧消化污泥处理餐厨垃圾,在酸性条件下（pH=4．5）,对实验装置容积负荷从1．0kgVS／（m3·d）分9次逐级增加到5．0kgVS／（m3·d）的过程进行了跟踪监测,并较深入地研究了驯化污泥代谢活性和处理效果。实验结果表明,pH4．5的耐酸厌氧消化污泥,最佳投加负荷约为4．5kgVS／（m3·d）,此负荷下容积产气率,CH4含量平均值均达最大,分别为1．68m3／（m3·d）,75．0％。耐酸厌氧消化装置持续增料运行46d,产甲烷菌仍能保持较高的活性,其COD去除率范围为40．4％-75．0％,仍能保持pH7．2时处理效果的65．0％-91．8％,表明在低pH、低碱度下实现稳定的产甲烷过程是可行的。     

厌氧氨氧化菌接种污泥的选择培养过程研究

厌氧氨氧化菌的2种不同接种污泥培养实验表明,厌氧消化污泥和好氧硝化污泥均可成功启动厌氧氨氧化过程.接种厌氧消化污泥比好氧硝化污泥培养的厌氧氨氧化菌启动快,但后者去除效果较好.接种好氧硝化污泥的反应器的厌氧氨氧化速率随着氨氮基质进水浓度的增加呈线性增加.进水氨氮浓度为280 mg/L时的氨氮平均去除率达91%;而接种厌氧消化污泥的相应氨氮平均去除率仅为52%.厌氧氨氧化过程以接种好氧硝化污泥来启动为宜.     

低溶解氧污泥微膨胀污染物去除性能的研究

为了研究低溶解氧微膨胀状态下污染物的去除效果,采用SBR反应器,平均DO浓度为0.5～0.9 mg/L,通过好氧/缺氧(O/A)的运行方式,对污染物处理效果进行研究。结果表明：低溶解氧丝状菌污泥微膨胀状态下,SVI可稳定控制在200 mL/g左右,出水SS含量很低,COD去除率在80%以上,氨氮去除率90%以上,除磷效率在90%之上,出水水质良好,同时可以节约曝气量约46.7%。低溶解氧微膨胀状态下,可保证出水处理效果,污泥沉降性能影响小,同时可以节约动力费用。     

厌氧-立体循环一体化氧化沟除磷脱氮工艺中影响厌氧释磷的因素研究

本研究考察了厌氧-立体循环一体化氧化沟工艺(AN-IODVC)中厌氧释磷效果及诸影响因素.研究结果表明,AN-IODVC除磷脱氮系统中好氧污泥的VSS/MLSS值比厌氧污泥小,好氧污泥含磷量与厌氧污泥含磷量的差值和TP去除率、厌氧磷释放率及厌氧ORP呈良好的线性相关关系.厌氧磷释放的最佳条件为:污水COD/TP＞55,维持厌氧区ORP低于-400mV.     

用微电极测定曝气量对SBR系统中硝化作用的影响

为了研究曝气量对硝化作用的影响,实验采用3个相同的SBR装置,分别在曝气量为4、10和16 L/h的条件下处理人工污水,并采用自制的溶解氧、NO3-、NH4+和pH微电极测定了活性污泥絮体内部微元环境中相应基质的浓度。结果表明,曝气量为4 L/h时,活性污泥絮体内存在厌氧微区,NO3--N浓度减小了,发生了反硝化作用;而曝气量为10 L/h和16 L/h时,活性污泥絮体内发生的都是硝化反应,且NH4+-N浓度的减小量、NO3--N浓度的增大量都随着曝气量的增大而增大,pH随着曝气量的增大而减小。     

Characteristics of leachate from pyrolysis residue of sewage sludge

The pyrolysis residue (SP) of sewage sludge (SS) produced at 500 degrees C was subjected to batch and column leaching tests to investigate the release of its organic and inorganic constituents and metals. For comparison, incineration ash (SI) obtained from a SS incinerator was also tested. Pyrolysis and incineration reduced organic matter of SS from 0.78 kg kg(-1)-dry SS to 0.16 and 0.01 kg kg(-1)-dry SS, respectively. Heavy metals remained in SP without being volatilized, although Cd and Pb were transferred into the off-gas during incineration. In the batch leaching test with the leaching liquid-to-solid mass ratio (L/S)=10, the pH of the SS, SP, and SI filtrates was 6.3, 7.9, and 11.0, respectively. The total organic carbon concentrations were in the order SS (877 l mg l(-1))>SP (99 mg l(-1))>SI (26 mg l(-1)). The SP and SI filtrates met the landfill standard for the Cd and Pb concentrations (<0.3 mg l(-1)). In the column tests, although the SP contained more organic matter than that of SI, its carbon discharge into the leachate under aerobic conditions was similar to that of SI under anaerobic conditions. The leaching of heavy metals, such as Cd, Cr, Pb, and Zn, was also suppressed in SP during the active decomposition of organic matter. We demonstrated that pyrolysis reduces the potential release of pollutants from sewage sludge in landfill, making it a promising method of treating sewage sludge before landfilling.