Towards phosphorus circularity: biofilm EBPR with subsequent struvite production at the Hias WWTP: insights from full-scale laboratory testing

Abstract

ABSTRACT The Hias wastewater treatment plant (WWTP) has developed a novel biological removal process (the Hias Process) and now operates at full scale. Additionally, a struvite reactor is installed to capture phosphorus. The Hias WWTP aims to reduce its CO2 footprint and move towards circularity by recovering influent phosphorus as a struvite fertilizer and increasing plant availability of phosphorus in biosolids. The main factors affecting recovery include the use of precipitation metals and bypass of the enhanced biological phosphorus removal (EBPR) treatment, as well as temperature's impact on PO4 release from EBPR sludge. The Hias Process, which combines EBPR and moving bed biofilm reactor (MBBR), has demonstrated stability and effectiveness even in cold climates and during stormwater events. The Hias Process reduced the use of precipitation chemicals, leading to a lower carbon footprint. This combination of EBPR and MBBR also contributes to increased phosphorus circularity. That is achieved through improved plant availability of phosphorus in biosolids and the production of struvite. This study aligns with Sustainable Development Goals and emphasizes efficient phosphorus recovery through the Hias Process, P-stripper, and struvite reactor.