bluuebunny/crossref_metadata_2025 huggingface dataset:
Water quality monitoring: the basis for watershed management in the Oldman River Basin, Canada
Authors: Koning C.W. , Saffran K.A. , Little J.L. , Fent L.
Published: July 2007

The Oldman River flows 440 km from its headwaters in south-western Alberta, through mountains, foothills and plains into the South Saskatchewan River. Peak flows occur in May and June. Three major reservoirs, together with more than a dozen other structures, supply water to nine irrigation districts and other water users in the Oldman basin. Human activity in the basin includes forestry, recreation, oil and gas development, and agriculture, including a large number of confined livestock feeding operations. Based on the perception of basin residents that water quality was declining and of human health concern, the Oldman River Basin Water Quality Initiative was formed in 1997 to address the concerns. There was limited factual information, and at the time there was a desire for finger pointing. Results (1998–2002) show that mainstem water quality remains good whereas tributary water quality is more of a challenge. Key variables of concern are nutrients, bacteria and pesticides. Point source discharges are better understood and better regulated, whereas non-point source runoff requires more attention. Recent data on Cryptosporidium and Giardia species are providing benefit for focusing watershed management activities. The water quality data collected is providing a foundation to implement community-supported urban and rural better management practices to improve water quality.
Screening level analysis for monitoring pesticide in river water using a hydrological diffuse pollution model with limited input data
Authors: Matsui Y. , Narita K. , Inoue T. , Matsushita T.
Published: July 2007

To predict rice-farming pesticide concentrations in river water with imprecise model inputs for screening-level analysis, a basin-scale runoff model was developed. The Monte Carlo method was applied to create estimates of input data regarding agricultural work schedules and parameters for pesticide decomposition and sorption in solids and water. The prediction accuracy of the model was evaluated when used with non-optimised pesticide parameters; the model was calibrated using hydrological data alone without reference to observed pesticide concentration data. Overall, predictions for the pesticide concentrations were successful within order-of-magnitude accuracy. The pesticide rankings according to the predicted concentration roughly agreed with those observed. The success of screening-level analysis indicates that the model prediction can help in selection of pesticides to be monitored and in determining the monitoring schedule for the river basin.
The restoration of Loch Leven, Scotland, UK
Authors: D'Arcy B.J. , May L. , Long J. , Fozzard I.R. , Greig S. , Brachet A.
Published: July 2007

This paper reviews the progress made towards the restoration of Loch Leven, the largest lake in lowland Scotland, over the last 20 years. In particular, the importance of direct regulation and of setting water quality objectives and targets is examined. Various means of engaging with stakeholders and the general public are also considered. Success criteria and catchment management initiatives are described and briefly reviewed.
Tracing nitrates and sulphates in river basins using isotope techniques
Authors: Rock L. , Mayer B.
Published: July 2007

The objective of this paper is to outline how stable isotope techniques can contribute to the elucidation of the sources and the fate of riverine nitrate and sulphate in watershed studies. The example used is the Oldman River Basin (OMRB), located in southern Alberta (Canada). Increasing sulphate concentrations and decreasing δ34S values along the flowpath of the Oldman River indicate that oxidation of pyrite in tills is a major source of riverine sulphate in the agriculturally used portion of the OMRB. Chemical and isotopic data showed that manure-derived nitrogen contributes significantly to the increase in nitrate concentrations in the Oldman River and its tributaries draining agricultural land. It is suggested that hydrological conditions control agricultural return flows to the surface water bodies in southern Alberta and impart significant seasonal variations on concentrations and isotopic compositions of riverine nitrate. Combining isotopic, chemical, and hydrometric data permitted us to estimate the relative contribution of major sources to the total solute fluxes. Hence, we submit that isotopic measurements can make an important contribution to the identification of nutrient and pollutant sources and to river basin management.
Sediment management in sustainable urban drainage system ponds
Authors: Heal K.V. , Hepburn D.A. , Lunn R.J.
Published: July 2007

Since removal and disposal of sustainable urban drainage system (SUDS) sediment can incur high maintenance costs, assessments of sediment volumes, quality and frequency of removal are required. Sediment depth and quality were surveyed annually from 1999–2003 in three ponds and one wetland in Dunfermline, Scotland, UK. Highest sediment accumulation occurred in Halbeath Pond, in the most developed watershed and with no surface water management train. From comparison of measured potentially toxic metal concentrations (Cd, Cr, Cu, Fe, Ni, Pb, Zn) with standards, the average sediment quality should not impair aquatic ecosystems. 72–84% of the metal flux into the SUDS was estimated to be associated with coarse sediment (>500 μm diameter) suggesting that management of coarse sediment is particularly important at this site. The timing of sediment removal for these SUDS is expected to be determined by loss of storage volume, rather than by accumulation of contaminants. If sediment removal occurs when 25% of the SUDS storage volume has infilled, it would be required after 17 years in Halbeath Pond, but only after 98 years in Linburn Pond (which has upstream detention basins). From the quality measurements, sediment disposal should be acceptable on adjacent land within the boundaries of the SUDS studied.
Impacts of urbanization on West Nose Creek: a Canadian experience
Authors: van Duin B. , Garcia J.
Published: July 2007

