bluuebunny/crossref_metadata_2025 huggingface dataset:
Managing and Engineering Rivers for the Benefit of Man
Authors: HOCKIN D. L. , WHITTLE I. R. , BAILEY R. A.
Published: July 2007

SYNOPSIS

From earliest times flood, famine and drought have been scourges of mankind. River engineers alleviate floods, drain the land for agriculture, and conserve water resources. They construct engineering works, guide planners and developers, and provide warnings to minimize damage caused by storms over catchments and coasts. As the country becomes more developed, problems of reconciling conflicting interests require a flexible approach. This paper examines ways of providing the basic services in a climate of increasing public clamour for wildlife and landscape protection, and recreation.
Water Quality Changes in a Septic Tank Effluent Discharged to the Chalk
Authors: MONTGOMERY H. A. C. , SHAW P. J. , CHEESEMAN R. V.
Published: July 2007

Bucket‐type samplers were installed in the unsaturated zone to intercept septic tank effluent descending through the Chalf at Snowdown, Kent. Better than 90 per cent removal of BOD and COD, and of the order of 99 per cent removal of coiform bacteria, were observed after downward percolation through 2.1 m of Chalk. Nitrification of ammonia had begun at that depth, but not at intermediate depth. The results, though limited, suggest that septic tank effluent is purified in the Chalk in a similar way to settled sewage.
The Application of a Newly Developed Tubular Filter Press to the Dewatering of a Waterworks Sludge
Authors: TREFFFRY‐GOATLEY K. , BUCHAN M. I. , RENCKEN E. G. , BUCKLEY C. A.
Published: July 2007

SYNOPSIS

THE PROTOTYPE OF a tubular configured filter press has been installed at a local water treatment plant. The prototype unit dewaters the polyelectrolyte/Bentonite slurry resulting from the treatment of 30 Ml/d of surface water to a spadable cake. In this process a slurry is fed under pressure into a self‐supporting array of porous fabric tubes; the liquid in the slurry filters through the tube walls while the slurry solids are deposited as a thin layer on the internal walls of the tubes. After a relatively thin cake has been formed, it is dislodged from the tube walls by means of a roller cleaning device. The cake is transported out of the tubes and deposited on a perforated conveyor belt where it is drained and conveyed to a collection hopper. The plant is fully automated and has been operating successfully since January 1987.
Incineration of Sewage Sludge ‐ A Reappraisal
Authors: Lowe P.
Published: July 2007

The paper briefly reviews the history of incineration in the UK. The need for an integrated flow sheet concept in the design and operation of modern incinerators is stressed. Each element of the flow sheet (dewatering, predrying, the incinerator, waste heat recovery, flue gas cleaning, ash disposal) is reviewed. The economics of the process are discussed and the importance of autogenous combustion and need to avoid the inclusion of spare capacity is emphasised.
The Quality of Private Water Supplies in Calderdale ‐ the Implications of the EC Directive on Drinking Water Quality
Authors: BARRACLOUGH J. F. , HORAN N. J.
Published: July 2007

SYNOPSIS

The NUMBER AND nature of private water supplies in Calderdale Metropolitan Borough Council, West Yorkshire, were determined and each of these supplies sampled once or more to determine their compliance with the 1985‘EC Directive on drinking water quality’. A total of 560 private water supplies were located serving 1970 properties. Of a total of 1160 samples tested, 83 per cent failed to meet the maximum admissible concentration for one or more of the parameters specified in the EC Directive. These parameters monitored included faecal coliforms, for which 48 per cent of the samples failed, and lead, for which 25 per cent failed. Possible reasons for these failures are discussed and the implications of these results on the implementation of the Directive are considered.
Improved Sewage Treatment with Ozonated Activated Sludge
Authors: LEEUWEN J. VAN
Published: July 2007

Activated SLUDGE SEWAGE treatment processes are often inadequate to comply with effluent criteria as promulgated in anti‐pollution legislation. Ozonation was studied as a means of improving nutrient removal activated sludge processes without the salinity and other disadvantages of the often used polyvalent metal salt addition. Direct ozonation into the aeration basin of a 150 I/d Phoredox (modified Bardenpho) system led to improved removal of organic substances. Nitrification was improved while phosphate removal was not adversely affected. Beneficial biological activity in the activated sludge was enhanced. The trihalomethane formation potential was reduced. Pollutional loads could be lessened, while an effluent with increased reuse potential was produced.
The Application of Cross‐flow Microfiltration Technology to the Concentration of Sewage Works Sludge Streams
Authors: BINDOFF A. M. , TREFFRY‐GOATLEY K. , FORTMANN N. E. , HUNT J. W. , BUCKLEY C. A.
Published: July 2007

SYNOPSIS

A LOCALLY DEVELOPED cross‐flow microfiltration process using woven fabric tubes was used to concentrate waste activated sludge and anaerobic digested sludge from a conventional sewage works.

Results showed that waste activated sludge could be concentrated from 5 to 50 g/l total solids. The permeate quality was good (0 to 50 mg/l suspended solids), but deteriorated both with time and increasing feed solids concentration.

