Effectiveness of Sewage Treatment System and its Irrigation Potential: the Case of Main Campus of Hawassa University, Ethiopia Kannan Narayanan*and Brook Abate Hawassa University, Institute of Technology, School of Biosystems and Environmental Engineering Abstract - This research evaluated the performance of sewage water treatment system and also assessed its suitability for irrigation. Salient water quality parameters were determined at different stages of the treatment process and compared with the standard. The treatment unit comprised of anaerobic, facultative and maturation ponds in two series. Sampling were done in different time periods from 2014-2016. The university main campus produced an average of 320m 3 of wastewater per day. The effluents of the treatment system are discharged to nearby land whenever there is overflow from the system. After treatment BOD, COD and SS were reduced by 76, 45 and 53 percent respectively. Treatment performance has been on increasing trend since 2014. Water quality analysis revealed that the treated wastewater is slightly alkaline in nature. Percentage treatment efficiency of the pond for BOD, sulfide, Total Suspended solids, COD, Nitrate, Nitrite and Total Nitrogen were satisfactory. However, the effluent TSS concentration was higher than standard set by the EPA standards for treated effluents. In present conditions, the treated water can be used for irrigation purpose with some moderate restrictions. Even though EC and TDS permit to irrigate fruit trees and fodder crops, there is a risk of soil degradation due to high value of SAR. In such cases high efficiency irrigation systems are recommended rather than flood irrigation. Also, irrigation with treated waste water increased nutritive elements in soil that can be source of nutrition for plants. Continuous use of treated sewage water for irrigation will make the soil acidic. Analysis of other soil parameters indicates that there is an increase in nitrogen, phosphate and potassium nutrient levels considerably to benefit crop production but increase in soil EC is a serious concern. Key words: Sewage water, Treatment efficiency, Irrigation, Soil properties. I INTRODUCTION Wastewater irrigation is substantially a growing worldwide practice. Globally, around 20 million hectares of land are irrigated with wastewater and this figure is likely to increase during the next few decades. Wastewater irrigation has been practiced with several drivers. One, in water scarce areas (arid and semi-arid climate zones) the limited water source have insignificant contribution to support agricultural production, thus the direct or indirect use of wastewater is one way of sustaining agricultural production. Two, cities of low and middle income countries with rapid urban expansion produce a large volume of wastewater and this attracts farmers to enhance their agricultural practice with irrigated agriculture. Moreover, the rapid population growth results in market demand rise for vegetables which cannot be transported longer distance and encourages farmers near cities to grow vegetables. Three, the direct use of wastewater in some cases is driven by its ready availability compared with the huge cost needed to construct irrigation structures. Four, availability of plant essential nutrients from the biodegradable constituents of wastewater attracts farmers to use it for agriculture. In that sense, it enables farmers to reduce the expenditures on fertilizer and better production can be achieved. In some cases up to 37% increase in harvest is possible when raw wastewater is applied compared to freshwater irrigation with chemical fertilizer (Martijn and Redwood, 2005). The value of wastewater for crop irrigation has also been recognized in India, China and lately, the Middle East (Pescod and Alka 1988). In Egypt, acute shortage of water necessitates the development of new water sources. The supplies of sewage water effluent progressively increase with increasing the population. At present, land application of wastewater is considered to be the best solution for disposal problems. It is a low-cost method for the disposal of wastewater; land application permits the reclamation and reuse of valuable resources such as water and nutrients from sewage (Abdel Ghaffar et al. 1985, Wang 1984). Despite its positive contribution to stimulate agricultural production, unwise use of wastewater for irrigation has associated adverse impacts on environment public and animal health. Wastewater mostly comprised of organic matters, nutrients, heavy metals, pathogens and other miscellaneous constituents. The direct discharge of wastewater into nearby streams without pre-treatment will modify the natural water constituents. When the mixed water is used for irrigated agriculture, the wastewater constituents flowing to the field interferes beneficially or harmfully to the crop, environment public and animal health. When the concentration of harmful water constituents goes beyond the acceptable level, it has associated adverse effect on the crop, growing environment, public and animal health. Pond systems are commonly employed for municipal sewage purification, especially in developing countries, due to its cost effectiveness and high potential of removing different pollutants. Oxidation ponds are designed to achieve different forms of treatment up to three stages in series, depending on the organic strength of the input waste and effluent quality objectives. Usually, classical oxidation ponds consist of an anaerobic pond, followed by primary or International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 http://www.ijert.org IJERTV6IS100146 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Published by : www.ijert.org Vol. 6 Issue 10, October - 2017 296