Aerated treatment pond technology with biofilm promoting mats for the bioremediation of benzene, MTBE and ammonium contaminated groundwater

A novel aerated treatment pond for enhanced biodegradation of groundwater contaminants was tested under field conditions. Coconut fibre and polypropylene textiles were used to encourage the development of contaminant-degrading biofilms. Groundwater contaminants targeted for removal were benzene, methyl tert-butyl ether (MTBE) and ammonium. Here, we present data from the first 14 months of operation and compare contaminant removal rates, volatilization losses, and biofilm development in one pond equipped with coconut fibre to another pond with polypropylene textiles. Oxygen concentrations were constantly monitored and adjusted by automated aeration modules. A natural transition from anoxic to oxic zones was simulated to minimize the volatilization rate of volatile organic contaminants. Both ponds showed constant reductions in benzene concentrations from 20 mg/L at the inflow to about 1 μg/L at the outflow of the system. A dynamic air chamber (DAC) measurement revealed that only 1% of benzene loss was due to volatilization, and suggests that benzene loss was predominantly due to aerobic mineralization. MTBE concentration was reduced from around 4 mg/L at the inflow to 3.4-2.4 mg/L in the system effluent during the first 8 months of operation, and was further reduced to 1.2 mg/L during the subsequent 6 months of operation. Ammonium concentrations decreased only slightly from around 59 mg/L at the inflow to 56 mg/L in the outflow, indicating no significant nitrification during the first 14 months of continuous operation. Confocal laser scanning microscopy (CLSM) demonstrated that microorganisms rapidly colonized both the coconut fibre and polypropylene textiles. Microbial community structure analysis performed using denaturing gradient gel electrophoresis (DGGE) revealed little similarity between patterns from water and textile samples. Coconut textiles were shown to be more effective than polypropylene fibre textiles for promoting the recruitment and development of MTBE-degrading biofilms. Biofilms of both textiles contained high numbers of benzene metabolizing bacteria suggesting that these materials provide favourable growth conditions for benzene degrading microorganisms.     

Remediation of groundwater contaminated with MTBE and benzene: the potential of vertical-flow soil filter systems

Field investigations on the treatment of MTBE and benzene from contaminated groundwater in pilot or full-scale constructed wetlands are lacking hugely. The aim of this study was to develop a biological treatment technology that can be operated in an economic, reliable and robust mode over a long period of time. Two pilot-scale vertical-flow soil filter eco-technologies, a roughing filter (RF) and a polishing filter (PF) with plants (willows), were operated independently in a single-stage configuration and coupled together in a multi-stage (RF + PF) configuration to investigate the MTBE and benzene removal performances. Both filters were loaded with groundwater from a refinery site contaminated with MTBE and benzene as the main contaminants, with a mean concentration of 2970 ± 816 and 13,966 ± 1998 μg L⁻¹, respectively. Four different hydraulic loading rates (HLRs) with a stepwise increment of 60, 120, 240 and 480 L m⁻² d⁻¹ were applied over a period of 388 days in the single-stage operation. At the highest HLR of 480 L m⁻² d⁻¹, the mean concentrations of MTBE and benzene were found to be 550 ± 133 and 65 ± 123 μg L⁻¹ in the effluent of the RF. In the effluent of the PF system, respective mean MTBE and benzene concentrations of 49 ± 77 and 0.5 ± 0.2 μg L⁻¹ were obtained, which were well below the relevant MTBE and benzene limit values of 200 and 1 μg L⁻¹ for drinking water quality. But a dynamic fluctuation in the effluent MTBE concentration showed a lack of stability in regards to the increase in the measured values by nearly 10%, which were higher than the limit value. Therefore, both (RF + PF) filters were combined in a multi-stage configuration and the combined system proved to be more stable and effective with a highly efficient reduction of the MTBE and benzene concentrations in the effluent. Nearly 70% of MTBE and 98% of benzene were eliminated from the influent groundwater by the first vertical filter (RF) and the remaining amount was almost completely diminished (∼100% reduction) after passing through the second filter (PF), with a mean MTBE and benzene concentration of 5 ± 10 and 0.6 ± 0.2 μg L⁻¹ in the final effluent. The emission rate of volatile organic compounds mass into the air from the systems was less than 1% of the inflow mass loading rate. The results obtained in this study not only demonstrate the feasibility of vertical-flow soil filter systems for treating groundwater contaminated with MTBE and benzene, but can also be considered a major step forward towards their application under full-scale conditions for commercial purposes in the oil and gas industries.     