A cross‐flow microfilter was coupled to a pilot scale anaerobic digester and the digester solids were increased from 26 to 55 g/l total solids. The organic loading to the digester was increased from 1.8 to 3.1 kg volatile solids per m3 per day. The solids retention time was held constant at 26 days, while the liquid retention time was decreased from 26 to 14 days. The permeate quality was significantly better than the supernatant liquor from a comparable digester (suspended solids 122 and 570 mg/l, respectively).

Data obtained from the cross‐flow microfiltration of waste activated sludge was used to regress for the constants in a mathematical model of steady‐state flux.
A Study into the Cause of Decline in pH During Water Distribution
Authors: SMITH PAUL G. , WATKER ANNE F.
Published: July 2007

This STUDY INVESTIGATES the decline in pH of soft waters during distribution. The fieldwork and laboratory data confirmed and quantified the pH decline in soft water that had had the pH increased by lime addition at the treatment stage. A pH of 9.0 can decline to 7.5 during distribution. The role of humic acid as a causative agent of pH decline is examined in detail by modified jar test experiments and the development of a dialysis technique. The results of these experiments show that binding or complexing occurs between the humic acid and the calcium ions. This complexing generates H+ ions with the consequential decline in pH of the water.
Upgrading Disinfection Installation in Strathclyde Region
Authors: GREENE L. A. , FADZEAN C. J.
Published: July 2007

In 1984‐85 Strathclyrde Regional Council Water Department received 108 EC Directive (80/778/ EEC) Article 20 Delays in Respect of Microbiological Parameters 57 and 58. This paper details the strategy which was adopted by the Department to complete the programme within a limited timescale, together with the associated costs. Plant performance data based on divisional and regional assessments are discussed, together with some ancillary information on trihalomethane production. Reference is also made to some public opposition to chlorination in remote areas on the grounds of aesthetic supply acceptability.
The EC Bathing Water Directive: a Sampling Problem
Authors: CURRAN J. C.
Published: July 2007

The relatively frequent observation, during periods of onshore drift, of a surface line of convergence in nearshore coastal waters may have significant implications for the sampling procedure used for monitoring compliance with the EC Bathing Water Directive. A simple theory is developed for predicting the formation of the convergence line, and a possible alternative sampling method is suggested.
Water Source Protection and Protection Zones
Authors: HARRYMAN M. B. M.
Published: July 2007

This paper discusses Government policy to August 1989 on the use of protection zones to protect UK water sources from pollution by nitrate. It outlines the use of the powers in the Water Act 1989 to declare Nitrate Sensitive Areas, and the procedures that would be followed in declaring such zones. The circumstances are outlined in which compensation would be paid in Nitrate Sensitive Areas and the reasons for departing from the ‘polluter pays’ principle. UK policy is related to the proposed European Community Directive on the control of nitrate, and the similarities between the two approaches are illustrated.
The Elimination of Pentachlorophenol Pollution from the Forth Catchment
Authors: CAMPBELL D. , RIDGWAY I. M.
Published: July 2007

Following adoption of the EC Directive 86/280/EEC, three major point sources of pentachlorophenol (PCP) were identified in the River Forth catchment. At least one of these was known to be causing serious water pollution. While methods to determine low concentrations of PCP in the environment were being developed, discussions were held with the dischargers on ways to eliminate PCP from their effluent. Despite the additional costs involved, agreement was reached on the substitution of alternative, biodegradable fungicides. Although these major polluting discharges of PCP have now been eliminated, background levels of PCP found in rivers in the Forth River Purification Board's area show that other minor sources of PCP remain, indicative of the widespread use of this powerful and persistent fungicide.
The Seaford Sea Defence Scheme
Authors: HOLMES A. E.
Published: July 2007

During THE LaST 100 years the shingle beach levels at Seaford have gradually declined, with the result that the 10‐m high sea wall, protecting low‐lying areas of the town against flooding, came under serious threat of collapse.

Southern Water Authority assumed responsibility for the frontage in 1981, and the paper briefly describes the history of events leading into the problem, model studies, and the solution which was adopted. Details of behaviour of the beach during the months following completion, including the great storm of October 1987, are also given.
Application of Granular Activated Carbon in the Water Industry
Authors: HYDE R. A.
Published: July 2007

Until the mid 1980s granular activated carbon (GAC) was used in only a small number of water‐treatment plants in the UK. Since then the material has been installed in over 30 plants, either as a result of an operational decision to treat the water by GAC or for the purpose of full‐scale experiments. GAC is used for a variety of reasons including taste and odour control, removal of a wide range of synthetic organic compounds (for example volatile chlorinated solvents, pesticides, oils) of molecular weight 100–500, and adsorption of trihalomethane precursors (molecular weight 103‐105). The performance of different GACs for a particular duty may vary by a factor of 10, and the best GAC for one application may be the worst for another. Thus, to minimize the cost of GAC treatment, it is essential to identify the purpose for which GAC is being used and then to select, by pilot trials or by more rapid laboratory procedures and mathematical modelling, the most appropriate GAC for that particular application.
Improvements to Activated‐Sludge Plant Aeration Systems at Hawick and Jedburgh Sewage‐Treatment Works
Authors: Wallis B. F. J.
Published: July 2007

In response to the requirement of the Tweed River Purification Board for a higher standard of effluent, improvements have been carried out to the activated‐sludge aeration systems at Hawick and Jed‐burgh sewage‐treatment works.

