浮萍与剩余污泥厌氧消化产沼气实验

为了提高浮萍厌氧消化产沼气能力,对比浮萍和剩余污泥的单独以及混合厌氧消化过程的产气情况,得到当两种底物混合厌氧消化时,具有互补优势,缩短了产甲烷过程的酸化期,累积产气量实际值比计算值提高11%。此外,研究底物的预处理以及底物与接种物比例对厌氧过程的影响,结果表明,浮萍经热碱预处理后比未处理组甲烷产量增加了8%,且厌氧消化产沼气时间缩短;当底物与接种物比例为1∶1时,整个反应过程的pH维持在6.00以上,利于产甲烷过程,体系中积累的挥发性脂肪酸(VFAS)最多,且获得的总沼气产量和总甲烷产量最大,分别为3 309 m L和1 883 m L,比最低的1∶2.5组分别高出151 m L和304 m L。     

猪粪与玉米秸秆混合中温发酵产气效果

以猪粪及碱液预处理后的玉米秸秆为原料,在恒温35℃和料液总固体质量分数为5%的条件下,以实验室内培养的不产气厌氧活性污泥为接种物,研究猪粪与玉米秸秆不同配比(干物质比分别为1∶3、1∶2、1∶1、2∶1、3∶1和0∶1(单一猪粪))混合发酵对产气效果的影响。研究结果表明,在35℃条件下,猪粪与玉米秸秆以2∶1配比的累积产气量最大,为15 157 mL;其次是1∶1样品,累积产气量为15 088 mL。但甲烷产量最高为1∶1样品,56 d共产甲烷9 137 mL,甲烷气占总产气量的60.6%。通过对发酵过程中pH及COD的测定,证明经碱液预处理后的玉米秸秆能与猪粪混合稳定发酵,发酵前后厌氧消化液中COD的降解率可达50%以上。进一步研究分析得出,将玉米秸秆和猪粪按一定比例混合发酵不仅可以缩短发酵周期、提高产气速率,而且可以大幅提升原料的产气潜力。     

渗滤液添加量对餐饮垃圾厌氧消化的影响机制

系统地研究了渗滤液添加量对于餐饮垃圾厌氧消化产气过程的影响,结果分析表明,餐饮垃圾与渗滤液联合厌氧消化,可以有效地缓解酸抑制现象,增强厌氧消化系统的稳定性,提高沼气产率。当餐饮垃圾负荷为40 g·L~(-1),渗滤液与水的比例为1.227∶1,将厌氧消化原液的氨氮调节至2 000 mg·L~(-1)时,厌氧消化效果最好。沼气产率可达到840 m L·g~(-1)(以TS计),甲烷产率可达到375 m L·g~(-1),累积沼气产量达到理论值的94.32%,累积甲烷产量达到理论值的74.77%。     

青岛市餐厨垃圾与菜市场垃圾混合高温厌氧消化研究

在中试规模下,研究青岛市餐厨垃圾与菜市场垃圾混合(质量比1∶1)高温厌氧消化实验,通过监测厌氧消化过程中产气量、气体组成等产气情况和消化液中pH值、SCOD、NH3-H、VFAs含量和组分等化学指标变化,确定混合厌氧消化的最大有机负荷,并分析混合高温厌氧消化技术的可行性,结果表明,(1)青岛市餐厨垃圾与菜市场垃圾混合高温厌氧消化产甲烷具有技术可行性;(2)混合厌氧消化的最大有机负荷可达4.069 kg VS/(m3.d);(3)当系统最大有机负荷时,每天每千克VS最高可产生甲烷量0.346 m3;(4)混合厌氧消化可削减氨氮对餐厨垃圾单独厌氧消化产沼气的影响。     