The lower reaches of West Nose Creek have been subject to urbanization since the 1970s, leading to channel widening and excessive erosion. This paper discusses what would likely happen if urbanization were allowed to continue in the same manner. Comparisons are presented of the channel width and depth for both the upstream rural and downstream urbanizing reaches. Estimates of the evolution of the creek were generated by linking the dominant discharge to the entire shape and volume of the hydrograph that the creek is subjected to rather than solely considering peak discharges. Potential remedial measures and stormwater management philosophies are discussed in relationship to instream flow needs (IFNs) initiatives. IFNs are generally developed by relating the amount of suitable aquatic habitat to the quantity of flow. The emphasis has so far been on IFNs for large river systems. Unfortunately, none of the IFN approaches cover streams that are subject to significant urbanization. In urbanized streams the issue is not as much the impacts due to withdrawals but due to significantly increased runoff rates and volumes generated within the urban areas. Examples are provided how fisheries habitat is impacted by the changed hydrologic regime and changed stream morphology.
Implementation of the Alberta Water for Life Strategy: strategic partnerships in action
Authors: Berzins W.E. , Harrison R. , Watson P.
Published: July 2007

Alberta's Water for Life Strategy was introduced in 2003 with three main goals: safe, secure drinking water supply; healthy aquatic ecosystems; and, reliable, quality water supplies for a sustainable economy. The strategy establishes a framework of partnerships within the province that are charged with stakeholder consultation, integrated watershed planning, policy recommendations and implementation of a broad range of initiatives within this diverse prairie ecosystem. The Government of Alberta has established a framework of partnerships charged with implementation of the strategy: the province-wide Alberta Water Council, watershed planning and advisory councils that work on a basin-wide basis and watershed stewardship groups that deliver on-the-ground programs at the local and community level. The authors discuss the mandate(s) of each partnership group, key actions and deliverables. Examples are provided of specific projects undertaken by each partnership and a summary is provided of lessons learned based on the authors' direct experience over the past five years.
The CatchMod toolbox: easy and guided access to ICT tools for Water Framework Directive implementation
Authors: van Griensven A. , Vanrolleghem P.A.
Published: July 2007

Web-based toolboxes are handy tools to inform experienced users of existing software in their disciplines. However, for the implementation of the Water Framework Directive, a much more diverse public (water managers, consultancy firms, scientists, etc.) will ask for a very wide diversity of Information and Communication Technology (ICT) tools. It is obvious that the users of a web-based ICT-toolbox providing all this will not be experts in all of the disciplines and that a toolbox for ICT tools for Water Framework Directive implementation should thus go beyond just making interesting web-links. To deal with this issue, expert knowledge is brought to the users through the incorporation of visitor-geared guidance (materials) in the Harmoni-CA toolbox. Small workshops of expert teams were organized to deliver documents explaining why the tools are important, when they are required and what activity they support/perform, as well as a categorization of the multitude of available tools. An integration of this information in the web-based toolbox helps the users to browse through a toolbox containing tools, reports, guidance documents and interesting links. The Harmoni-CA toolbox thus provides not only a virtual toolbox, but incorporates a virtual expert as well.
Integrated watershed management in Quebec (Canada): a participatory approach centred on local solidarity
Authors: Baril P. , Maranda Y. , Baudrand J.
Published: July 2007

The Quebec Water Policy was launched in November 2002 in support of reform of the water governance. One of the government commitments is to gradually implement watershed-based management for 33 major watercourses located primarily in the St. Lawrence plain. At the local and regional levels, watershed organizations are responsible for implementing integrated management, from a sustainable-development perspective, by preparing a master plan for water (MPW), which will include watercourses, lakes, wetlands and aquifers. These watershed organizations rely on public consultation, as well as local and regional expertise, on the responsibilities for water of the municipalities and regional county municipalities of the territory, as well as those of the ministries and other government agencies. They are also required to observe national priorities regarding protection, restoration, and development of water resources and to comply with relevant guidelines, directives, standards, regulations, and legislation.

