bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Drying of Sewage Sludge
Authors: C. GROSS T. S.
Published: July 2007

Over the next decade the UK will experience significant, imposed changes in the quantity of sewage sludge produced and in the means available for its disposal. Existing practices are being reappraised and new technologies are being explored to cope with a predicted 40% increase in the quantity for disposal. Thermal drying of sludge undoubtedly has a role to play in coping with this demand.

The two principal process types, i.e. direct and indirect heat application, are appraised in depth and a comparison is drawn. A case study is identified to examine the energy demands of the process, including the potential for heat recovery and for resource reuse. The environmental impact of a typical process is also examined.
Accreditation of Products and Services for the Water Industry
Authors: STOKES R.
Published: July 2007

This paper describes the programme of work being undertaken in a number of European organizations supported by the European Commission, which is designed to achieve the Single European Market. In particular, an explanation is provided on the organization of European standards, concentrating on the work affecting the water cycle. Reference is made to the public procurement, utilities and construction products Directives, and the need for accreditation using certification and testing. Also, an explanation is provided of the committee structure being established to facilitate mutual recognition of certification and test procedures to satisfy both regulatory and voluntary requirements of products and services.
Pilot‐Plant Trials on River Dee Water at Huntington
Authors: TAYLOR G. S. , HILLIS P. , WALKER I.
Published: July 2007

A pilot plant which has been used to examine the suitability of a number of treatment options for upgrading North West Water's water‐treatment plant at Huntingdon, Chester, is described. Processes tested include biological pretreatment using a fluidized sand bed to remove manganese and ammonia, chemical coagulation, chemical oxidation using chlorine, ozone and potassium permanganate, and both primary and secondary filtration with sand and granular activated carbon. The reduction of trihalomethanes and pesticides was also investigated.
Maintaining Groundwater Supplies during Drought Conditions in the Brighton Area
Authors: MILES R.
Published: July 2007

The very low level of recharge to the chalk of the South Downs, which provide Brighton with its water supply, has meant that the groundwater levels are very low. Despite this, no restrictions have been necessary since February 1991. This is perhaps due to the instigation of public information campaigns, together with media coverage of the drought, as well as a successful programme of leakage control. This paper looks at how the growth of public water supply has been accommodated operationally while ensuring that groundwater quality is maintained. Options for the future expansion of supply, and their cost‐effectiveness, are also considered.
Legionellosis: A Concise Review
Authors: ELLIS K. V.
Published: July 2007

The development of the awareness of Legionnaires disease and Pontiac fever is outlined, and the causative organisms are considered together with their environmental sources. Modes of transmission of the infections are discussed and the multiplication of the organisms within, and dangers associated with, water cooling towers and hot and cold water systems are investigated. Consideration is also given to the resistances of the Legionellae to temperature and chemical disinfectants. The elimination of Legionellae from, or their control within, waste systems and cooling towers are pursued and some definite suggestions made.
Climatic Change and Future Rainfall Predictions
Authors: ROWNTREE P. R. , MURPHY J. M. , B. MITCHELL J. F.
Published: July 2007

The models which are used to estimate equilibrium and evolving changes in climate, due to increases in greenhouse gas concentrations, are described. Results from a 75‐year experiment with carbon dioxide increasing at 1%/annum using a coupled model of the atmosphere, land and deep ocean, are presented and compared with those from equilibrium experiments. Rainfall over the UK increases over the year as a whole, with the largest changes in winter; however, in summer it decreases except in the north. Soil moisture decreases except in winter. Results from an equilibrium experiment show that rainfall tends to be more intense but less frequent with a doubled atomospheric concentration of CO2. A scenario of climate change over western Europe is included, based on these and other experiments.
A Joint US and UK Approach to Water Supply and Distribution Modelling
Authors: BRAMMER L. F. , SCHULTE A. M.
Published: July 2007

Network analysis has been practised in the water industry for many years, both in the UK and US, especially for capital investment planning and operational strategies. Driven now by the need to improve and maintain customer service levels, the management of water distribution is beginning to rely more on network analysis techniques. The combination of large, detailed models and easy‐to‐use software is moving network analysis into new areas of benefits in Severn Trent Water using the Stoner workstation service. By providing a simple, geographic interface with the user, the use of network simulation facilities has been increased tenfold in the company. In addition to the hydraulic benefits, Severn Trent Water has followed a lead from the US with water quality modelling, including nitrate blending, source water mixing and chlorine residual analysis.
Nitrogen Removal from Returned Liquors
Authors: THORNDAHL U.
Published: July 2007

