Kinetic Analysis of Thermophilic Anaerobic Digestion of Wastewater Sludge

Conventional mesophilic anaerobic digesters are sometimes subject to process upset and have earned the reputation of being difficult to cope with sludge overloading. This study was conducted to examine the thermophilic process as a viable alternative. An analysis of field data from an operating mesophilic sludge digester was conducted in parallel with experimental runs on a laboratory thermophilic reactor using similar sludge. The results showed that thermophilic anaerobic digestion was a viable alternative to the mesophilic process especially for overloaded digesters in warm climates. The optimum hydraulic retention time for the thermophilic process was 10 days which can lead to substantial savings in digester capacity. A simplified kinetic model was developed and applied in the analysis of steady-state operation of thermophilic anaerobic sludge digesters.     

NaOH预处理花生壳厌氧发酵制取沼气的试验研究

为了探索花生壳厌氧发酵制取沼气的产气特性和潜力,利用NaOH在无流动水和常温的条件下,分别用质量分数为2%、4%、6%、8%的NaOH溶液对花生壳进行了碱性化学预处理,在中温（35±1）℃、总固TS质量分数为8%、pH为7.0～7.6条件下,利用自行设计的厌氧发酵实验装置进行批量厌氧消化试验,研究NaOH预处理对花生壳厌氧发酵过程中产气量、pH值和甲烷含量的影响规律。结果表明,4%NaOH预处理下的花生壳的总产气量为28083mL,比不使用NaOH和8%NaOH预处理的总产气量分别高48.91%和35.72%;甲烷含量最高超过60%,且平均甲烷含量高于不处理、2%和8%NaOH预处理;pH初期波动,13d后基本稳定在7.2左右。4%NaOH预处理下的TS产气率、VS产气率以及甲烷含量和不处理以及8%NaOH预处理下的差异性显著（P〈0.05）,和其他两组试验之间的差异不显著（P〉0.05）,表明4%NaOH预处理是较优的工艺条件。     

Digestion Activity of Thermophilic Bacteria Isolated from Ash-Amended Sewage Sludge Compost

Previous experiments had shown thatco-composting sewage sludge with coal fly ash resultedin a decrease in microbial activity during thethermophilic phase. Therefore, attempts were made toutilize isolated dominant thermophilic bacteria fromash-amended sludge compost to enhance thedecomposition of organic matter in digestion testsinvolving mixtures of sewage sludge and coal fly ash.Cultures of three Bacillus species, i.e., B. brevis, B. coagulans, and B.licheniformis were inoculated into sewage sludgeamended with 25% coal fly ash at cell densitiesranging from 10⁵ to 10⁷ CFU g^-1 drysludge, and were incubated for 10 days in aqueoussuspension. The digestion test showed that aninoculation level of ≥10⁶ CFU g^-1dry sludge was suitable for achieving an acceptablerate of digestion of ash-sludge mixture, as indicatedby the significantly higher evolution of CO₂compared to the control receiving no inoculation.Weight loss and contents of soluble organic carbon,protein, and amino acids were lower in ash-sludgemixture with bacterial inoculation. Hence, all thethree bacilli were able to decompose the organicmatter in ash-sludge mixture faster than that of thecontrol. Among the three bacilli, B. brevis wasless efficient in decomposing the organic matter inthe ash-sludge mixture than the other two bacilli atan inoculation rate of 10⁶ CFU g^-1 drysludge, but no significant difference was noted amongthe three bacilli at an inoculation rate of 10⁷CFU g^-1 dry sludge. It can be concluded that thethree bacilli all exhibited the ability to improve thedecomposition of organic matter in ash-sludge compost.     

