bluuebunny/crossref_metadata_2025 huggingface dataset:
Water shortage and needs for wastewater re-use in the north China
Authors: Wang X.C. , Jin P.K.
Published: July 2007

This paper analyses the present condition of the water shortage in north China where annual rainfall is low and per capita water resource is below the line of regular water stress, or even the line of absolute water scarcity. Of the available water resources, the percentge of water withdrawal in all the north basins is high – the Yellow River and Huai River basins being greater than 80% and the Hai River basin mainly depending on interbasin water transfer. Over-withdrawal of water also results in serious water environmental problems including “flow cut-off” of the Yellow River main channel and water pollution of many rivers. The paper also analyses the potential of wastewater as a resource and the demand for treated wastewater re-use. In north China, due to low rainfall and high potential evaporation environmental re-use, gardening, afforestation, etc. is considered as the main usage of the treated wastewater. Considering the economic restrictions in the less developed area, a decentralised system can be taken as an important option in formulating water re-use strategies.
Technology in the high entropy world
Authors: Tambo N.
Published: July 2007

Modern growing society is mainly driven by oils and may be designated “petroleum civilisation”. However, the basic energy used to drive the global ecosystem is solar radiation. The amount of fossil energy consumption is minimal in the whole global energy balance. Economic growth is mainly controlled by the fossil (commercial) energy consumption rate in urban areas. Water and sanitation systems are bridging economical activities and global ecosystems. Therefore, vast amounts of high entropy solar energy should always be taken into account in the water industry. Only in urban/industrial areas where most of the GDP is earned, are commercial energy driven systems inevitably introduced with maximum effort for energy saving. A water district concept to ensure appropriate quality use with the least deterioration of the environment is proposed. In other areas, decentralised water and sanitation systems driven on soft energy paths would be recommended. A process and system designed on a high entropy energy system would be the foundation for a future urban metabolic system revolution for when oil-based energy become scarce.
Biological wastewater treatment by a bioreactor with repeated coupling of aerobes and anaerobes aiming at on-site reduction of excess sludge
Authors: Yu Anfeng , Feng Quan , Liu Zehua , Zhou Yunan , Xing Xin-Hui
Published: July 2007

Activated sludge has been widely used in wastewater treatment throughout the world. However, the biggest disadvantage of this method is the by-production of excess sludge in a large amount, resulting in difficulties in operation and high costs for wastewater treatment. Technological innovations for wastewater treatment capable of reducing excess sludge have thus become research topics of interest in recent years. In our present research, we developed a new biological wastewater treatment process by repeated coupling of aerobes and anaerobes (rCAA) to reduce the excess sludge during the treatment of wastewater. During 460-day continuous running, COD (300–700 mg/L) and TOC (100–350 mg/L) were effectively removed, of which the removal rate was above 80 and 90%, respectively. SS in the effluent was 13 mg/L on average in the rCAA bioreactor without a settling tank. The on-site reduction of the excess sludge in the rCAA might be contributed by several mechanisms. The degradation of the grown aerobes after moving into the anaerobic regions was considered to be one of the most important factors. Besides, the repeatedly coupling of aerobes and anaerobes could also result in a complex microbial community with more metazoans and decoupling of the microbial anabolism and catabolism.
Pilot study on municipal wastewater treatment by a modified submerged membrane bioreactor
Authors: Wei Chunhai , Huang Xia , Wen Xianghua
Published: July 2007

A pilot-scale modified submerged membrane bioreactor (SMBR) with the capacity of 18.1 m3d−1 was developed on the basis of the principle of air-lift internal-loop reactor. Economical aeration intensity of the SMBR was determined as 96 m3m−2h−1 according to hydrodynamic investigation. Corresponding economical air-flow rate was selected as the working air-flow rate in the long-term run. Under economical aeration intensity, the critical flux zone of the modified SMBR was as high as 30–35 Lm−2h−1 when MLSS was less than 13 gL−1. Therefore, a sub-critical flux of 30 Lm−2h−1 was selected as the working membrane flux in the long-term run. Membrane fouling was effectively controlled by sub-critical flux operation and periodic on-line chemical cleaning in the long-term run. When the average influent CODCr, NH3-N and turbidity were 310 and 44.3 mgL−1 and 161 NTU, respectively, the average permeate were 38.5 and 19.5 mgL−1 and 0.96 NTU under hydraulic retention time (HRT) was only 2.8 h. Corresponding removal was 86, 58.2 and 99.4%. DO deficiency caused by high MLSS was demonstrated as the main reason for low NH3-N removal.
Design and operation of the bio-toilet system
Authors: Lopez Zavala M. A. , Funamizu Naoyuki
Published: July 2007