The role of watershed organizations is to act as planning and consultation tables. Government representatives are present, on the initial process, as the facilitator and for scientific and technical support. They do not have, at this moment, any voting or decisional rights. After two years, integrated water management mobilized water stakeholders on watersheds and they are on their way to initiating their first MPW.
Impacts on water quality in the upper Elbow River
Authors: Sosiak A. , Dixon J.
Published: July 2007

Recent work has found evidence of deterioration in water quality in the Elbow River upstream from Calgary, Alberta, Canada. We sampled this basin to describe spatial and temporal trends and factors that could be contributing to this deterioration. Sources near Calgary generally contributed most of the total phosphorus (TP) entering the river, and most total suspended solids (TSS) during low to average flows. During high flows, a large influx of TSS occurred further upstream. Sources of TP could include runoff from residential developments and agriculture, and groundwater, while re-suspension of bed material, erosion, and storm sewers may contribute TSS. Increasing trends in dissolved phosphorus (TDP) and ammonia suggest that sources in this reach are also contributing dissolved nutrients. Appreciable loading of nitrate + nitrite also occurred near Calgary, with a significant increasing trend in nitrate + nitrite occurring at every Elbow River site and several tributaries. Fecal coliforms have increased significantly over time at a downstream site. Runoff from residential developments, agriculture, or contributions from groundwater could account for this trend. In the 2003 bacterial source tracking study, DNA markers from ruminant animals were found in samples from most locations sampled in this basin, even at some headwaters sites, but no human markers were found.
Optimization and risk analyses for rule curves of reservoir operation: application to Tien-Hua-Hu Reservoir in Taiwan
Authors: Kuo J.-T. , Hsu N.-S. , Chiu S.-K.
Published: July 2007

Tien-Hua-Hu Reservoir is currently under planning by the Water Resources Agency, Taiwan to meet the increasing water demands of central Taiwan arising from rapid growth of domestic water supply, and high-tech industrial parks. This study develops a simulation model for the ten-day period reservoir operation to calculate the ten-day water shortage index under varying rule curves. A genetic algorithm is coupled to the simulation model to find the optimal rule curves using the minimum ten-day water shortage index as an objective function. This study generates many sets of synthetic streamflows for risk, reliability, resiliency, and vulnerability analyses of reservoir operation. ARMA and disaggregation models are developed and applied to the synthetic streamflow generation. The optimal rule curves obtained from this study perform better in the ten-day shortage index when compared to the originally designed rule curves from a previous study. The optimal rule curves are also superior to the originally designed rule curves in terms of vulnerability. However, in terms of reliability and resiliency, the optimal rule curves are inferior to the those originally designed. Results from this study have provided in general a set of improved rule curves for operation of the Tien-Hua-Hu Reservoir. Furthermore, results from reliability, resiliency and vulnerability analyses offer much useful information for decision making in reservoir operation.
Enhancing flexible fiber filter (3FM) performance using in-line coagulation
Authors: Lee J.-J. , Jeong M.-K. , Im J.-H. , BenAim R. , Lee S.-H. , Oh J.-E. , Woo H.-J. , Kim C.-W.
Published: July 2007

A new packing for deep bed filtration using Flexible Fibers has been proposed and developed on a very large scale for tertiary treatment of wastewater. The purpose of this study is to check the possibility of using this technology for the production of drinking water from surface water. In this study, the feasibility of the fiber filter application on water treatment was examined and the removal efficiency of fiber filter was improved using an in-line coagulant injection method. The experiments were carried out at pilot scale. The filter was packed with bundles of polyamide fibers with a bed porosity of 93%. Nak-dong River was used as the filter influent water and alum, PSOM, and PAC were used as the coagulants. The coagulants were injected by the in-line injection method. Small dosages (1–5 mg/L) of the polymeric coagulants (PSOM and PAC) showed an increase of removal efficiency compared to the operation without coagulants. Specifically, 1 mg/L of PAC showed the longest filtration time. Considering filtration time, filtrate quality, and filtered volume, the filtration velocity of 120 m/hr was chosen as an optimum value. For long-term operations, the effluent quality was 0.4 NTU and the removal efficiency was stable for the given optimum conditions.
Modeling of extracellular polymeric substances and soluble microbial products production in a submerged membrane bioreactor at various SRTs
Authors: Ahn Y.T. , Choi Y.K. , Jeong H.S. , Chae S.R. , Shin H.S.
Published: July 2007

Extracelluar polymeric substances (EPSs) and soluble microbial products (SMPs) produced by microbial cultures involved in membrane biofouling have been widely investigated. A mathematical model of EPS and SMP formation and degradation was established based on the activated sludge model no. 1 (ASM1) and was applied to the membrane bioreactor sludge with different sludge retention times (SRTs). The unified theory that the distinct products from the EPS and SMP overlapped each other was integrated into the ASM1. Two components, five processes and eight parameters were newly added to set up the model. To increase the accuracy of model simulation, microbial kinetic parameters were determined by respirometry method and applied to the model instead of microbial kinetic constant offered in ASM1. From the respirometry result, both of heterotroph and autotroph showed different yield value, growth rate and decay rate from activated sludge. There was no significant effect of SRT on SMP production and the experimental results showed good agreement with the predicted values by the model simulation. With the developed unified EPS and SMP model, EPS and SMP production could be simulated so well that it can be applied for the membrane biofouling control.
Removal efficiency of subsurface vertical flow constructed wetlands for different organic loads
Authors: Langergraber G. , Prandtstetten C. , Pressl A. , Rohrhofer R. , Haberl R.
Published: July 2007

