| dc.description.abstract | Agriculture in Uganda is predominantly rain-fed and this has been increasingly affected by climate change and variability, erratic rainfall patterns, prolonged dry periods, flood. The government of Uganda constructed irrigation schemes that include Mubuku I & II, Doho I &II and other schemes to meet the production of food for the growing population. These schemes abstract water from rivers/ streams which they use for irrigation and later discharge it into the original water source downstream. This research project was aimed at Water quality audits of Mubuku I irrigation scheme and treatments for environmental discharges. As it is just presumed that the scheme adds pollutants in the water used for irrigation and other domestic use in a way that after the scheme, its quality is so bad that would negatively impact the environment. Therefore, the baseline water quality data in relation to the established standards by NEMA and WHO and characteristic flows of the river was developed, water quality assessment was carried around the Mubuku I irrigation scheme and the treatment operation unit was designed to treat the water before being discharged into the environment. Baseline water quality data in relation to the established standards by NEMA and WHO and characteristic flows of the river was determined from the water quality standards for discharge to the environment and portable water standards. Then following the standards, a table of the parameters that were aimed at with their corresponding ranges was developed to be used in water quality testing and monitoring. Water samples were picked at five different points that is one at the diversion point before the water enters into the scheme, then two points with in the scheme and two points at the final discharge of two phases. The samples were picked three times and carried to the laboratory for testing of parameters that is pH, EC, Phosphorus, Potassium, Calcium, Nitrates, Lead and Magnesium. The results obtained were, Potassium range was from 0.68 – 2.38 mg/L, for Phosphorus was from 0.16 – 0.51 mg/L, for Magnesium was from 0.2 – 3.59 mg/L and for Nitrate was from 0.012 – 0.119 which were too low as compared to the standards. However, it was observed that the values with in the irrigation scheme kept on increasing and the results downstream of the irrigation scheme were higher than the ones up stream and from the discussion with farmers, during planting period due to the fertilizers applied, the scheme releases very contaminated water that can’t be used for other purposes downstream hence a call for design of the constructed wetland to treat that water. The constructed wetland was designed as the treatment operation unit, water from the irrigation scheme first enters in the basin, the pipe that lets in water into the constructed wetland was sized with the diameter of 0.3 m, then the length and width of the wetland as 80 and 30 m respectively. The depth of water in the constructed wetland was 1 m. From the simulation analysis of the constructed wetland, as the concentration of nitrates increases, the hydraulic retention time increases and for phosphorus and potassium, the hydraulic load rate reduces to enable the treatment of water to acceptable standard discharge to the environment. Therefore, the constructed wetland can help to treat the polluted water from the irrigation scheme so as to enable the reuse of water for other purposes from the irrigation and also to avoid pollution the river downstream. | en_US |
