New energy approaches to the use of waste biosorbents of microalgae Chlorella kessleri (Chlorellaceae, Chlorellales)

The use of microalgae Chlorella kessleri VKPM A1-11 ARM (RF, NPO Algobiotechnology) for environmental and energy purposes is considered. The results of our study of the use of C. kessleri microalgae biomass as a biosorbent to purify model wastewater from Cu2+ ions under static conditions are presented. Biosorption is a promising technology for the treatment of industrial effluents containing various heavy metal compounds, but the issues of economic benefits of using biosorbents, their environmental safety and the cost of disposal of used sorbents are subject to much discussion. The paper proposes to dispose the used biosorbent formed after wastewater treatment from copper as an additional fuel. The copper concentration in the filtrate was determined by colorimetric analysis with sodium diethyldithiocarbamate. The cleaning efficiency and sorption capacity of the dry mass of C. kessleri were obtained by calculation. The maximum sorption capacity for Cu2+ ions was 4.2 mg/g. The purification efficiency reached 87% at the initial concentration of Cu2+ ions being 97 mg/l. Tests to estimate the specific heat of combustion of C. kessleri biomass and used biosorbents based thereon were carried out by the calorimetric method using a bomb calorimeter. The specific heats of combustion were 22,125 kJ/kg and 21,674 kJ/kg, respectively. A comparison of these values with traditional energy carriers is given. A technological scheme has been developed for a waste-free cycle of using C. kessleri to treat wastewater from industrial enterprises with the production of several valuable resources as end products, such as purified water, energy resources, fertilizers, and recycled metals. The obtained results of our study can be applied in technologies for post-treatment of wastewater from various industrial enterprises using biological non-waste resources.