Estimation of energy potential of microalga from the genera Nannochloropsis and Isochrysis

Mikroalge rodova Nannochloropsis i Isochrysis predstavljaju sirovinu koja se može koristiti za proizvodnju energije. Cilj ovog rada bio je opisati uzgoj mikroalgi rodova Nannochloropsis i Isochrysis u različitim tehnološkim sustavima te laboratorijskim metodama istražiti njihove kemijske i fizikalne karakteristike za preliminarnu procjenu energetskog potencijala za proizvodnju bioplina i biodizela. Analizom uzoraka mikroalgi Nannochloropsis oculata, utvrđene su srednje vrijednosti sadržaja vode 95,28 %, sadržaja pepela 76,5 %, sadržaja masti 0,3271 %. Salinitet otopine uzoraka mikroalge N. oculata iznosio je 37,114 ppt. Utvrđena je kemijska potrošnja kisika (KPK), od ostataka mikroalgi nakon proizvodnje biodizela, koja je iznosila 1244 mg/L. Analizom uzoraka mikroalgi Isochrysis galbana, utvrđene su srednje vrijednosti sadržaja vode 95,42 %, sadržaja pepela 77,91 %, sadržaja masti 0,3395 %. Salinitet otopine uzoraka mikroalge I. galbana je iznosio 36,516 ppt. Utvrđena je kemijska potrošnja kisika (KPK), od ostataka mikroalgi nakon proizvodnje biodizela, koja je iznosila 999 mg/L. Može se zaključiti da postoji potencijal u proizvodnji biogoriva iz mikroalgi, te da je moguća integrirana kružna proizvodnja. Međutim, potrebno je optimizirati sustav proizvodnje kako bi prinosi bili što veći, a troškovi proizvodnje što manji. Nannochloropsis and Isochrysis microalgae represent a raw material that can be used for energy production. The aim of this research was to describe the cultivation of the Nannochloropsis and Isochrysis microalgae in different technological systems and to determine their chemical and physical characteristics using laboratory methods for a preliminary assessment of the energy potential for the production of biogas and biodiesel. Analysing the Nannochloropsis samples, the average values of water content was measured at 95.28 %, ash content at 76.5 %, fat content at 0.3271 % were determined. The solution salinity of the Nannochloropsis samples was measured at 37.114 ppt. The chemical oxygen consumption (COD) of microalgae residues after biodiesel production was determined, which was 1244 mg/L. Through the analysis of the Isochrysis galbana samples, the average values of water content was measured at 95.42 %, ash content at 77.91 %, fat content at 0.3395 % were determined. The solution salinity of the I. galbana samples was measured at 36,516 ppt. The chemical oxygen consumption (COD) of microalgae residues after biodiesel production was determined, which was 999 mg/L. It can be concluded that there is potential in the production of biofuel from microalgae, and that integrated circular production is possible. However, it is necessary to optimize the production system so that yields are as high as possible and production costs are as low as possible.