Using subsurface vertical flow constructed wetlands (SSVFCWs) with intermittent loading it is possible to fulfil the stringent Austrian effluent standards regarding nitrification. For small plants (less than 500 persons) standards for ammonia nitrogen concentration have to be met at water temperatures higher than 12 °C, effluent concentrations and treatment efficiencies for organic matter have to be met the whole year around. According to the Austrian design standards the required surface area for SSVFCWs treating wastewater was 5 m2 per person. Within the first part of an Austrian research project the goal was to optimise, i.e. minimise the surface area requirement of vertical flow beds. Therefore, three SSVFCWs with a surface area of 20 m2 each have been operated in parallel. The organic loads applied were 20, 27 and 40 g COD/m2/d, which corresponds to a specific surface area requirement of 4, 3 and 2 m2 per PE, respectively. The paper compares the effluent concentrations and elimination efficiencies of the three parallel operated beds. It could be shown that a specific area demand of 4 m2 per person is suitable to be included in the revision of the Austrian design standard. Additionally it could be shown that during the warmer seasons (May–October) when the temperature of the effluent is higher than 12 °C the specific surface area might be further reduced; even 2 m2 per person has been proven to be adequate.
Effect of loading rate on performance of constructed wetlands treating an anaerobic supernatant
Authors: Chazarenc F. , Maltais-Landry G. , Troesch S. , Comeau Y. , Brisson J.
Published: July 2007

The effect of organic loading, season and plant species on the treatment of fish farm effluent was tested using three-year old mesocosm wetland systems. During one year, nine 1 m2 mesocosms (horizontal subsurface flow), located in a controlled greenhouse environment, were fed with a reconstituted fish farm effluent containing a high fraction of soluble components (1,600 μS/cm and in mg/L: 230±80 COD, 179±60 sCOD, 100±40 TSS, 37±7 TKN, 14±2 TP). Combinations of three hydraulic loading rates (30, 60 and 90 L.m−2 d−1) and two plant species (Phragmites australis, Typha angustifolia) and an unplanted control were tested for treatment performance and hydraulic behaviour. Loadings higher than 15 g COD m−2 d−1 resulted in a net decrease of hydraulic performances (generation of short circuiting) coupled with low TKN removal. Maximal TKN removal rates (summer: 1.2, winter: 0.6 g.m−2 d−1) were reached in planted units. In all mesocosms, phosphorus was removed during summer (maximal removal rate: 0.3 g TP m−2 d−1) and was released in winter (release rate= ∼ half of summer removal rate). This study confirmed that constructed wetlands are susceptible to clogging when treating anaerobic storage tank supernatant rich in highly biodegradable compounds. Contributions of plants to hydraulic efficiency were mainly observed in summer, associated with high evapotranspiration rates. Both plant species gave a similar removal efficiency for all pollutants.
Interaction of oxygen concentration and retention of pollutants in vertical flow constructed wetlands for CSO treatment
Authors: Woźniak R. , Dittmer U. , Welker A.
Published: July 2007

The EU Water Framework Directive (WFD) calls for a good quality of all water bodies. Retention soil filters (RSF) have been developed to treat discharges from combined sewers systems. RSF have proved over the past 15 years to be the most effective measure to meet the EU WFD standards, especially for small or particularly sensitive receiving waters, which require an enhanced reduction of emissions from combined sewer overflows (CSOs). The paper presents results from laboratory-scale experiments, in which the oxygen measurement in the filter plays a main role. The results show remarkable differences in oxygen concentrations in different filter depths. The highest oxygen consumption takes place in the upper part of the filter. In the lower part the re-aeration of sewage from the soil air dominates. This indicates that the biological activity is limited to the upper part of the filter. The availability of oxygen in the filter is a sign for degradation of wastewater compounds (ammonium, COD) under certain conditions and already takes place during the filter operation. The removal of ammonium especially cannot be strictly divided into phases of sorption during the loading and oxidation during the dry period any more.
A mass balance study on nitrification and deammonification in vertical flow constructed wetlands treating landfill leachate
Authors: Sun G. , Austin D.
Published: July 2007

A laboratory-scale, mass-balance study was carried out on the transformation of nitrogenous pollutants in four vertical flow wetland columns. Landfill leachate containing low organic matter, but a high concentration of ammoniacal-nitrogen, was treated under dissolved oxygen concentrations close to saturation. Influent total nitrogen (TN) comprised ammoniacal-nitrogen with less than 1% nitrate and nitrite, negligible organic nitrogen, and very low BOD. Nitrification occurred in three of the four columns. There was a substantial loss of total nitrogen (52%) in one column, whereas other columns exhibited zero to minor losses (<12%). Nitrogen loss under study conditions was unexpected. Two hypotheses are proposed to account for it: (1) either the loss of TN is attributed to nitrogen transformation into a form (provisionally termed α-nitrogen) that is undetectable by the analytical methods used; or (2) the loss is caused by microbial denitrification or deammonification. By elimination and stoichiometric mass balance calculations, completely autotrophic nitrogen-removal over nitrite (CANON) deammonification is confirmed as responsible for nitrogen loss in one column. This result reveals that CANON can be native to aerobic engineered wetland systems treating high ammonia, low organic content wastewater.
Diversity of ammonia oxidising bacteria in a vertical flow constructed wetland
Authors: Tietz A. , Hornek R. , Langergraber G. , Kreuzinger N. , Haberl R.
Published: July 2007

