Thesis Details


Thesis Title: A study of the suitability of the standard BOD5 test to characterize the biodegradability of selected textile chemicals
Thesis Author: Charles H. Dawson, Jr.
Abstract: When split samples of wastewaters or textile chemicals are tested at several laboratories, large discrepancies in Biochemical Oxygen Demand (BOD) values are usually obtained. The poor interlaboratory reproducibility of BOD test results is a topic of concern to textile operations whose effluent discharge permits are based on BOD values. Also, one way for textile operations to reduce the discharge of organic contaminal is to use textile chemicals that are more readily-degraded duril biological waste treatment. The BOD test has been used to characterize the biodegradability of textile chemicals. The general objective of this thesis was to study the suitability of the standard BOD test to characterize the 5 biodegradability of textile chemicals. The specific objectives were (1) to study the effects of laboratory procedure variables on the reproducibility, accuracy, and reliability of BOD measurE ments (2) to study the effects of microbiological seed variable~ on the measurement of BOD of textile chemicals, and (3) to study the effects of source of seed material and concentration of chemical used in BOD bottles on the measurement of BOD of textile chemicals. The results of this thesis suggested that the standard BOD determination is not a suitable test to characterize the biodegradability of textile chemicals, as well as textile wastewaters. A number of laboratory procedure variables can cause BOD test results to have poor reproducibility, accuracy, and reliability. The BOD of textile chemicals can be more a function of the source of the seed material used, the volume of seed used, and the characteristics of the seed material used than a function of its biodegradability. The concentration of the chemicals in the BOD bottle has an effect on the measurement of BOD. In addition, some textile chemicals are more effectively degraded when the ratio of food-to-microorganism is low as in aeration basins of biological waste treatment systems. The inherent nature of the BOD test prevents the use of high microorganism concentrations in BOD bottles, and, therefore, a low food-to-microorganism ratio cannot be used in a BOD bottle.