DISTRIBUTION OF TRITIUM IN THE LEACHATES AND METHANE GAS CONDENSATES FROM MUNICIPAL WASTE LANDFILLS IN KOREA

In this paper, the tritium levels in the leachates and methane gas condensates which have occurred at 13 sanitary landfills of municipal solid wastes (MSW) are investigated and reported. During the 6 months investigation period, the mean tritium concentrations of the raw leachates were distributed from 17 to 1,196 TU. They corresponded to several scores or hundreds higher tritium levels than that of the normal environmental level except for two cases. High tritium levels were also detected in the effluents of the leachate treatment facilities. Generally, the tritium existed in the dissolving fraction of the leachate but for some cases about 10% of the total tritium content was present as colloidal particles of over 0.45 μm in size. In general, the relationship between the tritium and other contaminants in the raw leachate was low, but it was relatively high between the tritium and TOC. Thus, it is predicted that the dissolving state of the tritium in the leachates would be affected by the tritium sources of the tipped wastes in a MSW.     

Characterization and Treatment of Leachates from Hong Kong Landfill Sites

Development of a large landfill site in the North-Eastern New Territories of Hong Kong, which will receive 25 million m³ of wastes during a life of about 13 years, must include the provision of a scheme to manage leachates which will arise in the tropical climate of the region.
The paper presents detailed results from a study commissioned by the Environmental Protection Department of the Hong Kong Government, to characterize and treat leachates generated by landfills in Hong Kong, in order to design a suitable management scheme. Field and laboratory trials which were carried out during 1989 showed that, although leachates from Hong Kong landfills have some specific characteristics (e.g. concentrations of amm.N to 5000 mg/l), they can be treated to high standards by aerobic biological processes.
As a result of these studies, a scheme has been designed which will provide a high degree of environmental protection in respect of leachate, as the landfill is developed.     

Fluvial Redistribution of Chernobyl Fallout: Reservoir Evidence in the Severn Basin

Sediments in the Chelmarsh pump-storage reservoir have provided a valuable record of the ¹³⁷Cs levels associated with suspended particulates transported by the River Severn since 1965. The presence of Chernobyl-derived ¹³⁷Cs and ¹³⁴Cs within the sedimentary record of the site, despite the absence of any direct fallout on the local area, confirmed that radiocaesium from the Ukrainian reactor accident has been mobilized from the upper reaches of the Severn basin where atmospheric deposition was relatively high. The incorporation of Chernobyl radiocaesium within these sediments can be used to date the 1986 fallout episode, and the established geochronology indicated variable rates of post-1986 sediment accumulation. As radiocaesium is strongly bound to fluvial particulates, this mechanism of redistribution has not adversely affected the quality of the drinking-water source at the site which was studied.     

Leachate Collection, Treatment and Disposal

As landfills become larger, the enormous quantities of putrescible wastes which they contain have increased the potential to generate highly polluting leachates as they decompose anaerobically over many years. If severe environmental impacts are to be avoided, operators must control these liquors: many landfill proposals stand or fall on the ability of the operator to demonstrate that leachate can be collected, managed and disposed of in an environmentally acceptable manner. During the early years of tipping in containment cells, high BOD and COD values (to 50 000 mg/l or more) are measured, with very high ammonia concentrations (to more than 1000 mg/l as N) persisting for many years.
The authors have been involved with the full-scale on-site treatment of leachates to high standards in automated aerated lagoon plants since the early 1980s. The first plant was constructed in 1982, and a further seven have since been built at landfills throughout the UK, with many more at various stages of design and construction – both in the UK and overseas.
This paper describes detailed operational experiences from several of these landfill sites, with particular emphasis on the reduction of ammonia concentrations to low values. The use of reed-bed treatment schemes as effluent polishing facilities is also discussed.     

Application of Granular Activated Carbon in the Water Industry

U ntil 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.     

Design and Construction Quality Assurance

The paper describes the development, introduction and operation of quality assurance, with specific application to the design and construction industry and the consequential benefits which can be derived from the adoption of formalized quality assurance supported by third-party certification.
The main objectives of formalized third-party quality-assurance certification are in respect of: (i) quality-management systems of firms who provide a service to the industry and who meet the requirements of BS 5750¹, EN 29000², ISO 9000³; and (ii) product conformity to firms who show compliance with a national or other approved specification and who operate a BS5750 quality-management system.     