德国的城市建设与规划设计思想的演变

该文简要阐述了德国战后的城市建设，通过分析不同时期具有代表性的建设项目和规划设计方案，对规划设计思想的发展和演变加以探讨，以期为我国的城市建设提供有益的启示。     

浅析德国经济萎缩地区的城市更新

两德统一后原东德地区的经济与人口结构的巨大变化,导致了当地城市功能的明显萎缩。本文通过介绍近年来德国规划领域针对这一问题进行的相关更新改造实践,总结出对我国城市衰落地区规划方法的若干启示。     

Manganese concentrations in Scottish groundwater

Groundwater is increasingly being used for public and private water supplies in Scotland, but there is growing evidence that manganese (Mn) concentrations in many groundwater supplies exceed the national drinking water limit of 0.05 mg l^− 1. This study examines the extent and magnitude of high Mn concentrations in groundwater in Scotland and investigates the factors controlling Mn concentrations. A dataset containing 475 high quality groundwater samples was compiled using new data from Baseline Scotland supplemented with additional high quality data where available. Concentrations ranged up to 1.9 mg l^− 1; median Mn concentration was 0.013 mg l^− 1 with 25th and 75th percentiles 0.0014 and 0.072 mg l^− 1 respectively. The Scottish drinking water limit (0.05 mg l^− 1) was exceeded for 30% of samples and the WHO health guideline (0.4 mg l^− 1) by 9%; concentrations were highest in the Carboniferous sedimentary aquifer in central Scotland, the Devonian sedimentary aquifer of Morayshire, and superficial aquifers. Further analysis using 137 samples from the Devonian aquifers indicated strong redox and pH controls (pH, Eh and dissolved oxygen accounted for 58% of variance in Mn concentrations). In addition, an independent relationship between Fe and Mn was observed, suggesting that Fe behaviour in groundwater may affect Mn solubility. Given the redox status and pH of Scottish groundwaters the most likely explanation is sorption of Mn to Fe oxides, which are released into solution when Fe is reduced.Since the occurrence of elevated Mn concentrations is widespread in groundwaters from all aquifer types, consideration should be given to monitoring Mn more widely in both public and private groundwater supplies in Scotland and by implication elsewhere.     

德国移动性调查与可持续城市移动性规划

可持续城市移动性规划是全球城市解 决城市交通污染问题,应对全球气候变化,实 现城市可持续发展的重要战略之一。移动性调 查是制定城市可持续移动性规划的重要数据及 基础。本研究首先对移动性和交通概念和区别 进行了辨析与讨论,并进一步解析了可持续移 动性概念。其后,以德国为例,对比分析其2002 年、2008年和2017年三次的移动性调查内容的 差异与更新。继而,在概述德国可持续移动性 规划的政策发展基础上,以具有高品质城市生 活质量的三个代表城市慕尼黑、杜塞尔多夫和 法兰克福为例,简述了三个城市的移动性战略 规划,并比较了城市移动性规划的改善成果。最 后,重点探讨了德国汉堡市的移动性调查与可持 续移动性规划。该研究显示德国通过定期、系 统的全国移动性调查,为德国各城市制定可持 续移动性战略规划提供了重要的基础数据信息 和指导方向,德国各城市开展的可持续城市移动 性规划策略,呈现出显著的数字化时代、全民化和生态化的特征。该研究将为我国城市开展科学与系统的移动性调查,制定符合我国国情的可持 续城市移动性战略规划提供可资借鉴的经验。     

