Showing papers in "Water and Environment Journal in 1999"
TL;DR: In this article, the authors propose new sets of program aims and objectives in relation to impact and sustainability, which can be used in programme design, monitoring and evaluation, and also make longer term recommendations to external support agencies.
Abstract: Sound strategies for community water supply and sanitation programmes in developing countries should be based on a clear understanding of the existing problems, the beneficial impacts achievable, and the factors which determine sustainability. The impacts of many water and sanitation programmes are limited, and many systems break down and are abandoned prematurely. Only limited impacts are achievable in the short term without greatly increased investment. Sustainability, in the sense of continued delivery and uptake of services, is threatened by numerous attitudinal, institutional and economic factors, and community participation approaches alone are no guarantee of success. The key to sustainability is that all stakeholders involved in consumption/use, maintenance, cost recovery, and continuing support perceive it in their best interests to deliver high quality services. The paper proposes new sets of programme aims and objectives in relation to impact and sustainability, which can be used in programme design, monitoring and evaluation. It also makes longer term recommendations to external support agencies.
277 citations
TL;DR: Modifications to the guidelines are proposed to better represent the delicate balance between protection of public health and the levels of risk posed by greywater re-use within the context of everyday human activity and areas where there is either an expectation for responsibility or a personal acceptance of responsibility with regard to public or personal health are identified.
Abstract: This paper discusses the potential threat to health associated with the microbial contamination of greywater. Although it has been shown that greywater may contain large numbers of potentially pathogenic microorganisms, the incidence of disease is dependent upon more than just the concentration of organisms. Other factors include the degree of exposure and the health and age of affected individuals. Proposed guidelines for the re-use of greywater focus upon faecal coliform contamination and suggest limits based upon the end use of recycled water. The paper (a) proposes modifications to the guidelines to better represent the delicate balance between protection of public health and the levels of risk posed by greywater re-use within the context of everyday human activity, and (b) attempts to identify areas where there is either an expectation for responsibility or a personal acceptance of responsibility with regard to public or personal health.
96 citations
TL;DR: In this article, pilot-plant experiments were carried out to optimize removal by varying the ferric chloride coagulant dose (3-9 mg/1 Fe) and pH value (pH 5.5-8.0) in raw water which contained an average arsenic concentration of 0.44 mg/l.
Abstract: Many raw waters in the arid North of Chile contain high concentrations of arsenic (0.1–1.0 mg/l) and, during the 1970s, drinking-water treatment using coagulation was introduced in an attempt to comply with the Chilean standard of 0.05 mg/l. The new World Health Organization recommendation of 0.01 mg/1 for drinking water has led to efforts to enhance arsenic removal.
This paper describes pilot-plant experiments which were carried out to optimize removal by varying the ferric chloride coagulant dose (3–9 mg/1 Fe) and pH value (pH 5.5–8.0) in a raw water which contained an average arsenic concentration of 0.44 mg/l. At pH 5.5, arsenic adsorption was best; however, a pH of 6.5 was considered to be the most suitable for treatment when considering floc elimination. An empirical formula to predict residual arsenic under different operational conditions was obtained and this was confirmed by data collected at a full-scale water-treatment plant.
44 citations
TL;DR: In this paper, a four-month pilot study on peracetic acid disinfection of unchlorinated tertiary effluent for unrestricted re-use in agriculture carried out at West Bari (Italy) sewage-treatment works.
Abstract: This paper describes a four-month pilot study on peracetic acid disinfection of unchlorinated tertiary effluent for unrestricted re-use in agriculture carried out at West Bari (Italy) sewage-treatment works. Dosages and contact times ranging from 1 to 500 mg/l and 5 to 60 mins, respectively, indicated that 10 mg/l of peracetic acid, with a 30-min contact time, achieved the WHO faecal coliform guideline (1000 CFU/100 ml). Much higher doses (≥400 mg/l and 30 mins) were required to meet the corresponding Californian limit of two colony-forming units/100 ml, which has also been adopted in Italy. Efficient mixing of the disinfectant (in one shot addition) was mandatory - particularly at lower dosages (1-10 mg/l) where there was a higher concentration of suspended solids (>5 mg/l).
43 citations
TL;DR: A full-scale wetland was installed at the Stanley Burn in County Durham as discussed by the authors, where waste manures and composts have been used as the main substrate which is contained within embankments constructed from compacted pulverized fuel ash.
