Browsing by Author "Woldesenbet Fantahun"

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    Evaluation of Nitrogen Removal Rates from Abattoir Wastewater in a Pilot Predenitrification-Nitrification Activated Sludge Wastewater Treatment Plant
    (Addis Ababa Universty, 2005-07) Woldesenbet Fantahun; Assefa Fassil (PhD)
    Abattoir wastewater has a complex.composition and is very harmful to the environment. It causes eutrophication, suffocation of aquatic life and contamination of ground water. Nitrogen is the main component of the abattoir wastewater. Because of environmental and health problems they cause, nitrogen compounds should be reduced to the acceptable discharge limit level before the wastewater is released to water bodies and the environment. Biological methods of nitrogen removal are considered to be cost effective and environmentally friendly alternatives than chemical treatment. The objectives of this study were therefore: to evaluate the treatment processes of a predenitrification-nitrification activated sludge system for abattoir wastewater treatment; Characterize the activated sludge involved in the treatment process through Ammonium uptake rate and Nitrate uptake rate, and its seUlability by sludge volume index. Abattoir wastewater was sampled from Addis Ababa Abattoirs Enterprise, analyzed for selected parameters to check its biodegradability and fed into a predenitrification nitrification activated sludge wastewater treatment system at varying operational parameters. The removal efficiency for the selected parameters and the characteristics of the sludge at each operational condition was evaluated. A removal efficiency of 94- 98% for COD, 95-99% for BOD5, 85-97% for total nitrogen, 58-95% for AmmoniumNitrogen and 46-53% reduction in phosphate was obtained in the treatment processes. The predenitrification-nitrification rates measured as Ammonium Uptake Rate and Nitrate Uptake Rate ranged from 5.9-9.8 mg NH4-N/gVSSh and 8.2-12.1 mg N03- N/gVSSh respectively. The sludge volume index (SVI) ranged from 51.5 mUg to 87.6 mUg. The abattoir wastewater was found to be suitable for biological wastewater treatment. It is also showed that the predenitrification-nitrification system was efficient in organic matter and nitrogen removal from abattoir wastewater.