During recent years it has become clear that, particularly to protect the quality of sea waters, nitrogen and phosphorus discharges have to be substantially reduced. Nitrogen reduction can take place by conventional biological treatment. However, the problem can be partly, or perhaps completely, resolved by treating the returned liquors resulting from sludge dewatering. These normally create a substantial load on sewagetreatment works; in fact the nitrogen in the returned liquors can contribute 15–25% of the total nitrogen load entering the works. It therefore seems appropriate, particularly with a view to future nitrogenreduction requirements, to treat the returned liquors before they are returned to the works’inlet. Since 1987, Watergroup has been working on these problems, and the company now has full‐scale plants at Frederikshavn, Denmark (population equivalent 130 000) and Eslöv, Sweden (population equivalent 250 000). Normally this treatment can be carried out at a considerably lower cost, per kg nitrogen removed, than when applying traditional methods. An additional advantage is that the method makes it possible to reuse the nitrogen content of the returned liquor, e.g. in the form of ammonium sulphate which is an excellent fertilizer.
The Impact of Dry Years on Crop Water Requirements in Eastern England
Authors: LEEDS‐HARRISON P. B. , A. ROUNSEVELL M. D.
Published: July 2007

Agricultural water demand is weather and climate driven. Irrigated crop production which makes the largest agricultural demands is highly seasonal, water only being required in a few summer months. A ‘droughtiness’factor which is based on crop type and potential soil moisture deficit indicates large differences in the amount and timing of water demand for different crops. Soils with low water retention capacity are shown to be marginal for the potato crop unless irrigation is available in these areas. Economic data are presented which indicate that potato production realizes a considerable benefit from investment in irrigation, but this leads to inertia in the relocation of agricultural production centres in dry years. It is concluded that investment in on‐farm winter water storage for irrigation should be a priority investment in eastern England.
The National Rivers Authority's Need for Models
Authors: PICKLES LINDSAY
Published: July 2007

The Water Resources Act 1991 requires the National Rivers Authority to exercise a general supervision over all matters relating to flood defence. There is need for information in order to manage flood defence – not only as part of the overall management of the catchment but, at a more detailed level, to plan and monitor capital and maintenance programmes.

The information requirements of the National Rivers Authority can be satisfied either by witnessing historic flood events, an approach disadvantaged by the infrequency of flood events, or by modelling the system, i.e. the rivers, coasts and flood plain. Once models are calibrated by specific flood events they can be used to predict the outcome of other events and to assess the response required to alleviate potential flooding. The different needs of the Authority can be satisfied by different modelling techniques using different levels of accuracy. Models can be used to analyse river and coastal systems to assess performance and target resources for maintenance and improvement.

The management of flood defences by specifying and monitoring their performance is considered, and a recent trial in reach specification based on modelling techniques is described.
Three Examples of the Use of Physical River Channel Models by the National Rivers Authority, Yorkshire Region†
Authors: PELLEYMOUNTER D.
Published: July 2007

In recent years the Yorkshire Region of the National Rivers Authority has employed the technique of physical modelling to assist in the hydraulic design of urban flood‐alleviation schemes. The paper describes three examples of their use. On the River Worth at Keighley the introduction of a weir, to reduce siltation beneath a bridge, was modelled. The confluence of Batley Beck and Howley Beck in Dewsbury is located at the entrance of a culvert. A model was constructed and streamlining was introduced to improve self‐cleansing and reduce head‐losses. On the River Calder at Wakefield, two bridges and a weir form a complex hydraulic situation. The results of a physical model study were used to aid the calibration of a mathematical model of a much larger area. The paper reviews these model studies, indicating the costs and the likely savings resulting from reduced siltation. The paper concludes that physical modelling can provide a cost‐beneficial aide to river‐engineering design.
Isleham Ion‐Exchange Nitrate‐Removal Plant
Authors: ANDREWS D. A. , HARWARD C.
Published: July 2007

The ion‐exchange nitrate‐removal plant installed at Isleham, Cambridgeshire was commissioned during 1990. A description of the plant and design considerations is given, together with operational data. The nitrate‐removal plant treats up to 4.5 Ml/d of chalk borehole water. Problems encountered are presented together with information on capital and operating costs.
Toxicity Measurements and Their Use in Treatment Strategies
Authors: LANKFORD P. W. , SMITH L.
Published: July 2007

The use of measured toxicity for evaluating the effects of a chemical or effluent on the environment, or monitoring the performance of an effluent treatment plant, is becoming increasingly important to complement the analytical techniques which are conventionally used. Although many consents on effluent discharges refer to specific chemical components, regulatory authorities are increasingly realizing the value of toxicity measurements to evaluate a combined effluent effect, particularly in the case of complex effluent streams.

This paper (a) describes the basic principles of conventional methods of measuring toxicity, (b) highlights the benefits and shortcomings of these methods, and (c) outlines some promising methodologies which are being developed. The use of these measurements is then discussed in evaluating treatment alternatives, modifying existing treatment plants and conducting treatment evaluations. Several case studies are outlined to illustrate the use of toxicological measurements in assessing industrial wastewater treatment processes.
Application of the ‘Biothane’ Wastewater Treatment System in the Soft Drinks Industry
Authors: HOUSLEY J. N. , ZOUTBERG G. R.
Published: July 2007

This paper describes the experience gained by Yorkshire Water in the construction and operation of a wastewater treatment plant to deal with the effluent from Europe's largest canning and bottling factory (at Wakefield, West Yorkshire). The process which was chosen was the ‘Biothane’ upward‐flow anaerobic sludge blanket system. Commissioning of the plant was fraught with difficulties due to the erratic organic load being discharged from the factory, along with larger than anticipated volumes of caustic solution.
Agricultural Chemicals in Raw Wool and the Wool Textile Industry
Authors: SHAW T.
Published: July 2007

In common with most other agricultural products, wool contains residues of pesticidal substances. Until about 1985, the use of organochlorine pesticides for the treatment of sheep was common practice in some countries (including the UK), but the pesticides used now are usually organophosphates or synthetic pyrethroids.

