Metal behaviour in anaerobic sludge digesters supplemented with trace nutrients

Roussel, Jimmy (2013). Metal behaviour in anaerobic sludge digesters supplemented with trace nutrients. University of Birmingham. Ph.D.

Preview

Roussel13Phd.pdf
PDF - Redacted Version
Download (4MB)

Abstract

Trace nutrients (metals) supplementation has been demonstrated to have a beneficial effect on the welfare of anaerobic digesters but there was a lack of information on the chemistry controlling their fate. The aim of this research was to determine the reactions governing the chemical behaviour of metals in anaerobically digested sludge and predict the fate of those metals when supplemented as MeEDTA. After the assessment of a wide range of analytical techniques, a suite of suitable analytical techniques1 were used to determine the metals behaviour in two case studies of metals supplementation: iron dosing and MeEDTA supplementation. The behaviour of the metals was controlled by the solid phase throughout a primary reaction (sulphide precipitation) and secondary reactions (phosphate precipitation, adsorption and organic complexation). The competition between the strength of metal's binding and EDTA complexation controlled the fate of the supplemented metals in anaerobic digesters. Transfer of CoEDTA in the solid phase was found to be divided into two reactions, where the second has a slow kinetic depending on the availability of the counter-ion reacting with EDTA. A key conclusion was that the presence of weaker metal-bound compounds mixed with strong sulphide precipitates changed the understanding of metals speciation, especially concerning their potential availability and consequently their behaviour as trace nutrients.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):