bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTIVE DESIGN OF GAS‐MIXING SYSTEMS FOR THICK SLUDGE DIGESTION: TWO CASE STUDIES
Authors: Cumiskey A. , Harrison D. , Dawson M. , Jolly M. 
Published: July 2007

ABSTRACTIn the UK and elsewhere, advances in the design of anaerobic mesophilic digesters have resulted in a trend towards the digestion of thicker sludges. This includes a number of new facilities using ‘bolt‐on’ technologies such as thermal hydrolysis, pre‐pasteurisation and enzymic hydrolysis. Thermal hydrolysis utilises thickened sludge, and the digester is fed with a high dry‐solids content (typically 12%), thereby intensifying the digestion process and reducing reactor volumes. However, there is limited experience in the design of digester mixing systems for such applications. As the trend continues towards advanced digestion technology, more emphasis will be placed on the basic unit process operation of mixing.This paper describes the design of a gas‐mixing system for thick feed sludges for two full‐scale plants at Mogden and Aberdeen. Mogden is a refurbishment project and Aberdeen is a newly constructed plant.
A REVIEW OF THE EFFECTS OF SEWER LEAKAGE ON GROUNDWATER QUALITY
Authors: Reynolds J. H. , Barrett M. H. 
Published: July 2007

ABSTRACTExfiltration (of sewage into the ground from faults in ageing sewerage networks) has been recognised for many years but has never been quantified. It was considered that this leakage did not pose a groundwater‐contamination threat because it was assumed that pathogens in sewage would either die off or be attenuated before reaching the groundwater level.This paper identifies why sewers have faults that could allow sewage exfiltration where the sewer is above a groundwater resource. Because of a lack of UK data on sewage exfiltration, research work in Germany is discussed and analogies are made between the sewerage networks of the two countries.Until recently, it has not been possible to positively identify sewage contamination of groundwater because of other pollutants and potential sources within an urban environment. The development of sewage‐fingerprinting techniques has overcome these difficulties and provides conclusive evidence of sewage contamination of shallow and deep groundwater resources in researched areas. Studies of groundwater recharge and total solute loadings allow quantification of sewage exfiltration reaching the groundwater within the Midlands conurbation. The paper concludes that urban aquifers are potentially more vulnerable to microbiological contamination from leaking sewers than has previously been assumed.
USE OF A FULL‐SCALE TEST FACILITY TO EXAMINE SEWER‐SEDIMENT MOBILITY
Authors: Rushforth P. J. , Tait S. J. , Saul A. J. 
Published: July 2007

ABSTRACTThe mobility of granular in‐sewer sediments was measured in a study which was carried out at the National Combined Sewer Overflow Test Facility, Wigan. It is thought that these measurements are unique in that the facility permits tests using crude sewage and real in‐sewer sediments to be conducted under full‐scale controlled hydraulic conditions. Tests were carried out in which the bedload transport rates, resulting from different steady‐flow discharges and flow depths, were measured. The results were compared with transport‐rate predictions made using relationships which are recommended by the Construction Industry Research and Information Association. These comparisons indicated that, for the sewer sediments, the existing prediction methods are likely to significantly under‐predict the mobility of in‐sewer sediments — particularly if a range of grain sizes is present. This might have important implications both for the design of sewerage systems and for sewer flow quality modelling.
EMPIRICAL FACTORS FOR ESTIMATING OPEN‐WATER EVAPORATION FROM POTENTIAL EVAPORATION
Authors: Finch. J. W. 
Published: July 2007

ABSTRACTFor many years, the standard method for estimating rates of evaporation from open water has been to apply empirical factors to potential evaporation data. However, significant errors can occur through the use of these factors, essentially due to the limitations of the measurements upon which they are based. New empirical factors are presented here for use with the Meteorological Office Rainfall and Evaporation Calculation System for grass potential evaporation and Penman potential evaporation. However, uncertainty in the estimated evaporation rates remains at least 5–12 mm per month.
POTENTIAL GROUNDWATER IMPACTS FROM CIVIL‐ENGINEERING WORKS
Authors: Preene M. , Brassington R. 
Published: July 2007

