Wastewater treatment by microalgae

Abstract

The growth of the world's population increases the demand for fresh water, food, energy, and technology, which in turn leads to increasing amount of wastewater, produced both by domestic and industrial sources. These different wastewaters contain a wide variety of organic and inorganic compounds which can cause tremendous environmental problems if released untreated. Traditional treatment systems are usually expensive, energy demanding and are often still incapable of solving all challenges presented by the produced wastewaters. Microalgae are promising candidates for wastewater reclamation as they are capable of reducing the amount of nitrogen and phosphate as well as other toxic compounds including heavy metals or pharmaceuticals. Compared to the traditional systems, photosynthetic microalgae require less energy input since they use sunlight as their energy source, and at the same time lower the carbon footprint of the overall reclamation process. This mini-review focuses on recent advances in wastewater reclamation using microalgae. The most common microalgal strains used for this purpose are described as well as the challenges of using wastewater from different origins.We also describe the impact of climate with a particular focus on a Nordic climate. | INTRODUCTIONSince the industrial revolution, water pollution has increasingly become a concern to the public and societal authorities. With the development of the industrial world and a growing population, the demands for freshwater are drastically increasing. The global water demand for agriculture, industry, and municipalities is expected to rise by 20-30% by 2050 (Boretti & Rosa, 2019). One of the consequences of this increase is the generation of larger quantities and varieties of wastewaters, contaminated with a wide range and concentrations of chemicals. Besides utilizing several tons of pesticides per year, the agricultural sector also produces considerable amounts of organic waste (Bockstaller et al., 2009), and is one of the most significant sources of water contamination.These pollutants can have dire consequences for the environment and for ecosystems into which they are discharged. Some pollutants, mainly those of organic nature, are generally degradable (either naturally or with the help of microorganisms) and therefore do not cause major problems for the environment. However, some persistent organic pollutants (POPs), typically present in trace amounts, are known to bioaccumulate and exert toxic chronic health effects on animals (Schwarzenbach et al., 2010). Chemical Martin Plöhn and Olivia Spain contributed equally to this study.

Fe3O4-PEI Nanocomposites for Magnetic Harvesting of Chlorella vulgaris, Chlorella ellipsoidea, Microcystis aeruginosa, and Auxenochlorella protothecoides

“…The microalgal production systems do not directly compete with the food chain. Furthermore, they can be used to convert CO 2 to oxygen or for wastewater treatment [ 8 , 9 , 10 , 11 ].…”

Current Status and Perspective on the Use of Viral-Based Vectors in Eukaryotic Microalgae

“…Further, metabolites obtained from microalgae can be used in biofertilizer production as a source of nitrogenand phosphorous-rich biomass residues as feedstock and in the bioenergy industry as bulk oil and biomass residue feedstock for jet fuel, biodiesel, bioethanol, biogas, biochar, and biohydrogen production. Furthermore, some microalgae strains can be used in wastewater treatment by reducing the amount of nitrogen, phosphate, and chemical oxygen demand, as well as removing heavy metals (copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn)) and pharmaceutical pollutants (triclosan and hormones (17β-estradiol and 17α-ethinylestradiol) [108][109][110][111][112][113]. Interestingly, potential industrial applications and commercialization of microalgae-derived biomass and bioactive compounds in the food industry has recently been explored by Camacho et al (2019).…”

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

“…Depending on the environmental conditions, the effluent requirements and the specifics of the existing or newly designed WWTP, the studied algae-based wastewater treatment systems varied across a broad range of technological designs. Тhe treatment systems can generally be divided into three main groups-suspended, algal bead (active immobiliza-tion), and attached (passive immobilization) growth [39][40][41]. Each of these groups has specific reactor design variations (Figure 2).…”