Criteria for the proper design and operation of the bio-toilet have not been established either by the manufacturers or by the authorities. Based on the results of experimental research already reported by us, criteria for the proper design and operation of the bio-toilet system were established. The establishment of operation criteria led to the formulation of an operation scheme where three main zones are distinguished: i) green zone, where the best composting performance is expected; ii) yellow zone, where biodegradation can be conducted but performance is not the most efficient; iii) other zones where operation of the bio-toilet is not recommended because odour problems and human health risks will develop, or in the worst case, biodegradation of faeces will not occur. In the design criteria, the surface area required for evaporating the water loads due to contributions of urine and faeces was determined by applying concepts of drying theory. This theory was also applied to estimate the mass and volume of dried sawdust required for dealing with the critical water loading. However, the accumulation of stabilised solids transpired to be more critical and, finally, mass and volume of dried sawdust were estimated based on this factor.
Toxicity screening and evaluating in chlorination disinfection of wastewater reclamation processes
Authors: Wei Dongbin , Wang Lisha , Wei Jie , Hu Hong-Ying
Published: July 2007

Reclamation and re-use of wastewater is one of the most effective ways to alleviate the shortage of water resources, while the safety of reclaimed water becomes one of the critical problems for protecting human health and the ecosystem. While a toxicity test can vividly reflect biological effects of chemicals as a whole, in this study, the Microtox test was used to screen toxicity changes of wastewater during conventional reclamation processes. The results showed that toxicities of water samples decreased continuously along reclamation processes except chlorination/dechlorination in which the toxicity increased significantly. Furthermore, as for different forms of residual chlorine, toxicity of wastewater was quite different with increasing chlorine dosage. NH3-N had a trend to decrease toxicity of disinfected wastewater, while UV254 had a trend to increase toxicity. It was found that there was a good linear relationship between toxicity formation and UV254/NH3-N ratio for wastewater after disinfection with combined chlorine form before peak-point.
Effects of influent COD/N ratio and internal recycle ratio on nitrogen removal efficiency in the KNR process
Authors: Suh C.W. , Lee S.H. , Jeong H.S. , Kwon J.C. , Shin H.S.
Published: July 2007

In this study, with the KNR® process that has many advantages, the nitrogen removal efficiency of KNR was experimentally investigated at various COD/N ratios of influent conditions. The optimal operating condition of internal recycle ratio was evaluated. The TN removal efficiencies were 59.1, 72.5 and 75.9% at the COD/N ratios of 3, 5 and 7, respectively. These high removal efficiencies resulted from high denitrification rate in UMBR with high microorganism concentration. Furthermore, specific endogenous denitrification at MLVSS of 10.3 g/L that is similar to MLVSS in UMBR was over two times higher than that at MLVSS of 2.06 g/L. This result suggests that endogenous denitrification rate in UMBR is so high that the requirement of an external carbon source can be saved. As the internal recycle ratio increased from 100 to 400%, the TN removal efficiency also improved from 69.5 to 82.9%, and the optimal internal recycle ratio was 300%.
A pilot study on a step-feeding anoxic/oxic activated sludge system
Authors: Sheping Wang , Lifang Yu , Guanghui Han , Hairong Zhu , Dangcong Peng
Published: July 2007

A four stage pilot plant of step-feed biological nutrient removal (BNR) was employed to investigate reactor performance and process stability. The results obtained showed that step-feed BNR is efficient and cost-effective for nitrogen and carbonaceous removal from municipal wastewater. The total average removal efficiencies of COD, NH3-N, TN and TP could reach as high as 89.5, 97.8, 73 and 75%, respectively, with 50% of return activated sludge (RAS), 9 h of hydraulic retention time (HRT) and 20 d of sludge retention time (SRT). Step-feed BNR is an alternative and effective technology of nutrient removal for municipal wastewater treatment.
Membrane bioreactor application in wastewater re-use from the effluent of Bali primary WWTP, northern Taiwan
Authors: Chen H.H. , Shiau S. , Lin Y.C.
Published: July 2007

Two MBR pilot systems were constructed and tested in the Bali Primary WWTP. The pilot study shows that two MBR systems, i.e. the Green-MenBio system (MBR-1) and the Bio-MF system (MBR-2), can both fulfill the requirement of wastewater reclamation standard. The MBR-2 system is more economical compared with MBR-1 system. The cost of US$ 0.10–0.16/m3 is estimated to reclaim the effluent of primary WWTP in Taiwan. The Bali Primary WWTP has the capacity of 1,320,000 cmd which is the biggest in Taiwan. The domestic wastewater of partial Taipei City and Taipei County are collected and transported to the Bali Primary WWTP. The effluent of the Bali Primary WWTP is then discharged into the ocean through two 3.8 m marine outfalls. The AO processes are installed in both MBR systems. More than 90% of the NH3-N can be removed through the AO and membrane processes. The outflow of the MBR systems (without RO) can reach the quality of COD <30 mg/l, BOD <10 mg/l, SS <5 mg/l, NH3-N <3 mg/L. The outflow of the MBR system is proposed to transport 40 km south to the Taoyuan County where four new industrial parks are to be constructed. Part of the reclaimed water is to be used on irrigation and another portion is to be sent to the industries after RO treatment.
On site experiments of the slanted soil treatment systems for domestic gray water
Authors: Itayama Tomoaki , Kiji Masato , Suetsugu Aya , Tanaka Nobuyuki , Saito Takeshi , Iwami Norio , Mizuochi Motoyuki , Inamori Yuhei
Published: July 2007

