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Treatment of dye wastewaters in the anaerobic baffled reactor and characterisation of the associated microbial populations.

There is potential for the anaerobic baffled reactor (ABR) to be implemented on-site for pre-treatment of

coloured wastewaters. The implementation of waste minimisation and cleaner production strategies in

industry will result in the production of smaller volumes of concentrated wastewaters. With

implementation of the ABR, the concentrated waste stream could be pre-treated, with an acclimated

biomass, which should facilitate sufficient degradation such that the effluent could be discharged to sewer

for further treatment.

The ABR is a high-rate compartmentalised anaerobic bioreactor, the design of which promotes the spatial

separation of microorganisms. The use of molecular teclmiques to characterise the microbial populations

and the dynamics of these populations with time and/or changing operating conditions will add to the

current understanding of the process, which is based on the biochemical pathways and chemical analyses.

This knowledge will allow for optimisation of the design of the ABR.

The hypothesis of the horizontal separation of acidogenesis and methanogenesis through the ABR was

proven. Changes in the HRT affected the operation of the reactor, however, recovery from these upsets

was almost immediate and operation of the reactor was stable.

Two synthetic dye waste streams, one food dye (tartrazine) and one textile dye (Cl Reactive Red 141),

and a real industrial dye wastewater, were treated in separate laboratory-scale ABRs. These investigations

showed that successful treatment of a highly coloured wastewater is possible in the ABR. The design of

the ABR facilitates efficient treatment of concentrated dye wastewaters by protecting the sensitive

methanogens from the inhibitory dye molecules and promoting efficient colour and COD reduction.

The molecular-based method, fluorescent in situ hybridisation, allowed the direct identification and

enumeration of microbial populations active in the ABR. In all of the reported investigations, there was a

definite shift in the microbial populations through the ABR, with a predominance of eubacteria in the first

compartments (acidogenesis) and archaea (methanogenesis) in the later compartments. The number of

compartments involved in each depended on the strength of the substrate (organic loading rate - OLR). A

combination of FISH probing, and the analysis of 98 archaeal l6S rDNA clone inserts provided useful

descriptions of the methanogens actively involved within each compartment. These showed a

predominance of the Methanosaeta spp., particularly in the last compartments of the reactor.

Methanogens present in the first four compartments consisted of species of Methanobacterium and

Methanospirillum, a relatively unstudied methanogen Methanomethylovorans hollandica, and an

unidentified short filamentous species. / Thesis (Ph.D.)-University of Natal, Durban, 2002.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/4299
Date January 2002
CreatorsBell, Joanne.
ContributorsBuckley, Christopher A.
Source SetsSouth African National ETD Portal
LanguageEnglish
Detected LanguageEnglish
TypeThesis

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