City seeks alternative water chemicals

Source: City seeks alternative water chemicals | The Herald May 21, 2019

Yeukai Karengezeka Herald Correspondent

THREE companies have responded to the Harare City Council’s call for alternative water treatment solutions for Morton Jaffray (MJ) water treatment works. The local authority is seeking alternatives for water treatment due to challenges it’s facing in obtaining an average of US$2,5 million to $2,8 million every month to buy the required chemicals. The authority is using a cocktail of compounds — up to a dozen — to treat water that, however, has been condemned for its physical dirt and turgidity while the chemicals are feared to have the potential to cause cancer.

Harare pumps mainly recycled water from Lake Chivero, which experts say should have been decommissioned having reached unsafe levels of toxicity.

Acting Harare water director Engineer Mabhena Moyo told the Environmental Management Committee meeting that three companies had approached his department and conducted some tests at the plant, which could provide temporary relief.

“Three companies approached the Harare water department and carried out some experiments with various chemicals at the Morton Jaffrey water works with promising results,” he said.

The three companies, Vistma Technologies and Nanotech from South Africa did plant trials, while Kemira did laboratory trials.
All experimental tests carried out at the plant were aimed at improving both production throughput and quality of water through the use of the various chemicals as alternatives to the current water treatment chemicals.

“Vistma Technologies had carried out a plant trial with positive results that indicated the possibility of replacing most of the current chemicals with poly aluminium chlorohydrate that indicated a possibility of replacing most of the chemicals currently in use.

“Kemira did laboratory experiments with aluminium sulphate granular, PAX-XL 3903D flocculants and superfloc A120PWD as a flocculants aid, but did not do any plant trials.

“Though the laboratory tests had been positive, the chemicals used did not indicate if they would replace the current chemicals in use,” read the minutes of the meeting.

Eng Moyo also said Nanotech Solutions had conducted on-site laboratory trials and plant demonstrations using their three chemical solutions (that is chlorine dioxide high molecular liquid polymer (NT948) and silica based coagulant powder (NT750) chemical solution).

“The trials had indicated that chlorine dioxide would be used as pre-chlorination chemical with positive results on killing of algae. However, the chemicals used were in combination with current chemicals.”

A number of companies had approached the department of Harare water with the intention of setting up a chlorine dioxide production plant at the plant.

The committee resolved that council should invite more companies to participate in providing alternative solutions through an Expression of Interest (EOI).

It also resolved that seeking of alternative treatment techniques shall go through the normal procurement process as stipulated in the Procurement and Disposal of Public Assets Act through EOI for interested companies to submit solutions that can increase water production and improve water quality at the plant.

The town clerk Engineer Hosiah Chisango and Eng Moyo advised that the procurement process would be expedited through negotiations with PRAZ for a shorter procurement process.