In order to make a breakthrough for the acute problem of water shortage in the world, the key words “decentralization and re-use” are very important for new sustainable sanitation systems that will be developed. Therefore, we focused on a new treatments system called “a slanted soil treatment system” which combines a biotoilet system with a domestic grey water treatment system. Because this system is a low cost and compact system, the system can be easily introduced to homes in urban areas or in the suburbs of cities in many developing countries. In this study, we performed on site experiments carried out on Shikoku Island, Japan, for several years. We obtained the following results. The slanted soil treatment system could remove organic pollutants and total nitrogen and total phosphorus in grey water effectively. Furthermore, the system performance became high in the case of the high concentration of the influent water. The nitrification reaction and denitrification reaction were speculated to exist due to aerobic zones and anaerobic zones present in the slanted soil treatment system. The slanted soil treatment system could perform for approximately 3 years with zero maintenance. The plug flow model of 1st order reaction kinetics could describe the reaction in the slanted soil treatment system. However, it is necessary to improve the system to maintain the performance in all seasons.
Enhancing urban infrastructure investment planning practices for a changing climate
Authors: He J. , Valeo C. , Bouchart F.J.-C.
Published: July 2007

Climate change raises many concerns for urban water management because of the effects on all aspects of the hydrological cycle. Urban water infrastructure has traditionally been designed using historical observations and assuming stationary climatic conditions. The capability of this infrastructure, whether for storm-water drainage, or water supply, may be over- or under-designed for future climatic conditions. In particular, changes in the frequency and intensity of extreme rainfall events will have the most acute effect on storm-water drainage systems. Therefore, it is necessary to take future climatic conditions into consideration in engineering designs in order to enhance water infrastructure investment planning practices in a long time horizon. This paper provides the initial results of a study that is examining ways to enhance urban infrastructure investment planning practices against changes in hydrologic regimes for a changing climate. Design storms and intensity–duration–frequency curves that are used in the engineering design of storm-water drainage systems are developed under future climatic conditions by empirically adjusting the general circulation model output, and using the Gumbel distribution and the Chicago method. Simulations are then performed on an existing storm-water drainage system from NE Calgary to investigate the resiliency of the system under climate change.
Influence of natural vs. anthropogenic stresses on water resource sustainability: a case study
Authors: Fennell J. , Zawadzki A. , Cadman C.
Published: July 2007

Climate change has been identified as a major influence on basin water balances. However, land use and water use practices have also been identified as players. This case study was completed to better understand a changing water balance affecting a major basin in Alberta. The Beaver River basin is located in east central Alberta. Much of the basin has been developed for agricultural use; however, a number of heavy oil operations also exist. Both sectors use surface and groundwater. Evidence exists that the basin hydrology has changed since the mid-1970s. Coincidently, it was at this time that much of the land was cleared for agricultural development and commercial-scale oil development began. Oil industry use of water was suspected as the main cause for the changes observed. To investigate this further, data from regional hydrometric and meteorological stations were assessed along with water well hydrographs and historical satellite images. A significant correlation was found between basin responses and a climate phenomenon known as the Pacific decadal oscillation. Although the correlation between the Pacific decadal oscillation and basin hydrology appeared strong, deforestation for agricultural development also seemed to have an effect. Use of the local water resources was found to be of minor significance.
Using a GIS transfer model to evaluate pollutant loads in the Lake Kinneret watershed, Israel
Authors: Markel D. , Somma F. , Evans B.M.
Published: July 2007

Lake Kinneret (Sea of Galilee) is the only large surface water body in Israel, encompassing an area of 167 km2 and supplying some 30% of the country's fresh water. Pollution from anthropogenic sources and water abstraction for domestic and agricultural uses has long been threatening the water quality of the lake. Point-source pollution in the watershed has decreased drastically with the development of wastewater treatment. However, diffuse pollution from agricultural activities is still an unresolved issue. In this paper we present an application of AVGWLF (a GIS-based watershed load model) to the Lake Kinneret watershed. The model allows one to simulate daily stream flows and monthly sediment, nitrogen, and phosphorus loads discharged to the lake from the surrounding watershed. Results from simulations yield a satisfactory correspondence between simulated and measured daily water volume. Partition by source of total phosphorus delivered to the lake in the period of 2000–04 confirms the reduction in point source nutrient contribution due to improvement of wastewater treatment facilities in the area. Future management should focus on reduction of nutrients originating from septic systems (point sources) and pasture and cropland areas (diffuse sources). Results from simulations will enable watershed managers to prioritize effective management alternatives for protecting the water quality in the lake.
Geostatistical mapping of precipitation: implications for rain gauge network design
Authors: Nour M.H. , Smit D.W. , Gamal El-Din M.
Published: July 2007