ABSTRACTCivil‐engineering construction works often have a significant impact on groundwater conditions. Such an impact can range from the derogation of water sources by dewatering works, to the creation of barriers and pathways for groundwater flow formed by foundations or ground‐improvement processes. In some cases, not all these impacts are identified early enough during the planning and design process.This paper describes the full range of potential groundwater impacts which can result from construction activities. The effects are grouped into five rational categories as an aid to initial assessment. The need for accurate baseline groundwater environmental data is set out. and recommendations are made for the planning of monitoring programmes.
TREATMENT OF WASHWATER FROM SERVICE‐RESERVOIR CLEANING IN HONG KONG
Authors: Bradley R. M. , Watker‐Zeris A. , Ku C. C. 
Published: July 2007

ABSTRACTAs a result of increasing control of environmental pollution in Hong Kong. the practice of discharging untreated service‐reservoir washwater to the nearest watercourse is no longer permitted. This paper describes the results of field tests on alternative methods of treating the effluents produced from cleaning fresh‐water and sea‐water service reservoirs in Hong Kong, including trials of alternative cleaning procedures using high‐pressure jetting which were designed to (a) upgrade the cleaning efficiency and (b) reduce the resulting pollution load. The results of effluent treatment, based on pilot‐plant trials incorporating various combinations of filtration and centrifugation, are presented. The option which was selected for full‐scale implementation, based on a mobile centrifugation and microfiltration unit, using a membrane developed in China specifically for the water industry, is described
A METHOD FOR INVESTIGATING THE POTENTIAL IMPACTS OF CLIMATE‐CHANGE SCENARIOS ON ANNUAL MINIMUM GROUNDWATER LEVELS
Authors: Bloomfield J. P. , Gaus I. , Wade S. D. 
Published: July 2007

ABSTRACTPrevious approaches to assessing the impact of climate‐change scenarios on groundwater levels and groundwater droughts have focused on modelling specific recharge processes or phenomena. However, statistical methods, based on correlations between historic groundwater level and rainfall time‐series, provide an alternative and robust approach to predicting minimum groundwater levels and droughts. For the purposes of this study, groundwater droughts are defined in terms of the return period of a given groundwater level. A multiple linear regression model (regression of monthly rainfall totals for a given period against values of minimum annual groundwater levels for the same period), when used with synthetic rainfall data based on climate‐change scenarios, enables changes in future annual groundwater‐level minima to be modelled. The method is illustrated at three sites on the Chalk, Permo‐Triassic sandstone and Jurassic limestone aquifers.
ENVIRONMENTAL AND STRUCTURAL IMPLICATIONS FOR THE RE‐USE OF TYRES IN FLUVIAL AND MARINE‐CONSTRUCTION PROJECTS
Authors: Fenner R. A. , Clarke K. 
Published: July 2007

ABSTRACTThere is increasing interest in reclaiming tyres for use in bank‐side and coastal‐protection structures. However, concern has been expressed about the potential for tyres to release pollutants into the environment and to retain their long‐term structural stability. This paper describes laboratory leaching tests for heavy metals from new used tyres and tyres which have been exposed to an aquatic environment for thirteen years. The results show that the limiting factor to their use could be cadmium release. Tests found evidence of the loss of ultraviolet screening agents such as carbon black, suggesting that chemical breakdown of the tyre through leaching of vulcanising chemicals is more significant in the physical breakdown of the tyre, than the reverse. Three case studies of tyre flood‐protection and river‐control structures are presented, which examine the ability of tyres to retain structural integrity over long periods. Based on this evidence, guidance on design principles is offered. It is concluded that tyres can be used sustainably in a river or coastal environment, subject to careful consideration of local site conditions.
A NEW CONCEPTUAL GROUNDWATER‐FLOW SYSTEM FOR THE CENTRAL SOUTH DOWNS AQUIFER
Authors: Robins N. S. , Dance L. T. 
Published: July 2007

ABSTRACTThe central part of the South Downs Chalk aquifer is intensely used for public water supply. Although the aquifer has a long history of careful development and management, the outline conceptual groundwater‐flow vision has not been formally investigated for many years. A major programme of work has now been completed which (a) provides a new insight into the hydraulic workings of the aquifer, and (b) highlights a number of hitherto poorly understood concepts controlling groundwater movement in the Chalk. These include the key role of geological structure and the occurrence of hard bands and karst‐type groundwater flow as major controls over preferred flow‐paths. The new conceptualisation concludes that the main discharge area for the aquifer is laterally to the north‐south rivers and not directly southwards to the sea.
ECONOMIC DESIGN OF FLOOD‐ATTENUATION RESERVOIRS FOR URBAN AREAS EXPLOITING CATCHMENT HYDRODYNAMICS IN SOUTH‐WEST UK
Authors: Faulkner B. L. 
Published: July 2007

