According to Parkson, the installation at the wastewater treatment plant is the first of its kind to pair an MBR system with Parkson’s new DynaSand EcoWash sand filtration technology.
 
“The DynaSand was the best fit for this application because it has a proven record of producing very low phosphorous levels on a consistent basis,” said Marianna Novellino, Parkson product manager for ENR (enhanced nutrient removal) and filtration. “Additionally, the plant is benefiting from the new DynaSand EcoWash configuration, which keeps reject water and energy costs as low as possible.”
 
The installation in Korea consists of 10 DynaSand EcoWash filters, divided into two cells which process the flow from two separate membrane bioreactor units. Unlike traditional filters that operate on a continuous backwashing schedule, the EcoWash design relies on intermittent backwashing to achieve high quality filtrates with minimal energy use.
 
This wastewater treatment plant posed a unique setting for the DynaSand, because the membrane bioreactor system produces a very low level of suspended solids which makes phosphorous precipitation and flocculation more difficult. Another challenge was the alkalinity of the effluent water, which limits the amount of chemical addition to meet the minimum pH limit of 6. Despite these challenges, the DynaSand EcoWash can successfully maintain adequate flocculation and remove phosphorous to the required level of <0.3 mg/l with a Poly Aluminum Chloride (PAC) addition, while meeting the pH requirements. Notably, the DynaSand achieves these results without the benefit of additional residence time or equipment between the chemical addition and the filters. The chemical is injected in the feed pipe, passing through a static mixer, and into the filters where flocculation and separation occur.
 
The design at the plant also includes a Lamella gravity plate settler to treat reject water from the DynaSand to further reduce the overall reject flow from the filter system.