This study examined four univariate kriging techniques; simple kriging (SK), ordinary kriging (OK), multi-Gaussian kriging (MGC), and log-normal kriging (LNK); and two multivariate kriging algorithms; kriging with external drift (KED) using elevation and slope in two different models for the estimation of daily rainfall in a 250 m × 250 m grid over a 750 km2 area in the Canadian Boreal forest. Multivariate kriging did not enhance daily rainfall predictions. SK, OK, and LNK produced statistically comparative results with OK being slightly better. MGC was the worst univariate estimator, mainly due to the high percentage of data spikes. Sequential Gaussian simulation (SGS) was then implemented to produce 100 equiprobable maps of rainfall. A multi-objective approach; that is based on overlaying the map of the kriging variance, the DEM, and land use/land cover maps in a GIS framework to identify the areas of commonly favourable features; was proposed to identify potential future sampling locations.
Analysis of parameter variations in L–Q equations for river runoff processes from the viewpoint of spatial and temporal conditions
Authors: Fujii S. , Shivakoti B.R. , Shichi K. , Songprasert P. , Ihara H. , Moriya M. , Kitpati S. , Tanaka S.
Published: July 2007

This study aims to find out variation characteristics of the parameters of ‘a’ and ‘b’ in L=a ·Qb, an empirical equation for run-off loading (L) and flow rate (Q), by evaluating the effects of flow conditions and regional properties of the watersheds on the values. We selected the Kamo River basin (155 km2) as a study field, and conducted various kinds of investigations, such as 80 day high frequency observations, continuous monitoring for more than 2 years, storm event surveys, and simultaneous surveys of 39 stations. Then, we obtained 7–170 data in each of 39 sampling stations. The main results obtained are as follows: 1) L–Q equation with a range of ‘a’ can express L–Q relation in most of the WQIs (water quality indices); 2) ‘a’ receives temporal (flow condition) effects more in SS, VSS and Al, while it receives regional effect more in inorganic carbon, TN, Ca and Fe; 3) both of flow change in storm events, and base flow levels affect the L–Q relation, and their effects can classify the WQIs into several groups; 4) the effects of regional properties were obviously observed in ‘a’, and quantitatively evaluated, especially for density of population.
Modelling COD and N removal in the water and in the benthic biofilm for the River Wupper in Germany
Authors: Wichern M. , Kehl O. , Erbe V. , Luebken M. , Wilderer P.A.
Published: July 2007

The River Wupper, a tributary of the River Rhine, is at several locations influenced by anthropogenous nitrogen input, hydraulic structures, and influents from other tributaries. These influences have an impact both on the water quality and on the hydrodynamic conditions. The model approaches used for this article are based on work of Rauch et al. and the River Water Quality Model No. 1; they allow the simulation of the nitrogen conversion in the River Wupper. They are compatible with the activated sludge models and can thus be used also for integrated approaches. The calibration and validation of the model was realized using actual data of the River Wupper over a length of 60 km with one dam, 10 weirs, three wastewater treatment plants and 11 tributaries. The model considers the nitrogen conversion and COD removal and has a strong focus on biofilm processes in the benthic zone. Additional information is given about the sedimentation processes, the physical oxygen input processes, biofilm detachment processes, molecular diffusion, the influence of the laminar border layer and the changing of COD fractions and biofilm densities.
Evaluating characteristics of community riparian awareness program interactions
Authors: Ambrose N.E. , Fitch L. , Bateman N.G.
Published: July 2007

As part of its mandate to evaluate and monitor program delivery, the Alberta Riparian Habitat Management Society (Cows and Fish) has commissioned independent evaluations to examine the effectiveness and applicability of the community-based riparian awareness and management program. The society's aim is to improve the understanding of landscape function, to better enable landowners and managers to make management decisions. The staff interaction evaluation examined staff ability to deliver certain valued characteristics, and identified whether the program and staff increased awareness and management action. Respondents rated staff highly on all characteristics. Landowners that participated in riparian health programming as part of community/watershed groups were 19% more likely to have learned new information and 21% more likely to implement management change than those that were not part of a group. Repeat interactions are critical to learning new information and influencing management. All those with frequent interactions had learned new information, compared to only 70% of those with very little interaction. A diverse array of interactions led respondents to alter their management, indicating the need for a wide variety of extension tools and activities. The results strongly support the need for a community-based approach in resource management and awareness activities, which enables repeat, ongoing and diverse interactions with extension staff.
Protecting public health from the impact of body-contact recreation
Authors: Standish-Lee P. , Loboschefsky E.
Published: July 2007

Population growth and the increasing demand for recreational opportunities have put public and political pressure on water purveyors to make every water body available for multipurpose use. There is increasing evidence that full water-body contact recreation such as swimming, and water/jet skiing may add significantly more microorganisms such as viruses, Giardia, and Cryptosporidium to a water body when compared with non-body contact recreational waters. Body-contact recreation also poses a risk to the consumer inadvertently ingesting contaminated water. Waterborne disease outbreaks caused by recreation are well documented with the endemic rate and the risk level to the public estimated to be very high. Since 1989, 171 outbreaks, associated with recreational water, have been documented in the USA with more than 15,000 individuals infected; these outbreaks occurred in both natural and artificial settings.

