M.Sc Thesis


M.Sc StudentYu Yuejun
SubjectDeveloping and Study of On-Line Biotoxicity Sensing
and Control Unit for Wastewater Treatment,
based on a Cell Viability Monitoring
Assay
DepartmentDepartment of Chemical Engineering
Supervisor PROF. Yaron Paz


Abstract

Wastewater streams contain quite often a large number of contaminants, part of which can be quite toxic for the working bacteria in bioreactors, thus might hamper the efficiency of the bioreactors. In such cases, pretreatment by an Advanced Oxidation Process (AOP) might be needed. Since, in general, biotreatment is more economic than AOP, it is sensible to design the integrated system in a manner that would reduce the load on the AOP as much as possible. This could be a very difficult task, especially when the total concentration of the toxic compounds varies over time. The problem is aggravated by lack of inexpensive and fast technologies that are able to evaluate the toxicity under conditions in which the nature of the toxic compounds is unknown. Here we report on the developing of a unit that automatically measures the extent by which polluted water might put at risk a biological treatment unit. The sensing unit is based on PrestoBlue, a cell viability monitoring assay, and Bacillus Subtilis as reporting bacteria. The toxic compounds were modelled by three antibiotics (chloramphenicol, tetracycline and ciprofloxacin). The potential of embedding the sensing unit in a multi-technology system (AOP-biological) was demonstrated by connecting the sensing unit to a photocatalytic reactor and controlling the number of operating lamps in the photocatalytic reactor autonomously according to predesigned toxicity setpoint under both feedforward and feedback modes of control.