鸡粪与城市生物垃圾联合中温厌氧消化研究

在中温下,对不同质量比的鸡粪与城市生物垃圾的厌氧消化处理效果进行了为期50 d的实验.结果表明:(1)鸡粪与城市生物垃圾质量比为1/1、1/2和2/1时的累计产气量最终分别为420、480、460 mL/g(以每克挥发性固体计),高于纯城市生物垃圾(410 mL/g);(2)至产气停止为止,纯城市生物垃圾、纯鸡粪、鸡粪与城市生物垃圾质量比为1/1、1/2和2/1时的甲烷平均体积分数分别为56.6%、56.6%、58.1%、56.2%、56.1%}(3)鸡粪和城市生物垃圾联合厌氧消化缩短了厌氧消化的时间,更利于沼气的产生;(4)纯城市生物垃圾、纯鸡粪、鸡粪与城市生物垃圾质量比为1/1、1/2和2/1时的厌氧消化最终的生物降解率分别为64.6%、67.4%、65.5%、68.7%和70.6%,联合厌氧消化最终的生物降解率均高于纯城市生物垃圾.     

餐厨垃圾与剩余污泥混合消化产沼气协同效应

在(35±0.2)℃温度下,以餐厨垃圾和剩余污泥为原料,设置餐厨垃圾和剩余污泥混合比例(VS)分别为1∶0、2∶1、1∶1、1∶2和0∶1,研究其单独消化与混合消化的系统性能、产甲烷潜力及脱氢酶活性和F420浓度变化。结果表明,混合消化提高了系统稳定性,与餐厨垃圾单独消化相比,添加剩余污泥能调节pH、氨氮浓度和VFA浓度,缩短产气周期;与剩余污泥单独消化相比,添加餐厨垃圾能显著提高沼气产量。混合比例为1∶1组混合消化产甲烷潜力最佳,消化作用的协同效应最为明显,沼气和甲烷产量分别达358.2 mL/g VS和224.1 mL/g VS,较餐厨垃圾和污泥单独消化估计值分别提高了23.09%和36.80%。1∶1混合消化组脱氢酶活性最高达437.33 TFμg/(mL·h),比餐厨垃圾和剩余污泥单独消化分别提高93.60%和40.69%,辅酶F420浓度最高为1.718μmol/L,分别提高17.3%和100.7%。     

蓝藻与污泥混合厌氧发酵产沼气的初步研究

为了实现太湖蓝藻打捞后的快速处置，对厌氧颗粒污泥、消化污泥、剩余污泥与蓝藻混合厌氧发酵产沼气进行了研究。结果表明，蓝藻与污泥混合可以有效促进沼气发酵。在蓝藻与厌氧颗粒污泥物料比为6∶1时，产气效果最佳，沼气产率为73 mL/g VS，平均甲烷含量为69%，最大产气速率为138 mL/d，累计产甲烷量为50 mL CH₄/g干物质，分别是蓝藻与消化污泥、剩余污泥混合发酵时的1.5倍和2.3倍。厌氧颗粒污泥、消化污泥、剩余污泥与蓝藻混合，其VS降解率为11.40%～13.73 %，COD减少了27.97%～46.38%。厌氧发酵对蓝藻藻毒素的含量有较大影响，分别从356、366和244 μg/L降低到检测限5 μg/L 以下。     

猪粪与污泥不同配比对其厌氧共消化与微生物多样性的影响

研究采用猪粪与城市污水厂脱水污泥以5种不同VS比例(1∶0,2∶1,1∶1,1∶2和0∶1)进行中温厌氧消化实验,以研究反应器在不同配比下的产甲烷特性,同时结合16S rRNA扩增子测序技术分析了消化过程中微生物组成的多样性变化。实验结果表明,添加猪粪能明显提升消化效率,当猪粪与污泥以2∶1混合消化时甲烷累计产量最高可达684L·kg-1VS,比污泥单独消化提升了120%。2∶1组的VS去除率可达63.1%,且运行稳定,没有出现明显的酸抑制现象。随着猪粪的添加,优势菌种演替为Bacteroides、Clostridium、Methanosaeta和Methanosarcina。冗余分析结果表明共消化组中甲烷产生主要以氢营养型途径为主。添加猪粪参与共消化能明显提高微生物群落多样性,促进菌种间的协同作用,从而提升有机质转化效率。     

