Effect of carrier fill ratio on biofilm properties and performance of a hybrid fixed-film bioreactor treating coal gasification wastewater for the removal of COD, phenols and ammonia-nitrogen
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Date
Authors
Rava, Eleonora Maria Elizabeth
Chirwa, Evans M.N.
Journal Title
Journal ISSN
Volume Title
Publisher
IWA Publishing
Abstract
The purpose of this study was to determine the effect different biofilm carrier filling ratios would have on biofilm morphology and activity and
bacterial diversity in a hybrid fixed-film bioreactor treating high strength coal gasification wastewater (CGWW) for the removal of chemical
oxygen demand (COD), phenols and ammonia-nitrogen. Results showed that a carrier fill of 70% formed a ‘compact’ biofilm, a 50% fill formed
a ‘rippling’ biofilm and a 30% fill formed a ‘porous’ biofilm. The highest microbial activity was obtained with a 50% carrier fill supporting a
relatively thin biofilm. The highest level of biofilm bound metals were aluminium, silicon, calcium and iron in the ‘compact’ biofilm; nitrogen,
magnesium, chloride, sodium and potassium in the ‘rippling’ biofilm, and copper in the ‘porous’ biofilm. The bioreactor improved the quality
of the CGWW by removing 49% and 78% of the COD and phenols, respectively. However, no significant amount of ammonia-nitrogen was
removed since nitrification did not take place due to heterotrophic bacteria out-competing autotrophic nitrifying bacteria in the biofilm. The
dominant heterotrophic genera identified for all three carrier filling ratios were Thauera, Pseudaminobacter, Pseudomonas and
Diaphorobacter.
Description
Keywords
Anox-kaldness, Biofilm, Next-generation sequencing, Nitrification, Pollutants, Thauera, Coal gasification wastewater (CGWW), Chemical oxygen demand (COD)
Sustainable Development Goals
Citation
Rava, E & Chirwa, E 2016, 'Effect of carrier fill ratio on biofilm properties and performance of a hybrid fixed-film bioreactor treating coal gasification wastewater for the removal of COD, phenols and ammonia-nitrogen', Water Science and Technology, vol. 73, no. 10, pp. 2461-2467.