Fast food outlets in Bulawayo are among the major contributors to sewer blockages by discharging hot effluent that solidifies within the sewer pipe causing blockages.
This was said by City of Bulawayo Principal Chemist, Clout Moyo during a Water and Service Delivery meeting held at the Large City Hall on Thursday on the effects of trade effluent on water waste management.
Moyo explained that heavy solids may induce silting of the sewer line leading to reduced flows resulting in backflows, blockages and bursts.
He noted that this may also lead to septicity and the production of hydrogen sulphide. Said Moyo:
We have realised that fast food outlets have become a problem in this area. Every time, food outlets discharge effluent that is hot and this effluent leaves the plant company in liquid form because it’s very hot but along the way it changes and becomes solid.
That solid causes siltation of the sewer and downstream the sewer will not flow by backflowing.
That is a cost to the council because the council now has to clean those sewers and try to remove that dirt within the pipes.
Moyo also revealed that some industries even discharged acidic waste that eat away sewer infrastructure. He said:
Acidic vapours occasionally escape from the main effluent body to the upper part of the sewage pipe where they attack and weaken the sewer fabric, over time leading to sewer collapses in extreme cases.
The corrosive effect is common where the effluent contains a high concentration of sulphate for example.
In an acidic environment, sulphates are converted to hydrogen sulphide which is very corrosive and toxic to infrastructure and workmen respectively.
Moyo implored industry to establish pre-treatment facilities at their premises before discharging the effluent to the council sewerage system.