This paper describes the electrical and mechanical refurbishment involved, and the performance of the completed systems. Process control was considered to be of particular importance in these projects as the plant receives a high proportion of industrial effluent.
Experimental Assessment of Rates of Nitrate Removal by River Bed Sediments
Authors: WYER M. , KAY D.
Published: July 2007

Concentrations OF Chloride, nitrate‐N, sulphate, sodium, ammoniacal‐N and potassium were monitored for six days in 20 riverine sediment‐water flow tank experiments. Only nitrate‐N and ammonical‐N showed consistent patterns over a period of time. Nitrate‐removal rates ranged from −15 mg N/m2.d (coarse material) to +49 mg N/m2.d (fine sediment) when the initial concentration of nitrate‐N was 2 mg/1. An increase in initial concentration to 11 mg/1 produced corresponding removal rates of 67–241 mg N/m2.d. Likely removal mechanisms are discussed. The results suggest management possibilities for stream bed ecosystems and raw water impoundments with respect to nitrogen cycling.
The Ecology and Survival of Legionella Pneumophila
Authors: COLBOURNE J. S. , DENNIS P. J.
Published: July 2007

L. pneumophila serogroup 1 was detected in 12% of water sources used for the supply of drinking water in England in a survey carried out between September 1985 and June 1987. The bacterium, the causative agent of legionnaires' disease, was found more often in underground supplies in late summer–early autumn; the time of year when indigenous community‐acquired infections also increase in number. Using an immunofluorescent assay it was observed that L.pneumophila could survive conventional water treatment including disinfection with chlorine and, whilst being non‐culturable, retained its ability to colonize pipe surfaces and grow in the warmer water systems of buildings. Viability of non‐culturable legionella was demonstrated by heat shock. These findings confirm the importance of preserving water quality within buildings by good design, thorough maintenance, and careful operation of water systems, following the guidance issued by the Department of Health and the Health & Safety Executive.
Leakage Control in a Universally Metered Distribution System: Pinetown Water's Experience
Authors: MILLS R. E.
Published: July 2007

As a result of water losses reaching a high point of 16% in 1973, combined with a relatively high and increasing retail tariff, the Pinetown Regional Water Services Corporation embarked upon a programme to reduce losses to an acceptable level of about 10%. The programme involved: (i) the establishment of district metering throughout the distribution system; (ii) the replacement of certain retail meters; and (iii) the metering of new fire connections (other than those serving sprinkler installations). Further steps were taken to improve the situation and included: (a) the monitoring of minimum night flows, (b) regular sounding of distribution mains; (c) the establishment of a full‐time waste detection gang; and (d) with improved control valves becoming available, more effective pressure control of the system. The Corporation's computer was called upon to determine: (i) the monthly losses from each of the hundred or so districts; (ii) the life history, in graphical form, of retail meters under review; and (iii) a record of expenditure on leakage control. The paper describes the development of the methods used in leakage control, costing less than half a cent per cubic metre of water purchased, and outlines the practical experience gained in reducing losses from 16% to less than 5% over a period of 14 years.
New Technology in a Water Company
Authors: CARTER J.
Published: July 2007

The South Staffordshire Water Company serves a population of 1.25 million within an area of 1502 km2. This paper describes how the Company employs new technology across a broad spectrum of its activities, operational, scientific and administrative, and how it has benefited from these applications. It demonstrates how available technologies have been investigated, adapted and developed to meet the Company's particular requirements for improved efficiency, new regulations and standards, and cost savings. The Company is a leading innovator in the use of new technology, and the paper illustrates how this success has been achieved through the encouragement and development of new ideas and the careful control and monitoring of new projects.
Gravel Bed Hydroponic Systems Used for Secondary and Tertiary Treatment of Sewage Effluent
Authors: BUTLER J. E. , LOVERIDGE R. F. , FORD M. G. , BONE D. A. , ASHWORTH R. F.
Published: July 2007

Gravel bed hydroponic (GBH) systems planted with

emergent hydrophytes, such as Phragmites australis (the common reed), treat domestic sewage effluents to acceptable environmental standards in an economic and efficient manner. Biochemical oxygen demand (BOD), ammonia, and coliform bacteria can be reduced by over 90% and dissolved oxygen (DO) substantially increased. In temperate zones, such as Europe, GBH systems can be used to replace conventional small rural treatment works, and for tertiary treatment of final effluents. In tropical and arid zones, GBH systems can provide locally‐managed, cost‐effective alternatives to hightechnology systems which are inappropriate for use in developing countries. Portsmouth Polytechnic reed‐bed sewage treatment GBH projects in the UK and Egypt are discussed and current progress is assessed.
Eutrophication: Assessment, Research and Management with Special Reference to Scotland's Freshwaters
Authors: BAILEY‐WATTS A. E.
Published: July 2007