Vertical flow constructed wetlands (VFCWs) with intermittent loading are very suitable for nitrification. Ammonia oxidising bacteria (AOB) are the limiting step of nitration. Therefore the AOB community of a full-scale VFCW, receiving municipal wastewater, was investigated within this study. The diversity of the functional gene encoding the α–subunit of the ammonia monooxygenase (amoA), present only in AOB, was assessed by denaturing gradient gel electrophoresis (DGGE). Only very few amoA sequence types dominated the wetland filter substrate; nevertheless a stable nitrification performance could be observed. During the cold season the nitrification was slightly reduced, but it has been shown that the same AOB could be identified. No spatial AOB pattern could be observed within the filter body of the VFCW. The most prominent bands were excised from DGGE gels and sequenced. Sequence analyses revealed two dominant AOB lineages: Nitrosomonas europaea/“Nitrosococcus mobilis” and Nitrosospira. Species of the Nitrosomonas lineage are commonly found in conventional wastewater treatment plants (WWTPs). In contrast, members of the Nitrosospira lineage are rarely present in WWTPs. Our observations indicate that the AOB community in this VFCW is similar to that found in horizontal flow constructed wetlands, but differs from common WWTPs regarding the presence of Nitrosospira.
The removal of pathogens in surface-flow constructed wetlands and its implications for water reuse
Authors: Ghermandi A. , Bixio D. , Traverso P. , Cersosimo I. , Thoeye C.
Published: July 2007

Microbiological quality represents the biggest concern to the reuse of treated wastewater. This paper reports and discusses the results of an international survey on the removal of indicators of microbiological contamination in surface-flow constructed wetlands. Constructed wetlands consistently provide a reduction of 90–99% (1–2 log-removal) in the concentration of indicators such as coliform bacteria and faecal streptococci. This removal is found in wetlands treating water from different types of pretreatment (primary sedimentation, activated sludge, trickling filter, maturation ponds). On the other hand, when the influent is of high microbiological quality, wetlands act as sources of pathogenic contamination. The final water quality, however, is still compatible with medium to no-contact recreational activities and other final water uses. High variability in the effluent quality and seasonality might limit the opportunities for reuse. The role of constructed wetlands in different treatment schemes and the remaining open questions concerning removal mechanisms and reference pathogens are discussed.
Respirometric techniques for assessment of biological kinetics in constructed wetland
Authors: Andreottola G. , Oliveira E. , Foladori P. , Peterlini R. , Ziglio G.
Published: July 2007

The aim of this research was the development of a procedure to measure biological kinetics of organic matter oxidation and nitrification in constructed wetland, by using respirometric techniques. Columns simulating cores of vertical subsurface flow systems were investigated. The oxygen uptake rate (OUR) of the columns was calculated on the basis of the difference of DO concentrations measured continuously at the top and at the bottom of the column. From the respirogram, the following kinetic parameters have been evaluated: maximum rate of oxidation of readily biodegradable COD, maximum rate of nitrification, endogenous respiration of the biomass grown inside the bed. In order to improve the interpretation of the respirograms, additional respirometric tests were carried out on the wetland columns by using pure substrates, such as acetate (carbon source) and ammonium (substrate for nitrification). The kinetic parameters obtained from respirograms can be useful for control and design of constructed wetlands or for improving nutrient and carbon mass balances.
Upgrading constructed wetlands phosphorus reduction from a dairy effluent using electric arc furnace steel slag filters
Authors: Weber D. , Drizo A. , Twohig E. , Bird S. , Ross D.
Published: July 2007

In 2003, a subsurface flow constructed wetlands (SSF-CW) system was built at the University of Vermont (UVM) Paul Miller Dairy Farm as an alternative nutrient management approach for treating barnyard runoff and milk parlour waste. Given the increasing problem of phosphorus (P) pollution in the Lake Champlain region, a slag based P-removal filter technology (PFT) was established (2004) at the CW with two objectives: (i) to test the filters' efficiency as an upgrade unit for improving P removal performance via SSF-CW (ii) to investigate the capacity of filters technology to remove P as a “stand alone” unit.

