Wastewater Treatment Coagulant Reduced by Up to 50%... Seoul City Registers Patent for 'Wastewater Treatment Cost Reduction Technology'

Seoul Water Institute and Jungnang Water Reclamation Center Collaborate to Improve Coagulant Injection Method in Sewage Treatment
Reducing Coagulant Injection by up to 50%, Increasing Phosphorus Concentration Recovered as Resource by More Than 5 Times

[Asia Economy Reporter Lim Cheol-young] The Seoul Water Institute announced on the 23rd that it has developed and completed patent registration for a technology that can reduce the amount of coagulant used to remove phosphorus (P) at sewage treatment plants by up to 50% and increase the concentration of phosphorus recovered as a resource by up to five times, in collaboration with the Jungnang Water Reclamation Center.

The patented technology, named "Method for Dispersed Injection of Coagulant in Sewage Treatment Equipment" (Registration Number: 10-2289906-0000), involves the dispersed injection of iron- and aluminum-based coagulants to reduce sewage treatment operating costs while simultaneously recovering high concentrations of phosphorus (P).

As of last year, the annual amount of coagulant used at sewage treatment plants in Seoul was 56,000 tons, which translates to an annual cost of 11.4 billion KRW. The Seoul Water Reclamation Center purifies sewage by circulating the mixed liquor from the aerobic tank back to the anoxic tank in the biological reactor (anoxic tank + aerobic tank) to remove organic matter and nitrogen (N), during which coagulants are injected to remove phosphorus (P).

The institute conducted research to automatically control the injection location and ratio of coagulants during the sewage treatment process to reduce coagulant usage while increasing the concentration of phosphorus recovered as a resource. Previously, coagulants were only injected at the end of the aerobic tank in the biological reactor, but insufficient mixing intensity and time could lead to excessive coagulant injection.

The "Automatic Control Technology for Dispersed Injection of Coagulants" devised by the institute automatically disperses an appropriate amount of coagulant not only at the end of the aerobic tank but also in the middle of the aerobic tank and the anoxic tank, reducing the injection amount by up to 50% and improving phosphorus treatment efficiency. It automatically calculates the injection location and amount by comprehensively considering the mixing intensity and time of sewage and coagulants within the biological reactor, as well as biological treatment efficiency.

The institute conducted a two-stage research project consisting of pilot experiments and field experiments to verify the effectiveness of the technology. Both experiments confirmed a reduction in coagulant injection amount by 20-50%. Changing the coagulant injection location from the end of the aerobic tank to dispersed injection resulted in a 20-50% reduction in coagulant dosage compared to the previous method in both pilot and field experiments at the Jungnang Water Reclamation Center, while minimizing adverse effects on microbial activation.

Applying this technology in the field is expected to reduce coagulant costs, which account for a large portion of sewage treatment expenses, by at least 2.2 billion KRW and up to 5.7 billion KRW annually. Additionally, by automatically controlling the injection ratio of iron- and aluminum-based coagulants, it stably treats total phosphorus and enables phosphorus recovery from return water generated from sewage sludge at concentrations five times higher than before.

Dr. Jang Sin-yo of the Seoul Water Institute stated, "This patent is an innovative technology that significantly reduces coagulant usage and sludge generation during sewage treatment while enabling phosphorus treatment and recovery simultaneously." Kim Hye-jung, director of the Seoul Water Institute, said, "Our institute has completed registration of five patents related to sewage treatment, sludge, and odor, including this technology. We will continue to be a hub for research and development that can develop and apply new technologies through collaboration with the field."

This content was produced with the assistance of AI translation services.