含固率对牛粪常温厌氧消化的影响

在常温、pH值为7.0下,采用10 L玻璃瓶作为反应器对含固率(TS)分别为2%、6%、10%和14%的4组牛粪溶液进行厌氧消化实验,系统运行48 d,分析了厌氧消化过程中的COD(化学需氧量)、pH、VFA(挥发性脂肪酸)和产气量的变化。结果表明,进料TS是影响牛粪厌氧消化产气效果的重要因素,调节牛粪进料TS至10%,可以使其厌氧消化获得最佳的产气效果,COD去除率为24.6%,产气中甲烷含量为56.1%。     

添加NaOH对水生植物固体厌氧发酵产甲烷的作用

为了提高木质纤维素生物质的甲烷产率,固体厌氧发酵以及预处理技术得到了广泛应用。本研究以水生植物菹草为例,探讨了厌氧固体发酵同步碱处理提高甲烷产率的可行性。采用2种来源的微生物(厌氧污泥和牛粪),初始生物质浓度为20%TS(total solid,总固体重量),考察不同的NaOH添加量(基于反应体系总TS 0%、2.0%、3.5%和5.0%)对菹草厌氧发酵产气和固体水解效率的影响。结果表明,与对照实验组相比,初始NaOH加入量为3.5%时,接种污泥和牛粪的实验组中甲烷总产量分别为787.1 mL和1 165.4 mL,与对照实验组相比(619.1 mL和834.8 mL),分别提高了27.1%和39.6%,而且接种牛粪的实验组中单位挥发性固体(VS)产甲烷率最高,为186.5 mL/g。对发酵后的木质纤维素残渣组分进行分析,结果表明,NaOH有助于促进菹草中纤维素及半纤维素的分解,以及木质素结构的破坏,从而提高了菹草厌氧发酵产气产甲烷效率。     

不同氮源对常中温条件下麦秆厌氧发酵的影响

通过自行设计的厌氧发酵装置,研究不同氮源对常温（20℃）和中温（35℃）条件下麦秆厌氧发酵的影响。结果表明,在常温和中温条件下进行麦秆沼气厌氧发酵时,适量添加外部氮源可加快产气速率,增加产气量,缩短产气停滞时间,其中添加牛粪效果最好,分别在182 d和84 d时发酵完全,总累积产气3 486.80 mL和4 210.70 mL,干物质累积产气量为217.93 mL/g和263.17 mL/g,且在实验期间未出现产气停滞。添加尿素处理次之,分别在累积产气215.70 mL和238.00 mL时进入61 d和20 d的产气停滞期,在196 d和143 d时发酵完全,在实验结束时,累积产气2 784.20 mL和3 454.00 mL,干物质累积产气量为174.01 mL/g和215.88 mL/g。可见,在以秸秆为原料的沼气发酵过程中,可通过添加适量的外部氮源和提高发酵温度来提高沼气产量,而且在条件允许的情况下,应尽量添加畜禽粪便等有机氮源。     

褐铁矿与固体含量对牛粪秸秆混合厌氧干式发酵的影响

干式厌氧发酵是处理农业废弃物的有效途径之一,其中总固体(TS)含量和外源添加剂是影响有机质产甲烷过程的重要影响因素。以牛粪与水稻秸秆为例,研究了不同的褐铁矿添加量以及TS含量对牛粪秸秆混合厌氧干式发酵产甲烷过程的影响,并对沼渣特性进行表征。结果表明:固定TS含量25%时,添加1%褐铁矿(基于底物TS含量)显著促进产甲烷过程,产气量比对照组增加了21 mL·g~(-1)(以VS计);对照组(无褐铁矿)和添加1%褐铁矿时,纤维素降解均随TS含量升高而降低;TS含量40%时,添加1%褐铁矿对产甲烷过程具有抑制作用,甲烷产率相比于对照组(TS含量25%)降低了71%。可见只有当TS含量25%时,添加适量褐铁矿才能有效促进牛粪秸秆混合厌氧发酵产甲烷过程。研究可为优化农业废弃物甲烷化提供参考。     

推流式反应器厌氧消化浮萍和猪粪混合物

使用带隔板的推流式反应器(体积约为4 m3),对浮萍与猪粪(干重比1:1,湿重比7:1)的混合物、猪粪进行为期50 d的中温厌氧消化产气性能比较研究,结果表明,在有机负荷为3.5 g(VS)/(L·d)时,浮萍与猪粪(干重比1:1,湿重比7:1)混合物的VS产气率为0.31 L/g,COD转化率为63.2％,反应器容积产气率为1.00 m3/(m3·d)；猪粪的VS产气率为0.28 L/g,COD转化率为57.1％,反应器容积产气率为0.71m3/(m3·d).进料COD和SS的平均浓度分别为19.19 g/L和14.28 g/L,推流式反应器对其平均去除率分别为59.7％和68.7％.由此说明,带隔板的推流式厌氧反应器对浮萍和猪粪的混合物有较好的厌氧消化能力,浮萍与猪粪混合物的厌氧消化性能优于猪粪.     