Anaerobic Digestion of Olive Oil Mill Effluents: Evaluation of Wastewater Organic Load and Phytotoxicity Reduction

Olive oil mill effluents (OME) are of great concern worldwide dueto their role as pollutants. This work studies, on a laboratoryscale, the possibility of reducing the polluting load of olivewastewaters (organic, acid and polyphenolic) through chemical-physical processes (sedimentation-filtration) followedby a biological treatment (anaerobic digestion). This is in orderto produce biogas and obtain an effluent suitable for applicationto the soil. The anaerobic process was followed by determiningchemical-physical parameters (pH, COD, N-NH₃, polyphenols).The extent of anaerobic digestion was evaluated throughmeasurements of biogas and volatile fatty acids and the microbialmetabolism was examined through dehydrogenase activity. Finally,tests of plant germination and growth were carried out usingdigested waters to determine if they could be used in agriculture.The study demonstrated that anaerobic digestion of OME firstreduced the organic load by 78-89% and the content of polyphenolsby 33-43%, and secondly produced biogas (mean value of methane83-85%). Phytotoxicity tests carried out on Lepidiumsativum seeds showed that the anaerobic treatment considerablyreduced the phyto-toxic character of OME.     

The Phytotoxicity Changes of Sewage Sludge-Amended Soils

The aim of the present study was the estimation of changes in the phytotoxicity of soils amended with sewage sludge with relation to Lepidium sativum, Sinapis alba and Sorghum saccharatum. The study was realised in the system of a plot experiment for a period of 29?months. Samples for analyses were taken at the beginning of the experiment, and then after 5, 17 and 29?months. Two kinds of sewage sludge, with varying properties, were added to a sandy soil (soil S) or a loamy soil (soil L) at the dose of 90?t/ha. The addition of sewage sludge to the soils at the start of the experiment caused a significant reduction of both seed germination capacity and root length of the test plants, the toxic effect being distinctly related to the test plant species. With the passage of time the negative effect of sewage sludge weakened, the extent of its reduction depending both of the kind of sewage sludge applied and on the type of soil. Phytotoxicity of the soils amended with the sewage sludges was significantly lower at the end of the experiment than at the beginning. The species of the plants grown on the soils also had a significant effect on their phytotoxicity. The greatest reduction of toxicity was observed in the soil on which no plants were grown (sandy soil) and in the soil under a culture of willow (loamy soil). Solid phase of sewage sludge-amended soils was characterised by higher toxicity than their extracts.     

温度对生物强化粪便污泥厌氧消化减量及产气特性的影响

以化粪池粪便污泥为对象,研究温度在25～45℃条件下,分别投加0.01%的有效微生物（EM）和多功能复合微生物制剂（MCMP）对粪便污泥厌氧消化减量及产气特性的影响。结果表明,温度对EM和MCMP强化粪便污泥厌氧消化挥发性固体（VS）的减量有重要影响,分别投加0.01%的EM和MCMP的两试验组的VS的去除率均表现为35℃时最好,45℃时次之,25℃时最差,且各处理间的差异均达到极显著水平（P〈0.01）。经过20d反应,35℃时,投加0.01%EM的处理（E-T35）的VS去除率为39.04%,分别比25℃（E-T25）和45℃（E-T45）时高21.57%和6.90%;投加0.01%MCMP的处理（M-T35）的VS去除率为42.04%,分别比25℃（M-T25）和45℃（M-T45）时高20.16%和8.59%。至20d反应结束,两试验组各处理累积产气量大小分别表现为E-T35（14220mL.L-1）〉E-T45（11819mL.L-1）〉E-T25（7607mL.L-1）、M-T35（17695mL.L-1）〉M-T45（9065mL.L-1）〉M-T25（7430mL.L-1）。由此可见,EM和MCMP强化粪便垃圾厌氧消化减量并同时提高沼气产量的较佳温度为35℃。     

秸秆厌氧消化试验研究

采用清瓶培养消化方法,在中温（32～35 ℃）环境下,研究了小麦秸秆在不同固含率下的厌氧消化状态。结果表明,小麦秸秆在固含率5%～25%范围内,理论产气数值与实际气体量成线性相关,方程： y=1.846 2x-448.73,R^2= 0.926 5;无论产气还是产酸和用酸平衡上,固含率25%是较适宜物料厌氧消化的浓度,产气量超过理论数值109.0 mL·g^-1;3种不同粒径的产气量最大是〈0.5 cm,其次1～2 cm,3～5 cm,考虑到粒径小容易酸化的原因,故选择秸秆厌氧消化的粒径范围〈2.0 cm。     

