Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas

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Impacts of green roofs and rain water use on the water balance and groundwater levels in urban areas

     

Assessment of soil and groundwater impacts by treated urban wastewater reuse. A case study: application in a golf course (Girona, Spain)

Starting in July 2000, treated wastewater of urban origin has been used for the "Serres de Pals" golf course irrigation (Girona, Spain). To evaluate if the soil and the aquifer underneath are affected by the utilization of this type of water, samples have been taken along a period of several months from the wastewater treatment plant, the stabilization lagoon, groundwater and soil profiles. Analyses have been performed for total coliforms and aerobic bacteria, soil water pressure and soil water content as well as chemical analyses of the irrigation water, aquifer and water of the vadose zone. Soil profiles taken at several times during the study indicate the absence of coliforms except for a short period during summer. In the vadose zone an increase of more than 1000 mg kg(-1) of NaO(2) in the top 60 cm of soil was observed while Cl(-) concentration in the aquifer reached up to 1200 mg l(-1) ten months after starting the irrigation.     

Integrative quantification and balancing of contaminant fluxes in urban groundwater, case study Darmstadt

The qualitative and quantitative impact of a city on groundwater is presented in the case study of Darmstadt. The impact of land use on groundwater quality in Darmstadt is higher than the impact of background geological processes. The occurrence of Cl, B and Fe is only influenced by land use, while EC, HCO₃ and PO₄ are controlled by geology and land use. An integrative, spatially differentiating quantification of mass fluxes shows that e. g. Cl and B are introduced from urban sources such as leaking sewers and road salting. Input is highest under industrial areas (Cl 317 mg/d?·?m², B 0,6 mg/d?·?m²). For N_tot agricultural input (114 mg/d?·?m²) is more important than urban input with a maximum of 14 mg/d?·?m². Comparing overall urban input with estimated urban input, it can be concluded that there are additional sources for HCO₃, Ca, Mg, SO₄, Na, Cl, B and NO₃, which are not included in the estimated input (e. g. geogenic sources, fill material, industrial sources & degradation processes). PO₄ and N_tot on the other hand are being degraded and COD is consumed. A decrease of concentrations downstream from the city can be ascribed to diving plumes.     

矿石淋滤水对地下水污染影响的模拟预测

本文利用地下水数值模拟软件GMS,研究矿石淋滤水对地下水污染的影响。模拟在非正常状况下,矿石经雨水淋滤后,淋滤液中的污染物直接穿透包气带进入地下水运移的情景。经预测,泄漏的污染物铁经过运移后出现短暂超标现象,超标范围未出研究区范围,没有对下游敏感点造成影响。随着时间的推移,污染物在地下水的对流、弥散作用下,污染晕中心浓度逐渐降低,污染晕范围逐渐扩大,直至低于限值。研究成果可为该区的地下水保护措施提供依据。     

Natural organic matter (NOM) removal and structural changes in the bacterial community during artificial groundwater recharge with humic lake water

This study evaluated the removal of natural organic matter (NOM) and structural changes in the microbial community during infiltration of humic lake water at three artificial groundwater recharge (AGR) sites in Finland. The three sites were at waterworks in H?meenlinna, Jyv?skyl? and Tuusula, sites A, B and C, respectively. Site A used groundwater recharge by both basin and sprinkling infiltration, site B used only sprinkling infiltration, and site C used only basin infiltration. Reductions of total organic carbon at sites A, B and C were 91%, 84% and 74%, respectively, in the winter, and 88%, 77% and 73%, respectively, in the summer. The Finnish national recommended value of 2 mg/l for TOC was achieved at all sites and the TOC of natural groundwater at site C was much lower, at 0.6 mg/l. Large molecular fractions of NOM were removed more efficiently than the smaller ones. Total amount of DAPI-stained cells decreased during infiltration at sites A, B and C in winter by 94%, 94% and 75% and in summer by 96%, 97% and 94%, respectively. Bacterial communities in raw waters and extracted groundwaters were diverse with changes occurring during infiltration, which was shown by DNA extraction followed by PCR of 16S rRNA genes and denaturing gradient gel electrophoresis (DGGE) fingerprinting. While the natural groundwater microbial community was diverse, it was different from that of the extracted groundwater in the AGR area. Simultaneous organic carbon removal and the decrease of bacterial counts during infiltration indicated biodegradation. In addition, the changing DGGE profiles during the process of infiltration, demonstrated that changing environmental conditions were reflected by changes in bacterial community composition.     