牛粪工业化厌氧发酵生产工艺实验研究

针对牛粪的厌氧发酵设计了一套工业化试验装置,该装置是由降流式厌氧滤器(AF)和升流式厌氧污泥床(UASB)有机结合的新型动态序批式厌氧发酵系统,在此装置上对影响系统效果的进料浓度、日进料量和污泥回流量 3 个主要参数安排了二次正交同归试验研究,以产气量和 COD 去除率为目标甬数进行了分析,结果表明,系统整体产气效率较高,处理牛粪的产气率最高可达 2.3 L/(L·d),污泥回流量对产气效果的影响明显.在本实验设计的范围内,进料浓度在8.9%,日进料量在 7.2 L/d(相当于 0.15 L/(L·d)),污泥回流比在 25%时产气效果最佳,而进料浓度在 7.6%,日进料量在 6.8 L/d(相当于 0.142 L/(L·d)),污泥回流比大约在 25%时 COD 去除效果最佳.     

腐熟蓝藻与厌氧污泥混合厌氧发酵特性

采用批次小试实验对不同腐熟程度的蓝藻进行厌氧发酵产沼气实验研究。结果表明,新鲜蓝藻在30-35℃时腐熟7 d后,可在35℃的厌氧温度下获得最高的产气速率和246 mL/g COD的产气量,产气潜力为354 mL/g（VS）。厌氧反应15 d后,累计产气量、COD和VFA浓度趋于稳定。淀粉酶和脱氢酶的活性在厌氧反应初期受到抑制,蛋白酶活性和辅酶F420浓度在厌氧系统中逐渐增加,分别在第6天达到27.66μmol/（g VS·min）和第15天达到0.62μmol/g（VS）。15-18d是腐熟蓝藻适宜的中温厌氧发酵时间,少于以新鲜蓝藻为基质的厌氧消化时间。蓝藻腐熟过程促进了厌氧反应,腐熟7 d的蓝藻厌氧系统具有更高的微生物活性和产甲烷能力。     

中药渣不同有机负荷厌氧发酵工艺参数分析

以人参、赤芍和桂皮等混合中药渣为发酵原料,采用全混式厌氧反应器,在中温(35±1)℃,通过半连续厌氧发酵工艺,研究其发酵过程中不同有机负荷,沼气日产气量、甲烷含量、p H值、挥发性有机酸(VFA)和总无机碳(TIC)等参数变化相互关系。结果表明:厌氧消化过程呈现5个阶段,即发酵启动期、增长期、稳定期、超负荷期和恢复期;反应器高效稳定运行可承受的中药渣最大有机负荷为8.0 g TS·(L·d)-1,系统p H值稳定在7.0左右,沼气日产气量8.38 L,容积产气率为1.68 L·(d·L)-1,原料产沼气能力262 m L·(TS g·d)-1,VS去除率为20.69%。有机负荷为10.0 g TS·(L·d)-1时超负荷运行,沼气产量急剧下降,系统运行稳定性被破坏。因此,在中药渣厌氧消化过程中一定要控制有机负荷在最佳数值,实时监测反应器运行过程中的各参数变化,及时做出调整,保证工程的高效稳定运行。     

挥发性脂肪酸对厌氧干式发酵产甲烷的影响

为了提高中温干式厌氧间歇发酵效率,研究了发酵过程中间产物———挥发性脂肪酸对产甲烷的影响。实验分2批进行,第1批在牛粪发酵过程中分别添加乙酸、丙酸和丁酸,第2批发酵添加易产生挥发酸的厨余垃圾混合发酵。结果显示,添加单一挥发酸的发酵过程中,添加丙酸的产甲烷速度较慢,因为丙酸降解生成乙酸的速度较慢,减慢了甲烷的形成;混合发酵过程厨余垃圾产甲烷速度比牛粪快,发酵过程产生2个产气高峰;牛粪和厨余垃圾固体物质含量比在11∶1到5∶1范围内较好,比牛粪单独发酵产气多,产酸高但不酸败,产生的挥发酸主要是乙酸和丙酸,其中比例为7∶1混合发酵的产甲烷速率最大,为4.89 mL/(g VS·d)。实验表明,牛粪厌氧干式发酵过程添加一定量的厨余垃圾可加快挥发酸的产生并提高挥发酸产量,从而提高甲烷的产量,但是总挥发酸长时间超过10 000 mg/L,pH降到不适于产甲烷菌生长的范围时,将抑制甲烷的生成,挥发酸积累导致厌氧发酵酸败。     

