Activated-Carbon Water Treatment Plant
A R15 million lump-sum turnkey project to install a powdered activated-carbon
(PAC) mixing and dosing plant was completed for Rand Water’s System
4, Zuikerbosch Pumping Station at Vereeniging, RSA. This is the first
time that an activated-carbon process of this capacity as been used
in RSA.
Treating the raw water with activated carbon removes taste and odour
causing compounds released into the water by algae in the dams during
the summer months. These compounds are adsorbed on the carbon and are
removed together with the carbon and other solids during the sedimentation
process.
This PAC plant can dose up to1800million litres of raw water per day
with a maximum of 20 mg/l of powdered activated carbon, prior to the
water being fed to seven spiral flocculators. Each of these has the
capacity to treat either up to225 Ml/d or up to 450 Ml/d of raw water
and the maximum daily consumption of carbon is 36 tonne.
The plant supplied to Zuikerbosch comprises materials-handling, mixing
and dosing systems. Bulk deliveries of activated carbon are offloaded
and stored in a warehouse. A proprietary BATEMAN bag-unloader system
feeds the carbon into a BATEMAN Cyclonaire dense-phase pneumatic-conveying
system in which the conveying velocities, pipeline wear and product
degradation are kept to an absolute minimum.
The carbon is passed into two banks of three silos with hoppers designed
to ensure the contents flow en masse to two outlets. From here two identical
parallel trains pneumatically transport the carbon to dedicated mixing
tanks in which batches of carbon suspended in potable
water are prepared under reduced pressure. Each mixing tank is supported
on load cells so that the amounts of water and carbon supplied to the
tanks can be determined accurately to a 20 % concentration.
The suspensions are transferred to two 14 m³ holding tanks which
supply seven reductors which dose the seven spiral flocculators at a
maximum dosing ratio of20 mg carbon/l of raw water.
BATEMAN won the contract to undertake the work in open tender against
several other contractors n the basis that the BATEMAN proposal was
the closest to the specification, was technically acceptable and provided
innovative solutions.
For more details, please contact Marius Botha,
Manager, Water and Effluent Treatment, on +27-11-201-2300 or
email engtech@batemanengineering.com.
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