A pre-screening tool for the anaerobic treatment of complex industrial effluents and wastewaters.
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Date
2003
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Abstract
The objective of this investigation was to assess the potential of a titration bioassay i.e.: The
Methanogenic Activity and Inhibition Analyser (MAlA), to determine the biodegradability of
complex industrial effluents and wastewaters. Specifically, the project aimed to provide an
alternative experimental method to the serum bottle method so that hazardous effluents can be
pre-screened for treatment in under-utilised anaerobic digesters at sewage treatment plants in
KwaZulu-Natal, South Africa. This study also aimed to provide a protocol and a simple
mathematical model as experimental tools that could contribute to the development of future
pre-screening studies.
MAIA was used to conduct biodegradability and toxicity studies on semi-hazardous landfill
leachate and textile size effluent. Thereafter, selected studies were repeated using a
conventional screening method i.e.: serum bottle method. The investigation with MAlA
revealed that both effluent substrates had potential for anaerobic treatment. However, the
studies highlighted certain intrinsic limitations of the MAIA apparatus to effectively
pre-screen complex substrates. The existing titrimetric system is too coarse to accurately track
the biochemical pathways leading from the breakdown of complex compounds to methane
gas production. Further, temperature interferences and gas phase diffusion limitations
associated with the existing design make the assessment of activity difficult.
The titrimetric method is comparable to the serum bottle method only if a qualitative
assessment of toxicity and biodegradability is needed. However, the titrimetric method
produces results in a much shorter period of time compared to the serum bottle method.
Evaluated in this way the titrimetric method is the better alternative. However, the current
system cannot challenge the reliability of the serum bottle method to provide good
quantitative results.
A mathematical model was developed which is much less detailed than the existing one
provided by Remigi (2001). It comprises only two significant anaerobic processes namely
hydrolysis and acetogenesis. Simulation trials have suggested that the model is a necessary
and beneficial component ofthe titrimetric pre-screening protocol.
This investigation has also led to the development of a more refined operating manual for
MAIA.The manual provides a step-wise method for the preparation and conduction of
pre-screening tests. Specifically, it highlights the need for a suitable biomass acclimation
period and the importance ofnutrient use for better pre-screening assessments.
Description
Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.
Keywords
Factory and trade waste--Purification., Factory and trade waste--Biodegradation., Theses--Chemical engineering.