3种畜禽粪便产气特性差异分析

在实验室条件下,对鸡粪、猪粪和牛粪3种畜禽粪便进行了高温(55℃)厌氧发酵产气特性研究,分析了3种畜禽粪便的物质组成差异以及发酵过程中挥发性固体(VS)降解率、碳氮比(C/N)下降幅度和NH+4-N含量变化与累积产气量的关系。结果表明,累积产气量以牛粪最高,为5 481 m L,其次为猪粪,鸡粪最低,为3 692 m L;3种畜禽粪便发酵原料VS降解率及其粗蛋白和粗脂肪含量与其累积产气量呈负相关,而3种畜禽粪便碳水化合物和粗纤维含量及其发酵过程C/N下降幅度与其累积产气量呈正相关;厌氧发酵过程中,鸡粪发酵液NH+4-N含量显著高于猪粪和牛粪,后期高达2 348.33mg/L,鸡粪较猪粪和牛粪产气时间短,累积产气量少。可见,3种畜禽粪便自身的有机物质组成及接种物的物质组成差异是厌氧发酵累积产气量的重要影响因素。     

次氯酸钠发生器的研制

介绍了电解法生产次氯酸钠的原理 ,并在原有生产工艺的基础上进行了重新设计和对设备的重新选择、改造 ,得出了各个工艺参数的最佳值 ,生产出高品质的次氯酸钠     

Estimation of uncertainty of sampling for analysis of pesticide residues

Abstract

A computer model was used to take random samples from primary sample populations obtained from field trials to simulate the uncertainty of sampling for residue analysis of plant commodities and soil. The results indicate about 40%, 30% and 20% relative uncertainty when random samples of size 5, 10 and 25 are taken respectively, from a single lot. Therefore the sample size should be the same for establishing and enforcing legal limits.     

Evaluation of the presence of drugs of abuse in tap waters

A total of seventy samples of drinking water were tested for non-controlled and illicit drugs. Of these, 43 were from Spanish cities, 15 from seven other European countries, three from Japan and nine from seven different Latin American countries. The most frequently detected compounds were caffeine, nicotine, cotinine, cocaine and its metabolite benzoylecgonine, methadone and its metabolite EDDP. The mean concentrations of non-controlled drugs were: for caffeine 50 and 19 ng L⁻¹, in Spanish and worldwide drinking water respectively and for nicotine 13 and 19 ng L⁻¹. Illicit drugs were sparsely present and usually at ultratrace level (<1 ng L⁻¹). For example, cocaine has mean values of 0.4 (Spain) and 0.3 ng L⁻¹ (worldwide), whereas for benzoylecgonine, these mean values were 0.4 and 1.8 ng L⁻¹, respectively. Higher concentrations of benzoylecgonine were found in Latin American samples (up to 15 ng L⁻¹). No opiates were identified in any sample but the presence of methadone and EDDP was frequently detected. Total mean values for EDDP were 0.4 ng L⁻¹ (Spain) and 0.3 ng L⁻¹ (worldwide). Very few samples tested positive for amphetamines, in line with the reactivity of chlorine with these compounds. No cannabinoids, LSD, ketamine, fentanyl and PCP were detected.     

Mechanisms of biodegradation of dibenzoate plasticizers

Biodegradation mechanisms were elucidated for three dibenzoate plasticizers: diethylene glycol dibenzoate (D(EG)DB), dipropylene glycol dibenzoate (D(PG)DB), both of which are commercially available, and 1,6-hexanediol dibenzoate, a potential green plasticizer. Degradation studies were done using Rhodococcus rhodochrous in the presence of pure alkanes as a co-substrate. As expected, the first degradation step for all of these systems was the hydrolysis of one ester bond with the release of benzoic acid and a monoester. Subsequent biodegradation of the monobenzoates of diethylene glycol (D(EG)MB) and dipropylene glycol (D(PG)MB) was very slow, leading to significant accumulation of these monoesters. In contrast, 1,6-hexanediol monobenzoate was quickly degraded and characterization of the metabolites indicated that the biodegradation proceeded by way of the oxidation of the alcohol group to generate 6-(benzoyloxy) hexanoic acid followed by β-oxidation steps. This pathway was blocked for D(EG)MB and D(PG)MB by the presence of an ether function.The use of a pure hydrocarbon as a co-substrate resulted in the formation of another class of metabolites; namely the esters of the alcohols formed by the oxidation of the alkanes and the benzoic acid released by hydrolysis of the original diesters. These metabolites were biodegraded without the accumulation of any intermediates.     