Seasonal and daily variations in concentrations of methyl-tertiary-butyl ether (MTBE) at Cranberry Lake,New Jersey

Methyl-tertiary-butyl ether (MTBE), an additive used to oxygenate gasoline, has been detected in lakes in northwestern New Jersey. This occurrence has been attributed to the use of gasoline-powered watercraft. This paper documents and explains both seasonal and daily variations in MTBE concentrations at Cranberry Lake. During a recent boating season (late April to September 1999), concentrations of MTBE typically exceeded 20 microg/L. MTBE concentrations varied daily from 12 to 24 microg/L over a 2-week period that included the Labor Day holiday. Concentrations were highest on weekends when there is more boat traffic, which had an immediate effect on MTBE mass throughout the lake. MTBE concentrations decreased to about 2 microg/L shortly after the end of the summer recreational season. The loss of MTBE can be accounted for by volatilization, with a half-life on the order of 10 days. The volatilization rate was modeled with the daily decrease in MTBE then the modeled rate was validated using the data from the seasonal decline.     

城市形态设计方法——以德国城市形态设计发展为例

本文介绍了德国城市形态设计的主要内容和发展层次，通过实例分析了城市形态设计对城市发展的正面负面影响，指出了城市形态规划与城市和谐发展的互利关系，强调了城市形态设计的重要性。     

Laboratory column study for remediation of MTBE-contaminated groundwater using a biological two-layer permeable barrier

In this study, an in situ biological two-layer permeable reactive barrier system consisting of an oxygen-releasing material layer followed by a biodegradation layer was designed to evaluate the remediation effectiveness of MTBE-contaminated groundwater. The first layer containing calcium peroxide (CaO(2)) and other inorganic salts is to provide oxygen and nutrients for the immobilized microbes in the second layer in order to keep them in aerobic condition and maintain their normal metabolism. Furthermore, inorganic salts such as potassium dihydrogen phosphate (KH(2)PO(4)) and ammonium sulphate ((NH(4))(2)SO(4)) can also decrease the high pH caused by the alkali salt degraded from CaO(2). The second layer using granular expanded perlite as microbial carrier is able to biodegrade MTBE entering the barrier system. Batch experiments were conducted to identify the appropriate components of oxygen-releasing materials and the optimum pH value for the biodegradation of MTBE. At pH=8.0, the biodegradation efficiency of MTBE is the maximum and approximately 48.9%. A laboratory-scale experiment using two continuous upflow stainless-steel columns was then performed to evaluate the feasibility of this designed system. The fist column was filled with oxygen-releasing materials at certain ratio by weight. The second column was filled with expanded perlite granules immobilizing MTBE-degrading microbial consortium. Simulated MTBE-contaminated groundwater, in which dissolved oxygen (DO) content was 0mg/L, was pumped into this system at a flow rate of 500mL/d. Samples from the second column were analyzed for MTBE and its major degradation byproduct. Results showed that MTBE could be removed, and its metabolic intermediate, tert-butyl alcohol (TBA), could also be further degraded in this passive system.     

Sources and transport of selected organic micropollutants in urban groundwater underlying the city of Halle (Saale), Germany

In this study, we used isotopic (delta18O, delta2H, delta34S-SO4) and chemical tracers (boron) to assess the sources and transport processes of the micropollutants carbamazepine, galaxolide, and bisphenol A in groundwater underlying the city of Halle (Saale), Germany. Their ubiquitous presence in urban groundwater results from a combination of local river water infiltration, sewer exfiltration, and urban stormwater recharge. Attenuation during transport with infiltrating river water increased from carbamazepine (0-60%) to galaxolide (60-80%) in accordance with their increasing sorption affinity and decreasing recalcitrance against biodegradation. Distinctly higher attenuation during transport was found for carbamazepine (85-100%) and galaxolide (95-100%) if micropollutants originated from sewer exfiltration. Most likely, this is related to higher contents of organic matter and higher transit times of the respective flow paths. Although attenuation undoubtedly also affects the transport of bisphenol A, quantification is limited due to additional contributions from the urban stormwater recharge. As a consequence, micropollutant loads in groundwater indicate that groundwater discharge may dominate the export of bisphenol A from urban areas.     

