טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentHerzberg Moshe
SubjectBiological Degradation of Atrazine in FB Denitrification
Reactor with Activated Carbon as the Carrier for
the Biofilm
DepartmentDepartment of Agricultural Engineering
Supervisors Professor Emeritus Carlos Dosoretz
Professor Emeritus Michal Green


Abstract

To show that an adsorbing biofilm carrier (GAC) can be advantageous for atrazine bioremediation over a non-adsorbing carrier, fluidized bed (FB) reactors were operated under atrazine limiting concentrations with P. ADP as the atrazine degrading bacteria. The following interrelated subjects were investigated: 1) atrazine adsorption to GAC under conditions of atrazine partial penetration in the biofilm, 2) high atrazine degradation rate due to double flux of atrazine in the biofilm, and 3) increased stability of atrazine biodegradation under non-sterile anoxic conditions. Results from batch adsorption tests and modeling proved the existence of non-biofilm covered areas on the GAC particles. Atrazine adsorption occurs in the non-covered areas, even under conditions of atrazine partial penetration in the biofilm covered areas. Internal flux of desorbed atrazine from the GAC to the base of the biofilm increased the active biofilm surface area as observed by lower effluent atrazine concentrations in a BGAC reactor as compared to a FB reactor with a non-adsorbing carrier. Moreover, under non-sterile conditions and in the presence of external nitrogen compounds (nitrate), atrazine degradation stability was found to be higher using GAC as a biofilm carrier as opposed to non adsorbing carrier reactors which showed sharp deterioration within 30 days due to contamination of non-atrazine degrading bacteria.