摘要:

Dewatering of the residues produced by wastewater treatment has received increased attention in recent years as a result of increased sludge quantities and increased energy costs. While a wide variety of different processes are used for sludge dewatering, all involve flow of liquid through porous media in response to a pressure gradient. Quantitative evaluation of the rate at which liquid can be removed from sludge solids in various dewatering devices is complicated by the fact that most wastewater sludges are highly compressible — that is, the solid structure of the sludge deforms under applied pressure resulting in reduction in sludge permeability. In this review, theories of flow through compressible porous media are summarized (with special attention to developments since P. C. Carman's 1938Fundamental Principles of Industrial Filtration),comparisons between theories are drawn, and theoretical inadequacies are identified. The application of theory to wastewater sludge management practice is considered, and discrepancies between theory and practice are discussed. Characteristics of common sludges and common sludge dewatering equipment are reviewed.

ISSN:0007-8999    

DOI:10.1080/10643388009381682

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Granular media fillration as applied to water and wastewater treatment is reviewed in terms of the types of filter media available, the alternative filter configurations, their modes of operation, and backwashing procedures. Filtration kinetics and mechanisms are reviewed, together with the hydraulic equations which have been developed to predict the pressure drop across a filter bed. Studies on the physical parameters which affect filter performance are reviewed. These include flow rate, particle size, filter media grain size, and particle number concentration. The effect of variation of chemical parameters, such as pH, ionic strength, and ionic species on the surface chemistry of filter systems and filtration efficiency are reviewed. The use of polyelectrolytes in filtration, and possible mechanisms for their role as filtration aids are discussed. Studies on the influence of polymer structure, and the time and degree of mixing of the polymer with wastewater, prior to filtration, are reviewed. Methods of screening polymers and optimizing the dose for filtration applications are reviewed, together with other techniques which have been used in mechanistic studies of the process.

ISSN:0007-8999    

DOI:10.1080/10643388009381683

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor