乌干达卡塞塞钴矿人工湿地.doc

THE OPTIMISATION OF A REEDBED FILTER FOR EFFLUENT TREATMENT AT KASESE COBALT COMPANY LIMITED – UGANDA (Byekwaso, Evaristo1 ; Kansiime, Frank2; Logstrup, Jorgen3. and Andersen, Soren3) 1 Kasese Cobalt Company Limited, P. O. Box 524, Kasese, Uganda; 2 Makerere University Institute of Environment Natural Resources, P.O. Box 7062 Kampala, Uganda; 3Transform ApS, Danish Rootzone, Borgergade 6 DK-1300K Copenhagen, Denmark. E – Mail = byekwaso.evaristo@kccl.co.ug ABSTRACT Wetland systems are cheaper alternatives used to treat wastewater compared to conventional means. In the last decades, wetland systems are increasingly being applied in the treatment of various metal mine drainage waters. Kasese Cobalt Company Limited (KCCL) is currently testing the potential of using a constructed wetland to treat an effluent from its cobalt processing plant. Eighty per cent of the effluent (1498 m3/day) from the plant is discharged into River Rukoki. The remaining effluent is discharged into a constructed wetland for treatment. The constructed wetland is planted with Phragmites mauritianus and consists of two reedbeds Reed Bed Filter A (RBA) and Reedbed Filter B (RBB) with RBA feeding its effluent to RBB. The reedbed made up of two units of area 1000m2 and 800m2 designed to treat 20% of the nominal effluent flow of the plant. This pilot constructed wetland is being optimised for eventual treatment of all the effluent from the plant facilities. The study going on involves physical and chemical plant characterisation (growth, plant biomass density, and stem thickness, health, nutrients and heavy metal uptake) both in the constructed wetland and River Nyamwamba. The results so far obtained indicate that the reedbeds are efficient at the uptake and retention of heavy metals Cu, Ni, Co, Cd, Pd and Fe. The reedbeds are not retaining Zn and are releasing Mn. The reedbeds are also efficient in retention of nitrogen. There is phosphorous release from the reedbeds. Trend analysis of the