磷酸铵镁碱促(Mg(OH)_2)热解产物氨氮去除性能

磷酸铵镁热解循环技术可以有效降低磷酸铵镁结晶技术的药剂费用。同时,在磷酸铵镁热解过程中添加Mg(OH)2碱促媒介,能阻止磷酸氢镁向焦磷酸镁的转化,并降低热解产物氨氮去除过程中上清液磷酸盐的残留。在Mg(OH)2∶NH+4摩尔比为1∶1,热解温度为110℃条件下,热解产物沉氨效率接近84%,上清液磷酸盐残留量为0.02 mg/L。     

碱性条件下MgNH_4PO_4·6H_2O热解产物的氨氮吸附性能

研究了MgNH4PO4.6H2O(简称MAP)沉淀在NaOH存在条件下的热解行为,并考察其热解产物的氨氮吸附性能。结果表明,MAP在NaOH存在条件下热解时可将水和氨释放出来,其X射线衍射(XRD)谱图中主要出现无定形的MgNaPO4,但在吸附氨氮后,则主要出现MAP的特征衍射峰;在MAP与NaOH摩尔比为1.0∶1.0、热解温度为100℃、热解时间为2h的条件下热解MAP较适宜,其热解产物可循环用作氨氮的处理药剂,氨氮吸附反应体系初始pH在8左右较为适宜,在此条件下反应20min对氨氮的去除率就达98%以上。     

工艺条件对磷回收过程中鸟粪石沉淀颗粒粒径的影响

在鸟粪石沉淀法回收废水中磷的过程中,鸟粪石颗粒的大小将直接影响其沉淀的速率,进而影响鸟粪石的沉淀效果和磷的回收率。本文采用激光粒度分析仪测定鸟粪石的平均粒径,详细考察在小型连续搅拌反应-沉淀磷回收装置中不同的工艺条件下鸟粪石颗粒粒径的变化规律,并结合Stokes公式计算鸟粪石颗粒在废水出口处的沉降速率,为沉淀池的设计提供参考依据。结果表明:鸟粪石的平均粒径在12～25μm之间,沉降速率在5.46×10-5～2.37×10-4m/s之间。随着反应室水力停留时间的延长,鸟粪石颗粒的粒径逐渐增大,当停留时间超过18 min时,颗粒的粒径基本不变;随着沉淀室水力停留时间的延长,鸟粪石颗粒的平均粒径缓慢增大,当停留时间超过70 min后颗粒粒径的变化不大;鸟粪石颗粒的平均粒径在一定程度上受废水中磷初始浓度变化的影响,在磷初始浓度为62～128 mg/L时颗粒的粒径变化不大,当磷浓度为496 mg/L时粒径有较大增加,此时鸟粪石颗粒的沉降速率也大幅度增加;鸟粪石颗粒的平均粒径受pH值的影响不大;随氮磷摩尔比的增大,鸟粪石颗粒的平均粒径略有增加;随镁磷摩尔比的增大,鸟粪石颗粒的平均粒径逐渐减小,沉降速率则有明显的下降。     

基于天然椰丝纤维填料的低氨氮废水SNAP系统自然挂膜构建

针对低氨氮废水单级自养脱氮工艺(SNAP)系统的构建需要接种特殊种源且工程应用复杂的问题,采用生物亲和性好的天然椰丝纤维为填料,开展了低氨氮废水SNAP系统自然挂膜构建实验,考察了进水COD/TN对系统脱氮效能及脱氮路径的影响.结果 表明:在温度为(30±1)℃、进水氮负荷为0.1 kg·(m3·d)-1时,采用自然挂膜以及进水NH4+-N质量浓度梯度递减(由(100±3) mg·L-1降至(50±2) mg·L-1)的运行方式,经过85 d的运行,初步构建出低氨氮废水SNAP系统;该系统NH4+-N和TN去除率分别为94.58％和70.07％;系统脱氮功能菌属主要有Nitrosomonas、Candidatus Brocadia.此外,进水COD/TN对系统脱氮效能及脱氮路径影响显著.当进水COD/TN分别为0、0.2、0.5、1、2时,系统TN平均去除率分别为70.07％、72.09％、75.18％、82.19％、62.19％;对于低氨氮废水,当COD/TN≤0.2时,系统主要脱氮路径为厌氧氨氧化;当COD/TN为0.5～1.5时,系统脱氮路径以短程硝化反硝化为主,厌氧氨氧化为辅;当COD/TN≥2时,系统通过短程硝化反硝化、厌氧氨氧化路径脱氮能力进一步降低.     

