Upgrading the Sjölunda WWTP according to a novel process concept

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies

Background:

• The Sjölunda wastewater treatment plant in Malmö, Sweden, required upgrading to meet future stringent effluent standards.
• The upgrade focused on extended nutrient removal, specifically targeting biochemical oxygen demand (BOD7), total phosphorus (P), and total nitrogen (N).

Purpose of the Study:

• To detail the cost-effective and compact upgrading of the Sjölunda wastewater treatment plant for enhanced nutrient removal.
• To assess the plant's ability to meet future effluent standards of 10 mg BOD7/l, 0.3 mg total-P/l, and 8 mg total-N/l.

Main Methods:

• Conversion of existing trickling filters for BOD-removal to a nitrifying mode.
• Implementation of a sequencing batch reactor for supernatant nitrification to manage ammonia load.
• Utilizing a moving bed biofilm reactor with an external carbon source for denitrification.

Main Results:

• The upgraded plant successfully met the targeted future effluent standards.
• Nitrifying trickling filters demonstrated stable performance under varying loads, achieving high rates and low effluent ammonia.
• Effective post-denitrification was achieved through controlled carbon source dosage and prevention of phosphorus limitation.

Conclusions:

• The upgrading strategy proved cost-effective and compact, successfully integrating new processes with existing structures.
• The plant's modified trickling filters and sequencing batch reactor effectively managed nutrient loads.
• Stable and efficient nutrient removal, particularly nitrogen, was achieved through optimized denitrification processes.