In response to the extraordinarily high profile currently maintained by algae, this paper discusses aspects of pure and applied research on eutrophication. In addition to restating a number of issues which were raised decades ago when the importance of this environmental problem was first recognized, the following aspects are explored using data collected mainly over the last 20 years and referring primarily to Scottish studies: (i) algal‐nutrient relations and the contrasting manner in which nitrogen and phosphorus enter freshwaters and are sequestered by planktonic organisms; (ii) estimates of the loadings of phosphorus to freshwaters from various sources; (iii) the effects on our perception of algal problems and the use to which the waters are intended; (iv) the extent and limitations of existing scientific knowledge about eutrophication, and its application to the formulation and execution of eutrophication control strategies; and (v) the arguments for maintaining in‐depth limnological surveillance programmes.
Leaching of Pesticides from Treated Timbers ‐ a Source of Pollution
Authors: McNElLL A.
Published: July 2007

Observations at a sawmill where two major spillages of preservative had led to pollution of the River Lossie indicated that bad timber treatment practices. together with minor spillages when preservative was delivered to the premises, were contributing to the overall unsatisfactory state of the watercourse. Also, soil sampling at the sawmill, and laboratory trials, revealed that the storagc of freshly‐treated timbers can be a significant source of pollution. In order to prevent contamination of water from these sources, recommendations were issued to the sawmill, and the company relocated the timber treatment plant on a specially prepared self‐contained site to avoid pollution should further spillages occur.
The Self‐Protection of Escherichia Coli in Seawater
Authors: FINDLAY J. S. , CURRAN J. C. , MILNE D. P. , CROWTHER J. M. , WALLIS S. G. , WOOD B. J. B.
Published: July 2007

Many environmental variables are known to be involved in the inactivation processes affecting enteric bacteria in seawater. It is commonly believed that bacteria may attempt to reduce adverse effects by adhering together, thereby decreasing the surface area exposed to the hostile environment. This mechanism may be described as self‐protection and should enhance the survival of the bacterial population.

Controlled laboratory experiments, epifluorescence microscopy, and Coulter counter analysis were used to examine and elucidate the inactivation mechanisms for the enteric bacterium E. coli. In general, the survival of E. coli was found to be enhanced with increasing initial cell concentration in the absence of any suspended solids.
Drinking Water Directive and Proposed Water Supply (Water Quality) Regulations for Scotland
Authors: CHAMBERS E. G. W. , GREENE L. A.
Published: July 2007

Taken in conjunction with the clauses added to the Water (Scotland) Act 1980 by the Water Act 1989 in respect of quality, as opposed to organizational terms, the introduction of the EC drinking water Directive1 and the proposed water quality Regulations2 represents the most fundamental change to Scottish water supply legislation since the Water (Scotland) Act 1946.

The drinking water Directive1 was passed by the European Council on 15 July 1980, with the requirement for full compliance by Member States by 18 July 1985.

Water Supply (Water Quality) Regulations for Scotland were circulated in draft form by the Scottish Development Department for informal consultation during September 1989. This had been preceded by informal consultation through the Convention of Scottish local authorities during the discussion stage of the UK Advisory Group on Drinking Water Regulations.

This paper attempts to provide a simplified interpretation of the proposed Scottish Regulations on drinking water quality. It comments briefly on those requirements likely to have a significant impact on Scottish water authorities, including public communications, laboratory facilities, water treatment operational practices, and capital funding.
The Flood‐Prevention Scheme of Venice: Experimental Module
Authors: FICE J. LEWIN , SCOTTI A.
Published: July 2007

Records exist of the flooding of Venice from the days of the Republic. During the last century flooding incidents have become more severe due to subsidence of the city and rising water levels in the Adriatic. Calamitous flooding occurred in 1966, and two devastating floods were experienced during the last decade. The ‘Special Law for Venice’, enacted by the Italian Parliament in 1973, paved the way for a competition to devise a flood‐prevention scheme.

A consortium of Italian contractors, who were commissioned to submit proposals for the implementation of the scheme, designated Technital Spa of Verona to carry out the design of the flood‐prevention works and improvements within the lagoon. This resulted in the design of three movable barrages to seal off the Venice lagoon in the event of a flood. The construction of a full‐size gate and caisson (the prototype of the eighty gates forming the barrages) was subsequently authorized.

This paper describes the experimental module containing the buoyant gate and its caisson, its novel features as well as some of the events leading up to its design and construction.
The Channel Tunnel and its Impact on the Folkestone and District Water Company
Authors: MONK R. B.
Published: July 2007

Folkestone and District Water Company's statutory area covers south‐east Kent, being that part of England nearest to mainland Europe. Its principal source of water is the chalk ridge known as the North Downs.

The Channel Tunnel is an £8.5 billion scheme linking France to England by rail, beneath the Straits of Dover.

