Water and wastewater treatment equipment supplier Circuit Water Engineering Equipment commissioned a multimillion-rand supply contract for the Darvill wastewater treatment works in Pietermaritzburg, KwaZulu-Natal, in October last year, says company MD Ryan Beswick.

“As the Darvill wastewater treatment works is undergoing a significant capacity upgrade, Circuit Water Engineering Equipment has provided the client, a water management organisation, with nine of its 30 kW floating Aire-O2 Triton aerators as a temporary solution to cope with the higher flow and organic load,” he says.

Circuit Water Engineering Equipment locally distributes the surface-mounted fine bubble aerators, which are manufactured by Aeration Industries, in the US, Beswick explains, adding that the aerators provide efficient fine bubble aeration, while maintenance can be done on site, without stopping the flow or draining the reactors of water and effluent.

Other features of the aerators include a direct-drive low speed of 730 rounds per minute operation that extends aerator life, directional subsurface which significantly improves micro organism suspension, and ensures quiet operation, while the reduced energy consumption can result in up to 50% in electrical savings, he points out.

Further, he adds that the aerators were installed into the aeration basins with an instant improvement in the quality of the eff- luent. The aerators will assist in keeping the eff- luent within discharge limits, while the wastewater works is upgraded to a 90-million-litre-a-day capacity.

Meanwhile, Beswick notes that the Aire-O2 Triton aerator has become a popular temporary solution when a facility has a temporary or new demand for increased aeration, as it can be installed into existing wastewater treatment works aeration basins without requiring any prior civil adjustments.

“Owing to this ease of installation, Circuit Water currently has a fleet of mobile rental units . . . meeting the temporary needs of its customers and the municipalities.”

He adds that customers who have tried these units generally buy more aeration units, while an increasing number of rental customers have also been buying more units.

New Products
The company imported a Dynadisc pilot demon- stration plant last year, which has been installed for testing as a tertiary filter at a wastewater treatment works, where the old sand filters have not been able to cope with the flow, Beswick adds.

The Dynadisc filter is manufactured by Sweden-based screen manufacturer Nordic Water, and filters water, which is guided into a rotating drum and passed through the filter media on the sides of the sets of cassettes, which are covered by filter cloth. Suspended solids are then separated and accumulated on the inside of the cassettes.

High-pressure backwash spray removes the accumulated suspended solids into the reject flume inside the filter, while wash water for the cleaning process is provided by an internal pump using filtrated water.

The suspended solids are then discharged through the reject pipe, Beswick explains, adding that tests have thus far indicated positive results for the filtering plant being used as a tertiary filter for the wastewater works.