Six individual filters (F1–F6) were filled with electric arc furnace (EAF) steel slag, each containing 112.5 kg of material with a pore volume of 21 L. F1–F4, fed with CW treated water, received approximately 2.17 g DRP kg−1 EAF steel slag (0.25 kg DRP total) during the 259 day feeding period. F1–F4 retained 1.7 g DRP kg−1 EAF steel slag, resulting in an average P removal efficiency of 75%. The addition of filters improved CW DRP removal efficiency by 74%. F5 and F6, fed non-treated water, received 1.9 g DRP kg−1 EAF steel slag (0.22 kg DRP in total) and retained 1.5 g DRP kg−1 resulting in a P removal efficiency of 72%. The establishment of the EAF slag based PFT is the first in-field evaluation of this technology to reduce P from dairy farm effluent in Vermont.
Energy-saving wastewater treatment systems: formulation of cost functions
Authors: Nogueira R. , Ferreira I. , Janknecht P. , Rodríguez J.J. , Oliveira P. , Brito A.G.
Published: July 2007

Natural interactions between water, soil, atmosphere, plants and microorganisms include physical, chemical and biological processes with decontaminating capacities. Natural or energy-saving wastewater treatment systems utilize these processes and thereby enable a sustainable management in the field of wastewater treatment, offering low investment and operation costs, little or no energy consumption, little and low-skill labor requirements, good landscape integration and excellent feasibility for small settlements, especially when remote from centralized sewer systems.

The objective of this work is the development of cost functions for investment and operation of energy-saving wastewater treatment technologies. Cost functions are essential for making cost estimations based on a very reduced number of variables. The latter are easily identified and quantified and have a direct bearing on the costs in question. The formulated investment and operation cost functions follow a power law, and the costs decrease with the increase of the population served. The different energy-saving wastewater treatment systems serving small population settlements, between 50 p.e. and 250 p.e., present associated investment costs varying from 400 €/p.e. to 200 €/p.e. and annual operation costs in the range of 70 €/p.e. to 20 €/p.e., respectively.
Model experiments on improving nitrogen removal in laboratory scale subsurface constructed wetlands by enhancing the anaerobic ammonia oxidation
Authors: Paredes D. , Kuschk P. , Stange F. , Müller R.A. , Köser H.
Published: July 2007

Anaerobic ammonia oxidation (Anammox) has been identified as a new general process-strategy for nitrogen removal in wastewater treatment. In order to evaluate the role and effects of the Anammox process in wetlands, laboratory-scale model experiments were performed with planted fixed bed reactors. A reactor (planted with Juncus effusus) was fed with synthetic wastewater containing 150–200 mg L−1 NH+4 and 75–480 mg L−1 NO−2. Under these operating conditions, the plants were affected by the high ammonia and nitrite concentrations and the nitrogen removal rate fell within the same range of 45–49 mg N d−1 (equivalent to 0.64–0.70 g Nm−2d−1) as already reported by other authors. In order to stimulate the rate of nitrogen conversion, the planted reactor was inoculated with Anammox biomass. As a result, the rate of nitrogen removal was increased 4–5-fold and the toxic effects on the plants also disappeared. The results show that, in principle, subsurface flow wetlands can also function as an “Anammox bioreactor”. However, the design of a complete process for the treatment of waters with a high ammonia load and, in particular, the realisation of simple technical solutions for partial nitrification have still to be developed.
Effects of type of flow, plants and addition of organic carbon in the removal of zinc and chromium in small-scale model wetlands
Authors: Paredes D. , Vélez M.E. , Kuschk P. , Mueller R.A.
Published: July 2007

Constructed wetlands are used for the treatment of wastewater containing metals. In order to clarify the role of plants, flow and the impact of organic matter, an investigation of three factors, each at two different levels, was carried out in small-scale model wetlands. The evaluated factors and levels were: type of flow (subsurface and surface); presence of plants (planted with Typha latifolia and unplanted) and addition of organic matter (with and without). Eight different experimental units were run for a year. The units were fed with synthetic wastewater containing chromium (VI) (1.5 mg L−1), zinc (1.5 mg L−1), macro, micronutrients and organic matter (to those units in which this factor was being investigated). Subsurface flow wetlands showed a significantly higher rate of chromium removal in comparison with surface flow systems (97 and 60 mg m−2 d−1, respectively). Planted systems removed significantly more chromium compared to unplanted systems (85 and 76 mg m−2 d−1, respectively), and the addition of organic matter increased the removal rate in a comparison with the units without it (88 and 69 mg m−2 d−1, respectively). Similar results were found for zinc; however, the addition of organic matter made no significant difference to zinc removal.
Nitrogen dynamics in a constructed wetland system treating landfill leachate
Authors: Kinsley C.B. , Crolla A.M. , Kuyucak N. , Zimmer M. , Laflèche A.
Published: July 2007

A pilot scale treatment system was established in 2002 at the Laflèche Landfill in Eastern Ontario, Canada. The system consists of a series of treatment steps: a stabilisation basin (10,000 m3), a woodland peat trickling filter (5,200 m2), a subsurface flow constructed wetland planted in Phragmites sp. (2,600 m2), a surface flow constructed wetland planted in Typha sp. (3,600 m2) and a polishing pond (3,600 m2). The system operates from May to December with leachate being recycled within the landfill during the winter months.