The pesticides appear in the effluent from the wool‐scouring (washing) process, which is normally discharged to sewer, with or without partial treatment to remove wool grease. It is shown that the concentrations of organochlorine pesticides in rivers draining the regions of the UK where wool‐scouring activity is highest, have fallen substantially since 1985.

Environmental quality standards have recently been proposed for the organophosphates most commonly used for sheep treatments. Even if wool sources apply the best available techniques for treating their effluent before discharge to sewer, these standards may be unachievable unless means can be found of reducing the average concentrations of organophosphates present in raw wool.
Decision Aids for Planning in the Real World
Authors: SNELL M. J.
Published: July 2007

Planning the use of resources is an increasingly complex business as environmental and social concerns become more explicit and decisive. Many groups of people are affected, so that decisions have to be made from several viewpoints and with several criteria. Decision‐makers must not only apply the criteria which represent their own interests, but must also estimate the opinions and reactions of other affected people. If a decision is to be effective, these parties need to know how it was arrived at and to feel that it is their decision.

The paper uses a simple example and two case studies to describe decision aids, designed as means of (i) communication and persuasion, and (ii) analysis. Important characteristics are (a) transparency, (b) attention to presentation, and (c) grouping of criteria.
Mothproofing Agents in UK Wool Textile Effluents
Authors: SHAW T.
Published: July 2007

Mothproofing is an essential part of the manufacture of wool and wool‐blend carpets and until now has usually been combined with another textile wet process, such as dyeing, to save cost.

Environmental quality standards for mothproofing agents in surface waters have recently been introduced. Compliance with these standards will require a reduction of more than 90% in the mothproofing agent content of industrial effluents in parts of the UK where mothproofing activity is most concentrated. In order to achieve such a reduction, it is proprosed that the carpet industry should install new methods of applying mothproofing agents, aimed at source reduction, rather than by adopting end‐of‐pipe measures.

Two new low‐pollution mothproofing technologies are described in detail, and a summary is given of other possibilities.
Current Developments in Contaminated Land Treatment Technology in the UK
Authors: BARDOS P.
Published: July 2007

This paper reviews recent developments in contaminated land treatment (soil and groundwater) in the UK, particularly with regard to:

The combination/integration of individual soil‐treatment unit processes and the use of ‘extensive’ technologies;

UK demonstration and emerging projects including those in the NATO/CCMS (Committee for Challenges to Modern Society) Pilot Study on Research, Development and Evaluation of Remedial Action Technologies for Contaminated Soil and Groundwater; and

Contaminated land treatment technology research and development in the UK.
The Impact of Conservation Issues on a Sea‐Defence Scheme at Pennington
Authors: MARTIN D. J.
Published: July 2007

The reconstruction of 8.1 km of dilapidated sea wall protecting the Hampshire coast of the Western Solent, near Lymington, presented the National Rivers Authority (Southern Region) with particular problems and substantial extra costs in coping with the needs of conservation. The resulting scheme, however, can be seen not only to have preserved but also enhanced the conservation value of its immediate surroundings in addition to the wider area of protected land.
Sankey Brook Catchment Study
Authors: MACILWAINE R. V. , FLEW N. W. J. , COOPER J. N. M.
Published: July 2007

The Sankey Brook catchment lies in the heart of the Mersey basin. As part of a major study into development issues in the Sankey Brook catchment, a hydraulic model was constructed and successfully used to simulate the river system and to assist in the derivation of discharge control policies.

The background to the study and the subsequent hydrological and hydraulic modelling are described, particularly in relation to the more complex systems in the lower reaches of Sankey Brook.
Potential Impacts of Climatic Change and of Sea‐Level Rise on the Yields of Aquifer, River and Reservoir Sources
Authors: COLE J. A. , OAKES D. B. , SLADE S. , CLARK K. J.
Published: July 2007

Using regional statistics of daily rainfall, a simple water‐balance model was employed to generate runoff sequences with which to simulate the yield/storage behaviour of reservoirs in south‐east England, in north‐west England, and North Wales. Similarly sequences of recharge to an unconfined aquifer in eastern England were the basis of deriving its yield/storage behaviour. Then, taking scenarios of the year 2030 rainfall and evaporation, provided by the University of East Anglia's Climatic Research Unit, reductions in yield were calculated to be 5–15% below present‐day values. For direct supply reservoirs, greater percentage reductions in yield were found to apply to the south‐east region, as compared to the north‐west. The results from the aquifer example are interpreted on a novel basis which allows an immediate comparison with the surface reservoir examples.

