Microalgae-Enabled Wastewater Remediation and Nutrient Recovery through Membrane Photobioreactors: Recent Achievements and Future Perspective

Abstract

The use of microalgae for wastewater remediation and nutrient recovery answers the call for a circular bioeconomy, which involves waste resource utilization and ecosystem protection. The integration of microalgae cultivation and wastewater treatment has been proposed as a promising strategy to tackle the issues of water and energy source depletions. Specifically, microalgae-enabled wastewater treatment offers an opportunity to simultaneously implement wastewater remediation and valuable biomass production. As a versatile technology, membrane-based processes have been increasingly explored for the integration of microalgae-based wastewater remediation. This review provides a literature survey and discussion of recent progressions and achievements made in the development of membrane photobioreactors (MPBRs) for wastewater treatment and nutrient recovery. The opportunities of using microalgae-based wastewater treatment as an interesting option to manage effluents that contain high levels of nutrients are explored. The innovations made in the design of membrane photobioreactors and their performances are evaluated. The achievements pave a way for the effective and practical implementation of membrane technology in large-scale microalgae-enabled wastewater remediation and nutrient recovery processes.

Membrane Technologies for Nitrogen Recovery from Waste Streams: Scientometrics and Technical Analysis

“…The preferred form of nitrogen for microalgae is ammoniacal nitrogen which can be converted directly to amino acids [ 260 ]. However, the assimilation of nitrate or nitrite may require several cycles of reduction [ 261 ]. Nitrogen uptake can negatively be affected by the phosphorous deficiency.…”

“…A typical PBRM system consists of a membrane submerged in a photobioreactor supplied with light and CO 2 sources. Since fouling and biomass accumulation on the membrane surface takes place frequently in this system, aeration is normally applied [ 261 ]. MF and UF are commonly used in the PBRM system, however, some studies have utilized nonporous FO membrane (the system is referred to as OMPBR) [ 262 ].…”

“…The selection of appropriate HRT, SRT, and HRT/SRT is an important factor for microalgae biomass growth and nutrient uptake. High HRT is required for effective nutrient removal, but high SRT negatively affects microalgae growth and induces severe membrane fouling [ 261 ]. For the balanced operation of PBRMs, most studies select moderate HRT and SRT [ 263 ].…”

“…For the balanced operation of PBRMs, most studies select moderate HRT and SRT [ 263 ]. A temperature higher than 25 °C was also reported to have a negative effect on microalgae growth [ 261 ]. Reactor design plays an important role in achieving high photosynthetic efficiency.…”

“…In a recent review of PBRM application for nutrient recovery, it was reported that this technology could achieve nitrogen removal of 30–100% [ 261 ]. However, the collated results in this study were gathered from investigations that used synthetic wastewater or real wastewater in a controlled environment for short tests.…”