Hydraulic loading was increased three-fold over four operating seasons with nitrogen and organic mass loading increasing six-fold. Excellent removal efficiencies were observed with 93% BOD5, 90% TKN and 97% NH4-N removed under the highest loading conditions. Almost complete denitrification was observed throughout the treatment system with NO3-N concentrations never exceeding 5 mg·L−1. The peat filter reached treatment capacity at a hydraulic loading of 4 cm·d−1 and organic loading rate of 42 kg BOD·ha−1·d−1, which is consistent with design criteria for vertical flow wetland systems and intermittent sand filters.

The first order plug flow kinetic model was effective at describing TKN and ammonium removal in the SSF and FWS wetlands when background concentrations were taken into account. Ammonium removal k-values were consistent with the literature at 52.6 and 57.7 yr−1 for the SSF and FWS wetlands, respectively, while TKN k-values at 6.9 and 7.7 yr−1 were almost an order of magnitude lower than literature values, suggesting that leachate TKN could contain refractory organics not found in domestic wastewater.
Twenty years experience with constructed wetland systems in Denmark – what did we learn?
Authors: Brix H. , Schierup H.-H. , Arias C.A.
Published: July 2007

Full scale constructed wetland systems for wastewater treatment have been in operation in Denmark since 1983, mainly for the treatment of domestic sewage from small villages. The systems are constructed as soil-based horizontal subsurface flow systems but, because of low soil hydraulic conductivity, surface runoff is evident in most of the systems. Two decades of experience show that soil-based systems are generally efficient in removing suspended solids and BOD, but the removal of nitrogen and phosphorus is lower (typically 30–50%) and the systems do not nitrify ammonium. Contrary to earlier claims, the reeds do not increase the hydraulic conductivity of cohesive soils as much as necessary to secure sub-surface flow. Operation needs of soil-based reed beds are low and normally restricted to emptying of the sedimentation tank, cleaning of the distribution system and mowing of the grass around the system. The dead plant material and accumulated litter on the surface of the systems improve performance after the initial years. A significant number of systems have been shut down or extended with other technologies in order to meet new effluent standards, particularly demands for nitrification. New constructed wetland systems are either compact vertical flow systems which provide good nitrification, willow systems with no discharge or restored wetland systems for nitrate removal. If efficient removal of phosphorus is required, this is achieved by chemical precipitation in the sedimentation tank.
Potential nitrification and denitrification and the corresponding composition of the bacterial communities in a compact constructed wetland treating landfill leachates
Authors: Sundberg C. , Tonderski K. , Lindgren P.-E.
Published: July 2007

Constructed wetlands can be used to decrease the high ammonium concentrations in landfill leachates. We investigated nitrification/denitrification activity and the corresponding bacterial communities in landfill leachate that was treated in a compact constructed wetland, Tveta Recycling Facility, Sweden. Samples were collected at three depths in a filter bed and the sediment from a connected open pond in July, September and November 2004. Potential ammonia oxidation was measured by short-term incubation method and potential denitrification by the acetylene inhibition technique. The ammonia-oxidising and the denitrifying bacterial communities were investigated using group-specific PCR primers targeting 16S rRNA genes and the functional gene nosZ, respectively. PCR products were analysed by denaturing gradient gel electrophoresis and nucleotide sequencing. The same degree of nitrification activity was observed in the pond sediment and at all levels in the filter bed, whereas the denitrification activity decreased with filter bed depth. Denitrification rates were higher in the open pond, even though the denitrifying bacterial community was more diverse in the filter bed. The ammonia-oxidising community was also more varied in the filter bed. In the filter bed and the open pond, there was no obvious relationship between the nitrification/denitrification activities and the composition of the corresponding bacterial communities.
Wastewater treatment in tsunami affected areas of Thailand by constructed wetlands
Authors: Brix H. , Koottatep T. , Laugesen C.H.
Published: July 2007

The tsunami of December 2004 destroyed infrastructure in many coastal areas in South-East Asia. In January 2005, the Danish Government gave a tsunami relief grant to Thailand to re-establish the wastewater management services in some of the areas affected by the tsunami. This paper describes the systems which have been built at three locations: (a) Baan Pru Teau: A newly-built township for tsunami victims which was constructed with the contribution of the Thai Red Cross. Conventional septic tanks were installed for the treatment of blackwater from each household and its effluent and grey water (40 m3/day) are collected and treated at a 220 m2 subsurface flow constructed wetland. (b) Koh Phi Phi Don island: A wastewater collection system for the main business and hotel area of the island, a pumping station and a pressure pipe to the treatment facility, a multi-stage constructed wetland system and a system for reuse of treated wastewater. The constructed wetland system (capacity 400 m3/day) consists of vertical flow, horizontal subsurface flow, free water surface flow and pond units. Because the treatment plant is surrounded by resorts, restaurants and shops, the constructed wetland systems are designed with terrains as scenic landscaping. (c) Patong: A 5,000 m2 constructed wetland system has been established to treat polluted water from drainage canals which collect overflow from septic tanks and grey water from residential areas. It is envisaged that these three systems will serve as prototype demonstration systems for appropriate wastewater management in Thailand and other tropical countries.
Nitrogen isotope fractionation as a tool for determining denitrification in constructed wetlands
Authors: Søvik A.K. , Mørkved P.T.
Published: July 2007

