Reuse of recovered coagulants in water treatment: An investigation on the effect coagulant purity has on treatment performance

Date

2014-04-28

Authors

Keeley, James
Smith, Andrea D.
Judd, Simon J.
Jarvis, Peter

Supervisor/s

Journal Title

Journal ISSN

Volume Title

Publisher

Elsevier

Department

Type

Article

ISSN

1383-5866

Format

Free to read from

URI

http://dx.doi.org/10.1016/j.seppur.2014.04.033
 http://dspace.lib.cranfield.ac.uk/handle/1826/9955

Citation

James Keeley, Andrea D. Smith, Simon J. Judd, Peter Jarvis, Reuse of recovered coagulants in water treatment: An investigation on the effect coagulant purity has on treatment performance, Separation and Purification Technology, Volume 131, 27 June 2014, pp69-78

Abstract

Coagulant recovery offers many potential benefits to water treatment, by reducing chemical demand and waste production. The key obstacle to successful implementation is achieving the same levels of treatment quality and process economics as commercial coagulants.

This study has evaluated the selectivity of pressure-filtration in the role of a low-cost coagulant recovery technology from waterworks sludge. The treatment performance of the purified recovered coagulant was directly compared to fresh and raw recovered coagulants. DOC and turbidity removal by recovered coagulants was close to that of commercial coagulants, indicating that coagulant can be successfully recovered and regenerated by acidifying waterworks sludge. However, performance was less consistent, with a much narrower optimum charge neutralisation window and 10–30% worse removal performance under optimum conditions. This inferior performance was particularly evident for recovered ferric coagulants. The impact of this was confirmed by measuring THM formation potential and residual metals concentrations, showing 30–300% higher THMFPs when recovered coagulants were used.

This study confirms that pressure-filtration can be operated on an economically viable basis, in terms of mass flux and fouling. However, the selectivity currently falls short of the purity required for potable treatment, due to incomplete rejection of sludge contaminants.

Description

Software Description

Software Language

Github

Keywords

Coagulant recovery, Water treatment residuals, Waterworks sludge, Ultrafiltration, Alum recovery

DOI

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Staff publications (SWEE)