Discussions on the recently published Long-Term 2 Enhanced Surface Water Treatment Rule (LT2) have focused on varied treatment goals related to microbiological quality and source water protection methods at the heart of this discussion.

This paper highlights new studies on risk from recreation, proposed beach standards, modeling to assess the risk of infection, political issues associated with limiting recreation, and what water utilities can do to reduce risk.
Using mathematical modelling to inform on the ability of stormwater ponds to improve the water quality of urban runoff
Authors: Wallis S.G. , Morgan C.T. , Lunn R.J. , Heal K.V.
Published: July 2007

This paper concerns the mathematical modelling of flow and solute transport through stormwater ponds. The model is based on appropriate lumped system conservation equations that are solved using standard numerical techniques. The model was used to route a first flush pollution scenario through a cylindrical pond for 16 combinations of elevation and diameter of a submerged pipe outlet, in conjunction with a high level weir. Higher pipe elevations and smaller pipe diameters created larger pond volumes and hence led to greater dilution of the pollutant. In contrast, lower pipe elevations created larger storage volumes, leading to better flow attenuation. Interestingly, larger pipe diameters improved peak flow attenuation, even though the storage used decreased.
Good ecological status in a heavily urbanised river: is it feasible?
Authors: Weyand M. , Schitthelm D.
Published: July 2007

In Germany, a national instructions sheet, BWK M3, sets out how the impact of sewer system discharges on receiving water bodies is to be analysed. When applying the simplified assessment procedure defined therein and relying on traditional measures only, it becomes evident that in heavily urbanised rivers a large number of retention facilities would be needed to improve the hydraulic and qualitative conditions. However, the associated economics make the feasibility of such an immission-based approach to river restoration doubtful. In response, the Bergisch Rheinischer Wasserverband and the Ruhrverband started a common research project to find out whether and how the Rinderbach River, a heavily modified water body in terms of morphology and flow dynamics, could achieve the good ecological status required under the European Water Framework Directive. The focus of the survey was on the elaboration of an inventory, the identification of potentially attainable ecological objectives, and the discussion of measures with regard to their benefits and feasibility. The results obtained clearly show that it is possible to achieve good ecological status in already heavily urbanised rivers by making use of all existing natural potential within the river basin. They also demonstrated that a good interactive co-operation of experts in the fields of biology, urban drainage and hydraulics is indispensable.
Development and implementation of a watershed management plan for Lac la Biche, Alberta, Canada
Authors: White J. , Rawles M.
Published: July 2007

Lakeland County is experiencing increasing developmental pressures arising from the oil and gas boom at nearby Fort McMurray. There is increased industrial traffic passing through the county, and 600 new residential lots are proposed in 2005, almost double from 5 years ago. Deteriorating surface water quality has been a concern in the area due to an increase in development and agriculture, while excessive fish harvesting and winterkills have impacted commercial and recreational fisheries. Today, walleye and pike populations in the lake remain collapsed and restocking efforts have not been successful. Due to the lack of studies done on the watershed, the county is leading a multidisciplinary research study which includes a baseline water quality study, riparian health assessments, land use mapping and ground-truthing and projects with the local health authority. This research has been summarized in a comprehensive state of the watershed report, which will be used to complete a watershed management plan for the Lac la Biche watershed. Recommendations from the state of the watershed report and watershed management plan will also be incorporated into municipal planning documents and recommend changes to the Municipal Government Act itself.
Europe's Water Framework Directive: discovering hidden benefits
Authors: Riley C. , Tyson J.M.
Published: July 2007

The water utility companies in the UK are regulated by the economic regulator to ensure that they do not abuse their monopoly powers and operate under high efficiency targets to minimise costs to their customers. The requirements for improved environmental performance are set by the Environment Agency and, once agreed, incorporated in a five-year plan. Prior to the Water Framework Directive the companies had little choice but to meet a rigorous programme to achieve higher discharge standards as end-of-pipe solutions. The catchment-based approach of the WFD, coupled with the requirement to achieve ‘good status’ for receiving waters and the requirement for stakeholder involvement, has introduced much needed flexibility into the process which is expected to lead to better and more cost effective solutions to water quality problems.
Effect of different river water quality model concepts used for river basin management decisions
Authors: Vandenberghe V. , van Griensven A. , Bauwens W. , Vanrolleghem P.A.
Published: July 2007

