Agroindustrial Wastewater Treatment with Simultaneous Biodiesel Production in Attached Growth Systems Using a Mixed Microbial Culture

Abstract

The use of cyanobacteria in biological wastewater treatment technologies can greatly reduce operation costs by combining wastewater bioremediation and production of lipid suitable as biodiesel feedstock. In this work, an attached growth system was employed to achieve the above-mentioned dual objective using a mixed microbial culture dominated by Leptolyngbya and Limnothrix species in diverse heterotrophic consortia. Kinetic experiments on different initial pollutant concentrations were carried out to determine the ability of the established culture to remove organic load (expressed by d-COD, dissolved-Chemical Oxygen Demand), N and P from agroindustrial wastewaters (dairy, winery and raisin). Biomass and oil productivity were determined. It was found that significant removal rates of nutrients were achieved in all the wastewaters examined, especially in that originated from winery in which the highest d-COD removal rate (up to 97.4%) was observed. The attached microbial biomass produced in winery wastewater contained 23.2% lipid/biomass, wt/wt, which was satisfying. The growth in the dairy wastewater yielded the highest attached biomass productivity (5.03 g m−2 day−1) followed by the mixed effluent of winery-raisin (4.12 g m−2 day−1) and the winery wastewater (3.08 g m−2 day−1). The produced microbial lipids contained high percentages of saturated and mono-unsaturated fatty acids (over 89% in total lipids) in all substrates examined. We conclude that the proposed attached growth photobioreactor system can be considered an effective wastewater treatment system that simultaneously produces microbial lipids suitable as biodiesel feedstock.

Mediterranean Raisins/Currants as Traditional Superfoods: Processing, Health Benefits, Food Applications and Future Trends within the Bio-Economy Era

“…The synthesized lipids from cyanobacteria/microalgae consortia, containing saturated and mono-unsaturated fatty acids, were also evaluated as feedstock for biodiesel production. In a following study, winery-raisin wastewater was also used as substrate in mixed microbial cultures using a support matrix as an attached growth system, to produce biomass, lipids, and biodiesel [93]. The authors demonstrated an intracellular lipid content up to 23.2%, suggesting also the suitability for biodiesel production and correspondingly further optimization of the process for industrial-scale implementation.…”

Microalgal Systems for Wastewater Treatment: Technological Trends and Challenges towards Waste Recovery

“…UKM6 removed between 8.59 and 29.13% COD in undiluted POME [73]. The low removal rates result from a decreased light penetration in the WW due to the large amounts of suspended solids, thus interfering with light penetration and restricting microalgal growth [65,69].…”

Utilization of Biomass Derived from Cyanobacteria-Based Agro-Industrial Wastewater Treatment and Raisin Residue Extract for Bioethanol Production

“…The agro-industrial sector generates considerable amounts of wastewater, most of which are rich with inorganic and organic pollutants [46,47]. Using these pollutants as nutrient material for a microalgae-based cultivation system may minimize their discharge into the natural environment and further reduce a CO2 footprint by utilizing the resulting biomass in energy production processes [2].…”

“…Specifically, a microbial consortium dominated by the cyanobacterium Leptolynbgya sp. was proved effective in the treatment of agro-industrial effluents, such as raisin, winery and dairy wastewaters as well as poplar sawdust and grass hydrolysates, both in suspended and attached cultivation systems [45][46][47]. The same consortium also contained remarkable percentages of carbohydrates that exceeded 40% of dry biomass, thus making it a promising candidate as a substrate for bioethanol production [48].…”