DETERMINATION OF BIOLOGICAL OXYGEN DEMAND RATE CONSTANT AND ULTIMATE BIOLOGICAL OXYGEN DEMAND FOR LIQUID WASTE GENERATED FROM STUDENT CAFETERIA AT JIMMA UNIVERSITY A TOOL FOR DEVELOPMENT OF SCIENTIFIC CRITERIA TO PROTECT AQUATIC HEALTH IN THE REGION

Abstract

BACKGROUND: Except Addis Ababa, all towns of Ethiopia discharge every form of liquid waste anywhere. This wastewater ultimately enters to streams and rivers. Deficiencies of sanitary services and absence of regulation and scientific criteria for enforcement has presented an increasing environmental and public health hazards in major towns of Ethiopia. The aim of this study was to determine the strength of Jimma University cafeteria waste and propose the need for scientific criteria and treatment options before discharging into water bodies.

METHODS: Liquid waste generated from student cafeteria at Jinma University was sampled from December - March 2003 to determine Biological Oxygen Demand rate constant (R) and ultimate biological oxygen demand by incubating samples at three different temperatures. Rate constant was determined following Thomas Method and the potential impact of the waste on streams was evaluated.

RESULTS: The rate constant (k) determined at 3 three temperatures was of magnitude and the Ultimate Biological Oxygen Demand was found to be under the category of a strong waste (1047.33 mg/L) capable of destroying the self-purifying capacities of receiving water bodies. The rate constant (k) generated based on local Samples and environmental conditions can serve as feasible and reliable scientific criterion to optimize treatment facilities such as oxidation ponds in the region.

CONCLUSION: Liquid wastes generated from Jimma University student cafeteria is found to be under the category of strong waste that can degrade the quality of the Awetu-Gilgel Gibe river system and thereby limit its actual and potential use. Determination of Biological Oxygen Demand and rate constant (k) for other sources and consequent provision of wastewater treatment option is necessary to protect water resources downstream.