A statistical and geographical information system analysis for groundwater intrinsic vulnerability: a validated case study from Sfax–Agareb,Tunisia

The groundwater vulnerability to the pollution assessment was considered as an efficient tool to limit and to control its quantitative and qualitative degradation risks. The DRASTIC high, moderate and low groundwater vulnerability zones of the Sfax–Agareb basin (Tunisia) cover about 10, 29 and 61% of the study area, respectively. The validation of the DRASTIC vulnerability map was undertaken through comparison of areas of high nitrate concentration and their relative vulnerability index. The DRASTIC vulnerability map illustrates a good rate of coincidence between the nitrate concentration ranges and the various vulnerability classes as recognized by statistical analysis. The reliability of the final vulnerability map has been tested, showing a general positive trend relating the mean nitrate concentration in the wells to their relative vulnerability classes (R²=0.88). When correlating the 214 available groundwater nitrate concentrations to the DRASTIC index in these wells location, a significant positive correlation with Cor=0.55 was found.     

VLDA模型及其在潜水脆弱性评价中的应用——以新疆焉耆县平原区为例

在地下水脆弱性评价的GOD法和DRASTIC模型的基础上,提出了VLDA模型,其中V为包气带岩性(1ithology of vadose zone)、L为土地利用方式(pattern of land use)、D为地下水埋深(groundwater depth)、A为含水层特征(aquifer characterist...     

Rural ethos and urban development: the emergence of the first Hebrew town in modern Palestine

Since the late nineteenth century, the Zionist movement emphasized ruralism not only for the pastoral areas of Palestine, but also for its urban centres. This paper explores the emergence of Tel Aviv, the first Hebrew town, in the light of the Zionist rural/pastoral ideology and within the late nineteenth century discourse on city planning. It discusses early Tel Aviv’s rural images and the various means that were implemented by local and international planners, Zionist cultural agents, volunteer organizations and residents in order to materialize the green vision for the first Hebrew town. This paper argues that till the mid‐1930s, the development of Tel Aviv discarded the common modern dichotomy of nature/culture or pastoral/urban, proving that the development of the rural, agricultural landscape and the construction of the urban metropolis were complementary facets of the Zionist dream.     

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.     

Energy consumption in an urban wastewater treatment plant: the case of Murcia Region (Spain)

Of all the costs associated with the operation and maintenance of wastewater treatment plants (WWTPs), those associated with energy use tend to be the most significant. From this point of view, it is hence logical that energy efficiency and saving strategies should be one of the current focuses of debate amongst those involved with the management of WWTPs. The present study's objective is to determine the correlation between size and energy consumption for a WWTP. To this end, 90 WWTPs currently in service were analysed and their energetic impact quantified in terms of kWh/m³ of water treated. The results obtained demonstrate that energy consumption ratio increases as the size of WWTPs decreases, either in terms of treatment volume or population equivalent served.     

Analysis of a current water tariff and attitudes towards change: A representative study from a Palestinian city

The problem of an outdated tariff has become acute recently with increased water scarcity in Palestine. Therefore, the goals of the study were to analyse the factors that could affect the water consumption in Jericho governorate, Palestine; explore societal perceptions of alternative water sources; and to identify areas that need to be re-examined for tariff revision or changes to water source and delivery. A total of 76% of the respondents know the water tariff price, and 61% of the sample considers the tariff as high. Future suggestions to raise the price of water will meet resistance. Interestingly, 66% of the respondents agree with the possible future use of treated wastewater, and 46% of the respondents emphasize that treated wastewater is the most favoured solution for water scarcity. Overall, the results indicate the public identifies water conservation as possible and that alternative actions can be applied in order to manage and conserve water resources.     

Water use,sanitation and health in a fragmented urban water system: case study and household survey

In a study to identify strategies to deal with rapid urbanization and threatening climate change, in Can Tho City, Vietnam, a survey of 1200 households was undertaken to investigate water access and sanitation services. The survey targeted three different groups based on their access to water services: (a) those with piped water supply, (b) without piped water, and (c) a mix of (a) and (b). Socio-economic factors and level of urbanization significantly influenced the different water sources accessed by households and their type of sanitation. Results indicated that householders often employed multiple water sources in an attempt to match source with intended use. The use of multiple water sources, levels of sanitation and the quality of water were found to be good indicators of reported rates of illness. Results also showed that the provision of piped water does not always provide the desired health outcomes, as the definition of adequate water supply does not include water quality objectives. Therefore, more detailed assessments may be required to understand how people use and access water and sanitation, and the impacts on public health.     

