توصيفگر ها :
كروموكلريس زوفينجنسيس , آبزي پروري , تصفيه پساب , حذف مواد مغذي , كارتنوئيد
چكيده انگليسي :
The aquaculture industry plays an important role in solving the food shortage in the world. Traditional aquaculture is one of the most polluting activities due to the production of a significant amount of wastewater, and it is necessary to recycle the water used in aquaculture and treat it before discharging it into the environment. The use of microalgae in wastewater treatment has an economical, sustainable, and environmentally friendly approach. In this study, the growth of microalgae Chromochloris zofingensis in the wastewater from rainbow trout farming was investigated with the aim of nutrient removal, biomass production, and total carotenoid measurement in two types of batch and sequential batch cultivation under mixotrophic conditions. batch cultivation was investigated in two operational volumes of 3 and 30 liters over16 days with 4800 lux illumination and normal aeration .sequntional batch cultivation was investigated in two operational volumes of 1 and 2 liters in 6 stages over 36 days with 4800 lux illumination and normal aeration. In the sequential batch process, the first stage batch was carried out. then the grown microalgae cells from the first batch stage were separated and added to the raw wastewater and this process was repeated sequentially up to 6 times. Thus, the batch cultivation was carried out in up to 6 sequential stages. The nutrient removal efficiency, biomass productivity, and total carotenoid were calculated for all cultures. Changes in the parameters of nitrate, COD, phosphate, ammonia, total alkalinity, and pH were examined. The maximum reduction in nitrate, COD, phosphate, and ammonia was observed after the red phase. The nitrate, COD, ammonia, and phosphate removal efficiency were 99%, 97.9%, 84.8%, and 93.3% respectively in the 3-liter batch culture, 99.6%, -11%, 54.5%, and 92.3% in the 30-liter batch culture, 97.3%, 69.6%, 92%, and 94.4% in the 1-liter sequential batch culture, and 99.4%, 69.6%, -20%, and 94.4% in the 2-liter sequential batch culture. In this study, all parameters after the red stage, except one case where pH changes caused an increase in ammonia, met the national and international environmental standards for water discharge and recycling in all cultures. The results showed that the biomass productivity and total carotenoid extraction in sequential batch cultures were higher than in batch cultures. Total carotenoids in batch cultures of 3 and 30 liters were 0.42 ± 0.03 and 0.4 ± 0.02, respectively, while in sequential batch cultures 1 and 2 they were 0.6 ± 0.05 and 0.82 ± 0.04, respectively. Overall, the results indicated that by sequentializing the batch culture of the microalgae Chromochloris zofingiensis in rainbow trout aquaculture effluent, in addition to increasing biomass productivity from 0.03 to 0.1 and the subsequent increase in total carotenoids, a larger volume of wastewater was treated. Wastewater treatment in a recirculating path can provide nutrients for fish feed and treated water for fish farming, and reduce the consumption of freshwater. Therefore, in the field of circular economy, this research contributes to reducing the water footprint and sustainability of the rainbow trout production chain.