Non-agricultural sources of groundwater nitrate: a review and case study

Nitrate is often seen as an agricultural pollutant of groundwater and so is expected to be at higher concentrations in the groundwaters surrounding a city than in those beneath it. However the difference between rural and urban nitrate concentrations is often small, due to the non-agricultural sources of nitrogen that are concentrated in cities. This paper illustrates the source and significance of non-agricultural nitrogen for groundwater and presents a case study of nitrate loading in the city of Nottingham. Major sources of nitrogen in urban aquifers are related to wastewater disposal (on-site systems and leaky sewers), solid waste disposal (landfills and waste tips). The major sources of nitrogen in the Nottingham area are mains leakage and contaminated land with approximately 38% each of a total load of 21 kg N ha(-1) year(-1).     

Thirty years of urban regeneration in Britain,Germany and France: The importance of context and path dependency

It is a little over 30 years since Jim Callaghan's Labour Government passed the 1978 Inner Urban Areas Act. The following year marked a shift in power to Margaret Thatcher's Conservative Government and a very different approach to urban regeneration. These developments established and shaped the approach to urban regeneration in England for a generation. The economic context and the urban changes of the 1970s and 1980s and the nature of these responses put England at the forefront of the evolution of this type of urban policy in Europe. It is therefore timely to reflect on 30 years of urban regeneration and to do so from a comparative perspective, setting the English experience alongside that of Germany and France. In this paper the authors compare the experiences of these three countries. The great benefit of international comparison is that it allows the observer to step outside their own institutions and context, to compare with other countries and to look back at their own country from a new, foreign, perspective. The emphasis of this paper is on the contingent and contextualised nature of actions designed to foster urban regeneration. This reinforces the rationale for studying the evolution of this policy field in different nation-state settings.     

Probabilistic assessment of safe groundwater utilization in farmed fish ponds of blackfoot disease hyperendemic areas in terms of the regulation of arsenic concentrations

This work probabilistically explored a safe utilization ratio (UR) of groundwater in fish ponds located in blackfoot disease hyperendemic areas in terms of the regulation of arsenic (As) concentrations. Sequential indicator simulation was used to reproduce As concentrations in groundwater and to propagate their uncertainty. Corresponding URs of groundwater were obtained from the relationship of mass balance between reproduced As concentrations in groundwater and the As regulation in farmed fish ponds. Three levels were adopted to evaluate the UR - UR> or =0.5, 0.5>UR> or =0.1 and UR<0.1. The high probability of the UR> or =0.5 level presents in the northern and southern regions where groundwater can be a major water source. The high probability of the 0.5>UR> or =0.1 level is mainly distributed in the central-coastal, central-eastern and southeastern regions where groundwater should be considered as a subordinate water source. Being available, extra surface water has priority over providing aquacultural needs of the regions with the high probability of the UR> or =0.5 and 0.5>UR> or =0.1 levels. In the regions with the high probability of the UR<0.1 level, in the central-coastal and southwestern regions, groundwater utilization should be reduced substantially or even prohibited completely for no adverse effects on human health.     

