| dc.description.abstract | Wastewater treatment constitutes a major problem in urban centres of developing countries like Uganda. The world focuses on protecting the environment and ensuring sustainability, thus, low cost and less technical natural wastewater treatment methods like constructed wetland systems (CWS) are now preferred to conventional treatment methods. The objective of this study was to investigate the effect of continuous flow of domestic wastewater on phytoremediation using water hyacinth.
The treatment system was operated in continuous mode for 35 days. The physical and chemical characteristics of the influent and effluent of the units fed with clean water(control), the digested sludge, raw wastewater and facultative and physical characteristics of water hyacinth were determined.
The removal efficiencies: in the unit fed with digested sludge were 24.8%, 85.5%, 86.7%, 60.4%, and 67.8% for EC, COD, TSS, TN and TP respectively. In the unit fed with raw wastewater, the removal efficiencies were; 14.9%, 56.6%, 80.1%, 33.6%, and 4.8% for EC, COD, TSS, TN and TP respectively. In the unit fed with facultative effluent, the removal efficiencies were; 23.5%, -24.6%, 23.4%, 23.5% and 6.6% for EC, COD, TSS, TN and TP respectively. In the unit fed with raw wastewater, the removal efficiencies were; 31.6%, -149.6% -1053.4%, 62.1% for EC, COD, TSS and TN respectively. A harvesting interval of 21-28 days was recommended for phytoremediation of wastewater for efficient treatment performance. However, feasible harvesting methods need to be developed for removing only matured mother plants, leaving baby water hyacinth in the treatment system. The Stover-Kincannon was investigated for removal of TN and TP. The UMAX for TN were -13.64,1.27, -2.17, -13.32 and for TP were 3.09, 0.16, -0.08 mg/l/d for the unit fed with digested sludge, raw wastewater, facultative pond effluent and the control setup respectively. These values are very low, indicating decreased consumption and inefficiency of the system for removing TN and TP.
It was found that the effluent from all units fed with wastewater did not meet the discharge standards of Uganda, 2020 for the parameters investigated except pH. This study recommended that further investigation on the possibility of using water hyacinth for primary wastewater treatment as opposed to the common use in treatment of wastewater at tertiary stage. | en_US |
