Mystery white foam pollutes river

Banks of snow white foam accumulated in and around a section of the Sandspruit in Katherine Street, Sandton, on Wednesday.

The foam appeared to be soap suds from some kind of detergent, and had built up into towering walls - about 1.5m in height - particularly around fast-flowing water.

The foam appeared to be coming from a stormwater drain that feeds into the river, but there was too much of it to be certain.

According to The Star photographer Antoine de Ras, who had been at the same site a few weeks ago, there was a notable absence of wildlife.

On the last occasion he had seen ducks and kingfishers, but the only birds there on Wednesday were two hadedas.

Joburg Water spokesperson Baldwin Matsimela said there had been complaints about nearby factories in Wynberg dumping contaminants into the Sandspruit.

Wetlands and riparian expert Paul Fairall said the culprit was a washing powder factory in Wynberg.

He said the factory was regularly washing out its solphonic acid tanks into stormwater drains that filter into the Sandspruit.

Solphonic agent is the foaming agent of washing powders.

"It will kill any kind of living organism - in that concentration it has a horrible effect.

"What worries me is that it happens on a regular basis and it's never addressed," said Fairall.

CSIR research group leader in ecosystems and human health, Dr Paul Oberholster, said that if the contaminant was from a detergent it would change the chemical structure of the water by either raising or lowering the pH.

This would affect the entire food chain - birds, fish, microvertebrates, and phytoplankton (algae) - because some species have a certain ph tolerance.

Detergents also contain a lot of phosphate.

This encourages the growth of blue-green algae, which can be toxic, and is responsible for problems currently being experienced at Hartbeespoort Dam.