HTH Scientific

OR Tambo

Problem:

Proper sanitation of the drinking water at OR Tambo International Airport is of utmost importance. Failure to do proper sanitation will have serious health implications, as most of the 60 mega-liters flow per month, are used for human consumption.

Sodium Hypochlorite was formally dosed via a chemical dosing pump. The chemical dosing tank were underground, thus 20litre Sodium Hypochlorite drums needed to be de-caned once a month, to fill the 1000litre dosing tank. Sodium Hypochlorite damps use to fill the air, making the work environment uncomfortable and not save.

The customer had occasional problems with flooding in the pump room, as the 10 bar pressure would push the 6mm Sodium Hypochlorite dosing line out of the dosing point, releasing huge quantities of water into the downstairs pump room. The customer in question approached Arch Chemicals (Pty) Ltd to propose alternatives for both the chemistry and dosing equipment.

Pulsar SA

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Problem:

The proper sanitation of the final effluent at a Sewage plant is of utmost importance due to the fact that this water is released into the environment. Failure to do proper sanitation will have serious health implications for both people and animals that might be exposed to the water. Sodium Hypochlorite was dosed firstly via a gravity feed system and then through a chemical dosing pump. Due to the small feed rates the Sodium Hypochlorite would crystallize in low flow areas resulting in blockages and hence no sanitation takes place. The customer in question approached Arch Chemicals (Pty) Ltd to propose alternatives to both the chemistry and dosing equipment.

Phoenix NAB

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Problem:

Proper sanitation of the raw water at Phoenix NAB is of utmost importance. Failure to do proper sanitation will have serious health implications, as most of the water is used in the process for the manufacture of cool drinks for human consumption. Sodium Hypochlorite was previously dosed by means of a small chemical dosing pump into the make-up water line. When the incoming water flow rate increase the sodium hypochlorite dosing pump needed to be adjusted manually to ensure the correct levels were maintained for proper sanitation. Further problems were encountered as the dosing line became blocked due to crystallization of the chemicals in the tubing. It was also discovered that there were abnormally high levels of bromates and chromates in the finished product. The major contributing factor to these increased levels was found to be the Sodium Hypochlorite.

RWB Zuikerbosch - HTH dosing units as back-up chlorination system to Chlorine gas.

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Problem

Disinfection of the semi treated water with chlorine gas could be interrupted by either planned - or unplanned events which include the following:

Planned interruptions

Maintenance on chlorine gas dosing system.
Cutting new lines into existing lines of carriage water.

Unplanned interruptions

Isolated power trip on chlorine gas systems.
No carriage water available for injectors due to pipe bursts.
Evaporators’ breakdown.
Chlorine gas leaks.
Change-over valves on chlorine gas banks stuck.

In the above mentioned emergency events, it is not possible to continue Chlorine gas dosage at the suction head after the sand filters (Station 4) or in the suction ring with injectors feeding the main pumps (Station 1 & 3). An alternative disinfection program then needs to be followed in order to supply water quality that is within the specifications mentioned in point 3.

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