ABSTRACTRunoff from new development in urban areas tends to increase the downstream flood peak which has to be attenuated or accommodated in the river channel to avoid increases in flood risk. The built environment close to the river often makes river‐improvement works difficult, if not impossible. This paper introduces the concept of rising‐limb attenuation, to mitigate downstream flood risk — especially in urban areas. Relying on the implicit difference in runoff times of concentration between rural and urban areas, it is possible to design efficient, self‐regulating storage structures, to counteract increases in peak flow in the main urban watercourse, by attenuating the later contribution from less urbanised or rural tributaries. Because rising‐limb attenuation is partial and temporary, volumes of storage are much less than for conventional attenuation reservoirs, with consequent savings in land take and costs. Because the controlled flow is also less, the associated structure is also generally smaller and simpler. Implementations of this type of structure have been carried out in two locations in the UK, and the outline design of these structures is described by reference to a case study.
ANOMALOUS RESPONSE IN THE HALIFAX PROCESS
Authors: Dudley J. , Chambers B. 
Published: July 2007

ABSTRACTThe Halifax process was first proposed as a means of minimising the bulking of activated sludge. In one system using this process, bulking continued to occur. An analysis of the process, using dynamic modelling tools, predicted that the process contains the potential for effluent quality to become worse as the hydraulic loading to the process is reduced — contrary to common experience with more conventional layouts.
USE OF UKCIP02 CLIMATE‐CHANGE SCENARIOS IN FLOOD AND COASTAL DEFENCE
Authors: Hawkes P. , Surendran S. , Richardson D. 
Published: July 2007

ABSTRACTUnderstanding the uncertainties and risks from climate change is necessary for managing and adapting to those risks. Climate‐change scenarios provide a starting point for assessing climate‐change vulnerability, impact and adaptation. In April 2002, the UK Climate Impacts Programme released new future climate scenarios and was based on modelling at the Hadley Centre, which included temperature, soil moisture, rainfall, runoff, sea‐level rise and wind speed. These data provide a consistent source of information for use in UK climate‐change impact studies.This paper (a) summarises some of the results from this programme, (b) explores their implications, and (c) recommends how these results could be applied in UK flood and coastal defence. The opinions of about twenty selected individuals, who were involved in flood and coastal defence, were collated to assess current practice in the use of climate‐change information, requirements of climate‐change scenarios, and comparison of the content of UKCIP02 with those requirements.
DERIVING UNIT HYDROGRAPHS FOR SMALL CATCHMENTS
Authors: Gardner C. M. K. , Wilcock D. N. 
Published: July 2007

ABSTRACTAn examination of 190 storm events in seventeen small Northern Ireland catchments, along lines developed by the UK Institute of Hydrology, shows that the time‐to‐peak of the instantaneous unit hydrograph can be estimated from catchment characteristics and from the time between the centroid of mass of a flood‐producing rainfall event and of the resulting peak flow, but that equations calibrated on British data overestimate the time‐to‐peak. This might be due to the distinctive hydrology of Northern Ireland.
CONSERVING WATER VOLES: BRITAIN'S FASTEST DECLINING MAMMAL
Authors: Strachan R. 
Published: July 2007

ABSTRACTIn Britain, the water vole is a declining species because of habitat loss and land‐use change associated with the intensification of agriculture and urban encroachment. During recent years, this decline has accelerated due to predation by feral American Mink (escapees from fur farms) and population fragmentation. Legal protection and planning policy has allowed for conservation action to be incorporated into waterside developments. This paper examines the various options to maintain and enhance water‐vole populations through planning design, sensitive mitigation procedures and strategic habitat restoration.
KNOWLEDGE‐BASED SYSTEM ON WATER‐RESOURCE MANAGEMENT IN COASTAL WATERS
Authors: Chau K. W. 
Published: July 2007

