Date of Award

4-1991

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

First Advisor

Bill Forester

Abstract

This thesis explored the possibility of using ultrasonic treatment to reduce the amount of microbiological growth in a sample of contaminated mill wastewater. It was found that ultrasonic treatment reduces microbiological growth through the mechanism of cavitation. percent inhibition increases with both time of treatment and applied power. The most economical conditions were high power and a short treatment time.

The increase in cell volume had an inverse effect on the percent inhibition. The increase in consistency of the treated solution also had an inverse effect on the percent inhibition and 6% was the maximum treatable consistency.

Ultrasonic treatment was compared to three popular biocides at a 90% inhibition level. The biocides used were Methylene Bis(Thiocyanate), Isothiazolin, and a Thiadiazine type. Dosages to achieve 90% inhibition were 154 ppm., 161 ppm, and 127 ppm. respectively. The 90% inhibition level was reached with 0.0158 kW hrs. of energy, using ultrasonic treatment. This energy was scaled up to 8.030% HP day/ton.

Further studies are recommended in the areas of cell geometry, determination of the maximum power efficiency, and the development of a dynamic model to test ultrasonic treatment in a situation oriented more towards the paper mill environment.

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