Samenvatting

A lot of industries in the world use water and produce waste, and with limited water resources and an increasing population, industrial development has grown, putting even more stress on resources.
This issue of concern has been recognized and efforts into conserving these precious resources has been made in the form of limiting usage of water and maximizing reuse. Recovering material from waste water is also a priority. The separation of solid-liquid suspensions is a process that is commonly used for this and more recently acoustic separation has been investigated as new technique.
Ultrasonic standing waves (USW) are able to move suspended particles in a direction or fix them in specific locations, in order to generate USW, two opposite sound waves with the same frequency and magnitude are needed to create a fixed wave pattern. An USW filtration device design was made by H. J. Cappon and the operational settings were then further optimized by David Verschoor where he found two optimal settings, one for obtaining clean water and another for one for collecting the suspended particles. It was concluded that testing the system with an increase in power was needed in order to truly determine the effect of power on the filtration efficiency.
The aim of this research was to test this separator device and try to optimize the operational efficiency further by a combination of experiments and models involving influent flow rate, electric power input and frequency. The main research question being; How can the operational settings be optimized to achieve the highest filtration efficiency for starch recovery varying power, flow rate and frequency?
A model based optimization method known as the response surface methodology was used to form a response plot using MATLAB and the optimal settings for efficiency were derived from there.
The frequency was defined in two ways; filtration efficiency for producing clean water and retention efficiency for recovering starch particles. It was concluded that operational settings of 0.5 ml/s, power of 12.5 and a processed starch mass of 560mg (switching interval of 19 minutes and 40 seconds) are the optimal settings for filtration. The optimal settings for the retention efficiency was concluded to be 0.5ml/s, 17.5W and a processed starch mass of 560mg. These settings resulted in a filtration efficiency of 83% and a retention efficiency of 228%, the highest reached yet with this device. Varying the frequency in order to create quasi wave was not feasible using this separation chamber as it always creates a standing wave and no travelling waves. Overall, these settings have still resulted in the highest efficiencies so reached so far with this separation system.