In this research the applicability of two different water quality concepts, a QUAL2E-based and a RWQM1-based water quality model is evaluated in terms of management decisions. The Dender river in Belgium serves as a case study for the application of the methodology. By using sensitivity analysis on both model concepts the important processes are revealed. Further, the differences between the predictions for a future scenario are analysed. The scenario chosen here is a reduction in fertiliser use of 90%, which reduces the diffuse pollution. This way, the advantages or disadvantages of using one concept against the other for this scenario are formulated. It was found that the QUAL-based models are more focussing on algae processes while the RWQM1 also takes into account processes in the sediment. Further the QUAL-based models are easier to calibrate, especially when only a small amount of data is available. Both concepts lead to more or less the same conclusions. However for some periods the differences become important and to reduce the uncertainty in those periods, more efforts should be spent in calibration and in better detection of parameters concerning sediment processes and diffusion.
Cost-efficiency aspects for fish passage restoration in the Ruhr River Basin
Authors: Weyand M. , Redeker M. , Nusch E.A.
Published: July 2007

The protection and sustainable management of the aquatic ecosystems is the central aim of the European Water Framework Directive. Due to the aspiration for good ecological status of the water bodies free fish passage will play an important part in river basin management. The Ruhr River has seen severe anthropogenic modifications due to urbanisation and industrialisation in the 19th and 20th centuries leading in the existence of approx. 1,300 weirs within the Ruhr River Basin. The majority of the barriers are assessed as not passable or restricted passable.

Against this background the Ruhrverband made a holistic approach towards restoring fish passage within the Ruhr catchment. Besides the scientific and technical aspects, such as the determination of potential (spawning) habitats and the development of measures in order to reach them, they also considered cost-benefit-ratio considerations for the Ruhr catchment as a whole as well as for site-specific designs of fish passage structures. Various benefits were evaluated taking into account different fields of economic interest.

The model of financing all necessary measures should involve all responsible parties benefiting from the water utilizations. Such a mutual procedure delivers a fair cost distribution as well as an efficient implementation of measures.
Current and future water issues in the Oldman River Basin of Alberta, Canada
Authors: Byrne J. , Kienzle S. , Johnson D. , Duke G. , Gannon V. , Selinger B. , Thomas J.
Published: July 2007

Long-term trends in alpine and prairie snow pack accumulation and melt are affecting streamflow within the Oldman River Basin in southern Alberta, Canada. Unchecked rural and urban development also has contributed to changes in water quality, including enhanced microbial populations and increased water-borne pathogen occurrence. In this study we look at changing environment within the Oldman River Basin and its impact on water quality and quantity. The cumulative effects include a decline in net water supplies, and declining quality resulting in increased risk of disease. Our data indicates that decreases in the rate of flow of water can result in sedimentation of bacterial contaminants within the water column. Water for ecosystems, urban consumption, recreation and distribution through irrigation is often drawn from water-holding facilities such as dams and weirs, and concern must be expressed over the potential for contaminate build-up and disproportionate potential of these structures to pose a risk to human and animal health. With disruption of natural flow rates for water resulting from environmental change such as global warming and/or human intervention, increased attention needs to be paid to use of best management practices to protect source water supplies.
The Constructed Wetland Association UK database of constructed wetland systems
Authors: Cooper P.
Published: July 2007

There are now more than 1,000 constructed wetland systems (CWs) in the UK. The first UK CW database was constructed by Water Research Centre (WRc) and Severn Trent Water Ltd to accompany a book on the design and performance of these systems. In that database, constructed by Gareth Job et al. (1996), only 154 beds were listed, most of which were tertiary sewage treatment sites in Severn Trent Water. The Constructed Wetland Association (CWA) was formed in 2000 as a UK water industry body in response to problems caused by unscrupulous constructors. A group of experienced, reputable designers and constructors formed the CWA to bring together best UK practice in order to counteract this problem. The group contains major water companies, designers, constructors, academics, plant growers and operators. They decided that one of the best ways of countering the problem was to assemble a database of design and performance from well-designed systems. After negotiation the CWA group took over responsibility for the database from WRc. The CWA has produced eight updates of the database which now contains information from more than 900 beds. It contains examples of the different variants of CWs in use in the UK. Most of these sites treat sewage/domestic wastewater but the database also includes examples of systems for the treatment of minewater, sludge, landfill leachate, industrial effluents, surface runoff and road runoff. Particular treatment applications are illustrated by case studies which are summary articles describing design, construction and performance.
Helsinge sludge reed bed system: reduction of pathogenic microorganisms
Authors: Nielsen S.
Published: July 2007

