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This study focussed on extending and applying techniques to measure hydrodynamic characteristics in treatment units at sewage works. Use was made of tracer dye studies and a spreadsheet based analysis tool. The resulting infonnation about residence time, tank conguration and pathological behaviour was linked to other infonnation from respirometry and flow and load studies. Characterising the wastewater process will become increasingly important as the economic and compliance drivers in the operation of wastewater treatment facilities become increasingly pronounced. Case studies at Royton WWTW, Chorley WWTW, Preston WWTW and Montebello WWTW were used to develop, improve and apply the methodology. Tests at Royton and Chorley were used to develop the practical side of conducting tracer studies. The Preston case study was used to improve the diagnostic methodology. It was demonstrated that consent failures as a result of events are usually a result of a number of (linked) factors, in the case of Preston influenced by the tank conguration. The response of a pulse of dye was measured at Preston in vessel outlet throughout the works. The tracer dyeresponse was used to predict the response to a discharge of high ammoniacal leachate liquor and compared to measured data. This type of calibration experiment facilitated the simulation of different discharge event scenarios. The tracer and modelling techniques were incorporated in a general diagnostic methodology, which caters for a phased approach in diagnostic studies. A series of diagnostic tables take the user through cause - effect hypotheses and possible measurement techniques to use in the diagnostic investigation. Although the diagnostic methodology proved to be a versatile asset optimisation tool, which required considerable less effort than deterministic models, implementation in United Utilities' AMP3 Capital Investment Programme was problematic. The size of the programme and lack of resources forced the company to implement standard rather than tailor-made solutions. However, the diagnostic methodology can easily be applied elsewhere in the wastewater industry.

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The development of techniques for the removal and recovery of metals from industrial effluent taking account of the consequences of the definition of waste in the Basel Convention on transfrontier shipment of waste is reported. The use of fluidised bed cell electrolysis in the recovery of metals from dilute solutions is investigated, and the conditions for recovery optimised. For the first time the application of a novel activated carbon cloth concentrator cell to recover metals from effluent solutions is reported and the conditions for its use optimised. Comparative studies using conventional mesh and plate electrodes, and novel activated carbon cloth electrode for the recovery of cobalt from dilute solution, and copper from three different hydrometallurgical solutions viz (i) Cu/Zn, (ii)Cu/Zn/Fe and (iii) Cu/Zn/Cd containing effluents were carried out. Application of concentrator cell technology including activated carbon cloth and ion exchange resin to the recovery of metals, including precious group metals, from industrial as-supplied samples is reported. Optimisation leads to successful recovery of iridium and palladium from very dilute solutions. The alternative recovery of metal as added-value chemicals is also investigated. The Basel Convention is concerned with transfrontier shipment of waste from developed to developing countries and has produced a need to investigate the leachability of metals in various forms. In this work the leachability of copper and zinc is studied under various conditions that model environmental situations and the results have been used to develop a methodology to determine whether a metal containing material would be subject to a shipment ban under the Convention. As part of the development of the methodology, leaching studies were also carried out on single chemical compounds of copper, zinc, cadmium and lead, and their bioavailability determined.

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No description available.

As environmental awareness increases, it will become increasingly difficult to discharge pollutants to the environment without treatment. New and improved technologies can only be based on a knowledge of a large number of factors for each situation. These can be divided into: legislative requirements, environmental impacts, economics, and technical feasibility. Meeting all these criteria will often mean that no single technology will be sufficient to completely alleviate the problem. Hence, a combination of technologies can often be employed. Industrial wastewater, which is often very difficult to treat by conventional treatment, and the large volumes of sludge produced by the wastewater industry have opened up the potential for wet oxidation, which could be very effective in destroying many hazardous organic wastes, and also very effective in reducing the volume of sludge to be disposed of. The decant liquor from WO is often very concentrated and contains low molecular weight organic compounds, mostly acetic acid, but which could be treated to some degree by a biological treatment process. The Wet Oxidation (WO) process is recommended for the oxidation of organic effluent with a solids concentration of between 1% to 25% but which are too toxic to be biologically treated or too diluted to be incinerated. This research project was a continuation of a previous study by Luduvice (1992) and, when possible, most of his recommendations were investigated, including the use of pure oxygen instead of air in the reactor, the biotreatability of the heat liquor and an evaluation of the chemical characteristics of the liquor. It was not, however, possible to develop a continuous Wet Oxidation process capable of operating at both subcritical and supercritical conditions. This thesis describes the ability of wet oxidation to treat different organic wastewaters and sludges under conditions which included the stoichiometric requirement of oxygen being provided and with further biological treatment being given to the decant liquor. The organic wastewater and sludges tested were from different origins and characteristics, including paracetamol wastewater, detergent wastewater, from industries plus raw primary sludge and activated sludge from a biological wastewater treatment plant. Tests were carried out at temperatures varying between 1600 C and 3000 C at retention times of 10, 15, 30 and 60 minutes in a 3.78 1 stainless steel reactor. Temperature proved to be the most significant parameter, followed by retention time and oxygen overpressure. A considerable reduction in sludge volume and organic content was obtained in most runs, which in general produced an effluent liquor with a high oxygen demand and relatively stable residual solids. The residual WO solids, when dried were found to be capable of removing colour from a textile-dye wastewater, implying that dried WO sludge may have adsorption properties similar to that of activated carbon. Simplified empirical equations were developed from the experimental data. The equations adequately described the transformation pattern of the organic and inorganic components of the activated sludge in a WO environment. The empirical equations further demonstrate a direct relationship between the influent VTS and the transformed organic and inorganic components in the liquor after WO. The purpose of this study was also to demonstrate the feasibility of reducing the strength of heat treatment liquors to that approximating domestic wastewater. A range of aerobic and anaerobic biological treatment systems was investigated. Aerobic biological processes proved to be very effective and robust in COD and BCOD removal compared to the anaerobic biological processes.