I visited James Kleynhans Water Treatment Works (JKWTW) on Monday, 11 February, to see for myself the degree of turbidity in the water that was preventing the provision of water to the eastern areas of the city. My timing was fortuitous in that it coincided with a visit by Grocott’s Mail and Mayor Mpahlwa.
The existing plant is antiquated and the sludge draw-off system from the Settling Tanks is clearly inefficient. The demonstration of sediment settling by a gentleman at the GRA meeting on the evening of 11 February, while entertaining, has no relevance to the conditions at JKWTW. Flocculation Jar Tests are used for comparative assessment of efficiency of different flocculants and varying settling rates in a laboratory environment to assist with the operation of a water treatment plant. They do not replicate the actual conditions experienced at the works.
The Plant Foreman at JKWTW is certainly committed to running the plant as best possible and appears passionate about wanting to deliver water efficiently. However the necessity to provide more water than the plant is capable of, at the same time trying to maintain acceptable standards of quality, puts pressure on the operation as routine downtime for cleaning and maintenance is compromised. The treatment of the water should be varied according to the quality of the raw water. When turbidity is exceptionally high the flocculant dosing should be increased and flow reduced. Due to the water demand the foreman does not have the privilege to do this. Some improvement may be possible by using alternative flocculants when raw water turbidity increases and optimising sludge draw-off frequencies. The foreman was aware of these factors and is trying to address them.
The bottom line is that a constant delivery of acceptable water from JKWTW is limited until the plant extensions are completed. The plant should not be run beyond its capacity as this leads to poor quality. It is therefore essential that the available water is managed as efficiently as possible and the plant extensions are accelerated.
Peter Sturrock (MSc Civil Engineering: Water Treatment)