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Addis Ababa University Libraries Electronic Thesis and Dissertations: AAU-ETD! >
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http://hdl.handle.net/123456789/1752
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| Title: | DEVELOPING A LABORATORY SCALE SEQUENCING BATCH REACTOR AND EVALUATING ITS PERFORMANCE FOR THE TREATMENT OF TANNERY WASTEWATER |
| Authors: | Andualem, Mekonnen |
| Advisors: | Dr. Seyoum Leta |
| Keywords: | Biological organic matter and sulfide removal
ammonification
nitrification
denitrification
sequencing batch reactors
tannery effluents |
| Copyright: | Mar-2008 |
| Date Added: | 16-Dec-2008 |
| Abstract: | Tannery wastewaters contain high levels of organic matter, nitrogenous compounds, sulfides
and other pollutants. These pollutants can cause undesirable effect on the ecosystem and
public health. In Ethiopia most of leather industries discharge their effluent with out any
treatment to the near by rivers. This creates a serious effect on aquatic biota and surrounding
environment. To minimize the effects, these pollutants must be eliminated/reduced to the
acceptable limits during wastewater treatment. Biological treatment methods are both cost
effective and environmentally sound alternative for the treatments of tannery wastewater than
physic-chemical methods.
The objective of this study was to develop laboratory-scale sequencing batch reactor and
evaluate the biological removal efficiencies of various pollutants from tannery wastewater.
To achieve this objective, the removal efficiencies of COD and TN were investigated under
different cycle times in steady-state condition. The removal efficiencies of the sequencing
batch reactor for carbon, nitrogen, sulfur and phosphorus were also evaluated for a cycle time
of 8 hours. In addition, the effects of fill time on the overall COD removal efficiencies were
studied.
The overall COD removal efficiencies were 71 ± 3.6% at a cycle time of 6-h, 85 ± 1.5% at a
cycle time of 8-h, 89 ± 1.5 % at a cycle time of 12-h and 92 ± 2.6 % at a cycle time of 24-h.
The TN removal efficiencies were 33% at a cycle time of 6-h, 39% at a cycle time of 8-h,
44% at a cycle time of 12-h and 49% at a cycle time of 24-h. The overall COD removal
efficiencies were 94% for 180-minute fill time, 90% for 83-minute fill time and 85% for 48
and 39 minutes fill time. The removal efficiencies at 8 hour cycle were 85% for carbon, 38%
for total nitrogen, 35% for ammonia-nitrogen (NH4
+-N), and 99.9 % for sulfide, 100% and
54.3% orthophosphate and total phosphate, respectively.
In the steady-state condition, the removal efficiencies of COD and TN increased as the cycle
time (HRT) increased. The removal efficiency of COD increased as the length of feed time
increased. Thus, the Sequencing batch reactor was found to be efficient for the removal of
organic matter, sulfide and phosphorous from tanner wastewater. |
| URI: | http://hdl.handle.net/123456789/1752 |
| Appears in: | Thesis - Environmental Sciences
Thesis - Environmental Sciences
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