Tariff (un)sustainability in contexts of price (in)stability: The case of the Buenos Aires water and sanitation concession

We aim to analyze tariff sustainability in the Buenos Aires water and sanitation concession amidst price instability. We use the 3Ts model (Tariff, Taxes and Transfers) to discuss tariff resetting from 2002 to 2019. We show that both level and tariff structure reflect the national administrations' preferences as regards service cost allocation among stakeholders. Despite the efforts, revenue has been below operative expenditure, which shows the company's difficulty to remain operationally sustainable and the differences between the ex-ante and ex-post burden of the three Ts. We suggest recommendations for the regulator to shield the sector against price instability.     

A geostatistical approach for groundwater head monitoring network optimisation: case of the Sfax superficial aquifer (Tunisia)

In many developing countries, the groundwater monitoring network is randomly designed, and consequently needs to be revised and optimised to reduce operation time and cost, remove redundant piezometric data, and strengthen sparseness data zone with supplementary observation well. The geostatistical approach used in this work is based on the universal kriging variance combined with cross‐validation test. Hence, a rational interpolation of water table elevations was performed to evaluate the accuracy of data employed in the piezometric head modelling. In this study, the groundwater monitoring network of the Sfax superficial aquifer in the south east of Tunisia was optimised. The elimination of five observation wells induces the invariability in the variance of estimate due to their less contribution in interpretations of the groundwater level behaviour. However, 38 wells were added at areas of high variance of the kriging in order to ameliorate the spatial coverage of the monitoring network.     

Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor

Feasibility of grey water treatment in an upflow anaerobic sludge blanket (UASB) reactor operated at different hydraulic retention time (HRT) of 16, 10 and 6h and controlled temperature of 30 degrees C was investigated. Moreover, the maximum anaerobic biodegradability without inoculum addition and maximum removal of chemical oxygen demand (COD) fractions in grey water were determined in batch experiments. High values of maximum anaerobic biodegradability (76%) and maximum COD removal in the UASB reactor (84%) were achieved. The results showed that the colloidal COD had the highest maximum anaerobic biodegradability (86%) and the suspended and dissolved COD had similar maximum anaerobic biodegradability of 70%. Furthermore, the results of the UASB reactor demonstrated that a total COD removal of 52-64% was obtained at HRT between 6 and 16 h. The UASB reactor removed 22-30% and 15-21% of total nitrogen and total phosphorous in the grey water, respectively, mainly due to the removal of particulate nutrients. The characteristics of the sludge in the UASB reactor confirmed that the reactor had a stable performance. The minimum sludge residence time and the maximum specific methanogenic activity of the sludge ranged between 27 and 93 days and 0.18 and 0.28 kg COD/(kg VS d).     

Domestic wastewater management in South and Southeast Asia: the potential benefits of a decentralised approach

Owing to its enormous construction and maintenance costs, the management of wastewater in many urban centres of developing countries via a centralised wastewater management approach is very difficult. Often, untreated wastewater is directly discharged into adjacent natural water courses, causing a grave threat to both public health and the aquatic environment. A decentralised wastewater management approach is a prospective solution to overcome this adverse situation because of its low cost, simple operation and revenue return. To identify the potential of a decentralised wastewater management system in developing countries, the wastewater management policies, institutional frameworks, reuse practices and sanitation situations in selected Asian countries were reviewed and recommendations for effective wastewater management are proposed.     

Removal of individual off-flavour compounds in water during artificial groundwater recharge and during treatment by alum coagulation/sand filtration

The removal of individual off-flavour compounds during artificial groundwater recharge has been compared to the removal of such compounds during conventional alum coagulation/sand filtration. By using an evaluation technique based on gas chromatography with both instrumental and sensory detection (“column sniffing”) it was shown that alum coagulation/sand filtration had no significant effect on any of the off-flavour compounds that could be detected in the raw water samples (geosmin, 2-methylisoborneol, 2-isopropyl-3-methoxypyrazine, 2,4,6-trichloroanisole, 1-octen-3-one, 1-nonen-3-one, dimethyl trisulphide and a number of unidentified muddy or musty odours). During artificial groundwater recharge in sand and gravel ridges, however, the concentrations of all these compounds were substantially reduced, thus proving that artificial groundwater recharge is not only a suitable method for water storage but can also be an effective method for removing muddy and musty odours. The successful use of the column-sniffing technique for evaluating water treatment methods has shown the potential of this technique in resolving some of the present disagreements concerning the effectiveness of different treatment methods for removing tastes and odours from water.     