Abstract: Acidic spoil-heap drainage, containing elevated concentrations of iron, aluminium and manganese, has been polluting the Stanley Burn in County Durham for nearly two decades. Following the success of a pilot-scale wetland (the first application of its kind in Europe), a full-scale wetland was installed. Waste manures and composts have been used as the main substrate which is contained within embankments constructed from compacted pulverized fuel ash. The constructed wetland, which cost less than £20 000 to build, has consistently reduced iron and aluminium concentrations and has markedly lowered the acidity of the drainage. A third phase of activities at the site aims to identify and eliminate pollutant-release 'hot spots' within the spoil.
40 citations
TL;DR: A pilot passive-treatment plant was constructed during 1994, comprising three separate systems as discussed by the authors, each system contains the same main treatment stages which consist of five aerobic reedbeds, an anaerobic cell and an aerobic rock-filter.
Abstract: In 1992, Knight Piesold 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.
34 citations
TL;DR: In this article, a study was carried out to establish the extent to which source-control systems are being used in Scotland, and the level of knowledge of such systems was also initiated.
Abstract: The study was carried out to establish the extent to which source-control systems are being used in Scotland. An investigation into the level of knowledge of such systems was also initiated. Over 100 questionnaires were sent to organizations which have been involved in the development of surface-water drainage schemes, and the 43 responses were analysed.
Further work was then undertaken to establish the locations of source-control systems in use. The collated information was utilized and, with the help of the Scottish Environment Protection Agency consent files and correspondence with consultants, a database indicating the locations of sites, was compiled. Information was collected on approximately 79 examples of such systems, currently in use or proposed, in Eastern Scotland.
31 citations
TL;DR: In this paper, a specialized red-water testing facility was incorporated into an existing experimental pipeline to simulate conditions in a 'live' network, but on a pilot-scale, using computational fluid dynamics.
Abstract: Field surveys of Thames Water's distribution mains found the occurrence of'red water' to be highly variable and localized. To model the many inter-related factors identified in the field, a controlled pipeline-testing facility was required to simulate conditions in a 'live' network, but on a pilot-scale. This was achieved by incorporating a specialized red-water testing facility into an existing experimental pipeline. This paper describes the hydraulic and material design features, including the addition of a 'dead-end' section operated on a stagnation and flow regime, quantified using computational fluid dynamics. Following commissioning, the facility has provided detailed, time-sequenced observations on corrosion-deposit development and red-water generation under different hydraulic regimes.
24 citations
TL;DR: The UK has an obligation under various existing and proposed EU legislation (including the proposed water policy framework Directive) to derive environmental quality standards for the protection of the aquatic environment.
Abstract: 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.
22 citations
TL;DR: In this paper, the feasibility of fog collection in Jordan using various low-cost materials was evaluated using four standard fog collectors with different local materials and showed that local sacking material was the most effective.
Abstract: Water-supply augmentation along with supply and demand management in Jordan have been considered to meet the water demand. This paper evaluates the feasibility of fog collection in Jordan using various low-cost materials. Experiments were conducted using four standard fog collectors with different local materials. An analysis of fog-collection effectiveness was carried out and compared with international experience, and showed that local sacking material was the most effective. Recommendations for applying this technique are outlined.
21 citations
TL;DR: In this article, the authors examined the numerous factors which affect leakage levels and described how these vary regionally, showing that a company's level of leakage is dependent upon the local situation and that, at present, there is no basis for comparison which ensures equality in the stringency of leakage targets.
Abstract: In 1997, the Government introduced mandatory leakage targets for water companies, which were designed to (a) preserve water resources, (b) guarantee security of supply, and (c) promote efficiency within the water industry. It is intended that each target should reflect the individual situation of the company and that the targets should be achievable within reasonable economic constraints.
This paper examines the numerous factors which affect leakage levels and describes how these vary regionally. The evidence demonstrates that a company's level of leakage is dependent upon the local situation and that, at present, there is no basis for comparison which ensures equality in the stringency of leakage targets.
TL;DR: Results of dissolved-oxygen concentration from continuous monitors at one location on the (Yorkshire) tidal Ouse and two locations on the tidal Trent have revealed a strong dependence upon the concentration of suspended sediment as mentioned in this paper.
Abstract: Results of dissolved-oxygen concentration from continuous monitors at one location on the (Yorkshire) tidal Ouse and two locations on the tidal Trent have revealed a strong dependence upon the concentration of suspended sediment. High concentrations of sediment lead to a lowering in dissolved-oxygen levels. A comparison of this effect between the two rivers reveals lower dissolved-oxygen concentrations in the River Ouse than in the River Trent for a given concentration of suspended sediment, which is partly due to a difference in the quality and quantity of pollutant discharges into the Ouse compared with the Trent. Because the concentration of suspended solids at a given location is known to be dependent upon the fresh-water flow and the tidal range, it is concluded that the dissolved-oxygen concentration is also strongly dependent upon conditions of fresh-water flow and tidal range for these two tidal rivers.