Constructed wetlands (CWs) treat municipal wastewater through the retention of nutrients and particles. The retention of nitrogen (N) was studied in the laboratory using columns and meso-scale trenches filled with shellsand and light-weight aggregates (LWA). The objective was to examine whether measuring the natural abundance of δ15N in NO−3 could be used to estimate the relative contribution of denitrification to the total NO−3 removal in these treatment systems. In both the columns and the trenches it was seen that denitrification was more efficient in shellsand and LWA collected from on-site treatment systems compared to new LWA. This was due to the high pH value (about 10) of new LWA. The enrichment factors (ε) from the column study were in general lower than values found in laboratory tests of isotope discrimination in denitrification, but similar to ε values found for denitrification in groundwater systems. No enrichment factors could be found for the trench study due to simultaneous denitrification and nitrification and inhomogeneous N transformation patterns. When NH+4 was partially nitrified in the upper parts of the trench, this diluted the 15N enrichment of NO−3 due to denitrification. Thus, in systems with high NH+4 concentrations and partial aerobic conditions, the method of natural abundance is not suitable for estimating the relative contribution of denitrification to the total NO−3 removal.
Researching External Evaluators of Higher Education in Germany: Methods and Techniques
Authors: Harris-Huemmert Susan
Published: July 2007

Expert committees are frequently called into institutions to analyse the status quo and make recommendations for improvement or change. This is so within the fields of medicine and law, and increasingly so within the field of education, and higher education in particular. Little is known, however, about the mechanisms at work within such expert committees in any of these contexts as literature is surprisingly scarce. German higher education is presently undergoing a process of change as it moves towards a three-tiered degree structure: Bachelor, Masters and doctorate. Experts are being called upon to examine the state of education and make recommendations that can have a major impact on the future of a discipline or department. It is the aim of this article to reveal some of the issues that need addressing when the focus of study is the people who make up expert evaluation commissions.
Time and Comparative and International Education
Authors: Westlund Erik
Published: July 2007

This article argues that epistemological and theoretical issues surrounding time in relation to comparative and international education need further exploration in consideration of the new understandings of time that have emerged (or re-emerged) during the last century. By drawing on an interdisciplinary selection of ideas as well as various scholars' conceptualizations of time that range from antiquity to the present, the article suggests practical ways, supported by sociological and historical examples, to theorize time for application in comparative educational research. Appropriating a more nuanced understanding and abstraction of temporality is necessary and opens different time-worlds for comparison, resulting in knowledge informed and shaped by a time that transcends Newtonian linearity and discreteness. The article is written with the understanding that as technology continues to stimulate globalization and redraw the boundaries of space and time, the importance of reconsidering temporality in regard to educational research is clear.
The Commonwealth Teacher Recruitment Protocol: Its Impacts and Implications for the Global Teaching Profession
Authors: Miller Paul Washington , Mulvaney Guy , Ochs Kimberly
Published: July 2007

This article discusses the development and implementation of the Commonwealth Teacher Recruitment Protocol, which was adopted in September 2004. Following a review of the contextual issues of international teacher migration, the challenges of teacher recruitment are discussed. Key features of the Protocol are highlighted and discussed with regard to the current task of implementation. A comparison is made between recruitment before and after the adoption of the Protocol, focusing on the United Kingdom. In conclusion, the article highlights challenges and opportunities for Protocol implementation and areas for further research.
Exploring Turkish Pre-Service Science Education Teachers' Understanding of Educational Technology and Use
Authors: Türkmen Hakan , Pedersen Jon E. , McCarty Robbie
Published: July 2007

Helping prospective teachers become more knowledgeable and skilled in the use of technology in education is an important goal of today's teacher preparation programs. This article reports the results of a survey, ‘Pre-service Teacher Technology Survey: technology usage and needs of science educators', that determined pre-service science education teachers' perceptions of their preparation vis-à-vis technology and the pre-service teachers' knowledge and desired knowledge of technology. More specifically, the focus was to address the understandings of Turkish pre-service teachers regarding their current and desired knowledge of educational technology. The findings of this study show that Turkish pre-service science education teachers are relatively unfamiliar with the advantages of educational technology and do not maximize its use. However, they have a desire to know more about the advantages of educational technology and its use in the education of Turkish children.