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Addis Ababa University Libraries Electronic Thesis and Dissertations: AAU-ETD! >
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Thesis - Business Education >
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http://hdl.handle.net/123456789/64
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| Title: | BIOLOGICAL NITROGEN REMOVAL FROM TANNERY WASTEWATER USING ALKALIPHILIC SLUDGE |
| Authors: | Tesfaye, Minuta |
| Keywords: | Activated sludge
alkaliphiles
ammonification
nitrification
denitrification |
| Date Added: | 4-Sep-2007 |
| Abstract: | Untreated tannery wastewaters contain high levels of organic materials and nitrogen. The
principal forms of nitrogen in tannery wastewater are organic nitrogen (mainly proteins) and
ammonia obtained from hides and skins. The presence of nitrogen in wastewater discharge can be
undesirable because it has ecological impacts and can affect public health. Methemoglobin,
eutrophication and depletion of dissolved oxygen in aquatic ecosystems are some of the major
problems related to release of nitrogenous wastewater to the environment. Because of these
pollution problems, nitrogenous compounds must be eliminated or reduced to the acceptable
limits together with the organic carbon during wastewater treatment. The nitrogen in wastewater
will be converted to the harmless nitrogen gas by microbial processes mainly through
ammonification, nitrification and denitrification.
The objective of this study was to evaluate sludge biomass activity obtained from alkaliphilic
environment for removal of nitrogen and organic matter from tannery effluent using lab-scale
predenitrification/nitrification activated sludge system. This was fed with simulated and actual
tannery wastewater. The raw tannery wastewater was obtained from the Modjo Tannery. The
system was inoculated with sludge biomass prepared using sediment slurry from alkaline soda
lake and artificial wastewater in batch reactor. The potential of sediment sludge to remove
nitrogen and organic matter was analyzed using COD, BOD, TN/TKN, NH+
4-N, NO-
3-N, S2- and
SO4
2- concentrations. The sludge activity was also tested for the occurrence of denitrifiaction and
nitrification at higher pH using Nitrate and Ammonia Uptake Rates (NUR and AUR). The system
was operated at three different organic loading rates (OLR) (10, 5 and 2.5 gm l-1 d-1).
The influent had an average concentrations of 8193.33, 2355, 645.67, 686, 222.33 and 564.67 mg
l-1 COD, BOD, TKN, NH4
+-N, S-2 and SO4
2-, respectively, at 10 gm l-1 d-1 OLR. Average effluent
concentrations of the aforementioned parameters at 5 gm l-1d-1 OLR were 4209.33, 1409.33, 834,
578, 256.67 and 458.67 mg l-1 while at 2.5 gml-1d-1 OLR were 1886.67, 598.33, 672.33, 280.33,
241.67 and 401.33 mg l-1.
The sediment sludge biomass was able to achieve 65.3, 89.2 and 97.1 % removal of COD and
59.7, 87.8 and 97.3 % removal of BOD at 10, 5 and 2.5 gm l-1 d-1 of OLRs, respectively. In
addition, TKN removal efficiencies of 44.2, 86.7 and 96.6 % and NH4
+-N removal efficiencies of
62.2, 74.5 and 94.8 % were achieved at 10, 5 and 2.5 gm l-1 d-1 of OLRs, respectively. The
removal efficiency of sulphide was 38.2, 89.7 and 92.3 % at respective OLRs. Their potential to
remove nitrate and ammonia nitrogen during NUR and AUR Test were 69.5 and 82.8 % at range
pH values of 10.2 and 10.21 and 9.50 and 9.75, respectively. Maximum removal efficiencies
(97.1, 97.3, 96.6, 94.8 and 92.3 %) of COD, BOD, TKN, NH4
+-N and S2- were obtained at 2.5 gm
l-1d-1 of OLR. At this OLR, the final COD, BOD, TKN, NH4
+-N, NO3
--N and S-2 were 55.33,
14.67, 22, 14.6, 4.53 and 18.67 mg l-1, respectively. This is in line with the effluent discharge
limit values in Ethiopia. Thus, alkaliphiles could be a good alternative to be used as inoculums
for nitrogen and organic matter removal from industrial wastewaters. |
| Description: | I would like to express my deepest gratitude and appreciation to my advisors Dr. Amare Gessesse
and Dr. Seyoum Leta for their consistent support, help and encouragement through out the whole
study period. They were always willing to help me starting from installing the system to the end
of lab work in all aspects and extremely helpful in correcting any technical problems through out
the work.
I would like to thank my family Kassa W/mariam, Geremew Nisrane, Kore Mersha, Adanech
W/mariam, Alemnesh H/mariam, Seble G/silassie, Menbere G/silassie, Habte Neri, Deginesh
Minuta, Askale Yirga, Fantaye Berta and Gizeworqe Minuta for supporting me through my
graduate studies. They greatly encourage me to enroll in this program. With out their
encouragement and moral the study would have been much more difficult. I would like to express
my heartfelt and deepest thanks to my friend w/t Sisay Sahle for her continuous encouragement
and moral throughout my study period. My greatest appreciation and full thanks must go to my
friends Zewede Haile, Addisu Etifu, Nuru Bereda and Dessalegn Berga for their encouragement
and moral throughout my study period.
Also, appreciation is extended to my friend Abraham Mebrat for his endless support during write
up the thesis. I am grateful for technical assistance of w/t Hirut Teshome and w/o Tigist
Mengesha during working in laboratory. Special thanks must deserve to my friends indeed Hayal,
Dereje, Essayas, Tilahun, and other graduate friends.
I would also like to acknowledge SNNPRG, especially Guragae Zone education bureau for
granting me the study leave. Also, thanks to Addis Ababa University for funding of the research.
Lastly, above all, I want to thank God for helping me endures the rigorous of every day life and
to overcome the challenges of graduate studies. Without Him nothing is happened. So I want to
say Praise Lord!! |
| URI: | http://hdl.handle.net/123456789/64 |
| Appears in: | Thesis - Biology
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