Innovative, small footprint solution for secondary clarification stage
A food processing company’s wastewater treatment plant was struggling to meet local discharge limits and faced a hard deadline for compliance from the local authority. The problem centered on excessive solids in the effluent. To ease the hydraulic load on the existing concrete secondary clarifier and reduce total suspended solids (TSS), Xylem installed a Taron activated sludge filter.
Challenge: Meet effluent limits with minimal expansion
The plant’s treated effluent exceeded its chemical oxygen demand (COD) discharge limit of 39 mg/L. The high effluent COD was largely caused by solids carryover from the secondary clarifier, which did not have sufficient detention time to settle the solids. The plant also had a second issue: too much ammonium and nitrite in the effluent, due to insufficient aeration and nitrification in the biological treatment process. To address just the first of these issues, the facility was facing an expensive project to build a new secondary clarifier, with added footprint for the plant and significant civil costs.
Solution: Taron activated sludge filter
To provide additional hydraulic capacity for the secondary clarification stage in a more compact footprint, Xylem proposed the Taron activated sludge filter. Employing the structure of a rotating disc filter, the Taron filter uses dynamic buildup and removal of a sludge cake layer on a micro mesh support to provide direct, effective filtration of activated sludge. This reduces the space required to create high-quality effluent. The Taron filter arrived on-site fully configured, requiring minimal civil works, no excavation, and no interruption of the treatment process. This plug-and-play capability meant the client could meet the compliance deadline from the local authority.
Results: Reduced TSS
The Taron activated sludge filter was installed at the client’s treatment facility in parallel with the existing secondary clarifier, and the flow from the bioreactor split between the Taron unit and the clarifier. Return activated sludge (RAS) from the Taron filter tank was returned to the bioreactor. The Taron filter quickly outperformed the conventional clarification process. It reduced TSS to below 10 mg/L, which successfully kept the COD below the stringent discharge limit. By designing the Taron filter tank with a pre-reaction zone, Xylem was also able to allow for extra aeration to help the plant reduce nitrite (NO2-) and ammonium (NH4+) in its effluent.
Given the Taron filter’s success during its pilot test phase, the client ordered a permanent installation. The system was designed to be able to treat the plant’s full capacity, providing the client with maximum flexibility in plant operation. Versatile application The Taron activated sludge filter is a novel, easy-to-implement technology that can relieve hydraulic pressure on secondary clarifiers for both industrial and municipal wastewater treatment facilities. It can help operators:
- Meet effluent targets
- Accommodate changes in hydraulic loading
- Reduce the wastewater treatment footprint
- Address aging infrastructure
Key to the performance of the filter is the sludge quality. High-quality sludge with good settleability produces optimal flux and effluent quality with the Taron filter process. Xylem’s team of biological treatment experts can determine the Taron filter’s suitability and, where possible, adapt the Taron system design to improve the results.