טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentElena Aizenchtadt
SubjectReliability Approaches to Bio-Environmental Systems on
the Base of Wastewater Treatment Plants
DepartmentDepartment of Quality Assurance and Reliability
Supervisors Professor Ingman Dov
Full Professor Friedler Eran
Full Thesis textFull thesis text - English Version


Abstract

This research presents new approaches to reliability assessment, quality control and activated-sludge modeling of bio-environmental systems on the base of wastewater treatment plants.


The first part formulates the basic methods of assessing the reliability of bio-ecological systems, the basic principles of statistical process control (SPC) and the Taguchi Method. In spite of multiple failures that industry is suffering from, no proper reliability analysis of bio-ecological processes is available in literature and hardly any proper failure models have been suggested. It is shown that the classical SPC technique used in industry is inapplicable to wastewater treatment plants without adaptation, and that the Taguchi Method is likewise inapplicable in this case. Also outlined are the basic principles of existing activated sludge models and currently available techniques of control of a biochemical reactor.


The second part deals with the goals of the research: adaptation the principles of reliability concepts to bio-systems; creation of a set of descriptive quantitative parameters, which describes bio-ecological systems in terms of chemical, bacteria-life, symbiosis, mass and energy cycles; development of a biophysical-mathematical model of the systems based on monitoring of key elements and bio-energetic cycles; validation of the model on actual data from the "Greywater Pilot" (Technion experimental facility).


The third part deals with the above setup, which treats the greywater of 14 flats in a residential building in three parallel processes: RBC, MBR and stand-alone sand filter.


The fourth part presents a case study on the performance of a greywater treatment plant. Three SPC versions (Dynamic, Linear Regression and Dynamic Regression) developed in the course of the study are compared with a view to better applicability to bio-systems. In this context, the comparative beta error of DRSPC is used for the classical SPC. This parameter is called efficiency of DRSPC. The performance of the pilot plant is analyzed by means of cross-correlation between the input and output parameters, constant-density curves are constructed, and the pattern of the permeability coefficients is determined. All of the above are proposed as monitoring tools for wastewater treatment systems.


The proposed approach is an innovation in modeling of bio-environmental systems. A biochemical model of the bio-environmental systems on the base of wastewater treatment plant is suggested, as well as a phenomenological one. It is verified under a simulation regime over a set of scenarios and for realistic chemical data. The obtained results demonstrate its potential and provide reliable predictions versus the dynamic process.