Along with biological treatment of wastewater numerous species of microalgae are able to produce excessive oil-rich biomass that is considered a technically viable alternative energy resource for third generation biodiesel production (Tsukahara, Sawayama, 2005. Wang, et al., 2010. Anaerobic digested dairy manure as a nutrient supplement for cultivation of oil-rich green microalgae Chlorella sp. Bioresour. Technol. 101, 2623–2628). In its turn, microbial biofuels (referred to as third generation biofuels) production from renewable sources is recognized to be one of the most effective alternatives to fossil fuels and a viable means for economic and environmental sustainability (Nigam, and Singh, Production of liquid biofuels from renewable resources, Progress in Energy and Combustion Science, 37(1): 52–68), 2011).

The overall goal of the project is the development of economically viable bioprocess integrating heterotrophic microalgae based treatment of brewery and dairy wastewater with microalgae-for-biodiesel production.

Current status: Over the past decades the use of obligate phototrophic microalgae with simple growing requirements in naturally or artificially illuminated environments like open ponds and/or photobioreactors (PBR) was prevailing approach for integration wastewater biological treatment with biofuel production. In spite of relatively low construction and operating costs, efficiency of open pond systems for algal biomass-for-biodiesel commercial production proved to be limited due to low productivity of oils producing algal biomass caused by poor light diffusion inside the pond decreasing with depth; constant contamination of monoculture by fungi, bacteria and protozoa; poor utilization of CO₂ due to evaporation or stripping, dependence of environmental growth parameters of cultivation primarily on local weather conditions; laborious and costly harvesting; increasing costs for land use etc. Similar to the open-pond concept, large-scale PBR that are protected from direct fallout, relatively safe from invading microorganisms, where temperatures are controlled with an enhanced CO₂ fixation have some disadvantages that make their use uneconomical for microalgae-for-biodiesel production. In particular, at operational volumes of 50-100 l or higher it is no longer possible to disperse light efficiently evenly inside the PBR as developed microalgae biofilm fouls PBR surfaces and thereby limits light penetration into the culture; PBR needs high initial investment in infrastructure and increased costs for maintenance.

Referring to recent publications microalgae capable to treat wastewater in heterotrophic growth conditions with production of vast amount of oil rich biomass are considered promising for microalgae-for -biodiesel low-cost production at any scale. Bumbak et al.,2015, Rohit et al.,2011; Moreover, microalgae heterotrophic cultivation, which may allow large volume applications such as wastewater treatment combined, or separated with production of biofuels is far cheaper, simpler to construct facilities, and easier than autotrophic cultivation to maintain on a large scale (Hidalgo. AOP J Environ Waste Management 2015, 05/12) microalgae based wastewater treatment resulting both in pollutants removal and microalgae-for-biodiesel production is a relatively new field of research, the main biological challenges include bringing into industrial culture heterotrophic microalgae species with ‘optimal’ attributes such as high growth rate, high lipid content and tolerance to growth inhibitors (Espinosa-Gonzalez et al., 2014, Bioresour Technol 155:170-176; Gomez et al., 2013. Appl Microbiol Biotechnol 97(5): 2239-2249). The other challenge in microalgae based biodiesel production is the lack of cost effective technology for microalgae oil extraction. Number of methods like expeller/oil press, liquid–liquid extraction (solvent extraction), supercritical fluid extraction (SFE) and ultrasound technique applied for microalgae oil extraction didn’t show significant economic efficiency. Therefore, development of new methods both for disruption of cells and microalgae oil recovery becomes of high importance for making overall process cost effective. The participants’ expertise: Project builds on the extensive research and management experience of project participants in the creation and characterization of collections of microorganisms of all taxonomic groups. Development of environment protection and biofuels like biogas, bio-hydrogen and cellulosic ethanol production technologies are the main fields of research. From 1997 Up to now, project team members participated in 16 international R&D projects funded by NATO, ISTC, STCU, World Bank, CRDF Global, DTRA etc. Published more than 40 research papers, Chapters and monographs.

Scope of activities: Project aims to cover all stages of microalgae based treatment of brewery and dairy wastewater and microalgae oil production. Project realization includes creation and general characterization of microalgae collection for wastewater treatment abilities, water pollution control properties and high value compounds accumulation. In-depth studies will cover identification and screening of microalgae strains able to accumulate lipids in heterotrophic growth; study of optimal conditions and culture management for high effective treatment of brewery and dairy wastewater and sustainable high biomass and oil yields; design, construction and testing of lab-scale system that will be best suited to the selected strains and culture media and development of cost-effective method for microalgae oil extraction. Microalgae biomass residual after oil extraction will be studied for application as fertilizer and/or feed. Finally, ecological, energetic and economical parameters of the integrated process will be assessed.