混凝试验搅拌器的研制

影响混凝效果的因素众多,混凝沉淀烧杯试验是进行水的混合、絮凝、沉淀工艺研究、设计和生产指导的最有效方法之一,阐述了智能型混凝试验搅拌器的设计原理和技术性能.     

不同泥源对厌氧氨氧化反应器启动的影响

采用2套上流式生物膜反应器,分别接种少量厌氧氨氧化污泥和大量硝化污泥,考察其对厌氧氨氧化反应器启动的影响。污泥接种入反应器后,测得接种厌氧氨氧化污泥的反应器(R1)内MLSS为0.22 g/L,另一个反应器(R2)MLSS为2.7 g/L。与直接接种厌氧氨氧化污泥相比,R1经过72 d的运行才显现出厌氧氨氧化特性。经过114 d的培养,前者氮去除速率由0.23 kg/(m3.d)提升到5.29 kg/(m3.d),总氮去除率大于89%;R2的氮去除速率由0.01 kg/(m3.d)提升到1.1 kg/(m3.d),总氮去除率大于84.6%。说明普通污泥启动需要一个较长的筛选过程,直接接种少量的厌氧氨氧化污泥比接种普通的污泥能够更快启动厌氧氨氧化反应器。     

生物质快速热裂解主要参数对生物油产率的影响

以松木木屑为原料,在自制的小型流化床上,开展了生物质热裂解温度、生物质粒径和进料速率对生物油产率的影响实验研究.结果表明,在热裂解温度分别为450、475、500、525和550℃条件下,当热裂解温度为500℃时,生物油产率最高,平均产率达到53.33%（质量百分比）.反应温度越高,炭产量越低,不可冷凝气体产量越高,气体发热值越高;粒径＜1 mm的生物质其粒径对生物油产率影响不大;生物质进料速率增加时,生物油产率增加.本研究为生物能的利用提供了新的途径.     

An application of the theory of kinematics of mixing to the study of tropospheric dispersion

The most common technique used for numerical simulations of tracer mixing is that of the numerical solution of the advection–diffusion equation with the unresolved fluxes parameterized using the similarity theory. Despite correct predictions of the overall directions of transport, models based on a numerical solution of the advection–diffusion equation lack sufficient accuracy to correctly reproduce the coupling of mixing with small scale processes which are sensitive to the microstructure of the tracer distribution. The objective of this paper is to revisit the basic formalism employed in numerical models used to investigate atmospheric tracers. The main mathematical method proposed here is the theory of kinematics of mixing which could be applied effectively for simulations of atmospheric transport processes. At the beginning of the paper, we introduce simple mathematical transformations in order to demonstrate how complex topological structures are created by mixing processes. These idealistic flow systems are essential to explain transport properties of much more complex three-dimensional geophysical flows. An example of the application of the kinematics of mixing to the analysis of tracer transport on a planetary scale is presented in the following sections. The complex filamentary structures simulated in the numerical experiment are evaluated using some commonly applied statistical measures in order to compare the results with the data published in the literature. The results of the experiment are also analysed with the help of simple conceptual models of fluid filaments. The microstructure of the tracer distribution introduced in the paper is essential to increase our understanding of atmospheric transport and to develop more realistic parameterizations of small-scale mixing. The presented results could also be used to improve calculations of the coupling between microphysical processes and tracer mixing.     

造纸废水混凝处理中SFT助凝替代性研究

中小造纸厂废水处理常用PAC作混凝剂 ,PAM作助凝剂。由于PAM成本很高 ,影响了处理设备的投运率。用超细滑石粉 (SFT)替代PAM助凝 ,与混凝剂PAC配合 ,其混凝处理效果基本相当 ,但是处理成本降低 0 .10元 /m3 。由于SFT属环境无害材料 ,不会给排泥带来二次污染     

产油微藻培养与回收的关键技术研究进展

寻找廉价而高效的替代原料是实现生物柴油产业化的关键所在.微藻以含油量高、生长周期短、环境适应能力强、生物产量高等优点,有望成为一种极具潜力的生物柴油生产原料.然而,目前尚存在微藻培养低效成本高和微藻回收效率低两大难题.综述了微藻培养与回收过程中的关键技术,并对存在的两大难题及其改进技术进行了详细的探讨.最后,总结并展望了微藻培养、回收技术未来的发展趋势.