Thesis (MTech. degree inChemistry.)--Tshwane University of Technology, 2010. / Introduction: Since the establishment of relationships between BOD, COD and TOC in early 1980’s, total organic carbon (TOC) analysis has been the
analytical backbone of many water treatment laboratories (Furlong et al. 1999). It is only a question of time before South Africa follows suite, if only to
adhere to export legislation and requirements. The question is whether TOC is just another expensive analytical tool for policing effluent, or is TOC results valid criteria for monitoring pollution.
Aim: The purpose of this project was to evaluate the determination of TOC as a management tool on a wastewater treatment plant (WWTP) and compare it to the chemical oxygen demand (COD) analysis traditionally applied.
Experimental: Five sampling points throughout the wastewater treatment plant were evaluated. A possible comparison between TOC and COD was
investigated.
Sampling was done using an ISCO 3700 portable sampler at each individual sampling point. The samples were filtered and analysed for TOC in the
laboratory using an ISCO EZ 3500 TOC analyser. COD analysis was done colorimetrically by using a Hach DR 2000 photometer. Both analyses were
done according to standard methods for water and wastewater. Because the ISCO EZ 3500 TOC is an online instrument, it was evaluated at two of the
wastewater treatment plant.
Results: The analysis of TOC is a more rapid method than COD for the determination of organic load and thus has the potential for better early
warning and pollution control management.
The change in chemical composition of raw sewage made it difficult to find consistent correlation between COD and TOC results. However, it was found that an online TOC analyses was a practical alternative to COD for plant control, process management and monitoring of inflow and effluent flows in wastewater treatment plant.
Conclusion: Limitations of TOC analysis must be considered and include practical problems due to the high content of suspended solids in raw sewage and activated sludge, as well as the partial oxidation of certain organic compounds by ultra-violet/persulphate digestion.
Although COD analysis is chemically hazardous and time-consuming compared to TOC analysis, it is not likely that TOC will replace COD on the
WWTP, due to historical data accumulation, practicality and people’s natural opposition to change. However, it is hoped that the results of this study will
increase knowledge about TOC and be used for practical implementation where this technique has advantages over COD
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001043 |
| Date | January 2002 |
| Creators | Du Toit, Wynand |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | © 2002 Tshwane University of Technology |
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