Construction and Operation of a Submerged Aerated Filter Sewage-Treatment Works

The capacity of the sewage-treatment works at Silchester in Hampshire has been enhanced and the effluent quality improved to a high standard by the installation of a new submerged biological aerated filter plant. Ten prefabricated steel submerged aerated filters reduce BOD and fully nitrify settled domestic sewage from a population equivalent of 20 000.
Comprehensive operating data are presented to demonstrate the ability of single-stage submerged downflow aerated biological filters to produce a nitrified effluent. The final effluent quality remains consistently within consent limits at 4.8 mg/l BOD, 7.0 mg/l SS and 0.5 mg/l NH₃-N, all 95 percentiles. (Consent 7 mg/l BOD, 25 mg/l SS, and 5 mg/l NH₃-N, 95 percentiles.)
Data are presented on total coliform and E. Coli concentrations through the filter plant, showing better than 3 log reductions in the effluent.     

Climatic Change and Future Rainfall Predictions

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.     

Haptic Diagrams: From Cinematography to Architectural Performance

Contemporary design practices use the diagram as an active agent in the development of form and matter into architectural space. Deleuze and Guattari, following Foucault, ¹ defined the diagram as an "abstract machine," which " does not function to represent even something real, but rather constructed a real that is yet to come , a new type of reality ." ² This formulation emphasizes the diagram's configuration and its modes of operation through virtuality and potentiality. In this sense, the diagram is the architects' way of dreaming, the "no-place" encompassing the utopian act. Simultaneously being reality and process, the diagram delays the relation between sign and meaning and promotes a shift from architecture as form or sign to an architecture of forces, performance, and performativity. ³     

竖井抽水下垃圾填埋场渗滤液运移规律研究

城市固废由于组成成分的多样性及分层填埋等原因,导致渗滤液运移存在明显的优先流及各向异性现象。在成都某填埋场开展多口竖井抽水及水位恢复试验,同时结合高密度电法技术(ERT)现场大尺度研究渗滤液分布及运移规律。多口竖井水位恢复试验显示填埋体内渗滤液运移具有明显的不均质性,表现为同一填埋场不同位置的竖井抽排性能差异较大,竖井周围垃圾渗透系数值分布范围为2.35×10-5~3.90×10-4 cm/s。竖井抽水下周围监测井的水位异常变化表明渗滤液补给存在明显优先流特征。ERT监测渗滤液抽水及回灌过程中堆体内电阻率变化,进一步揭示了现场渗流存在显著的各向异性和优先流特征,主要渗流路径与水平向呈0~30°。     

In situ control of sulfide emissions during the thermophilic (55°C) anaerobic digestion process

Sulfide volatilization was found to be sensitive to the pH variations expected during normal anaerobic digester operation. As digester pH levels increased from 6.7 to 8.2, gaseous sulfide concentrations decreased from 2900 to 100 ppm H₂S(g). Although gaseous sulfide control through pH adjustment was technically feasible, its practical use was limited by the resulting increase in soluble sulfide concentration. pH adjustment for biogas sulfide control was recommended only under conditions in which the influent sulfur level was well below sulfide inhibitory concentrations.

Control of gaseous sulfide levels through insoluble iron (3+) phosphate addition was an efficient gaseous sulfide control process with no adverse effects on digester performance. By varying the influent FePO₄-Fe:SO₄²⁻-S input ratio from 0.0 to 3.5, gaseous sulfide levels decreased from 2400 to 100 ppm. The availability of iron under anaerobic conditions from an aerobically insoluble compound has been termed reductive solubilization.

Using results from this investigation, a unique anaerobic digestion system is outlined to treat sulfur rich wastes in which sulfide inhibition is minimized while maximizing energy recovery.     

Groundwater Nitrate Concentrations from the Old Chalford Nitrate-Sensitive Area, West Oxfordshire

This paper, describes nitrate concentrations in a groundwater catchment currently designated as a nitrate-sensitive area. Although the scheme has been operational for two years, groundwater nitrate concentrations have regularly exceeded the EC maximum admissible concentration of 11.3 mg/1 NO₃-N (50 mg/1 NO₃) from sources draining both arable and grassland management regimes. Nitrate levels from arable areas tend to produce a seasonal pattern of winter leaching and summer uptake, whilst no such pattern or fluctuation is observed from grassland areas. Four processes are defined which regulate nitrate inputs to the saturated zone of the Great Oolite aquifer: (i) availability of 'free'nitrogen, (ii) variations in nitrogen uptake, (iii) leaching of nitrates from the soil environment, and (iv) limited atttenuation within the unsaturated zone.     