沼液回流对秸秆与污泥混合中温厌氧消化的影响

为了提高秸秆与市政污泥混合厌氧消化的消化产率,以秸秆污泥混合物作为底物,在批次实验中研究不同沼液回流对中温(35℃)混合厌氧消化过程的影响。实验采用0%、20%、30%、40%、50%和60%等6种不同的沼液回流量,分析不同沼液回流量下产气量、甲烷含量、发酵过程氨氮含量、sCOD、总挥发酸(VFAs)的变化情况。结果表明:50%的沼液回流产气量和甲烷产量均最大,分别是1 645 m L和797.5 mL,TS和VS去除率达到17.5%和47.8%,单位VS甲烷产量为613.45 mL·g-1,较未加沼液的发酵瓶提高了37.7%,且无VFAs积累。过高的沼液回流量提升了厌氧反应的氨氮浓度,对厌氧产气过程产生了抑制。50%沼液回流量可以作为秸秆污泥混合厌氧消化最佳回流量。     

基于不同破解方法的市政污泥厌氧消化产气量优化

污泥溶胞破解是提高污泥厌氧消化产气量的重要手段。实验比较了热预处理、碱预处理、热碱预处理以及电化学热处理4种破解方法对市政污泥厌氧消化产气量的优化效果,通过分析比较沼气累积产量、日产气量、日产气速率和CH_4在沼气中的含量占比等指标得出实验结果和结论。结果表明,不同的破解方法对市政污泥厌氧消化产气量的优化程度是不同的,其中,电化学预处理破解方式的沼气累积产量最多,为648 L·kg~(-1)(以VS计),同时其CH_4在沼气中的含量也最多,从5 d后的56.2%一直持续上升到40 d后的64.8%,表明该种方式对于市政污泥厌氧消化产气量的优化是较为理想的。     

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.     

骆马湖富营养化和生态状况调查与评价

为了了解骆马湖水质状况，在2005年对骆马湖富营养化状态和生态特性进行了调查，并结合“十五”期间的监测资料进行了分析。2005年骆马湖水体中总氮和总磷的平均值超《地表水环境质量标准》（GB3838-2002）中Ⅲ类，超标情况分别为0．78倍和0．54倍，达到湖库特定项目Ⅳ类水标准，骆马湖处于轻度富营养化状态。对骆马湖生态特征分析表明，由于该湖泊的形态以及“藻型浊水状态”和“泥沙型浊水状态”交替出现，遏制了湖水从高营养盐含量向全面富营养化状态演变，保障了底栖动物的良好生长环境，从而形成了骆马湖独特的环境生态平衡。     

Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C₂ through C₈ organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene.     

Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.     

剩余污泥浓缩脱水投药量优化和模型建立

应用高分子阳离子絮凝剂（CPF-100）和聚丙烯酰胺（PAM）对污水厂剩余污泥进行浓缩脱水实验，研究表明：CPF-100的浓缩脱水效果优于PAM；当CPF-00投加量为1．16‰时，污泥沉降性能改善程度为37．51％；且在CPF-100投加量逐渐增大的初始阶段，污泥沉降性能改善程度随投加量的增加而增大，但CPF-100投加量也不宜过大，当CPF-100投加量超过1．16‰后，反而会使浓缩脱水效果变差。同时，建立了污泥沉降性能改善程度与絮凝剂CPF-100投加量、沉降时间之间的数学模型，其能较好地反映污水厂剩余污泥的浓缩脱水效果。     

Sources and distribution of polychlorinated-dibenzo-p-dioxins and -dibenzofurans in soil and sediment from the Yellow Sea region of China and Korea

Polychlorinated-dibenzo-p-dioxins and -dibenzofurans (PCDD/Fs) were measured in soils and sediments from the Yellow Sea region. Korean soils and sediments mostly contained detectable PCDD/Fs and showed a widespread distribution among locations. Soil and sedimentary PCDD/Fs from China were comparable to or less than those in Korea. The patterns of relative concentrations of individual congeners in soils were different between the two countries, but similar in sediments. Sources of PCDD/Fs in China and Korea were found to be independent of each other and their distributions reflected matrix-dependent accumulation. Spatial distribution indicated some point sources in Korea while Chinese sources were more widespread and diffuse. PCDD/Fs measured in the coastal areas of the Yellow Sea were comparable to or less than those previously reported in for eastern Asia. However, ∑TEQs in soils and sediments were near to or, in some cases exceeded environmental quality guidelines.     

