Photo-sequencing batch reactor with Klebsormidium nitens: a promising microalgal biotechnology for sustainable phosphorus management in WWTPs

This study aims at improving the existing algal-based wastewater treatment technologies by overcoming some of the major drawbacks of these systems such as large required land area, culture contamination and energy intensive algal harvesting. The experiments were carried out in an open photo-sequencing batch reactor (PSBR) at a laboratory scale for nearly two months. A specific strain ACUS00207 of the aero-terrestrial green microalga Klebsormidium nitens (Kutzing) Lokhorst was used. The strain is native to Bulgaria and belongs to a species that has never been used before in suspended growth systems for wastewater treatment for phosphorus removal. The culture of Klebsormidium nitens showed promising results: phosphorus removal rates (PRRs) ranging from 0.4 to 1 mg TP L-1 d(-1), efficient settling properties and resistance to culture contamination with native microalgae. On the basis of the observed phosphorus removal mechanism of 'biologically mediated chemical precipitation/phosphorus precipitation', an innovative working mode of the Sequencing Batch reactor (SBR) is suggested in regard to the potential for reduction of the Hydraulic Retention Time (HRT) and respectively the required land area.

Automated summary

This study aims to improve algal-based wastewater treatment technologies by using a specific strain Klebsormidium nitens, which shows promising results in phosphorus removal efficiency and resistance to culture contamination. The innovative working mode of the Sequencing Batch reactor proposed in this study has the potential to reduce Hydraulic Retention Time and required land area.