Title page for ETD etd-06252012-104038


Document Type Master's Dissertation
Author Mwakio, Joseph Mundu
Email mundu.jm@gmail.com
URN etd-06252012-104038
Document Title Continuous succinic acid production by Actinobacillus Succinogenes : suspended cell and biofilm studies in an anaerobic slurry reactor
Degree MEng
Department Chemical Engineering
Supervisor
Advisor Name Title
Prof W Nicol Supervisor
Keywords
  • continuous succinic acid production
  • Actinobacillus succinogenes
  • biofilm
Date 2012-04-17
Availability unrestricted
Abstract
Succinic Acid (SA) was continuously produced using glucose and a Mg2CO3(OH)2 slurry as feed. Glucose feed concentrations of 20 and 40 g ℓ-1 were employed with corresponding Mg2CO3(OH)2 slurry concentrations of 60 and 120 g ℓ-1. The reactor pH was passively maintained between 6,4 and 6,8 by the buffer properties of the slurry in conjunction with the pH adjusted glucose feed. The suspended cell (SC) reactor was operated at 37C with dilution rates varying between 0,04 h-1and 0,6 h-1. Groperl particles were used as inert supports in the biofilm reactor; dilution rates of 0,11 h-1 to 1 h-1 were investigated.

Two SC fermentations were conducted for the 20 g ℓ-1 glucose feed concentration and one for the 40 g ℓ-1. All SC fermentation runs were operated in excess of 12 days, while the biofilm run lasted 6,5 days. Fermentations were terminated only after contamination by lactic acid bacteria was observed.

SC fermentations with the glucose feed concentration of 20 g ℓ-1 achieved a maximum SA productivity of 5,2 g ℓ-1h-1 at 0,6 h-1 with a corresponding SA yield of 0,65 g g-1. SC fermentations with the glucose feed concentration of 40 g ℓ-1 achieved a maximum SA productivity of 3,76 g ℓ-1h-1 at 0,4 h-1 with a SA yield of 0,82 g g-1. The results were comparable to the other continuous studies with Actinobacillus succinogenes, despite the fact that either biofilms or membranes were employed in these studies.

The preliminary biofilm study demonstrated the capability of A. succinogenes to produce SA in high productivities and yields. SA productivities and yields for the dilution rates of 0,33 h-1 and 1,0 h-1, were 5,72 g ℓ-1h-1 (0,95 g g-1) and 12 g ℓ-1h-1 (1,0 g g-1), respectively. The biofilm reactor at 0,33 h-1 achieved twice the SA productivity of the SC reactor at 0,3 h-1 with a 42 % increase in SA yield.

Copyright 2012, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria

Please cite as follows:

Mwakio, JM 2012, Continuous succinic acid production by Actinobacillus Succinogenes : suspended cell and biofilm studies in an anaerobic slurry reactor, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-06252012-104038 / >

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