生物垃圾厌氧消化的强化机理探讨

综合分析了生物垃圾厌氧消化的各种强化技术与机理.由于传统化石燃料的枯竭和造成的生态环境问题,清洁再生能源的生物气体日益受到人们的青睐.但是,消化时间长,产气量较低,垃圾利用率不高等原因,导致生物垃圾厌氧发酵技术没有得到充分的开发与推广.研究认为,通过强化处理能够改善生物垃圾的物化性质,提高微生物对难降解有机物的分解能力,增加生物气产量,缩短水力停留时间,减轻后续处理的负担,优化垃圾厌氧消化过程.     

剩余污泥厌氧消化过程重金属形态转化及生物有效性分析

为研究污泥厌氧消化过程中物理化学性质的变化对典型重金属形态转化的影响,对其农用的可行性及生物有效性进行评估,对取自某城市污水处理厂的剩余污泥进行了序批式厌氧消化实验,在试验过程中测定了污泥理化学性质,采用Tessier分步提取法提取了污泥样品中的典型重金属,并采用电感耦合等离子发射光谱仪（ICP-OES）测定各形态重金属含量及总量。结果表明,厌氧消化过程中重金属的形态发生了显著变化,由不稳定态向比较稳定的残渣态和有机结合态转变,某些重金属形态与污泥理化性质如pH、碱度、VS/TS及氨氮显著相关。厌氧消化可以有效地降低污泥中重金属的潜在迁移能力和生物有效性,经厌氧消化后污泥可以更好地进行土地利用。     

Agronomic Traits of Corn Fertilized with Sewage Sludge

Although research on the environmental impacts of using waste as a fertilizer is of great importance, the basic principle for using a product as fertilizer is that it should provide nutrients for plants without causing any harm to them. The objective of this study was to evaluate the agronomic traits (number of nodes, plant height, leaf number, yield, and protein content of grains) and the nutritional status of corn treated with sewage sludge. The experiment was conducted in the municipality of Jaboticabal in a Red Latosol. A randomized block design with four treatments (0, 55, 110, and 167.5 Mg ha^?1 of sewage sludge) and five repetitions was used. At 30 days after emergence (DAE), the dose of 110 Mg ha^?1 dry weight presented greater values for plant height, leaf number and stem diameter. At 60 DAE, the treatments did not affect the agronomic traits. No influence from the treatments tested was observed for protein content of grains and yield. The dose of 167.5 Mg ha^?1 showed greater weight of 100 seeds. All treatments showed nutritional imbalances. This study confirmed the agricultural potential of sewage sludge as a source of nutrients.     

中国沼气利用现状

中国是世界上从事沼气研究、开发和推广最早和沼气利用最广泛的国家之一。当前沼气工程主要在4个方面得到广泛应用：农业废弃资源(AWT)、工业有机废水(IOWT)、城市生活污水和有机污泥(UWMT)、城市生活固体垃圾(USODT)等的处理。沼气工程已经实现了高产气率、优化工程设计和各个部分之间的最优搭配，同时成为生态良性循环中的关键一环。该文分析了几类常用工艺的特点和几种生态模式及沼气工程的效益和市场潜力，就解决沼气工程存在的问题提出了解决。     

Fractionation of Cu, Pb, Cr, and Zn in a Soil Column Amended with an Anaerobic Municipal Sewage Sludge

