Phosphorus recovery from domestic wastewater via Candida tropicalis: Performance and mechanism

Abstract

There is a widespread concern regarding the contradiction between the increasing scarcity of phosphate ore resources and the urgency of removing phosphorus from wastewater. In this study, a maximum of 168.33 mg of phosphorus was removed per gram of Candida tropicalis (C. tropicalis). The optimal fermentation conditions for phosphorus removal by C. tropicalis were determined through single-factor and orthogonal experiments. Phosphorus removal was up to >80 % under the conditions of glucose as sole carbon source, 60 rpm, dissolved oxygen of 7.0 mg/L, C/P of 100, N/P of 3.5, pH of 6.0, and temperature of 30 °C. 50 %–62 % and 38 %–50 % of phosphorus were transferred to yeast cells and extracellular polymers, respectively. Transcriptome analysis revealed unregulated genes of sat, cysH and cysJ in the sulfur metabolism under anaerobic conditions, with glutathione serving as a sulfur reservoir. A rational pathway for phosphorus metabolism was proposed, revealing phosphorus could be stored in its cells as polyphosphate under aerobic and anaerobic conditions.