Coastal sea‐water intrusion was modelled for three common geological conditions (i) the Grimsby Chalk (confined), (ii) the Brighton Chalk (unconfined), and (hi) the Otter Valley Sandstone (unconfined). In all three cases the effect of a possible 0.6 m rise in mean sea level was shown to have only a marginal effect on sustainable yields, which reduced by about 1.5%.

Estuarine fresh‐salt water interfaces are important to the abstraction regime of freshwater intakes in the lower reaches of rivers. The effect of a 0.6‐m sea‐level rise on the saline interface location at high tide was evaluated by hydrodynamic computational models. Only a minor inland shin of the interface was found, less man 800 m in the Thames tideway and less than 500 m in the Lune estuary. The Severn estuary is exceptional in having its saline interface move 3.5 km landwards for the same 0.6‐m rise in mean sea level.
The Reconstruction of Sewage‐Treatment Works in Osaka City
Authors: YASHITA T.
Published: July 2007

Osaka has nearly completed its sewerage system, and twelve sewage‐treatment works are now in operation. Tsumori and Ebie works, the two oldest, were commissioned in 1940. For these works, full‐scale reconstruction has just commenced.

This paper reports on the reconstruction of the Tsumori works, and outlines the plan for future reconstruction of the city's sewage‐treatment works.
Contaminated Land Remediation: Economics v Liability
Authors: BRAITHWAITE P.
Published: July 2007

Chemical investigations of contaminated land can be expensive and yet still leave the landowner unaware of his/her full environmental liability. An approach to an effective means of planning chemical investigations is described by a case study of a contaminated site near London. This approach limits environmental liability in a cost‐effective manner.

One of the main problems encountered in assessing the degree of contamination of land for the purposes of technical design, and ultimately for developer confidence, is the lack of recognized UK standards for acceptable levels of contaminants.

Using a second case study relating to a large contaminated site in the Midlands, the paper describes how a set of site‐specific standards, for soil and water, was derived and used to develop a reclamation strategy for an 81‐ha site. The case study also demonstrates the approach which was adopted in handling a large amount of analytical data and other quantitive information needed to produce a set of ‘constraint models’. From these constraint models, the strategy for reclaiming the site has been developed.
Biological Nutrient Removal: Design Snags, Operational Problems and Costs
Authors: COOPER P. , UPTON J. E. , SMITH M. , CHURCHLEY J.
Published: July 2007

The EC urban waste water treatment Directive will lead to some sewage‐treatment works in the UK having to remove nitrogen and phosphorus. The paper reviews the basic biological processes which are available for retrofitting existing activated‐sludge plants to achieve this removal, and then points to some of the problems which are encountered with these processes in other countries. The authors make suggestions as to how these problems can be overcome in design and operation. The paper also provides a cost comparison of different ways of uprating an existing nitrifying activated‐sludge plant to achieve nitrification/ denitrification and phosphorus removal.
Contaminated Land Remediation in the UK with Reference to Risk Assessment: Two Case Studies
Authors: ELLIS B. , REES J. F.
Published: July 2007

The approach to land reclamation in the UK has traditionally relied upon the use of cover and concealment, which can leave a legacy of problems below the ground. Alternatively, the bulk export of materials to licensed landfill has often been used, but this (a) simply transfers a problem, (b) can cause considerable disruption, and (c) is becoming increasingly expensive. Remedial strategies involving the use of barrier systems or off‐site removal both have their place in the efficient and economic development of contaminated sites. However, there is now increasing interest in the use of on‐site technology which can provide cost savings and by treating, destroying or stabilizing contamination, can serve to minimize future liabilities. The design, costing and application of treatment, as opposed to cover or disposal, depends fundamentally on understanding the problem and evaluating the capabilities and availability of appropriate technologies. With reference to UK case studies, this paper highlights some of the options available and routes taken in order to achieve site‐specific, commercially‐acceptable, remedial responses.
A Semi‐Empirical Investigation of the Influence of Flood‐Plain Storage on Flood Flow
Authors: McCARTNEY M. P , NADEN P. S
Published: July 2007

A simple model is used to assess the effect of flood‐plain storage on flood flows, with a view to developing methods for general use in flood‐frequency estimation. Recent floods on the River Severn at Montford are ‘unrouted’ in order to determine the shape and magnitude of the hydrographs, provided that there had been no overtopping and all flows had been contained within the banks. The model used to unroute the hydrographs has, at its core, a relationship between water depth and flooded area derived from a coarse (50 m) digital terrain model developed from Ordnance Survey 1:50 000 maps. The implications for flood‐frequency curves at sites downstream from significant flood‐plain storage are discussed.
Agriculture and Water Quality: A Regional Study
Authors: FOY R. H , KIRK M.
Published: July 2007

