Abstract:
Wastewater contains a variety of chemical, physical and microbial contaminants which may
significantly affect soil properties as well as ecosystem function when used for different
purposes such as irrigation. Around Harar city, brewery and municipal wastewater has been
in use for irrigating some crops cultivated in the area which may have impacted soil
properties. The study was aimed to investigate the impacts of brewery and municipal
wastewater (BMWW) on selected soil physico-chemical properties and to characterize its
quality for irrigation. Three irrigation sites were selected purposively from Harar city area.
The sites were categorized into three groups depending on the application of BMWW and long
term application: control (non-irrigated), BMWW irrigated farmland for less than ten years
and BMWW for more than ten years. A total of two brewery and municipal wastewater
samples were collected to characterize wastewater quality for irrigation. A total of 36 soil
samples were collected at depth of 0-20 cm for analysis of physico-chemical of the soil. The
brewery and municipal wastewater quality for irrigation analysis showed that pH has
moderate level which is prescribe by FAO and biological oxygen demand, chemical oxygen
demand and phosphorous concentrations were above the permissible limit of FAO
prescription for irrigation quality of water. The results of soil analysis showed that bulk
density was significantly decreased (P<0.001) with the long term application of brewery and
municipal wastewater and moisture contents and total porosity was significantly increased.
The soil electrical conductivity (P< 0.001), cadmium (p < 0.001), lead (p <0.05) available
phosphorus (P<0.001), soil organic matter (P< 0.001) and CEC (P<0.001) levels were
significantly increased as compared to the non-irrigated condition. Magnesium (Mg2+) was
significantly decreased (P<0.001) by wastewater application in irrigated farmland. In
conclusion, the brewery and municipal wastewater have considerable impact to soil physicochemical
properties. An increase of years of application of brewery and municipal wastewater
resulted in significant reduction of BD and Mg2+. The most effective way to reduce/ eliminate
the impact of these brewery and municipal wastewater on the soil is to develop and implement
an effective wastewater management plan.
