adminBULAWAYO residents could be faced with an unexpected water crisis, amid revelations that the local authority is faced with an acute shortage of some key water treatment chemicals, it has been learnt.
According to the latest council report, the local authority has run out of ammonia while their polyelectrolyte stocks are also running low. Ammonia is used to assist chlorine in the disinfection process of water while polyelectrolytes are used in a process coagulation and flocculation which helps clear murky waters.
The report states that while the city’s Ncema Treatment Works requires 300 kilogrammes a month of ammonia they currently do not have any in stock. At the same station, the city also does not have any stocks of polyelectrolyte, of which they require 450 kilogrammes a month. At Ncema, the city is also left with just nine days worth of Chlorine.
The local authority has also totally run out of Polyelectrolyte stocks at their Criterion. Commenting on this issue, Bulawayo City Council public relations officer Miss Bongiwe Ngwenya, however, said there was no need for residents to panic as these chemicals were not a crucial component of the water treatment process.
“Ammonia is simply meant to keep chlorine in water for a long period, of which if we don’t have any we simply increase the chlorine which we use. Polyelectrolytes on the other hand are a mere catalyst, therefore at the end of the day there is no need for residents to panic on this shortage,” said Miss Ngwenya.
However, a water and sanitation expert, Engineer Khonzaphi Dube, who is also a chemical engineer and member of the Water Institute of Southern Africa, said there was a need for a bit of worry, noting that the chemicals had their own crucial role to play in the water treatment process.
“Water contains impurities which include dissolved salts, colloidal natural organic matter and suspended materials which include clays, bacteria and algae. Water treatment facilities employ sedimentation and filtration processes to separate the suspended material from water. Polyelectrolytes facilitate bonding between the suspended particles to form larger flocs which settle at a faster rate. Improved settleability increases the capacity of the treatment plants to produce very clear water. In addition the polyelectrolytes improve the subsequent treatment of the sludge produced from these plants,” said Eng Dube.
He noted that less polyelectrolytes means slow water production and murky waters. Eng Dube said chlorine was a primary disinfection agent while ammonia was secondary, where he revealed that it was now an alternative that has been largely adopted by most treatment facilities as an alternative to the conventional chlorination process.
“Chlorine is primarily used as a disinfectant to reduce pathogenic micro organisms to levels deemed safe by public health standards. Ammonia can be added as a secondary disinfectant after chlorination. This chlorine reacts with the ammonia to form chloramines which are more stable and do not dissipate as quickly as chlorine and hence disinfection continues for much longer after addition. Other benefits provided by the use of chloramines is that the drinking water odour and taste is improved,” said Eng Dube.
He said the major crisis which the local authority could be faced with if the chlorine runs out totally.
“Chlorination as a standalone process is adequate for killing pathogens in water and improving taste and colour.
Given the financial constraints that the municipality might be having, they can operate without the ammonia step but should they run out of chlorine, and if they do not have an alternative disinfection method, I don’t think they will supply the water for public consumption,” said Eng Dube.
This is not the first time the local authority has faced a chemical shortage. A couple of years ago the city also endured an acute shortage of water treatment chemicals that resulted in a cessation of purification of water at its Criterion Water Works.
Bongani Ndlovu
Online Reporter