The objective of this study was to investigate the changes in the chemical partitioning of Cu, Pb, Cr and Zn within a column of soil incubated with an anaerobic sewage sludge (ANSS) for 2.5 months. The soil was irrigated during the incubation period. A sequential extraction method was used to fractionate these metals into exchangeable, weakly adsorbed, organic, Al oxide, Fe–Mn oxide, and residual, respectively. ANSS was applied at a loading rate of 69 Mg ha^?1. The soil is a Dystric Cambisol with low pH (<3.8), low CEC [<10 cmol(+) kg^?1 below the first 4 cm depth], and low base saturation (<7%). The addition of the ANSS caused a decrease in concentrations of Cu, Pb, and Cr in the A1 horizon, and an increase in the concentrations with depth. Below the A1 horizon, concentrations of Cu increased uniformly (~1 mg cm^?1), and the greatest increases were observed in the residual, Fe–Mn oxides, and weakly adsorbed fractions. Maximum increases in Pb occurred at 4–9 cm of depth (1.6 mg cm^?1), and mainly affected the weakly adsorbed fraction. Chromium essentially accumulated at the limit between the A2 and the Bw horizons (1.1–1.5 mg cm^?1) as residual and organic bound forms, probably through particulate transport. Zinc mainly accumulated in the A1 horizon (2.9 mg cm^?1) as exchangeable Zn. At depth, Zn increments were predominantly observed in the residual fraction. The results of this study thus demonstrate the redistribution of contaminants into different chemical pools and soil layers after sludge amendment.     

Influence of Amelioration of Strongly Acid Soils with Calcareous Materials and Sewage Sludge on Wheat Yield and Economic Results

Abstract

The amelioration of acid unproductive soils with various amendments may improve soil properties and increase crop yield. In this paper, the influence of several soil amendments (refuse sugar beet lime, calcium hydroxide, and municipal sewage sludge) on wheat yield and gross margin were studied in a three‐year (1995, 1996, 1997) field experiment, conducted in western Thessaly (Elassona area), central Greece. In order to evaluate soil amelioration from an economic point of view we estimated the profit that derives from soil amelioration for each year separately as well as for the whole period of the experiment. The results showed that sugar beet lime and sewage sludge at the rate 15 ton ha^?1 are preferable from an economic point of view compared to calcium hydroxide. This fact is supportive of all the efforts made to diffuse the use of quality by‐products for soil amelioration.     

采用厌氧分步固体反应器系统进行蔬菜废弃物厌氧分解

最近获得专利的厌氧分步固体反应系统(美国专利号6342378B1)是一种新型的用于将固体废弃物转化为沼气以获取生物能源的新技术。此技术已被用以转化多种固体废弃物的科学研究,其中包括作物秸秆、动物粪便、食品废弃物和城市固体废弃物。研究结果证明,此技术不仅先进可行,而且操作简单。根据此技术,一种大型的用于将废弃物转化为能源的厌氧分步固体反映系统已经在美国开发出来。该文主要介绍此技术用于大蒜废弃物转化的研究结果     

Synthetic Fibers as Indicators of Municipal Sewage Sludge,Sludge Products,and Sewage Treatment Plant Effluents

Because of concerns regarding health, safety, and aesthetics, a test that identifies the presence of sewage sludge or its products (biosolids) in commercial materials such as soil conditioners and composts would be useful. This test could also trace the effluent plume from a sewage treatment plant. We have discovered that synthetic fibers serve as such an indicator. Synthetic fibers are abundant in sludge, sludge products, and sewage treatment plant effluents. The fibers evidently are introduced from clothes-washing machines and survive the sewage treatment process. Synthetic fibers were identified using polarized light microscopy, which provided a simple, rapid method for determining the presence or absence of municipal sewage sludge or its products. False positives or false negatives have not occurred with any of the materials examined so far. We also monitored synthetic fibers in surface sediments of Huntington Harbor, Long Island, NY, a harbor receiving the effluent from a trickling filter sewage treatment plant. Fibers generally decrease in size and abundance with distance from the source. In Oyster Bay Harbor, Long Island, an advanced sewage treatment plant is operated with a final microfiltration step. Synthetic fibers are less abundant in the sediments of this harbor.     

