Rosser Park

Rosser Park Lake on the Gold Coast, Australia, had severe infestation of algae due to high nutrients in the water system as well as a significant number of harmful, toxic and pathogenic substances. It was in a very poor condition as seen in the pictures on the right. Further pumping was prohibited by the Environmental Protection Agency.

The lake itself had a severe bloom that was both foul smelling and pea green. The underlying cause for the deterioration of the lake has been a combination of events and practices that see run-off from the adjacent Royal Pines golf course flowing into the lake, the topping up of lake levels through the use of of partially treated effluent from a nearby Treatment Plant and increased local use of nutrients and fertilizers. The resultant condition of the lake is a culmination also of the above and general weather conditions which created an environment for the algae bloom. If left in this condition, it would cause a serious risk to health.

Cumminscorp used its own patent systems for purification treatment. No chemicals or additives have been used in any process.

Stage One

As part of a two-staged process, the first stage required the initial use of two land based treatment units either side of the lake to remove the solids and algae bloom with some water treatment aided by a small floating unit in the middle. These performed admirably and were immediately effective, however, the overall quality was still being affected by rainfall, fun-off and topping up with contaminated water.

Stage Two

The second stage of the process approached the overall water quality improvement. Because of the continuing inputs from a variety of factors, it was decided to operate a larger 4 unit floating system set in the center of the lake which ran for approximately 12 days. These results were both extremely successful and aesthetically pleasing to local residents and wildlife.

Independent tests by Simmonds & Bristow was done throughout the treatment period with the following conclusions:

• Turbidity (water clarity) has reduced at surface consistently over the monitoring period with an average total reduction of 79%.
• Total algae count was reduced by 33% over the entire period, with toxic species reducing by 94%. It should be noted that during the first half of the treatment period, algae numbers increased and after installation of larger treatment systems, the numbers began to drop significantly, with the reduction of total count from peak levels approximately 75%. Of particular interest was the disproportionate reduction in the numbers of toxic algae species throughout monitoring, suggesting that the configuration of the treatment system favoured removal of toxic species. Note that the system was tailored specifically to deal with toxic algae as a priority in part generated by the run off from the Royal Pines Gold Course.
• Total Nitrogen reduced over the monitoring period dropping on average 27% from 1.5 mg/l to 1.1 mg/l. Like algae, total nitrogen levels did peak during the first half of treatment and it is suggested that the main reduction in total nitrogen was organic nitrogen associated with removal of algae. Note that actual percentage improvement is greater due to the fact that total nitrogen hit a peak of 1.8 mg/l which is a 40% reduction.
• Total Phosphorus reduced over the monitoring period dropping on average 55%.
• Initial start up readings for Faecal Coliforms and E Coli numbers decreased on average from 300 orgs/100ml to 150 orgs/100ml (50%) for FC and 300 orgs/100ml to 130 orgs/100ml (57%) for EC. Initial start up readings indicated levels in excess of 3200 orgs/100ml for both, indicating that actual performance in combating these numbers was significantly higher at 91% and 96% respectively.