• Enrofloxacin degradation has been studied by photolysis and (photo)-Fenton. • The effect of water constituents, pH and iron chelation has been determined. • There is a relationship between antibacterial activity and fluoroquinolone core. • EEM-PARAFAC is a simple and fast methodology to study a fluoroquinolone degradation.

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.

In the last decades, an increasing attention has been directed toward the possibilities of growing algae commercially. This interest has been partially due to the fact that some strains of microalgae and cyanobacteria have demonstrated the ability to produce a variety of bioactive products. Both, primary and secondary metabolism of these microorganisms has been demonstrated to play a key role in the production of special chemicals. Antioxidants, for instance, can be produced by some algal strains to protect photosynthetic cells from oxidative stress. Microalgae can produce a variety of polyunsaturated and monounsaturated fatty acids with clear health benefits for human nutrition. Potential products obtained from cyanobacteria and microalgae exhibiting interesting medical properties include polysaccharides, glycerol, glycoproteins, and antibiotics. From the aforementioned products, especially relevant has become the search of new antibiotics. The potential spread of bacterial resistance and the foreseen decrease on efficiency on antibiotics, has largely stimulated the research on novel antibiotics sources. Among these sources, cyanobacteria and microalgae have demonstrated a vast and just barely explored potential.

In this work, fluorescence excitation–emission matrices (EEMs), in combination with the chemometric tool and parallel factor analysis (PARAFAC), have been proposed as an unexplored methodology to follow the removal of the fluorescent contaminants of emerging concern, fluoroquinolones (FQs). Ofloxacin, enrofloxacin, and sarafloxacin were degraded by different advanced oxidation processes employing simulated sunlight (hν): photolysis, H2O2/hν, and photo-Fenton. All experiments were performed in ultrapure water at three different pH values: 2.8, 5.0, and 7.0. With the obvious advantage of multivariate analysis methods, EEM-PARAFAC allowed the monitoring of degradation from the overall substances (original and formed ones) through simultaneous, rapid, and cost-efficient fluorescence spectroscopy determinations. A five-component model was found to best fit the experimental data, allowing us to (i) describe the decay of the fluorescence signals of the three parent pollutants, (ii) follow the kinetics profile of FQ-like byproducts with similar EEM fingerprints than the original FQs, and (iii) observe the formation of two families of reaction intermediates with completely different EEMs. Results were finally correlated with high pressure liquid chromatography, total organic carbon, and toxicity tests on Escherichia coli, showing good agreement with all the studied techniques.

Chitin is a natural polymer extracted mostly from shrimp or crab shells and is the Earth's second most abundant polysaccharide. After a simple deacetylation procedure, chitin is converted into chitosan that consists in a polysaccharide structure of deacetylated-β-glucosamine. Chitosan has been largely employed in wastewater treatment the removal of colloids through coagulation-flocculation processes. Different chitosan based materials have been produced and tested in the removal of inorganic pollutants such as toxic metals and metalloids, nutrients, dyes, micropollutants and hydrocarbons. Sorbents such as magnetic-activated carbon chitosan have been successfully tested in the removal of antibiotics (ciprofloxacin, erythromycin and amoxicillin) from water. Raw chitosan and ZnO nanoparticles entrapped in chitosan have demonstrated an excellent potential for the removal of the insecticide permethrin from aqueous effluents. Chitin and chitosan in flake and powder form have also demonstrated a promising effectiveness in the removal of oil spilled in seawater. Superhydrophobic and superoleophilic sponges modified by thioles have been also prepared from chitosan and used for the removal of oil spills. Chitosan hydrogels have been tested as well as entrapment matrices for the immobilization of hydrocarbon-degrading biomass for oil spills. Strains such as R. corynebacteriorides (QBTo), Bacillus subtilis LAMI008 and B. pumilus have been successfully immobilized and employed in hydrocarbon degradation processes. In this book chapter, the use of chitosan and chitosan-based materials in the removal of organic pollutants from water is reviewed.