Physical consistency: a useful tool for sludge characterization to the implementation of European standards

Abstract

Physical consistency is an important property for sludge characterization, as it affects almost all treatment, utilization and disposal operations. Three physical states have been evidenced for sludge : liquid, paste-like, and solid, whose boundaries are defined by limits of "flowability" and "solidity". Characterization is completed by the evaluation of thixotropic and piling behaviours. In this paper, the work carried out by CEN/TC308 in this field is discussed. For evaluation of flowability, Coaxial cylinder viscometer, Flow cone, Magnesium penetration cone and Extrusion tube viscometer appear the recommended methods, and for that of solidity, Laboratory vane shear, Vicat needle, and Pocket penetrometer. The Penetrometer, coupled to an energy-input system, appears suitable for thixotropic behaviour evaluation, while the Cubic Piling Box (CPB) and the Oedometer for piling behaviour one.