Water quality, measured on a fisheries ecosystem scale of 1 (good/salmonid) to 6 (bad/fish absent), of forty‐two lowland streams in two Northern Ireland river catchments was inversely correlated with the stocking rate of grazing animals. A decrease in water quality of one class was associated with an increase in the combined grazing/stocking rate of cattle and sheep of 0.6 dairy cow equivalents/ha. This dairy cow equivalent stocking rate was significantly correlated with maximum BOD and total amm.N concentrations and minimum dissolved‐oxygen levels. The worst pollution events, with BOD concentrations in excess of 100 mg/1, occurred at the end of May and were caused by discharges of silage effluent. Smaller BOD peaks, which occurred in late winter and early spring, were related to the land spreading of animal slurries. It was concluded that poultry and pig farms were not having a major impact on water quality.
Developing Scientific Aspects of Water Treatment
Authors: SCHOFIELD T.
Published: July 2007

Severn Trent Water is currently undertaking an extensive capital programme to enhance water‐treatment facilities at many of its major plants, and this work is underpinned by the need to apply robust, cost‐effective solutions utilizing modern treatment technology.

The paper describes various aspects in the development of these functional designs in relation to treatment objectives, technical innovation and value engineering, drawing examples from Severn Trent schemes and particularly from the redevelopment of the Birmingham water‐treatment plant.
The Examination of Drinking Water in the Mid‐1990s
Authors: BREACH R. A.
Published: July 2007

This paper describes the principles underlying water quality examination in a large modern water company, and compares these present‐day techniques with the approach which was used 100 years ago. Although the analytical technology and regulatory framework for water testing has changed out of all recognition in this period, the author argues that many of the fundamental concepts remain the same. This illustrates the foresight of our predecessors. Nevertheless, despite, or perhaps because of, our modern analytical skills, public confidence in the high quality of current water supplies is being ‘strained’ by our ability to detect more and more minute trace contaminants in water. The challenge to water quality managers of today is to demonstrate to their customers that present approaches to water examination provide a very high degree of reassurance about water safety, not the converse.
Treatment and Disposal of Sewage Sludge in the Mid‐1990s
Authors: HUDSON J. A.
Published: July 2007

The paper reviews the current methods of sludge technology, and compares them with those discussed by Ashton in 1904. The paper also plots the development of some of the current technology over the last century, particularly those methods of treatment which were mentioned by Ashton but were not in existence at the time.

The 1990s have been a most interesting era, and have probably seen more changes in sludge technology than any other decade this century. The most significant impact will be due to the cessation of the sea disposal route which, at the beginning of the 1990s, was used for about 30% of the total sludge production in England and Wales and approximately 76% of the total sludge produced in Scotland.
A Methodology for Monitoring the Performance of Combined Sewer Overflows
Authors: BALMFORTH D. J. , LONSDALE K. , WALSH M. , NUSSEY B. B.
Published: July 2007

The authors have been involved with the field monitoring of combined sewer overflows and screens over a number of years. During this period they have developed a monitoring methodology which ensures reliability, consistency and accuracy of results. The paper recommends appropriate equipment to be used for monitoring the qualitative and quantitative performance of combined sewer overflows and gives recommendations on location and installation thereof. Particular reference is made to methods for cross‐correlating data amongst monitors and for proper interpretation of the results. The recommended methods have been proven in the field on a variety of working project.
A Comparison of ERS‐1 Satellite Radar and Aerial Photography for River Flood Mapping
Authors: Biggin D. S
Published: July 2007

The extent of floodwater inundation, whether caused by river flooding or coastal storm surges, is required quickly (a) to enable the planning of emergency relief and repairs to communications and services, and (b) for the production of river flood risk maps. Unfortunately, by their nature, most floods occur in bad weather, which can severely restrict the use of aircraft, and extensive cloud cover precludes the use of most earth observing satellites which rely on sensors operating at optical wavelengths.

Synthetic aperture radar, which can penetrate clouds, allows affected areas to be imaged, regardless of cloud cover or light conditions. This paper compares satellite acquired data of river flooding with photographic records obtained from a light aircraft to demonstrate the accuracy of the technique.
Enhancement of Anaerobic Digestion Using Duckweed (Lemna minor) Enriched with Iron
Authors: Clark P. B. , Hillman P. F.
Published: July 2007

ABSTRACT This paper describes the enhancement of biogas production in laboratory‐scale anaerobic digesters (with batch and semi‐continuous operation) using iron‐enriched duckweed as a supplement to the digestion of feedstock. The relationship between the level of enhancement achieved and the retention period of the digesters was also investigated. The trials demonstrated that, in batch digesters, iron‐enriched duckweed significantly improved the rate of microbial succession. Batch digesters receiving no duckweed took 40 days to reach peak methane production compared to 15 days when duckweed was added. In the semi‐continuous digesters, an increase in gas production of about 44% was observed.
Strategic Resource Development Options in England and Wales
Authors: Sheriff J. D. , Lawson J. D. , Askew T. E. A.
Published: July 2007

This paper describes the options which had to be considered for new water resources in the development of the † National Rivers Authority's water resource strategy for England and Wales. The options included interregional transfers, strategic reservoirs, and a range of unconventional schemes including aquifer recharge, effluent re‐use, groundwater abstraction where levels are rising, desalination, and transfer by sea. The main options are described and comparative costs are presented.
Current Technologies for Sludge Treatment and Disposal
Authors: Hudson J. A. , Lowe P.
Published: July 2007

This paper reviews the current sludge technologies and discusses likely future trends associated with those technologies. It describes the role of thickening, dewatering, pasteurization, stabilization, thermal destruction and product enhancement to satisfy environmental standards. Reference is made to technologies which, for decades, have been associated with sewage sludge but where market conditions have forced R and D initiatives to be introduced and commercialized.
Post‐Construction Effects of the Cameroonian Lagdo Dam on the River Benue
Authors: Toro S. M.
Published: July 2007

This paper examines the immediate and long‐term effects of the Lagdo dam on the Upper Benue river basin in Nigeria. From routine monitoring of the River Benue, it was found that some immediate deleterious effects were (a) siltation of the river bed and channel, (b) frequent flooding events, and (c) reduction in flow. Consequently, these factors have constrained irrigation, navigation and fishing activities which were formerly undertaken along the river. Similarly, water‐supply intake structures and irrigation abstraction facilities along the river have either been silted up or threatened. Allowing for assumptions on a real‐time operational schedule of the dam, coupled with future water demands in north Cameroon, longterm effects of the dam on the Benue basin within Nigeria are predicted.
Groundwater Resources in the Lagan Valley Sandstone Aquifer, Northern Ireland
Authors: Kalin R. M. , Roberts C.
Published: July 2007

Beneath Belfast and the Lagan Valley lies Northern Ireland's most important aquifer, the Triassic Sherwood Sandstone. Up to 300 m in thickness and with a total abstraction of around 31 000 m3/d, it is a modest aquifer by UK and world standards; nonetheless, it is an important local water source. The use of this aquifer system as a water supply will undoubtedly increase as growth of industry and population continues in the Belfast metropolitan area. Even with the mesic climate of Ireland, groundwater mining of this aquifer system is already occurring, and thus there is a need for detailed aquifer planning and protection to be implemented in order to preserve this resource for the future.
A Survey of Ferruginous Minewater Impacts in the Welsh Coalfields
Authors: Davies G. , Butler D. , Mills M. , Williams D.
Published: July 2007

The aim of this study was to locate all ferruginous discharges within the Welsh coalfield areas and to assess their impact upon receiving watercourses. The project was undertaken in two stages. In the first stage, visual assessments were carried out on an area of river bed affected by iron hydroxide deposition. Chemical samples of the discharges and the receiving watercourse were analysed for a suite of physico‐chemical determinands. Ninety discharges were located impacting upon 59.4 km of river, and an area of 22 ha was affected by iron hydroxide deposits.

A ranking method, incorporating the physical/chemical determinands, was developed to assess the comparative impact which discharges were having on receiving watercourses. A total of 33 of the top ranked discharges‐ (20 to classified watercourses and 13 to unclassified watercourses) having the highest environmental impact were selected; chemical, biological and fisheries impact assessments were then carried out on these discharges in the second stage of the project. The sites were then ranked on the basis of biological and fisheries impact. A list of the highest impacted sites was produced, and some of these were further investigated for remediation options and associated costs.
Predictive Chlorine Dosing: A New Paradigm
Authors: Johnson P. , Graham N. J. D. , Wilson M.
Published: July 2007

Disinfection by chlorine is common practice in potable water treatment. The most frequently used dose control method is to inject an overdose of chlorine at the inlet to the contact tank and adjust to the desired residual chlorine level in the effluent stream. However, this method of control may not be optimal. The advent of reliable predictions of retention time distributions and the widespread use of programmable logic controllers, coupled with a greater understanding of chlorine disinfection kinetics, offers the potential for more efficient chlorine dosing algorithms. This paper describes one possible algorithm, based on theoretical models, for predictive chlorine dosing.
Construction and Preliminary Performance of Reedbed Treatment Systems at Castle Espie Wildfowl and Wetlands Trust Centre, Northern Ireland
Authors: Worrall P. , Peberdy K. , McGinn H.
Published: July 2007

In 1993, the Wildfowl and Wetlands Trust constructed a demonstration reedbed treatment system at its Castle Espie Visitor Centre in Northern Ireland. The objectives of the project included (a) the treatment of septic‐tank effluent, (b) the protection of water quality in Strangford Lough, and (c) the establishment of a research base for constructed wetland systems. Parallel beds of equally sized sub‐surface and surface flow were constructed and planted, and a research project was initiated to provide data on performance.
The Effects of Oil and Chemical Spillages at Sea
Authors: Law R. J. , Campbell J. A.
Published: July 2007