TL;DR: In this article, the use of the Kielder transfers together with their impact upon flow regime, water quality, and the instream ecology of the River Derwent are discussed, and implications of the increasing use of water transfers in the UK are critically evaluated from the perspective of sustainability.
Abstract: During the dry years between 1989 and 1994, inter-basin water transfers from the Kielder system augmented flows in the River Derwent, and these flows substituted compensation releases from Derwent reservoir to retain storage for supply and recreational purposes.
The paper discusses the use of the Kielder transfers together with their impact upon (a) flow regime, (b) water quality, and (c) instream ecology of the River Derwent. Also, implications of the increasing use of water transfers in the UK are critically evaluated from the perspective of sustainability.
TL;DR: The use of sub-surface flow constructed wetlands planted with Phragmites australis (the common reed) for the treatment of sewage is now widespread in the UK as mentioned in this paper.
Abstract: The use of sub-surface flow constructed wetlands planted with Phragmites australis (the common reed) for the treatment of sewage is now widespread in the UK. The strategy for the use of reed-beds by a major UK water utility is reviewed in terms of whether the process (a) is appropriate within the rural environment, (b) offers satisfactory performance, and (c) meets criteria for sustainability. Its use for secondary, tertiary and storm-water treatment is considered. Odour generation has been a concern for secondary treatment reed-beds and has been measured and modelled to identify the required minimum distance to properties to eliminate any possibility of odour nuisance.
TL;DR: This article used the psychological framework of "mental modelling" to compare what experts and laypeople think about the hardness of drinking water and developed a drinking-water quality mental model using influence-directed network procedures.
Abstract: This study uses the psychological framework of ‘mental modelling’ to compare what experts and laypeople think about the hardness of drinking water. A drinking-water quality mental model was developed using influence-directed network procedures. This was evaluated in qualitative studies in Oxfordshire and the findings revealed gaps in laypeople's knowledge about the water-supply process.
TL;DR: In this paper, the authors describe the development and application of an empirical model based upon the performance of eleven sets of trickling filters at five sites covering a wide range of organic and hydraulic loading.
Abstract: Trickling filters represent the biological treatment component of about 70% of sewage works in the UK. Increasingly, they are being required to achieve a high degree of nitrification consistent with 95 percent compliance with effluent discharge contents as low as 2 mg/l of ammoniacal nitrogen. The available design models for the simultaneous removal of BOD and ammoniacal nitrogen are poor and have led to a lack of confidence in the ability of the process to comply with such standards. This paper describes the development and application of an empirical model based upon the performance of eleven sets of trickling filters at five sites covering a wide range of organic and hydraulic loading.
TL;DR: A review of the technology and development of biological aerated filters and submerged aerated filter systems can be found in this article, where the authors provide an overview of the early history of these types of filters.
Abstract: Biological aerated filters are wastewater-treatment systems which contain support media for the develop ment of a biofilm and provide oxygen at the base of the reactor for aerobic microbial processes. The origins of this type of filter date back to the early 1900s, and modem designs can provide a high level of treatment in small reactor ‘footprints’. This paper provides a review of the technology and development of biological aerated filters and submerged aerated filter systems.
TL;DR: In this paper, the authors proposed a method of prescription for underground aquifers based on the hydrogeological properties of the basins of the rock types, which enables source protection zones to be prescribed according to the Hydrogeological setting rather than by detailed data collection and modelling.
Abstract: Lower Palaeozoic and Precambrian rocks are distributed in Scotland, Northern Ireland, Cumbria, Wales and the Channel Islands, and coincide largely with upland areas. Groundwater flow and storage is mostly shallow and flow paths are short, although there is some limited deeper groundwater circulation. Groundwater quality is variable but often weakly mineralized, reflecting incomplete water-rock reaction. There are many small groundwater sources used for private supply and a number also for public supply; these offer an important social and economic asset to isolated rural and island communities. Groundwater occurs in four rock types: fractured rock, fractured rock with regolith, massive rock and karstic limestone. Identification of specific groundwater settings within these rock types provides an insight into the prevailing groundwater flow paths. This enables source protection zones to be prescribed according to the hydrogeological setting rather than by detailed data collection and modelling. This method of prescription is applicable universally to basement aquifers and is not limited to those in the UK.
