The Tasiast Gold Mine is owned by Kinross Gold Corporation, a leading gold mining company with headquarters in Toronto. In 2011, Napier-Reid provided the Mine with two sets of domestic sewage treatment systems for two new worker villages in different locations. The larger village has 9,000 residents, and the smaller village has 100 residents. Both sewage treatment systems have similar treatment processes.
Influent sewage is pumped to an equalization tank through a screw screen to protect downstream equipment. The sewage is then pumped to a Sequencing Batch Reactor (SBR) tank, where BIO-BATCH™ process takes place by activated sludge to remove BOD, TN, and partial TP. In the SBR tank, each operating cycle takes approximately 4 hours and contains 3 stages: Filling/Aeration, Settling, and Decanting. The aeration system provides oxygen through fine bubble diffusers in the tank and mixes sewage with activated sludge until uniform. According to the design criteria of TN, TP, and pH, chemical solutions of Alum and Soda Ash are added to the tank at this stage to decrease TN to 10 mg/l and TP to 2 mg/l.
In the disinfection process, sodium hypochlorite is added into contact with the clarified water. Effluent is then stored in an effluent storage tank for further reuse or discharge.
Surplus sludge from the SBR tank is pumped to the sludge holding tank, and then to Belt Filter Press to be dewatered. Filtrate flows back to the pump station by gravity to be retreated with influent, while dewatered sludge is discharged and incinerated.