Bioremediation at North End lake shows promising results

13th May 2016 By: David Oliveira - Creamer Media Staff Writer

Water-quality test results following the organic cleanup of the North End lake in Port Elizabeth, in the Eastern Cape, were positive in various critical parameters, suggesting a significant drop in pollution levels, which made the lake unsuitable for swimming events in the past.

According to ecosolutions provider Rhino Water director Sarel Bam, the toxic blue-green algae, faecal coliforms and E.coli levels in the lake have dropped substantially between January and March this year.

Rhino Water was appointed by Nelson Mandel Bay stadium operator Access Leisure and Facilities Management to conduct the organic cleanup, or bio- remediation, of the lake.

Bam highlights that the significant downward trend is a clear indication that the lake’s bio- remediation is taking effect, despite a continued influx of toxins and other pollutants into the lake. He adds that anecdotal evidence, such as a marked increase in the number of young fish, or fingerlings, further suggest improvements.

The most recent test results indicate that inorganic materials, such as dissolved metals and minerals, now meet the national SANS 241 specifications for potable water. Algae and bacterial levels have also dropped significantly, however, they still remain higher than the acceptable standards for recreational use set by the Department of Water Affairs and Forestry (DWAF).

Further, pollutant sludge levels on the lake floor have decreased by up to 200 mm from depths of about 800 mm since the first phase of the project started in November last year.

The second phase of the project, which started on January this year, will continue until the end of June, when another update will be provided.

“Based on the data we have, we are on the right track. Algae levels have improved substantially, while bacterial forms such as E.coli, faecal coliforms and enterococci have also improved, but are not yet where we would like them to be,” Bam notes.

DWAF guidelines state that E. coli and faecal coliform colonies should be less than 130 parts for every 100 mℓ, while toxic blue-green algae levels should be less than six blue-green units a millilitre.

“Some members of the public have also commented on improved water clarity, but this will change as the sludge continues to lift. We are looking at ways of expediting the process to have the North End lake remediated in the coming months,” Bam asserts.

The bioremediation process involves dosing the lake with an imported proprietary product containing natural bacteria and coenzymes, which effectively lift and digest sludge from the bottom of the lake.

“Our dosing regime currently involves spraying 3 400 ℓ of product into the lake a week . . .” explains Bam.

Gabions built by consulting engineers Africoast at various water-entry points have also contributed to containing the inflow of solid waste material such as plastic bags.

This two-part process is envisaged to allow for the holistic remediation of the lake.

The cleanup has been rolling out under the watchful eye of Access Leisure & Facilities Management, with company CE Chantal du Pisani noting that the progress at North End is the result of the good work carried out by Rhino Water and Africoast.

“The vision has always been to establish a world-class water sports location, adjacent to the . . . sport fields that we have in the Nelson Mandela Bay stadium. “This will provide a unique setting for all kinds of sporting and leisure activities, but the key to this is a safe, clean and well-maintained North End lake.”

Du Pisani adds that the rejuvenation of the North End lake precinct is critical to achieve this goal.

The lake is expected to open for the public towards the end of this year.