The English portal for the project is located in what was previously the centre of the Company's distribution network, at the Cherry Garden, Folkestone. The works include three tunnels through the Lower Chalk, dropping from a ground level of 60 m AOD at the portal to about 50 m below the sea bed at the coast. This has provided a possible risk of draining scarce fresh‐water resources from the Chalk into the sea, and allowing saline intrusion to extend into the centre of the aquifer.

As a major civil‐engineering project, the tunnelling and terminal works have required a temporary, but substantial, water supply. Detail design of the works proceeded as the scheme progressed, and consequently water demand could not be estimated precisely at the beginning of the contract. In excess of 30 metered supplies, varying in size from 15 mm to 250 mm in dia., have been provided, some being several kilometres from the Company's distribution system.

The paper gives a brief outline of the development of a fixed cross‐channel link, and describes the interaction between the project and the Water Company, in relation to the supply of Eurotunnel's temporary and permanent water requirements, protection of the Company's sources and changes to the trunk mains system. It will also be shown how active cooperation and constant review of proposals are leading to benefits for both parties, even through the two years of drought that have afflicted the water supplies in south‐east England.
Simazine Concentrations in a Stream Draining an Agricultural Catchment
Authors: WILLIAMS R. J. , BIRD S. C. , CLARE R. W.
Published: July 2007

This paper reports the concentrations of the herbicide simazine which were found in a stream draining a small agricultural catchment as a result of normal agricultural practice. The study, part of the National Rivers Authority Research and Development programme, shows that peaks in the concentration of simazine occurred very soon after rainfall events. It goes on to show that although the mass of simazine transported from the catchment during each rainfall event is small as a percentage of that applied (less than 1%), the concentrations observed are far from insignificant. It is suggested that monitoring programmes need to be designed to cover such pesticide pulses generated as the result of rainfall events occurring at times of peak application. Also, more realistic environmental‐quality standards need to be developed and applied where the EC drinking water Directive is inappropriate, and to reflect the intermittent nature of the problem.
Commissioning and Operation of Yau Kom Tau Water‐Treatment Works (Hong Kong) Using Direct Filtration
Authors: CHAN KIN MAN D. , SINCLAIR J.
Published: July 2007

The paper outlines the commissioning, performance trials, and operational experience of the direct‐filtration process at the Yau Kom Tau treatment works in Hong Kong.

The commissioning tests established the capability of the treatment plant to produce water of the required potable quality. However, the contractual performance trials were carried out at a time when adverse raw water might be expected, in order to assess the overall attainment of guarantees on the treated water quality, filter run, and washwater percentage.

Since the works became operational in November 1985, a number of incidents of raw water quality outside the design limits have been experienced. The use of polyelectrolyte was found to enhance the performance and reliability of the direct‐filtration process.

The paper also reports the results of some optimization tests and comments on the overall performance of the plant compared with expectations at the time of design.
The Development of Ion Chromatography for Metals Analysis in Saline Waters
Authors: COMBER S. D. W.
Published: July 2007

Previous attempts to utilize ion chromatography for the analysis of sea water samples have failed through chronic interference by the major ions (na, Mg, Ca) during the preconcentration stage. As part of ongoing research into ion chromatography, a technique has been developed to overcome these interferences, using a two‐stage preconcentration step, prior to separation on a cation‐exchange column. This has made it possible to detect μg/l quantities of trace metals in samples containing g/l concentrations of sodium, magnesium and calcium. A modified commercially‐available ion chromatographic system was used to analyse copper, nickel, zinc, cobalt and manganese in saline waters. Detection limits were typically less than 1 μg/l, with relative standard deviation of less than 10%. Hence this new method has the potential to provide an inexpensive multi‐elemental sea water analysis with the minimum of handling. In addition, the simplicity and sensitivity of the technique may make it suitable for unattended use as a remote monitor of metals.
A Small‐Scale Study of Wastewater Discharges from Domestic Appliances
Authors: BUTLER D.
Published: July 2007

The pattern and daily total production of waste‐water from domestic sanitary appliances is a subject area in which a very limited amount of research has been carried out, despite its need for rational and economic drainage design. This paper consists of an analysis of data from a small‐scale diary survey of domestic wastewater production and a comparison with previously published data.

The diurnal variation of activity for each major appliance has been established to give both peak and average frequencies of use. Good correlation has been shown for average (daily) values with published water‐supply data. Peak values were difficult to compare, but were probably lower than previously‐reported data. The wash basin and kitchen sink were found to have two modes of discharge, namely: running to waste and emptying a full bowl. The former mode was the most common in both appliances, although, surprisingly, the volume of each type of discharge was found to be approximately the same. Tests on appliance discharge durations, volumes and flow rates were also carried out.
Alternative Methods of Procurement for Works of Water and Environmental Management
Authors: McGILL R. E. N.
Published: July 2007

The paper considers methods of procurement for the construction of water‐ and sewage‐treatment works other than the traditional use of the ICE 5th Edition Conditions of Contract and Bills of Quantities. This is as a consequence of the speed at which schemes are currently required within the water industry.