A combined approach to the evaluation of organic air pollution - a case study of urban air in Sarajevo and Tuzla(Bosnia and Herzegovina)

Organic pollution is a complex mixture where besides usually discussed polycyclic aromatic hydrocarbons (PAHs) a lot of other toxic or potentially toxic compounds occur. In this case, the organic air pollution in two important industrial cities, Sarajevo and Tuzla, in Bosnia and Herzegovina (part of former Yugoslavia) was assessed with the emphasis placed on genotoxic risks using both chemical (PAHs analyses) and biological approaches (genotoxicity testing with a screening bacterial genotoxicity test - SOS chromotest). The study was performed as a part of the APOPSBAL project (ICA2-CT2002-10007). So far there has not been any information either about the PAHs pollution or the genotoxic activity of the organic air pollution for the localities under the study. Therefore, the presented information is considered absolutely unique. Both used approaches made possible to identify the localities with the highest pollution level and genotoxic risks in both cities. Generally, higher levels of both parameters were determined in Tuzla, which is much more industrialized than Sarajevo, and especially at localities close to city centers and affected by traffic emissions, but also at localities polluted by emissions from industry and household heating. Even if benzo(a)pyrene concentrations exceeded the maximum permitted levels for this pollutant at some localities in Tuzla, the PAHs concentrations were fully comparable with the levels determined in other industrial European cities. Significant genotoxicity of the organic extracts was detected for almost all of the urban localities in the test both without (-S9; direct genotoxicity) and with the addition of metabolic activation (+S9; indirect genotoxicity). The observed direct genotoxic activities were discussed in relation to a potential presence of PAHs derivatives in the air. The indirect genotoxic activities were apparently higher at the localities with higher contents of carcinogenic PAHs. The significant relationship between the determined genotoxic activities and the PAHs pollution was also confirmed by a regression analysis. However, the correlations were not absolute because the observed genotoxic activity was also dependent on the presence of other organic pollutants than the PAHs. It concerns predominantly direct genotoxicity which is not related with the PAHs, but with their nitro-, oxi-, and hydroxy-derivatives and also other unknown polar organic pollutants. However, the concentrations of the direct genotoxins apparently correlated with the PAHs contents in the air. The study showed that screening genotoxicity tests, such as the SOS chromotest, could be effectively used for the identification of localities with increased genotoxic risks. In comparison with the health risk assessment which is usually based on the chemical analyses of only a small part of the pollution mixture, the bioassays enable us to evaluate the risks of all the mixture. The localities with the highest detected human health risks according to the screening bioassays may then be analyzed in detail with specific chemical methods to identify their causes.     

Evaluation of ornamental plant resources to urban biodiversity and cultural changing: A case study of residential landscapes in Trabzon city (Turkey)

The residential vegetation features in urban landscapes play an important role as indicators regarding urban biodiversity potential and cultural changing. They also include ornamental resources in the context to landscape appreciation for human environment. Therefore, this paper provides quantitative information on the distribution of plant species in urban residential landscape areas of Trabzon city (Turkey). In a total of 218 sampled areas, 274 plants species belonging to 70 families were surveyed with respect to residential use types of the city. The study results showed that among the species recorded in five residential type (traditional housing, detached housing, villa, apartment blocks and sites, mass housing for employees), non-native taxa frequency of a total species are much and dominantly represent residential landscape structure. Additionally, the species richness and diversity is positively related to new urban development areas. But, it was clearly determined that the vegetation structure has tended to ornamental purposes different from traditional residential gardens including fruit and other benefiting species. Consequently, it can be evidence that the residential vegetation is ornamental plant resources to urban biodiversity and that the distribution of the species in urban landscapes follows necessities of city and human quality.     

The long-term reform of the water and wastewater industry: The case of Melbourne in Australia

Since the 1980s, one of the most important parts of Australian microeconomic reform has been the restructuring of the country’s government owned utilities - including water supply and wastewater disposal. This process was encouraged by the perception that the state owned authorities performed poorly in the 1970s and 1980s. This paper analyses economic performance of the Melbourne water and wastewater industry from the early 1970s. Over the longer term, the industry has improved its economic performance in terms of productivity and returns to the shareholder, however, consumers have not substantially benefited from this process in terms of lower prices.