Algae can produce biofuels from wastewater
Algae can be used to treat wastewater and produce biofuel simultaneously
India’s climatic conditions are suitable for farming algae in wastewater
Selected algae strains can be grown in tanks with wastewater to produce biofuel
The findings of the Rice University team published in March in Algae show that strains of oil-rich algae were capable of removing more than 90 per cent of nitrates and more than 50 per cent of phosphorus from wastewater.
A similar study done by Indian Institute of Technology, Kharagpur in 2010 on algae grown in municipal wastewater had achieved similar results.
Meenakshi Banerjee Bhattacharjee, India-born co-author of the Houston study, tells SciDev.Net that the method can be readily replicated. “It would work very well in a country like India where the climate is suitable for algal growth and where there are many indigenous strains.”
Algal culture, which is in its early stages, has so far relied on heavy investment in land and water making algae cultivation for biofuels unsustainable. But these studies have found that using wastewater at a treatment facility proves a win-win situation by providing a nutrient-rich base for growing while cleaning wastewater of pollutants.
Bhattacharjee however cautions that the method may not be suitable for systems in which water was flowing such as polluted drains and rivers. “For this to work you have to have stagnant waters (or wastewater contained within an area) such as in a wastewater treatment system or a sewage processing plant.”
To make this system economical and sustainable oil-rich species of algae are used to treat wastewater by reducing nitrate and phosphate content which are the main causes of eutrophication (oversupply of nutrients inducing explosive growth of plants and algae in water bodies).
The Houston scientists showed that it was possible to maintain a single strain of algae (monocultures) in tanks, unlike in open ponds where there usually is contamination with other algae strains. “If monocultures can be maintained that opens up avenues for obtaining special products — this cannot be done if the water becomes contaminated with other strains,” Bhattacharjee explains.
The IIT- Kharagpur study had also examined biodiesel production with algae in multiple settings including at a municipal waste treatment plant which showed high biodiesel production.
Nirupama Mallick, author of the 2010 study and professor at the department of agriculture and food engineering at IIT-Kharagpur, says that suitable indigenous algae strains are available in India. “They just need to be screened for the twin uses (processing wastewater and generating biodiesel).”
This article has been produced by SciDev.Net's South Asia desk.