Effect of different nitrogen sources on the growth of microalgae Chlorella vulgaris cultivation in aquaculture wastewater

К. Velichkova*

Department of Biology and Aquaculture, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

Abstract. Nitrogen is one of the most important limiting nutrients and nitrogen control is critical for the intensive cultivation of algae. The aim of the present study was to explore the effect of different nitrogensources on biomass accumulation in microalgae C. vulgaris during its cultivation in aquaculture wastewater. Microalgae cultivation was initiated in abioreactor from 500 ml Erlenmeyer flask containing 250 ml wastewaterfrom fish-ponds „Getov” – Pleven, Bulgaria. The cultures were kept at room temperature (25–27oC) at fluorescent light with a light:dark photoperiod of 12:12 h. The experiment was conducted in variants with urea (1.125g.l-1) and ammonium nitrate (1.125 g.l-1). The growth of the strain was checked for a 96-hour period. In the present study C. vulgaris showed better growth in wastewater from aquaculture with urea utilization as nitrogen source thanas a source of nitrogen ammonium nitrate.


The influence of organic carbon on bioremediation process of wastewater originate from aquaculture with use of microalgae from genera Botryococcus and Scenedesmus

I. Sirakov, K. Velichkova, G. Beev, Y. Staykov
Abstract. Advantages of using algae for wastewater treatment include: low operational cost, possibility of recycling assimilated nitrogen and phosphorus within the algae biomass as a fertilizer, accumulated biomass for biofuel. Our purpose was to study the influence of organic carbon on bioremediation process of wastewater originate from aquaculture with use of microalgae from genera Botryoccocus and Scenedesmus. Algae cultivation was initiated in a bioreactor of 500ml Erlenmeyer flask containing 250ml wastewater. The experiment was conducted in variants without any organic carbon sources and the other with organic carbon source – glucose (1,125g.l-1). Light regime was adjusted at 15:9 h light:dark cycle in an illumination incubator until the end of experiment. The temperature was kept between 25 and 27oC. The pH varied between 6.5 and 7.5 and by this reason it was not adjusted. Species grown in wastewater with added glucose showed a better cleansing effect compared with the same grown in wastewater without any carbon sources. Better growth indicators and faster absorption of wastewater compounds was observed in S. dimorphus.


Cultivation of Scenedesmus dimorphus strain for biofuel production

K. Velichkova, I. Sirakov, G. Georgiev
Abstract. Microalgae have several advantages, including higher photosynthetic efficiency as well as higher growth rates and higher biomass production compared to other energy crops. The Scenedesmus dimorphus strain was studied by using two media – BBM and 3N-BBM, and its potential for biofuel production was established. The temperature varied between 25 – 27ºC during the experiment. Fluorescent light was used to assure optimal light condition and a photoperiod of 15/9h light and dark cycle was maintained.The duration of the experiment was 25 days. Dry weight, optical density, chlorophyll, carotenoids and total lipids were measured for the biomass evaluation. The received results showed that the maximum vegetative growth was reached after approximately 16 days of incubation. The maximum growth rate during this period was 1.690 mg.l -1 dry weight in 3N-BBM medium, and in BBM medium – 0.960 mg.l -1. The lipid content which we received from the examined strain was 21.6% in BBM medium, and in 3N-BBM – 18.5%.