ABSTRACTComputers which are used conventionally in numerical models for problem‐solving and fast number‐crunching are not user‐friendly and lack knowledge transfer in model interpretation. Recent advances in artificial intelligence make it possible to systemise the experience and decision‐making procedures of human experts. This paper describes the development of a prototype knowledge‐based system (an advanced technique of artificial intelligence) as a knowledge‐transfer tool for water‐resource planning and management in coastal waters. The system can (a) run on a desktop computer and (b) act as a design aid, to assist in numerical modelling to simulate flow and/or water quality. Using the application in Hong Kong coastal waters, it was verified that the prototype system had the capability to undertake the reasoning process to select the model and associated parameters, equivalent to a human expert.
THE FORMATION OF A RIVER‐BASIN AUTHORITY THROUGH LOCAL PARTICIPATION: A CASE STUDY FROM THE SOUTHERN PHILIPPINES
Authors: Evans D. 
Published: July 2007

ABSTRACTSince Dublin hosted the International Conference on Water and the Environment in January 1992, the importance of (a) managing water resources at the most appropriate level, (b) the catchment, and (c) participation have been stated repeatedly at international forums. The developing principles in ‘integrated water‐resources management’have built upon these needs. Much effort and resources have been concentrated at the national and transboundary level; however, it is at the local level, in mainly financially resource‐starved countries, that such principles often need to be implemented.This paper examines the progress in the formation of a river‐basin authority, through local initiation and consultation, and with limited resources within the Southern Philippines. It highlights the benefits of the process and the problems which were encountered, and draws together lessons that have a wider application than the case study itself.
EFFECT ON ESTUARINE FINE‐SEDIMENT TRANSPORT OF INTERMITTENT PUMP DISCHARGE AT PAGHAM HARBOUR, WEST SUSSEX
Authors: Mitchell S. B. , Burgess H. M. 
Published: July 2007

ABSTRACTField investigations were undertaken to identify the mechanisms of fine‐sediment transport at a landward limit of Pagham Harbour. Which is a semi‐enclosed natural harbour in West Sussex, UK. Measurements of water level, velocity, salinity and turbidity were made during three tidal cycles between June and August 2002. Near‐bed measurements revealed that, for spring tides, the most significant transport occurs during the flood tide, with smaller turbidity peaks recorded at times of intermittent pumped discharges at low water. Vertical profiling revealed that the timing of these discharges acts as a control on the landward transport of fine sediment by increasing salinity stratification. The resulting graphs show that, while increased near‐bed velocity leads to increased turbidity and sediment transport, the degree of vertical salinity gradient is also linked with landward transport of fine sediment. These results help to explain the role of tides and fresh‐water flow in controlling the transport of fine sediment in natural harbours, emphasising the importance of taking stratification into account when using 2‐D depth‐averaged predictive numerical models.
WATER, LIFE AND CULTURE: THE WATER FRAMEWORK DIRECTIVE
Authors: Lewin K. , Burston P. 
Published: July 2007

ABSTRACTAlthough wetlands are referred to in the statement of purpose of the Water Framework Directive and in the objectives for groundwater status. there are few further references to Member States’obligations towards them in the body of the Directive or its annexes. This paper (a) describes wetlands and their functions, and argues that they play an essential role in aquatic systems, (b) explains the place of wetlands within the Directive, and (c) advocates approaches to implementation in the UK which will ensure maximum human and ecological benefit.
PYROLYSIS AND GASIFICATION OF SEWAGE SLUDGE IN A SPOUTED‐BED REACTOR
Authors: Paterson N. , Zhuo Y. , Reed G. P. , Dugwell D. R. , Kandiyoti R. 
Published: July 2007

ABSTRACTThe use of sewage sludge as the fuel for fluidised‐bed gasifiers, which form part of combined heat and power systems, has been studied in an EU funded project. A laboratory‐scale spouted‐bed reactor was used to investigate the pyrolysis and gasification behaviour of a suite of sewage sludges in the temperature range 770–980°C and pressures between 0.2 and 0.4 MPa. High solids conversions were measured, on a dry ash‐free basis, which were consistent with the high volatile‐matter content of the sludge‐based fuels. It seems that most of the fuel was pyrolysed and converted to gas and condensable tars/oils. The proportion of hydrogen which was formed increased with the gasifier temperature and with the char bed height in the reactor, and this was consistent with an increase in the extent of cracking of the tars/oils. The nitrogen content of the sewage sludge was high, and this led to high ammonia concentrations in the fuel gas. Operating at the higher end of the temperature range tended to decrease the amount of ammonia in the fuel gas.
A RISK‐BASED CONSENTING TOOL FOR SETTING SUSTAINABLE DISCHARGE CONSENTS
Authors: Hankin B. G. 
Published: July 2007