沼气发酵系统在生态农业中的地位和作用

沼气发酵系统是生态农业系统能量和物质转化运行中起着一定枢纽作用的环节，它能够有效地回收农业废弃物的能量和物质。开展沼气综合利用，能够促进农村生态环境的良性循环，改善农村环境卫生条件。     

水泡粪物料中固体和氨氮含量对厌氧消化产气特性的影响

目前不少猪场使用水泡粪清粪工艺清理猪粪便,同时对水泡粪清理的粪污进行沼气工程处理,但不同水泡粪贮存条件对其粪污后续厌氧发酵的影响尚不清楚.本试验将猪粪和尿液通过不同贮存温度（20℃,30℃）和时间（7d,14d,21d）组成6种前处理条件,模拟不同条件水泡粪出水,研究水泡粪物料特性对出水厌氧发酵的影响.结果表明,水泡粪出水的单位挥发性固体（VS）的厌氧发酵产气率在369.2 ～702.0mL/g,厌氧发酵前7d的日产沼气量一直处于较高水平,之后快速下降,厌氧发酵10d后产气基本处于较低水平且下降平缓;氨氮对厌氧发酵有显著的抑制作用,厌氧消化甲烷产率（y）与氨氮浓度（x）的关系为y =4＆#215;10-5x2-0.3618x＋1283（R2=0.9846）.水泡粪物料总固体物含量越高厌氧发酵产气越低,据此建议适当缩短水泡粪时间以提高后续厌氧发酵产气量.     

The Influence of Humification Degree of Humic Acid on Its Sorption of Norfloxacin During Sewage Sludge Composting

Norfloxacin (NOR), an antibiotic widely used in livestock and poultry production, has become ubiquitous in the aquatic and terrestrial ecosystems as a result of veterinary excretion of the parent compound or its active metabolites. The sorption of NOR onto humic acid (HA) may influence the fate of NOR in the environment. In the present study, HA was extracted from sewage sludge in different composting stages of days 0, 10, 30, and 70 to investigate the sorption of NOR onto HA as affected by the humification degree of HA. The results of elemental and Fourier transform infrared (FTIR) spectrum analyses showed that the contents of aromatic and carboxylic groups in HA increased with composting time, indicating an increase of humification degree. The result of sorption experiments demonstrated that the HA had a high sorption capacity for NOR with strong nonlinearity. A two-stage sorption was observed in the sorption process with an equilibration time of 48 h. Both the Freundlich model (Adj. R² range 0.988–0.994) and Langmuir model (Adj. R ² range 0.917–0.928) fitted well with all sorption isotherms of the HA samples of different humification degrees. Moreover, the increase of sorption distribution coefficient (K _d ) value with composting time indicated that the sorption affinity of HA for NOR increased with increasing humification degree of HA. The major sorption mechanism was the interaction between NOR and rich aromatic moieties and carboxylic group in the HA.     

污泥改良锰矿尾渣对4种花卉植物生长及其富集重金属的影响

采用盆栽试验方法,研究了污泥改良锰矿尾渣对紫茉莉（Mirabills jdapa）、青葙（Celosia argentea）、一串红（Salviasplendens）和鸡冠花（Celosia cristata）4种花卉植物生长及其富集铅、镉、锌和锰的影响。结果表明,添加污泥增加基质的EC值、总氮、总磷、总钾和有机质含量,而降低铅、镉、锌和锰含量。紫茉莉与青葙生物量、株高和根长大于一串红和鸡冠花。紫茉莉根部铅、镉和锰含量分别为3110．93～4189．16、300．28～399．16和31100．93～36809．77mg·kg-1,都远高于其地上部分含量。青葙根部铅含量超过1000mg·kg-1,而其地上部分含量少;其地上部分镉和锰含量分别为322．13～441．88和21888．54～26511．31mg·kg-1,都大于其根部含量,青葙具有镉和锰超富集植物的特性。污泥改良锰矿尾渣促进这4种花卉植物生物量、株高和根长增加。除紫茉莉锌含量外,添加污泥改良锰矿尾渣增加这4种花卉植物的铅、镉、锌和锰含量。在锰矿尾渣污染区进行植物修复时,采用紫茉莉、青葙和添加污泥强化植物修复效率可行。