TL;DR: The North London Artificial Recharge scheme is designed to boost resources during a drought as mentioned in this paper, in which all sources discharge groundwater either to the Lee Valley reservoirs or the New River during the abstraction, which avoids the need for expensive onsite water treatment and significantly enhances the cost effectiveness of the scheme.
Abstract: The North London Artificial Recharge scheme, which comprises thirty-seven wells and boreholes, is designed to boost resources during a drought. All sources discharge groundwater either to the Lee Valley reservoirs or the New River during the abstraction, which avoids the need for expensive on-site water treatment and significantly enhances the cost effectiveness of the scheme. Fully treated drinking water provides the source of gravity-fed artificial-recharge water, via the normal distribution system.
This paper describes the strategy which was introduced in 1997, in response to a deteriorating water-resources situation. Abstraction occurred over a period of four months prior to the onset of autumnal winter rainfall. Daily abstraction rates peaked at 150 Ml/d, and a total of about 10 700 Ml were withdrawn.
TL;DR: The initial findings of such an investigation for a macrophyte raft-lagoon system which was used in the treatment of sewage at Sowerby Bridge, West Yorkshire, England are reported.
Abstract: During recent years, many studies have attempted to determine the efficiency of macrophyte systems in removing a wide range of chemical substances and in the amelioration of wastewaters to attain effluent-quality standards. However, despite the importance of microbiological indicators of water quality for determining the suitability of water for recreational and public-supply purposes, little research has focused on the dynamics of sanitary indicator bacteria in macrophyte systems. This study reports the initial findings of such an investigation for a macrophyte raft-lagoon system which was used in the treatment of sewage at Sowerby Bridge, West Yorkshire, England.
TL;DR: In this paper, the authors examined the ability of consumers in a typical medium-sized African town to pay for a piped water supply, and the implications for the financial viability of the local water undertaking.
Abstract: This paper examines (a) the ability of consumers in a typical medium-sized African town to pay for a piped water supply, and (b) the implications for the financial viability of the local water undertaking. It demonstrates that, at present, people are paying about 10% of their income for water, and this appears to be near their limit of affordability. However, it is shown that it is possible for the water company to improve its revenue, whilst maintaining its present tariffs, by providing more private connections. Furthermore, the aim of improving water-company revenues is compatible with providing improved services to its urban customers.
TL;DR: In this paper, the authors evaluated the feasibility of water importation from Turkey, Turkey, the Litani River pipeline, the Euphrates River pipeline and a pipeline from Egypt, and concluded that the most viable scheme is the litani river followed by the Peace pipeline from Turkey.
Abstract: The future management and development of water in Jordan presents a challenge for decision makers and water-sector planners. The gap between the available water supply and demand has opened in the agricultural and domestic sectors and is likely to widen unless adequate measures are taken. Water importation for Jordan is a sound future option in water-resources planning. The options are (a) the Peace pipeline from Turkey, (b) the Litani River pipeline, (c) the Euphrates River pipeline, and (d) a pipeline from Egypt. An analysis and evaluation of the options reveals that the most viable scheme is the Litani River, followed by the Peace pipeline from Turkey.
TL;DR: In this article, the authors describe the considerations dictating site identification, the establishment of potential power and energy outputs, the selection and arrangement of plant, and the connection of the generating sets to the electrical system.
Abstract: Small hydro-power technology is well established in the UK. A relatively recent renewal of interest in the development of mini hydro-electric projects may be attributed in part to the privatization of the electricity supply industry, various changes in legislation, and the provision of Government grant funding.
With particular reference to potential applications in the water-supply industry, this paper describes (a) considerations dictating site identification, (b) the establishment of potential power and energy outputs, (c) the selection and arrangement of plant, and (d) the connection of the generating sets to the electrical system. Typical plant and project costs, together with aspects of economic viability, are outlined.
TL;DR: In this paper, the same cylindrically shaped plastic elements were used both as a biofilm carrier and as a filter medium in the floating filter for a high-rate secondary-treatment plant.
Abstract: This paper describes experiments which were carried out on a high-rate secondary-treatment plant which incorporate a moving-bed biofilm and floating filter. The same cylindrically shaped plastic elements were used both as a biofilm carrier and as a filter medium in the floating filter.
TL;DR: In this paper, a recently developed nitrification model for biological filters has been applied to the design of three sites to increase nitrification, and all three sites responded well to the modifications and achieved compliance with ammoniacal nitrogen consents of 3-5 mg/l on a 95%oile basis.