Microbial contamination of two urban sandstone aquifers in the UK

Development of urban groundwater has historically been constrained by concerns about its quality. Rising urban water tables and overabstraction from rural aquifers in the UK have led to a renewed interest in urban groundwater, particularly the possibility of finding water of acceptable quality at depth. This study assessed the microbial quality of groundwater collected from depth-specific intervals over a 15-month period within the Permo-Triassic Sherwood Sandstone aquifers underlying the cities of Nottingham and Birmingham. Sewage-derived bacteria (thermotolerant coliforms, faecal streptococci and sulphite-reducing clostridia) and viruses (enteroviruses, Norwalk-like viruses, coliphage) were regularly detected to depths of 60 m in the unconfined sandstone and to a depth of 91 m in the confined sandstone. Microbial concentrations varied temporally and spatially but increased frequency of contamination with depth coincided with geological heterogeneities such as fissures and mudstone bands. Significantly, detection of Norwalk-like viruses and Coxsackievirus B4 in groundwater corresponded with seasonal variations in virus discharge to the sewer system. The observation of low levels of sewage-derived microbial contaminants at depth in the Triassic Sandstone aquifer is explained by the movement of infinitesimal proportions of bulk (macroscopic) groundwater flow along preferential pathways (e.g., fissures, bedding planes). The existence of very high microbial populations at source (raw sewage) and their extremely low detection limits at the receptor (multilevel piezometer) enable these statistically extreme (microscopic) flows to be traced. Rapid penetration of microbial contaminants into sandstone aquifers, not previously reported, highlights the vulnerability of sandstone aquifers to microbial contamination.     

Occurrence and concentrations of pharmaceutical compounds in groundwater used for public drinking-water supply in California

Pharmaceutical compounds were detected at low concentrations in 2.3% of 1231 samples of groundwater (median depth to top of screened interval in wells = 61 m) used for public drinking-water supply in California. Samples were collected statewide for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program. Of 14 pharmaceutical compounds analyzed, 7 were detected at concentrations greater than or equal to method detection limits: acetaminophen (used as an analgesic, detection frequency 0.32%, maximum concentration 1.89 μg/L), caffeine (stimulant, 0.24%, 0.29 μg/L), carbamazepine (mood stabilizer, 1.5%, 0.42 μg/L), codeine (opioid analgesic, 0.16%, 0.214 μg/L), p-xanthine (caffeine metabolite, 0.08%, 0.12 μg/L), sulfamethoxazole (antibiotic, 0.41%, 0.17 μg/L), and trimethoprim (antibiotic, 0.08%, 0.018 μg/L). Detection frequencies of pesticides (33%), volatile organic compounds not including trihalomethanes (23%), and trihalomethanes (28%) in the same 1231 samples were significantly higher. Median detected concentration of pharmaceutical compounds was similar to those of volatile organic compounds, and higher than that of pesticides.Pharmaceutical compounds were detected in 3.3% of the 855 samples containing modern groundwater (tritium activity > 0.2 TU). Pharmaceutical detections were significantly positively correlated with detections of urban-use herbicides and insecticides, detections of volatile organic compounds, and percentage of urban land use around wells. Groundwater from the Los Angeles metropolitan area had higher detection frequencies of pharmaceuticals and other anthropogenic compounds than groundwater from other areas of the state with similar proportions of urban land use. The higher detection frequencies may reflect that groundwater flow systems in Los Angeles area basins are dominated by engineered recharge and intensive groundwater pumping.     

Oxidation kinetics and effect of pH on the degradation of MTBE with Fenton reagent