The Options Available for Ammonia Removal at Davyhulme Sewage-Treatment Works

Davyhulme sewage-treatment works, which serves the Manchester drainage area, is one of the lagest in the UK. The dry-weather flow is 300 000 m³/d, and the plant receives a wide range of industrial effluents. The works has been identified as a major source of pollution in the Mersey estuary, with an average discharge of 6500 kg ammonia/day. As part of its initiative to improve the Mersey estuary, North West Water intends to reduce the daily ammonia load from Davyhulme to about 1000 kg/d by 1995. In order to assess the capabilities of both conventional and novel processes to achieve this degree of ammonia removal, a number of on-site pilot plants were established. This paper reports on the pilot-plant studies and the selection of process options. Recommendations with regard to design parameters and final process selection are given.     

Determination of heavy metals in samples of urban solid wastes by means of the ICP atomic spectrometry technique

The concentration of elements of environmental significance in the leachate from landfills of urban solid wastes was determined by means of Inductively-Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The suitability of extraction tests which simulate the leaching process were undertaken. Both highly toxic elements (As, Cd, Co, Cr, Pb and V) and elements present at major concentrations (Al, B, Cu, Fe, Mn, Ni and Zn) were quantified at different levels within and under the landfill. Results showed that the extraction test recommended by EPA is acceptable in order to simulate natural leaching compared with the amounts of the elements which are brought into solution after digestion with nitric acid. Furthermore, significant correlations were found in the landfill composition at different levels for element pairs such as Al-Mn, Co-Cr, Co-Cu, Co-Fe, Co-Mn, Co-Zn, Cr-Fe, Cr-Mn, Cu-Fe, Cu-Zn, Fe-Mn, Fe-Zn, Mn-Zn and Pb-Zn.     

Architecture and Public Space Between Reassurance and Threat

"We modern civilizations have learned to recognize that we are mortal like the others," declared the French poet Paul Valéry shortly after the end of World War I in his essay La Crise de l'Esprit . ¹ In the aftermath of September 11, architecture and urban design have been struck by a similar realization of the frailty of what they had tried to achieve from the very beginning of modernity: an environment that would contribute to the political and social pacification of the planet. The attack against the World Trade Center meant that the twin towers were not interpreted as innocent symbols. Although initially they had been intended as a tribute to global prosperity, the terrorists targeted them as the embodiment of a worldwide system of economical and cultural oppression. ²     

Above-Ground Landfill: The Engineered Approach

The UK waste management industry remains committed to landfill as the principal means of disposal for a large proportion of controlled wastes. Whilst the development of landfills above ground has been practised for many years in certain countries overseas, the concept has only become more widely accepted in the UK during the 1980s.
It is vital that such sites are well planned, designed, operated, and restored. In particular, such sites need to be well engineered, and the following key issues have to be addressed: (i) Site identification and assessment; (ii) Peripheral bunding; (iii) Filling and compaction; (iv) Drainage; (v) Water management; (vi) Landfill gas management; and (vii) Monitoring programmes.
The practice of above-ground landfilling is gaining greater acceptance in the UK. In certain respects such sites can have advantages over conventional infilling of voids.     

A Massively Parallel Time-Dependent Least-Time-Path Algorithm for Intelligent Transportation Systems Applications

This article is concerned with the problem of computing in parallel time-dependent least-time paths that can be used in real-time intelligent transportation systems applications. A message-passing scheme is presented, and its correctness is proved. The algorithm's computational complexity is shown to be O (| T |²| V |²), an improvement by | V | over the best-known sequential algorithm. The algorithm is implemented, coded, and computationally tested on actual and random networks with promising results. The algorithm is implemented on a CRAY-T3D supercomputer using a Parallel Virtual Machine environment that allows portability to lower-end multiprocessor machines.     

Leachate Ammonia Flushing from Landfill Simulators

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.     

WATER RE-USE - CAPTURING A WASTE RESOURCE

The east and south-east of England has the lowest rainfall in the UK, water resources are limited and under pressure through increased demand and population growth. In the late 1990's AW Innovation (the AW R&D group) developed a process that could produce high purity water from sewage effluent using membrane technology. In late 1999 Texas Utilities (TXU) signed a contract with Alpheus Environmental for the supply of high purity water for Peterborough Power Station. The novel treatment plant was built in 1999 - 2000 and opened in July 2000 by the Mayor of Peterborough. This paper is a review of the plant design, the technology used for the treatment process and a summary of the first four years of operation.
Changing from potable water to high purity water produced from sewage effluent has brought significant benefits for the power station resulting in higher purity steam generation while reducing chemical, power and effluent discharge costs. In addition Anglian Water is now saving 1,000 m³/day of potable water.