İNŞaat mühendiSLİĞİ anabiLİm dali

Membrane Surface Modıfıcatıon By Usıng Plasma Technıques And Applıcatıon To Membrane Bıoreactors
In recent years the use of membrane bioreactors (MBR) has widespread in wastewater treatment. However, the most important reason that prevent widespread use of this comes to the high operating costs as a result of rapid contamination of the membranes. Studies on different membrane modification methods to reduce these costs has increased. One of these modification methods is the membrane surface modification with plasma treatment. In this thesis study, it is aimed to have the hydrofobic membranes become hydrofilic by the plasma surface modification method and to use these membranes in MBRs.
In this study, it is aimed to treat wastewater of fruit juice industryby using plasma treatment method with modified and non-modified membranes in different organic loading and different sludge retention time at MBR.
For this purpose, firstly the characterization of real fruit juice wastewater was made and then synthetic fruit juice wastewater was prepared. Two different UF membranes (PS and PVDF) were modified with plasma treatment methods with N₂ and water vapour at different times (1, 2.5, 5, 15 and 30 min.), dose and power (20, 40, 60, 80, and 100 W). Then the best plasma conditions of contact angle measurements for the modified membranes were determined (100W 15 min. with water vapour for PS membrane, 80W and 30 min. with water vapour for PVDF membrane). Two different types of both modified and unmodified membranes (PS₀, PS_mod, PVDF₀, PVDF_mod) were tested in the same conditions at a laboratory scale aerobic MBR system with four membrane modules. MBR system is operated with two different sludge age (SRT=15 days ve SRT=30 days) of three different organic loading (COD=500 mg/L, 1000 mg/L ve 2000 mg/L). Operating and treatability studies showed the relationship between the contaminated membranes andcontents of extracellular polymeric substances (EPS ) and soluble microbial products (SMP ), floc structure of microorganisms, surface properties ( hydrophobicity and surface charge), COD, dissolved oxygen, nitrogen, TKN–N, NH₃–N, NO₂–N, NO₃–N, phosphorus wastewater viscosity, particle size distribution andzeta potential. Treatability of membranes were examined in permeate by performing SMP, EPS, TSS and COD analyses. After modification with plasma membranes hydrophobic / hydrophilic structure was analyzed by contact angle and the fouling which may occur in the pores and surface of the membrane during the MBR application was examined by AFM, SEM and FT/IR–ATR analyses and modified and unmodified membranes were compared. This analysis revealed a result of membrane fouling properties. In addition, the modeling of flux provided the investigation and clarify of fouling mechanisms which may occur in the membranes. Flux losses caused by membrane fouling were calculated.
As a result, surface of the membranes which are modified with plasma treatment have become hydrofilic and total resistance have decreased. Accordingly, in the modified plasma membrane permeate flux was observed to be significantly increased compared to unmodified membrane. The best results in this study has been obtained in the following operating conditions with PVDF_mod membrane SRT=30 days, COD=2000 mg/L (COD=98% removal efficiency, J_d = 55 L/m².h permeate flux).

ERŞAN Gamze
Danışman : Doç. Dr. Yasemin KAYA

Anabilim Dalı : Çevre Mühendisliği

Programı : -

Mezuniyet Yılı : 2014

Tez Savunma Jürisi : Doç. Dr. Yasemin KAYA

Prof. Dr. Neşe TÜFEKÇİ

Doç. Dr. Coşkun AYDINER

Prof. Dr. Mehmet ÇAKMAKÇI

Doç. Dr. İlda VERGİLİ