Date of Award
Master of Science in Engineering Science- (M.S.)
Chemical Engineering and Chemistry
Howard David Perlmutter
David S. Kristol
Gerson L. Ram
The specific scope of this work is to study the biological and chemical effects of a single genetic strain of bacteria, Bacillus subtilis #9524, on the specific destruction to innocuous products of sodium nitrilotriacetate (NTA) and sodium tripolyphosphate (STPP). Insofar as the same strain of bacteria was used each time, under limited variability and sterile conditions, the side effects of multiple bacterial strains and their inter-relationships among themselves and the organic substrates are eliminated. This has allowed for excellent replication of results.
This is a generalized technique for the evaluation of the biodegradability of a compound. Whereas tests with activated sewage sludge may show results of oxygen consumption, it may be due to multiple variable reasons associated with unknowns for the breakdown of the compound in question.
Tests also need to be extensive, in that while tests with lower levels of concentration (1-5ppm) may prove to be somewhat effective, higher concentration levels (10 20ppm) of the compound may prove to possess toxic effects on the bacterial strain in use, due to physical factors of altered solution surface tension and lack of isotonicity.
As a result of this study it was found that while there was a minute amount of oxygen consumption at lower levels of NTA, it was not enough to justify saying that NTA was biodegradable. Further experimentation at higher levels of concentration, while having slightly higher levels of oxygen consumption, also showed a trend of increasing toxicity, where an increase in the concentration of the NTA resulted in a lowering of the oxygen demand. Tests on the STPP proved that there was no breakdown, because there was relatively no oxygen consumption, but a known re-entry into the life biochemical processes of the very useful phosphate ion.
Hammerman, Saul, "Biocatalytic oxidation of nitrilotriacetate" (1973). Theses. 2299.