The paper particularly focuses on the use of target contracts, using the Institution of Chemical Engineers’Green Book form, and considers various types of target. It also discusses the form which tender documents may take, and how targets may be calculated.

Tendering procedures, including the use of two‐stage tenders and negotiated targets, are considered, as are the procedures for cost monitoring and the financial management of the contract. Finally, the role of the engineer and quantity surveyor is considered.
Bulking Sludge: A Theory and Successful Case Histories
Authors: SIMPSON J. R. , LIST E. , DUNBAR J. M.
Published: July 2007

Filamentous bulking sludge is the most difficult problem encountered in the operation of activated‐sludge plants. A number of reasons have been cited as the cause of the problem, but none explains why slow‐growing filamentous micro‐organisms predominate over faster‐growing flocculent microbes. Competition or inhibition are suggested as possible reasons why filamentous forms predominate.

The paper briefly reviews certain aspects of microbial growth and waste treatment, drawing attention to the fact that, while it is known that nitrogen and phosphorus nutrients must be present, equally other essential substances must be present, including a number of trace metals. The theory is proposed that where trace metals are limiting growth, the filamentous micro‐organisms predominate because they are more competitive in adsorbing and absorbing these scarce materials. This is so because the filaments have a higher surface to volume ratio than the flocculent forms. The roles of metals are briefly discussed, and data are presented on the composition of cells. The theory is used to explain some of the reported causes of bulking, and the results of several full‐scale field trials are presented.
The Importance of Hydrological Source Areas in Terrestrial Liming
Authors: WATERS D. , JENKINS A. , STAPLES T. , DONALD A. P.
Published: July 2007

Terrestrial liming experiments have been carried out in the Welsh uplands at Llyn Brianne, 30 km northwest of Brecon. Limestone has been applied to an entire moorland catchment and to the hydrological source areas of a moorland catchment. The hydrological source areas were derived from topographic data. Blanket liming and source area liming proved successful in (a) raising the pH value of the stream, (b) increasing the calcium concentration, and (c) decreasing the aluminium concentration. The response to the source area liming proved to be more successful, resulting in a higher calcium concentration. Neither site showed any signs of long‐term exhaustion, although the initial response in stream chemistry indicated the importance of the soil exchange complex in determining optimum application rates. Source area liming has economic and environmental advantages over blanket liming, and its increased effectiveness suggests that it is the most viable technique for ameliorating acidification in upland areas.
Pesticides in Surface Waters and Groundwaters
Authors: CROLL B. T.
Published: July 2007

Diffuse pollution by pesticides, particularly herbicides, has been recognized in the UK for several years. Atrazine, Simazine, Mecoprop, Dimethoate and, more recently, Isoproturon and Chlortoluron have been found frequently in surface waters at concentrations up to 0.5 μg/l, with a maximum of 11.5 μg/l. Pesticides are detected less frequently in groundwaters, at concentrations generally lower than 0.1 μg/l. Atrazine is found most frequently. Concentrations in untreated surface and ground‐waters have generally been below the maxima recommended for drinking water by the Department of the Environment (DoE). Concentrations in treated drinking water have not exceeded the DoE recommended maximum concentrations, but measures are being taken to reduce concentrations to below 0.1 μg/l.
Energy Saving Using Jacked Aerators at Biddulph Sewage‐Treatment Works
Authors: SODIPO B. O. , GREENWOOD WENDY , CLOUGH G. F. G.
Published: July 2007

A means of improving the energy efficiency of an existing mechanically aerated activated‐sludge system by mounting the existing aeration units on jacked platforms is described. The level of the platforms, and hence the immersion of the aerators, is automatically controlled to maintain a constant concentration of dissolved oxygen in the mixed liquor. Comparison of the controlled stream, in which there were two aerators, against an otherwise identical control stream showed energy savings of 20% and 13% respectively when the control involved both or only one aerator, without adverse effect on final effluent quality.
Durban's Newest Water Resource ‐ The Inanda Dam
Authors: TOLLOW A. J.
Published: July 2007

The Inanda Dam is one of a series of reservoirs constructed to utilize the water resources of the Umgeni River, which rises in the Natal midlands and reaches the Indian Ocean at Durban, South Africa. The structure exploits the local topography and geology, with mass concrete founded on the granite forming the right bank and river bed, and a clay core earth embankment on the weaker left bank. Due to high ambient temperatures, the placing temperature of the concrete had to be controlled to avoid crack formation. Mix designs were modified by the addition of blast‐furnace slag, and the mix water was cooled using liquid nitrogen to reduce the placing temperature of the concrete. Major floods also occurred, and although they caused little damage to the structure itself serious damage was sustained by the existing water‐supply infrastructure, resulting in a review of the operational strategy of the system. The reservoir is to be operated initially as a river regulator with downstream abstraction. However, in order to provide additional security, a tunnel aqueduct linking the reservoir directly to the water‐treatment works is under construction.
Paris Improves Its Drinking Water Treatment Plants
Authors: BARBIER J. M. , RICCI O. , MONTIEL A. , RICHARD Y.
Published: July 2007

