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

Abstract

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 (Kützing) 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.

Reclamation Potential of Onsite Wastewater Post-Treatment with Microalgae: Chemical Elements Perspective

“…The DO and pH in the reactor show high variations (Table 2). This is a common observation for these types of bioreactors since the values of these two parameters are strongly affected by the illumination and the photoperiod of the bioreactor [41]. The values of DO and pH affect the P removal in the algal reactor due to a process known as "alkaline precipitation" as well as metals removal and accumulation by the algal biomass, as discussed in the introduction.…”

A Review on the Reliability and the Readiness Level of Microalgae-Based Nutrient Recovery Technologies for Secondary Treated Effluent in Municipal Wastewater Treatment Plants

“…); the accommodation period is shorter and the treatment process is initiated faster. Another advantage of this approach is that the system is more stable and there is less chance of displacement of the preliminary selected culture [21,30,31].…”

“…If not addressed properly, this process could lead to inefficient nutrient removal due to decreased algal activity and lower effluent quality [8,65,102]. Such dynamics of the three parameters-CO 2 , pH, and DO-occur in all algae-based wastewater treatment reactors [8,21,34,104]. Both the preferred pH level of the strain and the CO 2 concentration in the reactor should be synchronized, when this is possible, in order to achieve the most favorable conditions for the specifically used algal strain for the optimal removal of nutrients from the wastewater medium [8,102].…”

The Readiness of the Water Utilities in Bulgaria for Transition toward a Circular Economy

“…After presenting the SWOT analysis, the managers of Sofiyska Voda are interested in launching investigations for the reuse of filter backwash water in the DWTPs, as well as application of green roofs to decrease and retardation of stormwater runoff to further increase the efficiency of the biogas yield. Furthermore, the effluent of Sofiyska Voda WWTP Kubratovo was experimentally studied for the possibility of the application of post-treatment with algae-based bioreactors-a circular solution technology that has emerging economic and ecological potential [32,33]. Sludge and wastewater from UWWTPs operated by ViK Burgas were studied concerning P-recovery through the production of struvite [34,35], The cooperation of the remaining selected WSSOs with research institutions needs to be intensified in the future.…”