טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentEilon Guthman
SubjectDomestic Wastewater Treatment for Unrestricted Reuse and
Irrigation Based on CEPT and Constructed Wetlands
DepartmentDepartment of Civil and Environmental Engineering
Supervisors Professor Emeritus Green Michal
Dr. Tarre Sheldon
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

Chemically enhanced primary treatment (CEPT) together with constructed wetlands (CW) was investigated as an appropriate domestic wastewater treatment system in small and medium sized communities for unrestricted irrigation. Using a low dosage of 10 to 13 mg/l of Fe (given as FeCl3) as the coagulant in the CEPT unit, removals of 69%, 79% and 60% for CODT, TSS and P, respectively, were obtained. The remaining CEPT effluent was treated for nitrogen and COD removal in both a single unsaturated vertical flow CW unit and in a dual unit composed of a saturated (anoxic) subsurface flow CW and unsaturated (aerobic) vertical flow CW connected by recirculation (feed to recycle ratio of 1:1). The results show that for the single unit unsaturated vertical flow CW with ponding, the average monthly values as well as the peak values all comply with unrestricted effluent reuse for irrigation regulations regarding COD, TP, TN and ammonium, under organic loading conditions of up to 60 g/m2/day. The reduction of total N from about 60 mg/L to an average about 25 mg/L demonstrated significant simultaneous nitrification and denitrification in the single unit CW. Similar results were obtained for the dual CW unit at organic loading of up to 90 g/m2/day. The large reduction in COD and suspended solids from the wastewater by CEPT allows for the design much smaller CW footprint for the subsequent CEPT effluent treatment step with the corresponding lesser evaporation, smaller increase in salinity and lower land costs.