At sea around England and Wales, in an average year there can be 10–12 oil and chemical spillage incidents which require action to be taken, and occasionally a major spill may trigger monitoring studies and local controls on fishing activity. This paper discusses the scope of such incidents and their consequences by reference to two particular incidents; the loss of a container of the pesticide lindane from MV Perintis in the English Channel in 1989, and the grounding of the oil tanker Sea Empress in Wales in 1996 and the consequent oilspill. The latter of these incidents is also compared with the loss of the tanker Braer in Shetland in 1993.
Sequencing Batch Reactor Technology: Concepts, Design and Experiences (Abridged)
Authors: Morgenroth E. , Wilderer P. A.
Published: July 2007

The sequencing batch reactor is a specific fill‐and‐draw version of the activated‐sludge process. In contrast to the continuous‐flow alternative, metabolic reactions and solid‐liquid separation are carried out in one tank and in a well‐defined and continuously repeated time sequence.

This paper reviews the historical development of sequencing batch reactor technology and describes the different modes of operation. Mass‐balance equations are introduced to allow for a quantitative comparison of sequencing batch reactor and continuous‐flow technologies and for the design of such systems. The initial design dynamic simulation and in‐situ adjustment of the cycle program under the actual process conditions can be used conveniently to further optimize the sequencing batch reactor plant.
Intensification of the Activated‐Sludge Process (Abridged)
Authors: Boon A. G. , Thomas V. K.
Published: July 2007

During the last thirty years, attempts have been made to increase the rate of treatment of wastewater in compact activated‐sludge systems whilst ensuring (a) an adequate supply of dissolved oxygen, (b) good settleability of activated sludge, and (c) consistently high‐quality effluents.

This paper describes two successful systems, i.e. oxygenated activated sludge and the deep‐shaft process, which are used to intensify the rate of treatment in relatively compact aeration tanks. Data are presented of full‐scale oxygen activated‐sludge systems, including Vitox and Unox, together with information on the operation and performance of the deep‐shaft process.
The Effect of Borehole Sealing on the Southern Lincolnshire Limestone Catchment
Authors: Johnson D. , Rushton K. R. , Tomlinson L. M.
Published: July 2007

The Southern Lincolnshire Limestone is an important groundwater resource; however, for many years water has been lost from the aquifer system through uncontrolled artesian flow from wild‐bores in the Fenland area. During 1991–92, there was an extensive programme of sealing or controlling the wild‐bores, and compensation flows for ecological and farming purposes were provided at some sites.

This paper describes a field study which was designed to identify the important features of part of the catchment; this was followed by the development of an existing groundwater model to provide an improved representation of the uncontrolled and controlled wild‐bores. The model is used to assess the consequences of controlling or sealing the wild‐bores.
The Role of Habitat Enhancement in the Return of the European Otter (Lutra lutra) to Northumberland
Authors: Fox A.
Published: July 2007

Riparian habitat enhancement, or ‘haven’ creation, is considered to be the best way to facilitate the return of the UK's otter population to its former status. Using map and statistical analysis, results of Northumberland county otter surveys and the habitat improvements implemented by the North Northumberland Otter Project are examined and relationships between the two are identified. A statistically significant increase in the incidence of positive survey sites was identified between 1991 and 1995, and this increase was statistically related spatially to the creation of otter havens.
Passive Treatment Systems for the Remediation of Acid Mine Drainage at Wheal Jane, Cornwall
Authors: Hamilton Q. U. I. , Lamb H. M. , Hallett C. , Proctor J. A.
Published: July 2007

In 1992, Knight Piésold was appointed to formulate a long‐term treatment strategy for the remediation of acidic metal‐rich minewater issuing from the abandoned Wheal Jane mine in Cornwall, UK. The study has investigated both passive and active treatment technologies. As part of the study, a pilot passive‐treatment plant was constructed during 1994, comprising three separate systems. Each system contains the same main treatment stages which consist of five aerobic reedbeds, an anaerobic cell and an aerobic rock‐filter. Two of the systems also incorporate pretreatment, one in the form of lime dosing and the other in the form of an anoxic limestone drain. This paper discusses the theory and design criteria used in the construction of the plant and examines performance data during the period June 1995 to November 1996.
The Derivation of Environmental Quality Standards for the Protection of Aquatic Life in the UK
Authors: Zabel T. F. , Cole S.
Published: July 2007

The UK has an obligation, under various existing and proposed EU legislation (including the proposed water policy framework Directive), to derive environmental quality standards. These standards form the basis of the UK's pollution control strategy as adopted in national legislation, and the Regulatory Authorities need them as operational standards for setting consents. The paper outlines the procedure which is currently used in the UK for the derivation of these standards for the protection of the aquatic environment.
Preliminary Investigation into the Microbiological Quality of a Freshwater Bathing Site: A Case for Official Identification?
Authors: Pond K. , Petersen T. , Rees G. , Perry R.
Published: July 2007

The quality of recreational waters has become of increasing importance and, where water‐based activities are permitted, such waters should be required to comply with minimum standards to protect public health. At present, there are no freshwater sites in the UK which are identified as official bathing areas, despite a significant proportion being identified in other EU Member States and the increasing use of such waters for bathing. This paper presents a case for the official identification of three freshwater bathing sites which, traditionally, have been used for bathing for more than ninety years.
The Mersey Estuary – Back from the Dead? Solving a 150‐Year Old Problem
Authors: Jones P. D.
Published: July 2007

The Mersey Estuary has suffered a legacy of abuse and neglect since the beginning of the Industrial Revolution. The discharge of effluents from manufacturing processes, together with wastewater from the burgeoning centres of population, resulted in the estuary gaining the unenviable reputation of being one of the most polluted rivers in Europe.

