Wastewater Treatment by Algae
Wastewater treatment involves the removal of organic carbon, nitrogen, phosphorus, heavy metals, and other pollutants using physical, chemical, and biological processes.
Limitations of Conventional Wastewater Treatment
Conventional wastewater treatment processes require energy-intensive aeration to drive the oxidation of organic carbon by bacteria and the nitrification phase of biological denitrification.
The oxidation of organic carbon releases carbon dioxide directly into the atmosphere, while the energy used for aeration results in indirect carbon dioxide emissions. In addition, significant amounts of the potent greenhouse gas nitrogen dioxide are released during the biological denitrification process. Another limitation of conventional wastewater treatment is that although nitrogen and phosphorus may be removed, they are usually not recovered in a useful form.
Novel Wastewater Treatment by Algae
In contrast, treating wastewater with algae is considered a more environmentally friendly method, especially for nitrogen and phosphorus removal and recovery. During growth, algae take up nitrogen and phosphorus along with carbon fixed by photosynthesis. In addition, the harvested algal biomass can be processed into useful products such as animal feed, slow-release fertilizer, or biofuel, thus turning waste into a resource. In addition, algae can be used to degrade antibiotics, such as tetracycline, sulfadiazine, and ciprofloxacin, in wastewater. When exposed to antibiotics, algae initiate a stress response mechanism that degrades the toxic antibiotic and helps the algae to survive.
Fig.1 Mechanisms of antibiotic removal by algae. (Xiong, Q., et al., 2021, Environment International)
Algae Used in Wastewater Treatment
Algae occur in a variety of forms, and both micro- and macro-algae can be used to treat wastewater.
Microalgae for Wastewater Treatment
Most of the studies on algae treatment of wastewater have focused on the treatment of wastewater by microalgae. Microalgae, including eukaryotic algae and cyanobacteria, have been shown to be an environmentally friendly and sustainable alternative to the energy-intensive and conventional biological treatment processes currently in widespread use.
| Advantages of Microalgae Wastewater Treatment | Bottlenecks in Microalgae Wastewater Treatment |
| The main advantage of incorporating microalgae into wastewater treatment is the simpler steps. Due to the ability of microalgae to directly assimilate ammonia (NH3) and phosphate (PO4), the wastewater treatment process no longer requires different operating environments to facilitate the removal of inorganic nitrogen and phosphorus. | Although microalgae have been shown to be technically feasible in wastewater treatment applications, harvesting small microalgal cells remains a major problem. Microalgae are naturally difficult to harvest due to their small cell size, near-neutral buoyancy, and negative surface charge. |
Macroalgae for Wastewater Treatment
Macroalgae, particularly filamentous freshwater algae, have distinct advantages over microalgae for wastewater treatment, including their ease of harvesting and greater resistance to predation. Their larger size facilitates biomass harvesting, thus reducing the cost and complexity of implementing algae-based wastewater treatment processes. There are two main approaches to wastewater treatment using freshwater filamentous algae, including Algal Turf Scrubbers (ATS) and raceway pond monocultures.
Fig.2 Diagram of macroalgae treating wastewater. (Liu, J., et al., 2020, Bioresource technology)
Our Services
As an integrated company in algae research, Lifeasible is dedicated to multiple environmentally sustainable applications of algae and algae research in other fields. Therefore, we can provide high-quality algae isolation and culture services, algae engineering services, algae analysis services, algae genetic screening services, algae-based production services, algae monitoring services, algae treatment services, and algae-based biosensor services for environmental monitoring. Please contact us for more information.
References
- Xiong, Q., Hu, L. X., Liu, Y. S., Zhao, J. L., He, L. Y., & Ying, G. G. (2021). Microalgae-based technology for antibiotics removal: From mechanisms to application of innovational hybrid systems. Environment International, 155, 106594.
- Liu, J., Pemberton, B., Lewis, J., Scales, P. J., & Martin, G. J. (2020). Wastewater treatment using filamentous algae–a review. Bioresource technology, 298, 122556.
Our services are for research use only and not for any clinical use.