The upgrading of the Ivry‐sur‐Seine water‐treatment plant, which produces potable water for consumption in Paris, is described. This upgrading is based on the slow biological filtration stage. The pretreatment comprises a primary filtration stage through biolite, and a secondary filtration stage through sand, with the possibility of coagulation. The polishing treatment includes ozonation and biological filtration through granular activated carbon. Ozone is produced from pure oxygen, with two ozone generators operating at medium frequency and producing a total of 52 kg/h. A description of pilot tests of the upgraded plant is given, together with the first results.
Waste Stabilization Ponds in Europe
Authors: MONTE M. H. DO MARECOS
Published: July 2007

The European countries where sewage treatment in waste stabilization ponds is largely developed and commonly used are West Germany (more than 2000 operational systems) and France (about 2500 plants). Portugal has over 50 systems at present and will have about 100 by the year 1993. Spain has more than 10 operational plants and in Denmark there are 50 ponds for tertiary treatment. A survey on the present practice in the countries where the process is largely applied, including size of plants, type of ponds, type of influent and design criteria, is presented. It is found that waste stabilization ponds are particularly appropriate for full treatment of effluents from small communities (less than 5000 population equivalent) and for tertiary treatment following conventional larger plants.
Septicity in Sewers: Causes, Consequences and Containment
Authors: BOON A. G.
Published: July 2007

This paper reviews research and development on the causes, consequences and methods of controlling septicity in sewers. It draws on information given in 55 published papers on the subject. Explanations are given on the deviation of equations used to predict critical conditions in sewers and rising mains. The consequences of septicity, including toxicity, corrosion and odour nuisance, are described and discussed. Prevention is always recommended over cure, but where this cannot be achieved the methods of controlling septicity generally rely on maintaining an adequate supply of oxygen (dissolved or chemically available) to oxidize previously‐formed sulphide. Other options to cure the effects of septicity include minimizing the emission of hydrogen sulphide into the atmosphere, deodorizing vented air, and the use of protective coatings or corrosion‐resistant pipes.
UK Developments in Sewage Sludge Processing
Authors: BRUCE A. M.
Published: July 2007

A considerable amount of research and development has been undertaken in the UK during the last 25–30 years in the field of sewage sludge processing. The research has been sponsored mainly by the water utilities with the objective of improving process efficiency and reliability and reducing costs. Government‐funded research has focused mainly on the environmental aspects of sludge disposal to land and to the sea.

Finding ways of reducing sludge production has proved difficult, but one new method of sewage treatment has some advantages in this respect.

Arising from the research on sludge processing, (a) new methods of characterization of sludge have been developed, (b) an improved method for the design and operation of gravity thickeners has been successfully implemented, (c) advances have been made in the process of heated anaerobic digestion, and (d) an effective system for aerobic thermophilic digestion of sludge at small works has been established. A new method for measuring sludge filtrability – the PFT meter – has been developed, and the economics of flocculation have been improved by the introduction of a new type of mixer. An improved method for controlling the operation of filter presses is now available.

The problems of odour nuisance from sludge operations may now be controlled using biological systems to treat odorous air.
Parallel Processes in Hydrology and Water Quality: A Unified Time‐Series Approach
Authors: YOUNG P. C.
Published: July 2007

Most well‐known time‐series methods treat the system as a univariate, bivariate or multivariate ‘black box’whose parameters provide a convenient and concise description of the data. This is in contrast to physically based, mechanistic models, whose parameters normally have an identifiable physical interpretation. The present paper describes a unified ‘data‐based mechanistic’approach to the modelling of dynamic systems from time‐series data using continuous or discrete‐time transfer function models in the time derivative, backward shift or delta operator. This approach, which exploits recursive methods of parameter estimation, represents a useful compromise between the physically based methods of mechanistic modelling and the ‘black box’methods of time‐series analysis. It provides a powerful tool for the objective investigation of environmental dynamic systems when time‐series data are available for analysis. Its practical potential is illustrated by several real examples concerned with the objective investigation of parallel processes in hydrology and water quality.
Land Disposal Practices in Europe and North America
Authors: LITTLE R. H. , GROGAN H. A. , SMITH G. M. , TORRES C.
Published: July 2007

This paper compares the land‐based disposal of municipal and hazardous waste in Europe and North America, and the various disposal options are examined for each type of waste. It is concluded that landfill is still the most widely practised disposal method for most wastes in both continents. Other methods include composting, land farming, trenching/spraying, and deep underground disposal. More stringent controls on waste disposal are being introduced and a trend to seek greater uniformity of practice and standards is developing. However, local conditions, such as the nature of the wastes and the availability and nature of disposal sites, continue to work against this trend. There is no single method which is suitable for all wastes and for all conditions. The best environmental option for waste management will vary from place to place and waste to waste, therefore an imposed uniformity of practice is not in the best environmental interest.
Ten Years’Operational Experience with an Activated‐Sludge Plant in a Gulf State
Authors: GLOVER A. H. , GLOVER P. D. , LEWIN V. H.
Published: July 2007

