## 3 Application Sectors and Valuable Products from Microalgae Biomass
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Application Area** & **Process** & **Effect** & **Species** & **References** \\ \hline \multirow{6}{*}{Environmental} & Wastewater treatment & & _Chloella vulgaris_, _Chorella_ & \\  & Wastewater treatment & N, P, COD, & _protollecoides_, _Senedesmus obliquus_, & [32; 33; 34] \\  & & micropollutant removal & _Botryococcus branii_ & \\ \cline{2-4}  & Leachate and & & _Chloella sp._, _Chloella vulgaris_, & \\  & digestate treatment & & _Anabena sp._, _Senedesmus_ sp. & [24; 35; 36] \\ \cline{2-4}  & Flue gas treatment & NO\({}_{\text{x}}\), SO\({}_{\text{x}}\), fly & _Chloella vulgaris_, & \\  & and Protection & ash removal & _Senetesus dinorplus_, & [23; 37; 38] \\  & & & _Sriulina platensis_ & \\ \cline{2-4}  & CO\({}_{2}\) biosequestration & CO\({}_{2}\) removal & _Nannochloropsis_ _culata_, _Chloella_ & \\  & & _pyrenoidosis_, _Senedesmus obliquus_, & _Phaeodactylum tricornutum_, _and_ & [27; 39; 40] \\  & & _Chlamydomonas reinhardtii_ & & \\ \hline \multirow{6}{*}{Transesterification} & Biodiesel & _Nannochloropsis_ sp._, _Chloella_ & \\  & & _vulgaris_, _Botryococcus braunii_ & [41; 42; 43] \\ \cline{2-4}  & Alcoholic fermentation & Bioethanol & _Chloella vulgaris_, _Sriulina platensis_ & [44; 45; 46] \\ \cline{2-4}  & Photodissociation & Biohydrogen & _Chlamydomonas reinhardtii_, & \\  & & _Seenedesmus obliquus_ & [47; 48; 49] \\ \cline{2-4}  & & Biogas & _Chloella vulgaris_, _Chloella sp._, & \\  & & & _Nannochloropsis_ sp. _Seenedesmus_ & [50; 51; 52] \\ \cline{2-4}  & Anaerobic digestion & & _Pinnularia_ sp. & \\ \cline{2-4}  & Biomethane & _Chloella vulgaris_, & \\  & & & _Chloella prototheoides_, & [53; 54; 55] \\ \cline{2-4}  & & Biohydrogen & _Chloella_ sp._, & \\  & & & _Tetraselmis subcordiformis_ & [56; 57; 58] \\ \cline{2-4}  & Gasification & Syngas & _Chloella vulgaris_, & \\  & & _Galdieria sulphuraria_ & [59; 60; 61] \\ Bioenergy & & & _Chloella sp._, & \\  & & & _Chloella sp._, & \\  & & & _Chloella prenoidos_, _Spirogyna_ sp._, & \\  & & & _Cladophora sp._, & \\  & & & _Microspora_, & \\  & & & _Rhizcolonium_ & \\ \cline{2-4}  & Pyrolysis & & _Nannochloropsis_ sp._, _Arthrospira_ & \\  & Oil & & _platensis_, & [65; 66; 67] \\  & & & _Chloella sp._, & \\  & & & _Scenedesmus obliquus_ & \\ \cline{2-4}  & Pyrolysis gas & & _Chloella vulgaris_, _Arthrospira_ & \\  & & & _Pidensis_, _Tetraselmus obliquus_, & \\  & & & _Nannochloropsis_ sp. & \\ \hline \multirow{2}{*}{Combustion} & \multirow{2}{*}{Heat, Electricity} & _Chloella vulgaris_, _Arthrospira_ & \\  & & & _platensis_, _Nannochloropsis_ sp._, & \\  & & & _Tetraselmis_ sp. & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Utilisation of microalgal biomass in environmental engineering and bioenergy. phycocyanin, a blue pigment produced by cyanobacteria; phycoerythrin, a red pigment synthesised by red algae; and astaxanthin, produced by green algae [78; 79]. In addition, certain microalgae have the ability to biosynthesis fatty acids, including \(\gamma\)-linolenic acid (18:3 \(\omega\)6), arachidonic acid (20:4 \(\omega\)6), eicosapentaenoic acid (EPA, 20:5 \(\omega\)3), and docosahexaenoicenoic acid (DHA, 22:6 \(\omega\)3) [80]. Since long-chain polyunsaturated fatty acids are not synthesised by higher plants, animals, or humans, their presence in the diet is essential [81]. The main uses of the biomass of selected microalgae species grown under controlled conditions for industrial purposes are listed in Table 2.  
Both the bibliometric data presented and the overview of the applications and products derived from microalgae biomass are crucial for a proper understanding of the need to further develop optimisation and monitoring methods in the cultivation technologies of these organisms.