Researchers develop cheaper, cleaner way to grow biodiesel producing microalgae

In a significant breakthrough that could boost the production of biodiesel, researchers at the CSIR-National Institute of Oceanography (Goa), Goa have found a cleaner, cheaper to grow biodiesel producing microalgae -- one that uses wastewater from fishmeal plants rather than artificial nutrients.

The team of researchers led by Dr Deepti Jain, has found that the species of microalgae Chlorella vulgaris NIOCCV -- a strain of microalgae that was isolated from nature and characterized at NIO -- grew well in a medium of seafood industry wastewater and was tolerant to different salinity regimes and higher concentrations of carbon dioxide, making it an ideal candidate for an effective, economically favorable and environmentally sustainable strategy of cultivation in wastewater.

The move to use wastewater and CO2 could kill two birds with one stone.

“We made an attempt to utilize seafood processing industry wastewater as nutrient source which dispense off the need of nutrient supplementation, thereby reducing the cost which otherwise could be 80% of the total cultivation cost,” Vishal Gupta, the corresponding author of the paper explained.

The cheaper the cost of growing the microalgae, the cheaper the cost of producing biodiesel.

In the search for alternative and renewable sources of fuel and energy, microalgae have been established as a renewable feedstock for clean fuel (biodiesel).

“In general, about 69% of global biodiesel production comes from vegetable oils like soybean, rapeseed and palm. This is a serious concern towards food security. Microalgae, thereby, has gained global consideration as renewable feedstock for biodiesel production,” Gupta said.

However, the cost of growing microalgae that needs nutrient supplements as well as the shortage of freshwater available for commercial cultivation was a hindrance to the economic sustainability of microalgae-based energy production.

“Microalgae has gained considerable global attention as alternative renewable fuel source. However, the cultivation cost is the major bottleneck because of the need for nutrient supplementation,” Gupta explained.

Cholera vulgaris NIOCCV’s ability to thrive in wastewater makes it the best candidate for sustainable production.

Besides being cheaper, the method also helps clean the waste water that would otherwise need to be treated before being discharged, a cost industries want to avoid.

“As nutrients from wastewater were assimilated by algae for their growth, it helped clean the wastewater and that makes it possible to directly discharge it saving treatment costs,” Gupta said.

Prof N Ramaiah, former head of the biological oceanography division, CSIR-NIO, Goa, and their group initiated and successfully showed the utilization of microalgae for industrial wastewater treatment.

“We are trying to make industrial collaborations either with food processing or fuel producing to test our method at a scale,” he said.

The study also showed that the microalgae strain is tolerant to CO2 concentration levels as high as 20% which makes it ideal to be fed with chimney stack gases otherwise released in the atmosphere by industries.

“We have plans to test the same against flue gas to further assure the industrial applicability. By developing this model, we are hopeful that the gaseous discharge can directly be pumped in the cultivation pond along with wastewater. This way not only generate the biomass but also reduce the waste debt,” Gupta said.