Quantification of carbamazepine and atrazine and screening of suspect organic contaminants in surface and drinking waters

A new approach for the identification of suspect trace organic contaminants in drinking and surface waters is presented. Samples were initially analyzed using a target determination method for two contamination tracers, carbamazepine (CBZ) and atrazine (ATZ). This method used offline solid-phase extraction and online solid-phase extraction techniques coupled to liquid chromatography-triple quadrupole mass spectrometry to accelerate the sample preparation process and improve method performance. CBZ and ATZ were found respectively in 31% and 56% of the samples, and concentrations were usually <20 ng L⁻¹. These samples were re-analyzed with a similar method on a quadrupole time-of-flight mass spectrometer to identify suspect contaminants by means of exact mass measurements and isotope patterns. A database of 264 common organic contaminants was built and used in conjunction with a Molecular Feature algorithm to identify the presence of these substances in drinking and surface water collected from different sources at various locations across Canada. Several organic contaminants were identified in the samples, but only the presence of caffeine, desethylatrazine, simazine and venlafaxine could be verified by comparison to pure standards. The presence of desethylatrazine was also confirmed by MS/MS experiments. These results suggest that target analysis for tracers of organic contamination may be a helpful tool to prioritize samples which should be further screened for suspect contaminants. This study also shows that the combination of separation techniques (offline and online SPE, LC) contribute to advance the applicability of high-resolution mass spectrometry for the identification of trace organic contaminants by accelerating the preparation step, reducing complexity and increasing analyte concentrations for optimal detection.     

Persistence and dissipation kinetics of trifloxystrobin and tebuconazole in onion and soil

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha^?1. The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg^?1 for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg^?1 and tebuconazole 0.673 and 1.95 mg kg^?1 from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6–6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues.     

Effects of compositional heterogeneity and nanoporosity of raw and treated biomass-generated soot on adsorption and absorption of organic contaminants

A biomass-generated soot was sequentially treated by HCl-HF solution, organic solvent, and oxidative acid to remove ash, extractable native organic matter (EOM), and amorphous carbon. The compositional heterogeneity and nano-structure of the untreated and treated soot samples were characterized by elemental analysis, thermal gravimetric analysis, BET-N₂ surface area, and electron microscopic analysis. Sorption properties of polar and nonpolar organic pollutants onto the soot samples were compared, and individual contributions of adsorption and absorption were quantified. The sorption isotherms for raw sample were practically linear, while were nonlinear for the pretreated-soot. The removal of EOM enhanced adsorption and reduced absorption, indicating that EOM served as a partitioning phase and simultaneously masked the adsorptive sites. By drastic-oxidation, the outer amorphous carbon and the inner disordered core of the soot particles were completely removed, and a fullerene-like nanoporous structure (aromatic shell) was created, which promoted additional π-π interaction between phenanthrene and the soot.     

Sorption and Desorption Behavior of Chloroanilines and Chlorophenols on Montmorillonite and Kaolinite

The bioavailability of pollutants, pesticides and/or their degradation products in soil depends on the strength of their sorption by the different soil components, particularly by the clay minerals. This study reports the sorption-desorption behavior of the environmentally hazardous industrial pollutants and certain pesticides degradation products, 3-chloroaniline, 3,4-dichloroaniline, 2,4,6-trichloroaniline, 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol on the reference clays kaolinite KGa-1 and Na-montmorillonite SWy-l. In batch studies, 2.0 g of clay were equilibrated with 100.0 mL solutions of each chemical at concentrations ranging from 10.0 to 200.0 mg/L. The uptake of the compounds was deduced from the results of HPLC-UV-Vis analysis. The lipophilic species were best retained by both clay materials. The most lipophilic chemical used in the study, 2,4,6-trichloroaniline, was also the most strongly retained, with sorption of up to 8 mg/g. In desorption experiments, which also relied on HPLC-UV-Vis technique, 2,4,6-trichloroaniline was the least desorbed from montmorillonite. However, on kaolinite all of the compounds under study were irreversibly retained. The experimental data have been modelled according to the Langmuir and Freundlich isotherms. A hypothesis is proposed concerning the sorption mechanism and potential applications of the findings in remediation strategies have been suggested.