2011 YÜksek lisans tez özetleri

Investigation of Aerobic Granular Sludge Stability

Aerobic granulation process was developed as an innovative technology due to the several drawbacks of activated sludge processes. Aerobic granulation process has advantages such as having a compact and strong microbial structure, good settling properties, high biomass retention time compared with activated sludge process. Thus, aerobic granulation process requires less area than activated sludge processes in wastewater treatment.

The operation conditions such as aerobic starvation, feed composition, solid retention time, settling time, seed sludge, reactor congfiguration, shear force and presence of the diavalent metal ions affect the aerobic granulation process. In these factors, diavalent metal ions play an important role in the process of aerobic granulation. The researches showed that especially Ca²⁺ and Mg²⁺ promote the aerobic granulation in SBR. Divalent cations participate in bridging of negatively charged sites on the EPS and promote the granulation. The effects of the Fe²⁺ on the floculated sludge have been investigated but there is not any researches about the effect of Fe²⁺ on aerobic granular sludge.

The aim of this study is to investigate the effects of Fe²⁺ on the formation and stability of aerobic granular sludge. In this context the control reactor without Fe²⁺ addition and the reactor with 10 mgFe²⁺/L of Fe²⁺ addition were operated at the same operational conditions during 270 days. The aerobic granules obtained in these two reactors were compared for the formation, stability and structure of granular sludge together with the removal efficiencies of organic matter and nutrient.

The study showed that the Fe²⁺ addition supported the formation of stabil granular sludge and also improved the removal of nutrient. The formation of granul sludge in both of the reactors was achieved at the same time but, the granules presented the different characteristics in size and morphology. The mature granules in the reactor with Fe²⁺ addition were obtained at day 20 and sustained stabil. The mature granules in the reactor without Fe²⁺ addition were also obtained but, they disintegrated and grown again because of their filamentous and loose structures. The granules with Fe²⁺ addition exhibited better physical characteristics, and demonstrated better settleability and more compact structure than the granules without Fe²⁺ addition. The aerobic granules without Fe²⁺ addition were light yellow in color, round in shape and, loose and fluffy filamentouse structure. In the reactor fed with Fe²⁺ addition the granules were dark yellow- brownish in color, and smooth and non-filamentous structure. It was thought that the smoot and non-filamentouse structure resulted from the Fe²⁺ addition since it represed the growth of filamentouse bacteria. Nitrification could not be achieved in the reactor without Fe²⁺ addition. On the other hand the complete nitrification could be obtained in the reactor with Fe²⁺ addition starting from 70^th day of the study. The mature granules without Fe²⁺ addition had the similar structure for inner and outher layers but more FePO₄ precipitation in the granules with Fe²⁺ addition was observed in the inner layer than outher layer.

YERDELEN Yunus

Danışman : Yrd. Doç. Dr. Burcu ONAT

Anabilim Dalı : Çevre Mühensiliği

Mezuniyet Yılı : 2011

Tez Savunma Jürisi : Yrd. Doç. Dr. Burcu ONAT

Prof. Dr. Süleyman TANYOLAÇ

Doç. Dr. Nüket SİVRİ

Doç. Dr. Mehmeyt BİLGİN

Yrd. Doç. Dr. Ülkü ALVER ŞAHİN