The particular difficulties of sewage treatment in a Gulf State of the Middle East are highlighted. Ambient temperatures may at times exceed 50°C, and sand and dust can be a problem. A description is given of the sewerage and sewage‐treatment facilities at Al Ain in the United Arab Emirates, together with analytical data and flow records from commissioning until 1991. Attention is drawn to the problem of rapid anaerobic decomposition of sewage, consequent septicity, emission of foul odours, and hazardous hydrogen sulphide. There is a need for better control of this nuisance. Comment is made on high temperatures, and also on loss by latent heat of evaporation. The inability to reconcile sludge production with that indicated by empirical data, or predicted by sludge production formulae, is discussed.
Disinfection of Sewage Effluents: The Jersey Experience
Authors: C. GROSS T. S. , MURPHY R.
Published: July 2007

About 35 years ago the island of Jersey in the Channel Islands set about rationalizing and modernizing its sewage‐treatment operations. Treatment was carried out in one central, advanced sewagetreatment works producing a Royal Commission effluent which received nominal dilution in a small stream before discharging into the sea in one of the foremost bathing areas on the island.

In 1989, a thorough investigation was carried out on the options to secure an environmentally acceptable solution to effluent disposal. The investigation concluded that disinfection, in combination with a change to the outfall discharge point, offered the most cost‐effective solution. Alternative disinfection techniques were identified, which recognized the nature and sensitivity of the receiving waters and the limited space available on the site. Only ultraviolet disinfection was suitable.

An ultraviolet disinfection system depends on the exposure of the micro‐organisms causing disease to their germicidal wavelength. Light of this wavelength (about 253.7 nanometres) is absorbed by the nucleic acids in the cell which damages or rearranges the genetic information, effectively rendering the cell unable to replicate and resulting in the death of the cell.

In over 300 installations in North America the system has proven to be reliable, simple, economic and, above all, environmentally acceptable.

An ultraviolet disinfection system is currently being installed at Bellozanne, Jersey.
Experience of Cast‐Iron Mains Rehabilitation in the Gas Industry
Authors: JONES D. U.
Published: July 2007

Since 1987 British Gas plc has undertaken an extensive programme of medium pressure (up to 2 bar) cast‐iron mains replacement in urban locations, using a variety of rehabilitation techniques.

This paper describes the experience of North Thames Region of British Gas plc, over the period 1987–1991, when the rehabilitation of over 230 km of mains was undertaken in the size range 300–460 mm.

The techniques which were used favoured medium density polyethylene pipe wherever possible. However, about 100 km of rehabilitation was undertaken using hoselining, usually where mains were larger than 460 mm dia., or where aboveground access was restricted, or if the mains configuration included many changes of direction.

This paper deals with (a) various aspects of operating rehabilitation contracts from a public utilities viewpoint, (b) the special factors relating to the inspection and testing of hoselined mains including factors found to contribute to failure, and (c) some of the controls that have been introduced to improve reliability of rehabilitation systems.
Use of Cement Kilns in Managing Solid and Hazardous Wastes: Implementation in Australia
Authors: JONES P. H. , HERAT S.
Published: July 2007

The use of cement kilns for managing solid and hazardous wastes is facilitated by the high temperature, long gas retention periods, natural alkaline environment, minimum amount of waste produced and high thermal capacity. The main benefits include energy recovery, conservation of fossil fuels, reduction in cement production costs and the use of already existing facilities.

The test burns conducted in cement kilns worldwide have demonstrated very high destruction efficiencies for most stable organic compounds, with toxic contaminants barely above the background levels.

There are several cement plants in the US and Europe presently using solid and hazardous wastes as supplementary fuel. The application of this technology in Australia has been ignored in the past. An international conference (Kilnburn‘92) on the role of cement kilns in waste management was held recently in Australia and has enhanced the implementation of this technology in Australia.
Benefits of Flow Data for Flood‐Protection Design
Authors: CORDERY I. , CLOKE P. S.
Published: July 2007

Stream gauging data play a vital role in the planning of flood mitigation strategies. A study of the value of stream flow data for the design of levee systems shows that the availability of a reasonable sample of pertinent data can be worth many times the cost of collecting that data.
Standards, Costs and Benefits: An International Perspective
Authors: JOHNSTONE D. W. M. , HORAN N. J.
Published: July 2007

This paper considers the development of standards for the discharge of wastewaters from the perspectives of (a) the developed world, (b) the developing world, and (c) the newly industrializing nations. It considers the potential environmental benefits which can be obtained by the imposition of stringent effluent standards, and weighs this against the economic costs of meeting such standards. By means of case studies it considers how inappropriate standards can often arise in other countries of the world and how the imposition of unjustifiably high standards can be demoralizing, costly, and produce no environmental improvements. Finally, it considers how a more pragmatic approach to the setting of standards, especially in the newly industrializing and developing nations, place them in context of applicability, affordability, regulation and enforcement.