By Lungile Ngwenya and Abigirl Khupe
The Bulawayo City Council (BCC) has enough water treatment chemicals to last the city for the next six months, as a stop-gap measure to ensure an adequate and constant supply of the chemicals to avert a crisis.
The local authority uses aluminium sulphate, chlorine, ammonia, polyelectrolyte, lime and HTH to purify its water at a monthly cost of US$208 000.
Speaking during a tour of Criterion Treatment waterworks, Wednesday, BCC Engineering services deputy director, Engineer Sikhumbuzo Ncube said water chemicals are always stocked up in advance to avoid a crisis.
“Normally we keep a buffer stock for three months but because of the economic challenges, we have extended to six months, said Eng Ncube.
“If anything happens, we still have another three months to take us through while we are waiting for another replenishment especially for aluminium sulphate.”
He said Criterion Treatment waterworks is the main treatment plant and it is used to stock the water treatment chemicals.
“Criterion treatment plant is 180 megalitres compared to Ncema Water Treatment which is an 80 megalitres treatment plant,” said Ncube.
“If Ncema runs out of chemicals, they replenish from this treatment plant. However, Ncema has its own chemicals as we speak and Criterion also has enough chemicals that will last for six months plus.”
Criterion principal chemist Clout Moyo said, there are five chemicals that are used in purifying the water.
“We use aluminium sulphate, chlorine, calcium hypochlorite, ammonia and polyelectrolyte,” said Moyo.
“Chlorine is used in combination with ammonia. Chlorine is a gas that can evaporate at any time meaning it can escape anytime from the system. So, we have to use a heavier gas like ammonia which keeps chlorine in the water.”
He said the chemical requirement is the same but quantities differ depending on weather changes.
“When it is not raining, we use 40 bags a day at the Criterion treatment plant while at Ncema treatment plant we would be using 24 bags a day,” said Moyo.
“During the rainy season when the water is muddy, we use double the number of bags for polyelectrolytes to clear the mud.”