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Reprinted from Political science quarterly, vol. xx, no. 2. ; Mode of access: Internet.

ABSTRACTA 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.

AbstractOver the next decade the UK will experience significant, imposed changes in the quantity of sewage sludge produced and in the means available for its disposal. Existing practices are being reappraised and new technologies are being explored to cope with a predicted 40% increase in the quantity for disposal. Thermal drying of sludge undoubtedly has a role to play in coping with this demand.The two principal process types, i.e. direct and indirect heat application, are appraised in depth and a comparison is drawn. A case study is identified to examine the energy demands of the process, including the potential for heat recovery and for resource reuse. The environmental impact of a typical process is also examined.

The production of cement is responsible for 5 % of the global CO2-emissions (Development, International Energy Agency and World Business Council for Sustainable, 2009). It is thereby desirable to reduce the amount of cement used by replacing it, or part of it, with another material. Today the concrete industry is experienced in using fly ash from coal combustion. This project investigates how addition of incinerated sewage sludge ash (ISSA) to concrete affects the corrosion environment for reinforcement bars. This project used ISSA from Lynetten treatment plant. Relevant properties of the ISSA are investigated such as pH, Water Solubility, Water content, Content of organic materials, Electrical conductivity, and particle size. Furthermore the content of heavy metals and soluble anions in the ISSA was investigated. Tests were carried out on mortar samples as the mortar has smaller aggregates (<4mm) and therefore is more homogeneous than concrete. The castings were carried out according to the recipe from DS/EN 196:2005 (w/c-ratio: 0.5). Three types of mortar samples were used: Reference samples, samples where 10 % of the cement were replaced, and samples where 5 % of the sand was replaced. The mortar samples were investigated for changes in diffusion of chlorides, capillary suction, density, porosity, and samples with reinforcement were placed in an air-saltwater-cycle for investigating changes in chloride-induced corrosion. Generally the lab-test did not indicate critical properties for the ISSA from Lynetten. There was however found a content of heavy metals, which compared to the demands in the Danish legislation 1662 (Danish Ministry of the Environment, 2010), falls in category 2 hence its use is restricted for certain civil works. The properties of ISSAs generally seemed to vary between different batches from the same sewage sludge plant. Most of which can possible be explained by differences in the efficiency of the combustion. The test on the mortar samples yielded the following conclusions. The tests ...

AbstractTechnologies for the thermochemical treatment of sewage sludge are appraised with reference to their efficacy in terms of (a) operational parameters, (b) pre‐and post‐treatment requirements, and (c) the extent of their use for the application. Particular attention is given to the characteristics of the solid and gaseous products and how such characteristics affect post‐treatment, reuse or disposal – this being dictated by environmental legislation.Of specific interest is the off‐gas treatment, which can contribute significantly to operating and capital costs of incineration. On the other hand, gasification and pyrolysis generate a combustible product for use in heat and/or power generation. Available information, although limited, suggests that gasification offers significant advantages over the conventional incineration process, yielding a combustible gaseous product (which can be directly utilised on site) and a solid char product (which is less prone to leaching of toxic metals).

This book is part of a series of five, aims to promote the use of sustainable construction materials. It is different from the norm, with its uniqueness lying in the development of a data matrix sourced from over 600 publications and contributed by 1107 authors from 442 institutions in 48 countries from 1970 to 2016, all focusing on the subject of sewage sludge ash as a construction material, and systematically analyzing, evaluating, and modeling the information for use in cement, concrete, ceramics, geotechnics, and road pavement applications. Related environmental issues, case studies, and standards are also discussed. The book helps users avoid repetitive research and save valuable resources, giving them more latitude to explore new research to progress the use of sustainable construction materials