The fundamentals of the Fenton reagent-based degradation of low concentrations of methyl tert-butyl ether (MTBE) in batch reactors under initially anaerobic conditions are discussed in this work. The objective of the study was to quantitatively verify the feasibility of MTBE degradation with Fenton reagent under such conditions. The conclusions may be potentially helpful to further develop an effective in situ treatment of MTBE-contaminated groundwater. Initial MTBE concentrations ([MTBE](0)) of 11.4 and 22.7 microM (approximately 1.0 and 2.0 mg/L, respectively) were treated with Fenton reagent (FR) using a [FR](0):[MTBE](0) molar ratio of 10:1. FR was used in equimolar mixture of Fe(2+)and H(2)O(2) (i.e., [Fe(2+)](0):[H(2)O(2)](0)=1:1). This analysis considers the hydroxyl radicals (OH(*)) produced by FR as the main species responsible for the degradation processes. The effects of [MTBE](0) and pH on the oxidation kinetics were investigated. Under these conditions it was observed that: (i) MTBE was degraded at high extent (90-99%) after 1h of reaction time, (ii) MTBE mineralization was low in all cases and reached only 31.7% at the best conditions, and (iii) In all cases, most of MTBE degradation occurred during the initial 3-5 min of reaction. During this brief initial phase, MTBE transformation followed pseudo-first order kinetics, while the subsequent phase exhibited a sharp drop in degradation rate and had almost negligible contribution to the overall degradation. Experiments performed at acidic pH exhibited the best degradation results, while at neutral pH the degradation rates dropped significantly. Other parameters included in this analysis were: TOC reduction and total concentration of compounds containing the tert-butyl group in their structure (tBC). These compounds were analyzed because of the concerns related to their potential toxicity. Tert-butyl formate (TBF), Tert-butyl alcohol (TBA), acetone and methyl acetate were identified and quantified as major reaction intermediates.     

物化法去除MTBE的特性与影响因素

介绍了潜在致癌物甲基叔丁基醚(MTBE)的物理化学性质，综述了吸附、高级氧化、吹脱等物化法去除MTBE的特性，探讨了影响其去除效果的主要因素。     

城市区域小气候对建筑设计的影响

建筑师在建筑设计的过程中对当地气候条件因素的考虑是必不可少的一环，但气象数据的更新远跟不上城市规模和城市气候环境的变化，尤其对于特大型都市来说，同一时间内城市不同区域已出现了气象数据上较大的差异，建筑师或规划师若依然采用旧有的建筑气象数据来进行设计，则建筑与环境之间必然存在不协调之处。这是设计人员应留意的地方。     

Geophysical and hydrogeological evaluation of rising groundwater level in the coastal areas of Lagos,Nigeria

The paper reports the change in groundwater level observed in 30 wells in ten locations in southern Nigeria. Borehole data confirmed the electrical resistivity soundings which indicated the presence of topsoil, medium sand, sand, clayey sand and coarse sand. In some cases, there was little apparent change in the rate of groundwater rise, but from the data obtained it can be concluded that in the years 2000–2004 the average yearly rise was 0.3 m while between 2004 and 2007 it rose on average by 0.5 m. This rise in groundwater level has serious implications for both existing structures and the nature of the foundations for future building. The electrical resistivity survey was found to be a helpful tool in detailing the morphology of the groundwater surface and is recommended for ongoing monitoring.      

中德建筑产业之文化比较

当德国的建筑师正在为自身的建筑个性和风格而努力时,他们的中国同行则被视为繁荣的市场经济中的服务提供者和空间生产者。他们根据客户的要求生产建筑。首先重视的是建筑的外观及其形象价值。建筑的内在生命基本上是标准化的产物。在德国,建筑师扮演的角色和所处的地位和中国迥然不同。他更多地被当作专业的顾问。通常情况下他必须负责建筑的全过程：从第一张草图到建筑最后的验收。相应的,对建筑的要求不仅仅限于一个具有标准化房间的精美外壳。建筑应具有更多的价值,契合其所处的城市建设环境,通过富有创意的内部设计激发在其中工作或居住者的活力,提供生活的享受,或者增强建筑所有者的“公司形象”。在中国,市场是新生而无序的,客户本身毫无经验,企划过程非常混乱。数量依然比质量重要。这方面,建筑师事务所也只能是所处的时代的产物,这个时代的最高目标就是增长。如果在相同对间内能做三个项目,为什么只作一个呢？几乎所有的方案都有人买单,因为在德国的市场或多或少的已经饱和了的今天,中国却依然具有庞大的需求。因此,建筑的生产过程在中德两国有显著的区别。就像Joseph Rykwert所言,一个城市的肌理“是对无形事物,对其所在的社会以及对其精神的有形的反映。“城市的面貌和建筑的样式只是社会的一面镜子。而中国是个正处在巨大变动中的社会。