As a result of the long‐awaited remedial action which has been implemented over the last fifteen years, there is now unequivocal evidence that the water quality of the river and the biology of the system have improved significantly and will continue to do so as further planned alleviation schemes are completed.

This paper reviews the achievements which have been made at the half‐way stage in the 25‐year multi‐billion pound ‘clean‐up’campaign.
The Use of Riparian Vegetation in Stream‐Temperature Modification
Authors: LeBlanc R. T. , Brown R. D.
Published: July 2007

This paper describes a framework for estimating the effectiveness of riparian vegetation in modifying the water temperature in streams. A physically‐based model was incorporated into the framework and used to demonstrate that planting trees in strategic locations can have a substantial effect on water temperature in streams and, consequently, on the survival of target fish populations. Application of the framework suggested that equivalent plantings in different configurations can have markedly different outcomes in terms of resultant stream temperature. There is no single best solution for all stream‐restoration projects but, through the use of this framework, environmental planners, designers and managers can compare scenarios and make appropriate decisions for specific streams.
The Effect of Overbank Flow in a Meandering River on its Conveyance and the Transport of Graded Sediments
Authors: Loveless J. H. , Sellin R. H. J. , Bryant T. B. , Wormleaton P. R. , Catmur S. , Hey R.
Published: July 2007

A large‐scale model hydraulic study of inbank and over‐bank river flow, using a regular sinuous river channel with a mobile bed, was carried out in the Flood Channel Facility at HR Wallingford, UK. The selected sediment had a wide range of particle sizes present over the ‘fine sand to coarse sand’range. Flow velocity, local and global sediment transport rates, and channel conveyance were all measured. The resulting bed forms were determined and used to explain the secondary circulation in the sinuous channel as well as the size sorting of the sediment. The paper gives an early overview of this major project.
Water‐Recycling Technologies in the UK
Authors: Diaper C. , Jefferson B. , Parsons S. A. , Judd S. J.
Published: July 2007

Urban water recycling in the form of rain, grey or black water is becoming an important element of demand‐management practice in the UK, and appropriate technology allows the use of three different water sources for similar applications. The level of pollution in the water source and the application to which it is being recycled, dictate the level of technology which is used. This paper describes current water re‐use practices in the UK (in terms of water source, technology scale, type and efficiency) and examines five case studies. Of more than 150 schemes identified, most are rainwater‐collection systems and these are generally sited in rural areas. There are various single‐house greywater recycling sites, many of which are part of water company or Environment Agency monitoring programmes. Larger‐scale schemes employ both natural and hi‐tech treatment options. Operationally successful schemes utilise appropriate technology for the end‐use, although the economic benefits of many of the schemes are poor.
Assessment of Microbial Populations in Activated Sludge Using an Organism Diversity Index
Authors: Burgess J. E. , Mayhew M. E. , Stephenson T. , Clark T. A.
Published: July 2007

An organism diversity index for use with mixed liquor or wastewater samples was developed to assess the species richness and diversity of activated sludge. The index was used in several studies and was found to be fast and simple to perform using basic laboratory equipment. Two bench‐scale and two pilot‐scale studies found that the resulting ‘organism diversity index’value was a good indicator of process performance and was not influenced by the total concentration of the mixed‐liquor suspended solids but by their nature alone. The technique rapidly yielded pertinent information about the health of the sludge and could be used instead of genetic investigations to obtain population information quickly enough for wastewater‐treatment plant process control.
Nitrogen Release and Fertiliser Value of Thermally‐Dried Biosolids
Authors: Smith S. R. , Durham E.
Published: July 2007

Nitrogen production from five thermally‐dried biosolids plants was measured in two contrasting soil types and compared with samples of undried digested sludge cake from the same treatment works, using a controlled laboratory incubation‐extraction procedure. Inorganic‐N was lost from the digested biosolids during high‐temperature drying by ammonia volatilisation. Nevertheless, the production of nitrate‐N in soil amended with thermally‐dried biosolids was similar to, or greater than, conventionally‐treated dewatered sludge. The results indicate that thermal conditioning significantly increases the mineralisable organic‐N content in digested biosolids. Soil properties had subtle effects on the patterns of nitrogen release, but did not significantly affect the overall accumulation of mineral‐N from the biosolids. The results showed that thermally‐dried anaerobically‐digested biosolids are potentially highly‐consistent products and effective replacements for inorganic‐N fertiliser in agricultural production.