Abstract: A recently developed nitrification model for biological filters has been applied to the design of three sites to increase nitrification. The first site was upgraded by the installation of a dedicated recirculation facility, the second by reconfiguration to double filtration, and the third by the installation of a chemical pre-precipitation plant. All three sites responded well to the modifications and achieved compliance with ammoniacal nitrogen consents of 3–5 mg/l on a 95%oile basis. The key influence of hydraulic load on nitrification capacity and reliability was demonstrated on all three plants. The ability to upgrade existing biological filter installations to meet stringent ammoniacal nitrogen consents allows a significant reduction in environmental impact and revenue costs when compared with energy-intensive options such as the activated-sludge process.
TL;DR: In this article, the authors report on research into the development of a standard procedure for calculating headroom, which is a legitimate planning allowance to account for uncertainties in the supply/demand balance in a water-resource plan.
Abstract: This paper reports on research into the development of a standard procedure for calculating headroom Headroom is a legitimate planning allowance to account for uncertainties in the supply/demand balance in a water-resource plan Prior to this research, the UK water industry did not have an agreed method for calculating headroom, which resulted in inconsistencies in regulatory submissions The research built on previous studies to define an approach that would be practical and easy to apply A pragmatic methodology using a series of forms with clear guidelines was developed The methodology has been applied in the 1998 supply/demand balance submissions to the regulatory authorities as part of the Asset Management Plan 3 periodic review
TL;DR: In this article, a moving-bed bioreactor was used as the first stage of a two-stage process to provide an effective and simple means of reducing the biochemical oxygen demand of a wastewater prior to further treatment in a conventional second-stage activated-sludge plant.
Abstract: The paper describes a moving-bed bioreactor which was used as the first stage of a two-stage process to provide an effective and simple means of reducing the biochemical oxygen demand of a wastewater prior to further treatment in a conventional second-stage activated-sludge plant.
At Corby, a scheme was required to (a) meet the requirements of a more stringent effluent consent and (b) provide capacity for further anticipated growth in industrial effluent loads. The original works comprised conventional primary sedimentation tanks, biological filters and humus tanks, followed by an activated-sludge oxidation ditch and further settlement tanks. A pilot plant has been in operation at Corby for two years, and the results were used to design a moving-bed bioreactor to replace the existing filters.
At Pyewipe, a new coastal treatment plant was required and, following the change in status from a ‘high natural dispersion area &, a ‘normal’ programme was initiated to achieve the required completion date. A value-management workshop was held which identified the two-stage moving-bed bioreactor/activated-sludge process, and a pilot plant was operated for eighteen months. A full-scale plant is now under construction and incorporates a number of innovative features.
TL;DR: In this paper, the authors describe the development of a novel, compact and low-cost 'rusty-iron' chemical filter which catalyzes the oxidation of hydrogen sulphide and organic sulphides to colloidal sulphur and water.
Abstract: Several methods are available to remove hydrogen sulphide and volatile organic sulphides from ventilated air at sewage-treatment works. Some methods use alkaline and oxidative chemical scrubbers which may have high capital and operational costs. Other methods, such as bio-scrubbers anti bio-filters, are used to biochemically oxidize sulphides. Biological scrubbers have the advantage of low operating costs, but their performance may be adversely affected by a high concentration of sulphide (>100 ml/m 3 ). This paper describes the development of a novel, compact and low-cost 'rusty-iron' chemical filter which catalyzes the oxidation of hydrogen sulphide and organic sulphides to colloidal sulphur and water. Operating costs are relatively low, with no need for routine maintenance. Full-scale demonstration of the effectiveness of such filters was carried out over two years at several treatment works, the results of which are described and discussed together with details of capital costs. The overall percentage removal of hydrogen sulphide by compact multistage filters was found to exceed 95%, irrespective of inlet sulphide concentrations which varied from 34 to 500 ml/m 3 (ppm).
TL;DR: The flushing of ammonia from pulverized domestic waste was investigated using laboratory‐scale test cells to simulate landfill conditions and a simple mathematical model was used to describe the latter stages of ammonia reduction.
Abstract: The operational management of landfills is currently being reviewed in the UK and Europe. In the UK, the ‘flushing bioreactor’ approach to landfilling involves (a) enhancing microbially mediated degradation of domestic waste to promote rapid waste stabilization, (b) increased methane recovery, and (c) reduced timescales to final landfill stabilization. Flushing oeprations under bioreactive conditions could be used to optimize the removal of ammoniacal nitrogen from landfilled waste. In this study, the flushing of ammonia from pulverized domestic waste was investigated using laboratory-scale test cells to simulate landfill conditions. A simple mathematical model, based on test-cell water balance, was used to describe the latter stages of ammonia reduction.