Seasonal variability of water quality and nutrient removal efficiency of a restored wetland

Most studies of wetlands in Uganda use for water and wastewater treatment have focused on natural undisturbed pristine wetland and constructed wetlands. There exists a gap in literature surrounding treatment abilities of restored wetland or wetlands on a path to recovery. Water quality parameters were sampled covering wet and dry seasons in a restored wetland. Soil properties were also assessed and compared with a referenced natural site. The objectives of the study were to (i) determine the effects of wetland restoration on nutrient retention and release, (ii) analyze temporal dynamics of water quality parameters in the restored wetland, and (iii) describe soil properties in depths of the restored wetland in relation to a reference natural site. Values of pH, electrical conductivity (EC), temperature, total dissolved solids (TDS), TN and NO3-N showed significant differences across seasons. The wetland demonstrated little water quality benefits but the overall nutrient removal efficiency when compared to literature values was found to be not impressive. Rates for P and N removal were between 3.5 - 19% and -10.8 – 32.4% respectively. These results could be attributed to flooding, low residence time of the water, small size of the wetland, low influent load, extra nutrient inputs from fertilizers and pollution sources as well as release from soil. We recommended that management activities like harvesting; redesigning the channels for water distribution throughout the system and removal of invasive plant species be carried out. This study will form a baseline in understanding the ecology of restored wetlands in Uganda.