Document Type: Primary Research paper
Algae are the main components of primary production in sea and refinery wastewater. Microalgae and cyanobacteria are the most-used groups. In the present study, refined wastewater was collected from drainage of a refinery in Gorgan to evaluate efficiency of two algae mixture, Scenedesmus obliquus and Chlorella vulgaris, to remove water nitrate, phosphate, BOD and COD during 14 days. An equal number of either of the algae (24000 cells) was added to each treatment at the experiment initiation. The algae number were daily counted; whereas, the media nitrate, phosphate, ammonia, chlorophyll-a, biomass, BOD and COD were measured every other day. At the end of study, phosphate was completely depleted in M50 treatment and the highest phosphate level (1 mg/l) was observed in M0 treatment (p <0.05). Water nitrate was completely depleted in M50 treatment. The highest biomass levels (0.4 g/l) were observed in M0 and M50 treatments (p <0.05). The highest chlorophyll-a was observed in M0 treatment (2.83 mg/l). BOD and COD had similar pattern among the treatments. The lowest COD was related to M50 treatment (5 mg/l); whereas the lowest BOD level was observed in M0 treatment (0.05 mg/l). Overall, the algae mixture was efficient to uptake nutrients and produce biomass and chlorophyll.