Reduction of pathogenic bacteria: Salmonella, enterococci and Escherichia coli was investigated using the sludge reed bed system. The system at Helsinge was established in 1996 and has a capacity of 630 tonnes dry solids per year and consists of 10 basins. Since 2000 the individual basins have been subjected to an average area-specific loading rate of 46–56 kg dry solids/m2/year. The total sludge residue height in April 2006 was approximately 1.40 m. The sludge (approximately 0.5–0.8% dry solids), with which the individual basins were loaded, contained a large number of bacteria. Salmonella, enterococci and E. coli were found in the sludge in the following quantities: 10–300/100 g (wet weight), 7,000–25,000 CFU/g (wet weight) and 800,000–10,000,000 CFU/100 g (wet weight), respectively. The analysis of the reduction in pathogens in the sludge residue through a period of 3–4 months after the last loading indicated that the pathogen content was reduced down to <2/100 g (Salmonella), <10 CFU/g (enterococci) and <200 number/100 g (E. coli). For enterococci and E. coli the reduction was approximately log 5 and log 6–7, respectively. In the same period the sludge residue achieved a dry solids content of approximately 20–35%.
The effects of deep zones on wetland nitrogen processing
Authors: Kadlec R.H.
Published: July 2007

Twelve research wetlands were operated under varying conditions at a site west of the city of Phoenix. These were constructed as a triplicated design, with zero, one, two and three internal deep zones, all containing an inlet distribution and an outlet collection deep zone, together comprising 12.5–35% of the wetland areas. The water supply was partially nitrified effluent from a city wastewater treatment plant. Total nitrogen was reduced by about 50%, from inflow concentrations between 6 and 8 mg/L. Speciation of the inflow was approximately 25% organic nitrogen, 25% ammonium nitrogen and 50% nitrate nitrogen. Typical outflow concentrations were about 1.2 mg/L organic, 0.5 mg/L ammonium and 0.0–2.5 mg/L nitrate. Rate constants for total nitrogen were 15–20 m/year at 20 °C, and 20–30 m/year for nitrate, which agree well with other project reports. Temperature factors averaged 1.100 for total nitrogen, and 1.184 for nitrate. There were no differences in the internal hydraulics with deep zone numbers. Deep zone numbers in the wetlands did not affect nitrogen treatment performance. No differences with deep zone numbers were found for temperature, dissolved oxygen, pH, or nitrogen removals or rate constants. In conjunction with other reported results, there appears to be no large treatment benefit or detriment of incorporating internal deep zones in free water surface wetlands.
Damköhler number design method to avoid clogging of subsurface flow constructed wetlands by heterotrophic biofilms
Authors: Austin D. , Maciolek D. , Davis B. , Wallace S.
Published: July 2007

Clogging of subsurface flow (SSF) treatment wetlands from excess biofilm growth is a design problem for which only empirical guidelines exist. A method is proposed to systematically analyse this type of clogging as a design tool. In recognition of the physical reality that most SSF treatment wetland processes are a function of biofilm surface area, a Damköhler number (Da) definition based on aggregate specific surface area is used to investigate a method of predicting clogging induced by heterotrophic biofilms growing on treatment media.
Macrophyte zonation in stormwater wetlands: getting it right! A case study from subtropical Australia
Authors: Greenway M. , Jenkins G. , Polson C.
Published: July 2007

In Australia stormwater wetlands are becoming an increasingly popular component of water sensitive urban design. However, they must be designed to cope with the dynamic nature of urban hydrology, in particular, fluctuations in water level. The concept of macrophyte zonation relies on a thorough understanding of the water regimes of different plant species. Water depth is crucial and the hydroperiod, i.e. duration and frequency of inundation, has a significant impact on the survival of wetland vegetation. The aim of this study was to investigate plant establishment in a newly constructed stormwater wetland in Brisbane, subtropical Australia. Changes in plant distribution and density have been monitored since 2001. Rainfall and water depth data enabled us to use a hydrologic model to predict the extent of inundation of the different macrophytes zones. The field survey showed macrophyte survival was poor with the complete loss of several species in marsh and ephemeral zones. The main reason for the lack of macrophyte establishment and survival was the extended periods of inundation (supported by the hydrologic model) and deeper water levels. Stormwater wetlands must be designed to ensure that ephemeral species are not permanently inundated or the preferred water depths in marsh zones are not exceeded for extended periods.
Comparison of measured and simulated distribution of microbial biomass in subsurface vertical flow constructed wetlands
Authors: Langergraber G. , Tietz A. , Haberl R.
Published: July 2007

The multi-component reactive transport module CW2D has been developed to model transport and reactions of the main constituents of municipal wastewater in subsurface flow constructed wetlands and is able to describe the biochemical elimination and transformation processes for organic matter, nitrogen and phosphorus. It has been shown that simulation results match the measured data when the flow model can be calibrated well. However, there is a need to develop experimental techniques for the measurement of CW2D model parameters to increase the quality of the simulation results. Over the last years methods to characterise the microbial biocoenosis in vertical subsurface flow constructed wetlands have been developed. The paper shows measured data for microbial biomass and their comparison with simulation results using different heterotrophic lysis rate constants.
Life cycle assessment of wastewater treatment options for small and decentralized communities
Authors: Machado A.P. , Urbano L. , Brito A.G. , Janknecht P. , Salas J.J. , Nogueira R.
Published: July 2007