ABSTRACTThis paper describes the development of a guidance tool for assessing the ability of a receiving watercourse to assimilate pollution from point discharges. The ‘sustainable capacity tool’uses a framework that accounts for the ‘no‐deterioration’requirement of the Water Framework. Directive, in terms of the downgrading of a river‐stretch classification and the requirement to return all rivers to ‘good ecological status’. The second requirement results in a long‐term set of river‐quality targets or objectives, and it is generally assumed that ‘good’refers to ‘A2 quality in the Scottish Environmental Protection Agency classification system. The resulting sustainable capacity is defined as the risk‐based amount of capacity that could be allocated without causing a failure of the target class and which could also result in a negative capacity if the river stretch is currently failing the target class. This is plotted as a GIS layer and is intended to form an overview of water quality to help inform stakeholders who are participating in a water‐quality strategy for the next Scottish investment programme on Quality and Standards 3. The sustainable capacity tool could be used in conjunction with integrated catchment modelling for complete management of the Water Framework Directive river‐basin districts.
THE PERFORMANCE OF PILOT‐SCALE PRIMARY‐FACULTATIVE WASTE‐STABILISATION PONDS IN THE UK
Authors: Abis K. L. , Mara D. D. 
Published: July 2007

ABSTRACTThree pilot‐scale primary‐facultative waste stabilisation ponds were constructed at Esholt sewage‐treatment works, Bradford. Each pond received screened sewage at different BOD loading rates over a two‐year period. Concentrations of BOD, SS, amm. N and chlorophyll‐a were measured weekly in summer and bi‐weekly in winter, and sludge accumulation was measured after 3, 9, 15 and 20 months. BOD and SS removals were consistently high, although they were lower in summer than in winter due to high levels of algae. The removal of amm, N was generally much better in summer than in winter ‐ the removal mechanism being most likely related to algal activities. Sludge accumulation rates were very low.
PUBLIC PERCEPTION TOWARDS WATER RECYCLING IN CALIFORNIA
Authors: Bridgeman J. 
Published: July 2007

ABSTRACTThis paper considers ways in which water undertakers in the USA have overcome problems associated with pre‐conceived negative opinions regarding water recycling. Three key recycling sites in California were identified, and a survey of the principal players and stakeholders was undertaken.Research has indicated that outreach and educational programmes must be proactive in nature, focusing on the value of reclaimed water and emphasising the benefits to be gained from its use at an individual. community and environmental level. Recommendations are made regarding the format of public outreach programmes, stakeholder action plans and conclusions drawn regarding public opinion. Unless (and until) the concept is accepted by the general public, large‐scale water‐recycling projects, which ultimately include ingestion of the recycled product, are likely to fail.
ASSESSING AND MANAGING THE RISKS OF PATHOGEN TRANSFER FROM LIVESTOCK MANURES INTO THE FOOD CHAIN
Authors: Nicholson F. A. , Chambers B. J. , Moore A. , Nicholson R. J. , Hickman G. 
Published: July 2007

ABSTRACTA review was undertaken of (a) the levels and prevalence of Salmonella spp., Campylobacter spp., Listeria monocytogenes, Escherichia coli 0157. Cryptosporidium parvum and Giardia intestinalis in livestock manure, and (b) factors which affect their survival during storage and following land application. Pathogens are commonly present in livestock manures and can survive in soil for several months or years after spreading or excretion onto land. Temperature was identified as being the most important factor influencing pathogen survival, although pH, UV light and drying were also important. Various practical measures to minimise the risk of pathogen transfer into the food chain were identified, including treatment, extended storage and no/harvest periods following land spreading. Guidelines are being developed on managing farm manures to minimise the risks of microbiological contamination of ready‐to‐eat crops.