鸟粪石结晶法去除垃圾渗滤液中NH_4~+-N的效果研究

研究了鸟粪石结晶法对经混凝预处理后的垃圾渗滤液中NH4+-N的去除效果,考察了不同影响因素对NH4+-N去除效果的影响,并进行了磷酸铵镁(MgNH4PO4·6H2O,简称MAP)沉淀的表征及成分分析,并提出了反应后溶液中Mg2+、PO43-及MAP的回收利用办法。结果表明,反应的最佳条件为:pH8.5～9.5,Mg2+∶NH4+∶PO34-(摩尔比)=1.1∶1.0∶1.3,反应温度30℃,反应时间为25 min时,此时NH4+-N的去除率达94.70%;最佳沉淀剂投加组合为MgCl2.6 H2O与Na2HPO4·12H2O;pH为9.0时生成的沉淀符合典型MAP沉淀的晶体结构,生成的沉淀大部分为MAP,且没有氰化物、酚等有害物质的检出,而pH为10.5时生成的沉淀由许多疏松的微小沉淀颗粒组成,排列较杂乱,影响了沉淀的纯度。利用鸟粪石结晶法去除混凝预处理后的垃圾渗滤液中NH4+-N技术可行,经济效益合理,具有广阔的应用前景。     

酸性条件下剩余污泥中Ca2＋和Mg2＋溶出对磷回收的影响

为了在酸性条件下实现剩余污泥中磷的高效回收，对pH=3时剩余污泥水解酸化过程中氨氮、正磷酸盐和钙镁离子的溶出现象以及磷回收进行了研究分析。结果表明：当pH=3时，所溶出的氨氮、镁离子和钙离子与磷酸盐的摩尔比均大于1，能满足采用鸟粪石沉淀法或者羟磷灰石沉淀法回收磷的要求；但所溶出的钙镁离子的摩尔比大于1，会对鸟粪石沉淀法回收磷的顺利进行有较大影响；有无外加镁剂对磷回收率影响不大。采用改型后的镁型强酸性阳离子交换树脂进行离子交换可以得到较高纯度的鸟粪石沉淀产品，通过XRD检测其纯度为95％以上。     

酸性条件下剩余污泥中Ca2+和Mg22++溶出对磷回收的影响

为了在酸性条件下实现剩余污泥中磷的高效回收，对pH=3时剩余污泥水解酸化过程中氨氮、正磷酸盐和钙镁离子的溶出现象以及磷回收进行了研究分析。结果表明：当pH=3时，所溶出的氨氮、镁离子和钙离子与磷酸盐的摩尔比均大于1，能满足采用鸟粪石沉淀法或者羟磷灰石沉淀法回收磷的要求；但所溶出的钙镁离子的摩尔比大于1，会对鸟粪石沉淀法回收磷的顺利进行有较大影响；有无外加镁剂对磷回收率影响不大。采用改型后的镁型强酸性阳离子交换树脂进行离子交换可以得到较高纯度的鸟粪石沉淀产品，通过XRD检测其纯度为95%以上。     

苦土和氧化镁处理氮磷废水的对比研究

分别采用苦土、纯氧化镁为沉淀剂对模拟高浓度氮磷废水(N/P=0.8)进行了脱氮除磷研究,比较了沉淀剂投加量、pH对2种沉淀剂处理氮磷废水的影响,对沉淀产物进行XRD分析,并进行了经济效益比较。结果表明,pH是影响2种沉淀剂处理氮磷废水的主要因素,随着pH的增加,脱氮除磷效果提高,在平衡pH为9～10之间时氮磷处理效果最佳,pH继续增加,由于磷酸镁沉淀的形成使得氨氮去除率降低。此外,处理相同的废水,苦土的最佳投加量要大于纯氧化镁,但是经济效益比较结果表明,以苦土为沉淀剂处理氮磷废水可大大降低处理成本。     

苦土处理氮磷废水的研究

采用苦土为沉淀剂对模拟氮磷废水和实际氮磷废水进行了脱氮除磷实验研究,探讨了苦土投加量、pH及反应时间对废水中氮磷去除率的影响。此外,对苦土处理氮磷废水的动力学进行了研究,并对苦土及反应沉淀物进行了XRD分析。结果表明,以苦土为沉淀剂,处理氨氮浓度为200 mg/L的模拟废水的最佳条件为:苦土与氨氮(NH4+-N)的质量比为25∶1,平衡时间10 min,氨氮去除率可达到93%,磷去除率达到99%。用苦土为沉淀剂处理南京某厂的实际氮磷废水(氨氮浓度为590 mg/L,磷浓度为1 630 mg/L),氨氮的去除率达到92%,磷的去除率达到99%。苦土处理氮磷废水的动力学数据符合二级动力学模型,主要以化学反应为主。处理后废水中沉淀物的XRD分析表明其主要成分为磷酸铵镁,进一步证明苦土处理氮磷废水主要以化学反应为主。     

鸟粪石法回收制肥工业废水中氨氮的中试研究

制肥工业废水中氨氮浓度高,难以直接进行生化反应,采用鸟粪石沉淀法可有效去除并回收氨氮。利用中试反应器回收某制肥工业废水中的氨氮,采用氯化镁与氧化镁作为联用镁源,通过考察不同进料方式、搅拌速度、停留时间等因素的影响,确定了鸟粪石法回收氨氮的最佳工况:采用间歇进水、固体投加镁源的投料方式,搅拌速度300 r/min,停留时间2 h。最佳条件下,氨氮去除率达到93.5%,磷残余率小于0.3%,生成的鸟粪石纯度可达85.6%,砷和铅的质量分数分别为0.0036和0.0008,符合肥料中重金属限值(GB/T 23349-2009),其他重金属均未检出。因此,回收产品有很好的利用价值。经济分析表明磷源是此方法处理成本较高的主要原因。     

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.     

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。     

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.     

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.