Ankara : The Materials Science and Nanotechnology Program of the Graduate School of Engineering and Science of Bilkent University, 2012.Thesis (Master's) -- Bilkent University, 2012.Includes bibliographical references leaves 83-97.Surfactants are the main components in detergents and they are primarily
discharged from household and industry. Ammonia (or ionized form
ammonium) is a byproduct of animal and human metabolism and it is formed in
and discharged from aquaculture. Contamination of soil and water sources by
surfactants and ammonium is becoming a big problem because of their harmful
effects. These substances are highly toxic to many organisms, leading to
possible mass deaths in the freshwater ecosystem. As their presence causes a
potential environmental risk, industrial and household wastewater systems
should be adequately treated to reduce the concentration of ammonium and
surfactants.
Chemical and biological methods are primarily used to treat wastewater
systems. Biological treatment methods are more eco-friendly in comparison to
chemical methods. Among biological treatment methods, the use of specific
bacteria strains for removal of chemical contaminants is a widely applied
process for treatment of industrial and municipal wastewater. However, those
bacteria may not be capable of withstanding harsh environmental conditions or
they may not specifically degrade the contaminant of interest, so isolation of
bacterial strains more resistant to environmental extremes and more suitable for
bioremoval is a possible strategy to improve current wastewater treatment
strategies. By isolating bacteria well-adapted to the environmental and physical conditions of the system to be cleaned, very high efficiencies can be obtained for
wastewater cleaning. To this end, a two-step approach was used.
In the first part of this project, our aim was to find an integrated efficient
biological based method to clean up industrial wastewater from anionic
surfactants. Two main strategies were utilized to solve this problem: Finding and
applying a more biodegradable and eco-friendly detergent alternative, and
developing a biological treatment method specific for the anionic surfactants in
the wastewater system of interest. It is expected that, by combining these two
strategies, anionic surfactants in wastewater can be removed more efficiently.
In the second part of this project, a novel bacterial strain, which we
termed STB1, was isolated from a commercial sea bass farm and found to
display high heterotrophic ammonium removal characteristics. The species
identity of STB1 was determined to be Acinetobacter calcoaceticus. We
evaluated ammonium removal characteristics of STB1 at varying ammonium
concentrations, and observed that STB1 can almost completely remove
ammonium at low (50 mg/l) and medium (100 mg/l) concentrations within 72 h,
while 45% ammonium removal was observed at a higher concentration (210
mg/l) during the same time period. Trace amounts of metabolized ammonium
was converted to nitrite or nitrate and 22.16% of ammonium was introduced to
cell biomass, while 4.34% of total nitrogen was initially incorporated into
biomass and subsequently released to the supernatant fraction in the 100 mg/l
sample. Most of the remaining conversion products are expected to be gaseous
denitrification products. Toxicological studies with Artemia salina (brine
shrimp) nauplii revealed that STB1 strain is non-toxic to Artemia larvae, which
suggests that STB1 can be safely and efficiently utilized for water quality
enrichment in aquatic ecosystems.Sarıoğlu, Ömer FarukM.S
