Grey water treatment through biofilm development and sediment accumulation in a horizontal batch-operated open reactor

ABSTRACT

To upgrade grey water for higher-purpose reuse in decentralized systems, simple process unit operations for mineralization of bulk organic matter and removal of non- or slowly degradable particles are required. We conducted two 16-day experiments on light grey water, using a shallow, open to the air reactor of 2 m × 0.6 m × 0.05 m, equipped with a 0.05 m thick polyamide net to support passively aerated biofilm, and applying a gravity-driven batch flow-mode at 1.44 m³/day, first with full drainage of each batch (60 L), then with only half drainage (30 L), leaving a stagnant water layer behind. Turbidity, chemical oxygen demand and total suspended solids were significantly reduced in both experiments, documenting the passive aeration to be efficient, and some sedimentation to take place. Despite 50% shorter hydraulic residence time, the biofilm developed faster and was better distributed in the half drainage experiment, endorsing this principle.

KEYWORDS:

• Biodegradation
• decentralized system
• dual porosity filtration
• passive aeration
• reuse
• suspended solids

Acknowledgements

This work was supported by Danish Eco-Innovation Program MUDP (grant number: NST-404-00203), Ministry of Environment and Food, Denmark. Further support was obtained from Sofiebadet, Copenhagen Municipality, Copenhagen Water Utility Company HOFOR, Rambøll, and Wavin.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplementary data can be accessed here.

Additional information

Funding

This work was supported by Danish Eco-Innovation Program MUDP (grant number: NST-404-00203), Ministry of Environment and Food, Denmark.