Sustainability has strong implications on the practice of engineering. Life cycle assessment (LCA) is an appropriate methodology for assessing the sustainability of a wastewater treatment plant design. The present study used a LCA approach for comparing alternative wastewater treatment processes for small and decentralised rural communities. The assessment was focused on two energy-saving systems (constructed wetland and slow rate infiltration) and a conventional one (activated sludge process). The low environmental impact of the energy-saving wastewater treatment plants was demonstrated, the most relevant being the global warming indicator. Options for reduction of life cycle impacts were assessed including materials used in construction and operational lifetime of the systems. A 10% extension of operation lifetime of constructed wetland and slow rate infiltration systems led to a 1% decrease in CO2 emissions, in both systems. The decrease in the abiotic depletion was 5 and 7%, respectively. Also, replacing steel with HDPE in the activated sludge tank resulted in a 1% reduction in CO2 emission and 1% in the abiotic depletion indicator. In the case of the Imhoff tank a 1% reduction in CO2 emissions and 5% in the abiotic depletion indicator were observed when concrete was replaced by HDPE.
Subsurface constructed wetlands for wastewater treatment and reuse in agriculture: five years of experiences in Sicily, Italy
Authors: Cirelli G.L. , Consoli S. , Di Grande V. , Milani M. , Toscano A.
Published: July 2007

The paper reports the results of an investigation on a H-SSF constructed wetland for tertiary treatment in a small community located in eastern Sicily, Italy. The system is designed to reuse wastewater for the irrigation of olive orchards covering about 150 hectares. From March 2001 to September 2005, wastewater samples were collected and the following chemical–physical parameters were determined according to Standard Methods: temperature, pH, EC, DO, TSS (105 °C), BOD5, COD, TN, TP. The following microbiological parameters were also evaluated: total coliforms, faecal coliforms, Escherichia coli, faecal streptococci, Salmonella, helminth eggs. Mean removal efficiencies ranged from 77 to 92% (TSS), 37 to 72% (BOD5), 51 to 79% (COD), 97 to 99.5% (E. coli). Removal efficiency of Salmonella and helminth eggs was always 100% in all samples; however, only 15% of total samples matched the limit of E. coli (<50 CFU/100 mL) fixed by Italian legislation for wastewater reuse.
Slag columns for upgrading phosphorus removal from constructed wetland effluents
Authors: Chazarenc F. , Brisson J. , Comeau Y.
Published: July 2007

The current best option to upgrade constructed wetlands (CWs) for phosphorus (P) retention, in terms of efficiency, cost and simplicity, consists in using media having a strong P affinity. The media can be used either in the planted beds or in a filtration system downstream of the beds. The use of slag filters was shown to be efficient for removing P from wastewater as it represented a slow release source of calcium and hydroxide, favouring the formation of hydroxyapatite. Our study aimed at maximising the P retention capacity of slag filters located at the outlet of CWs since electric arc furnace slag has been shown to inhibit the growth of macrophytes when used in the filtration matrix. Bench-scale columns (Vtot = 6.2 L) filled with various combinations of filter media (slag, granite, limestone) of different sizes (2–5, 5–10, 10–20 mm) were fed on-site during four months with a CW effluent (in mg/L: 30 COD, 30 TSS, 10 Pt). Results showed that the best media combination enabling the maximum o-PO4 retention (more than 80% removal without clogging) consisted in a series of a ternary mix column (slag 5–10 mm, granite 2–5 mm, limestone 5–10 mm) followed by a slag column (slag 5–10 mm). Pilot scale columns (Vtot = 300 L), filled with the best media combination, were installed at the outlet of a 28 m2 CW. These columns showed more than 75% removal efficiency during one year and were designed to be easily replaced each year.
Nitrogen elimination from landfill leachates using an extra carbon source in subsurface flow constructed wetlands
Authors: Rustige H. , Nolde E.
Published: July 2007

A three-stage constructed wetland for leachate treatment was monitored on a landfill at a pilot scale. The plant had been designed to achieve at least 75% nitrogen removal. NH4-N input concentration was 240 (median) up to 290 mg l−1 and COD concentration was 455 to 511 mg l−1, respectively. A 14 m2 vertical flow sand filter plus a 14 m2 horizontal flow sand filter followed by a 3.3 m2 vertical flow sand filter was chosen. Acetic acid was added to the horizontal flow system for denitrification. The results showed a very stable nitrification rate within the vertical flow system of 94% (median) at NH4-N loading rates of about 10 (median) up to 17 g m−2 d−1. Denitrification was mainly dependent on the dosing of acetic acid and could reach a maximum of 98%. One interesting effect was the production of nitrite in the horizontal flow sand filter. This could efficiently be eliminated by the subsequent vertical flow sand filter. The chosen concept proved to be very effective for nitrogen removal. In combination with a final activated carbon filter the COD effluent concentrations could be easily and safely controlled. The design of denitrification reed beds showed a further potential for optimization.