Water Pollution/Quality Assessment in Relation to Wet Coffee Processing Plants in Surface and Shallow Groundwater in Sidama and Gedeo Zones (SNNPR)
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Date
2005-06
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Addis Ababa University
Abstract
The study area located in Southern Nation and Nationality People Region (SNNPR) and
encompass Sidama & Gedeo Zones that are among all the coffee growing region of Ethiopia,
bounded between 37° 54'N to 39°8 N latitude and 5° 52'E to 7° 13'E longitude in which most
part of it situated in the rift valley lakes basin and the remaining part in Genale Dawa basin .
The study area has different land form characteristics varied from High Mountain up to low
lands: its altitude varies from the highest peak (3000m) up to lowlands (1100 m)
High water usage, channeling residual water and the pulp together, in efficiency of the
traditional waste disposal pits, absence of monitoring and lack of sustainable wet coffee
production strategy and policy are some of the factors that aggravate the impact of the
processing plants on the poll ution of water bodies were di scussed in problem identification
and analysis.
Measured values of physical parameters such as turbidity and pH are out of the range of
WHO guideline values and standards. From the Physical observation itself during coffee
processing periods rivers and streams have objectionable color odor and taste so that the
waters have evil or pungent small and test.
TDS and EC values of rivers and streams in particular spring and boreholes in general shows
that the water is fresh.
Based on the measured value of the total hardness in terms of CaC03 the surface and
groundwaters of the study area classified as moderately hard.
The limited water chemical analysis fi'om previous representative sources indicated that the
river and ground waters are Na HC03 type of water, the dominant cation being Na and anion
bicarbonate.
The highest value BOD and COD in river water is 8750 and 3120mg/1 that have a potential
for decreasing greatly the level of dissolved oxygen in the rivers that reduces the diversity of aquatic life. The maximum COD value of the effiuent obtained from this analysis
(24,600mg/l) is 98 times higher than the EPA standard fro effiuent discharges to inland
waters. The highest BOD value was 39 times higher than the EPA standard.
The bad, evil and pungent smell that can be sensed along the river courses during coffee
processing periods were explained by the concentration of Ammonia (NH3) that was ranged
from 1.48to 90mg/1 and was much higher than the recommended limits.
The highest nitrite (N02-) concentration was 60mg/1 in Melkadimtu Rivers. From the total
analyzed samples about 50% of them had their values were nearly I mg/I, which are far higher
than levels in unpolluted waters (0.03mg/I). Rural communities that use river water as their
source of water supply may expose to carcinogenic effect due to this level of nitrite.
Coffee pulp, which is one of the bypro ducts of coffee processing, have some economical
applications that may become evident as their use is increased. Compost and fertilization,
Pulp beverage, animal feed, fuel wood substitutes are some of the suggested measures to be
taken to mitigate the effects.
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Water Pollution Quality Assessment