Bruma Lake gets cleaned up

SolarBee circulators and Eco-tabs are being used as the first step in a long-term plan to clean up the polluted lake and return it to a normal watercourse.
THE air around Bruma Lake is getting cleaner, and the noxious odour of the polluted lake is subsiding after the City launched three SolarBee circulators to deal with water quality issues on 25 January.

Residents around Bruma Lake will soon breathe in cleaner air, thanks to the solarbeesResidents around Bruma Lake will soon breathe in cleaner air, thanks to the solarbees“The SolarBee is a unique floating, solar-powered, high-flow circulator used in situations requiring improved oxygenation and circulation to address water quality problems,” explained the City spokesperson, Nthatisi Modingoane.

In addition to the circulators, there are other corrective measures in place to treat the lake. For instance, aeration in the lake is being improved through the use of a product called Eco-tabs.

“This will assist the water’s natural ability to deal with the inflow of biochemical oxygen demand,” Modingoane added. Biochemical oxygen demand refers to the amount of dissolved oxygen that is needed by organisms to break down organic material in a body of water.

SolarBee circulators have been implemented effectively around the world, notably in the United States, as well as closer to home in Rietvlei Dam outside Pretoria.

It draws up polluted water into the machine and spreads it across the distribution dish, where it mixes vertically and horizontally to eliminate stagnation and stratification. The SolarBee does this by increasing dissolved oxygen levels, which is the amount of oxygen transported in a specific medium, and improving sludge digestion.

“It has also been shown to be effective in reducing algae and odours by creating a slow but continuous movement of water,” Modingoane said. Best of all is that the circulator requires no infrastructural changes and can be used 24 hours a day because of the low voltage motor and onboard battery system.

While it will not resolve the pollution and odour problems permanently, Modingoane says it will go a long way towards relieving these problems until permanent remedial work can be put in place.

Eco-tabs have been used to treat the lake since December, with regular dosing to improve the product’s efficacy. “Early indications are that the new product appears to be making an impact on the lake, with water clarity improved, reduced odours and the sludge layer beginning to show signs of reduction in certain areas where it was previously exposed,” he said.

Measures have also been taken to try to treat the water before it enters Bruma Lake. “One such measure is the reinstatement of the Queens wetland upstream of the lake, to enable it to perform its natural function as a bio-filter.” A litter trap has also been placed in Bezuidenhout Park, and there are plans to introduce litter baskets and booms in storm water outlets.

“The long term plan includes the re-shaping of the lake basin and the reclamation and reinstatement of a grassed channel with parkland on either side of the lake, returning the area to a normal watercourse and reconnecting the upstream and downstream river reaches,” he explained.