Practical techniques to assess the dewaterability of sludge to optimise current and future performance
Minall, R1, Smyth, M1 & Horan, N2
1Aqua Enviro, 2The University of Leeds
(free)
Abstract
Sludge dewatering is integral to the cost effective recycling of Municipal Mesophilic Anaerobic Digestate to land, as such it is currently well understood. Any mass balance or cost model for a plant in the municipal MAD market will make reasonable assumptions based upon a historic database for; i) the dry solids content (%DS) of the cake ii) the mass of polymer or conditioning agent and dry solids (kg poly/tds); and iii) the quality of the return liquors.
A dewatering asset is designed to achieve performance guarantees for these components and this is critical to the long term financial and operational success of any given project. Process guarantees are held by the manufacturer and installer of the equipment using a knowledge base based upon municipal MAD, however recent and potential future developments in organic waste Anaerobic Digestion and Thermal Hydrolysis have produced sludges with different dewatering characteristics (dewaterability).
Through Research & Development, Aqua Enviro have developed a practical method that can be used to assess, compare and evaluate sludge dewaterability in a repeatable manner to optimise current and future performance. The tests can either be undertaken in
the laboratory or on site.
This paper focuses on the dewaterability of anaerobic digestate produced from sludge treatment processes incorporating Thermal Hydrolysis, Municipal Sewage Sludge and from the Anaerobic Digestion of Organic Wastes.
Keywords
dewatering, dewaterability, polymer consumption, cake dry solids
