Exceeding tertiary standards with a pond/reed bed system in Norway

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Ecological Engineering

Background:

• A community of 160 people, including food processing facilities, utilizes a pond/reed bed wastewater treatment system in Vidaråsen, Norway.
• The system integrates multiple stages: sludge settlement, constructed wetlands, enhanced facultative pond, stabilization ponds, sand filter, and horizontal-flow constructed wetlands.

Purpose of the Study:

• To evaluate the long-term treatment performance and ecological impact of an integrated pond and constructed wetland system.
• To assess the system's efficacy under harsh winter conditions.

Main Methods:

• The treatment train includes sludge settlement, pre-treatment with surface/vertical-flow constructed wetlands, an enhanced facultative pond with Flowform-cascades, stabilization ponds, a planted sand filter, and horizontal-flow constructed wetlands using lightweight aggregate (Filtralite-P).
• Flowform-cascades were employed for year-round aeration, rhythmical treatment, and mixing in the enhanced facultative and primary stabilization ponds.

Main Results:

• High treatment performance was consistently observed over the first five years, demonstrating resilience to harsh winter conditions.
• Average effluent quality: 0.25 mg/l phosphorus, 4 mg/l total nitrogen, 5 mg/l total organic carbon (TOC), and < 100/100 ml thermo-tolerant coliforms.
• The system fostered ecological diversity, supporting populations of ducks, amphibians, and carp.

Conclusions:

• The integrated pond and constructed wetland system provides effective and robust wastewater treatment, even in challenging climates.
• The system's design, incorporating Flowform-cascades and specific wetland media, ensures high effluent quality and promotes biodiversity.
• This approach offers a sustainable solution for community wastewater management, integrating ecological benefits with treatment efficiency.