A Rice University study at one of Houston's suburban wastewater treatment facilitiesfound that "algaculture" simultaneously yielded high-value strains of oil-rich algae whileremoving more than 90 percent of nitrates and more than 50 percent of phosphorous fromwastewater. CREDIT: E. Siemann/Rice University

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Algae from wastewater could remove harmful

nutrients, produce biofuel

April 8, 2015

Municipal wastewater could be used as a

feedstock for production of algae-based

biofuels, according to a new study at Rice

University.

As well as recovering renewable energy, the

process removes excess nutrients from the

wastewater. It also requires no chemical

fertilizers, making algae production

sustainable.

According to a report by the university,

scientists found they could easily grow high-

value strains of oil-rich algae while

simultaneously removing more than 90 percent

of nitrates and more than 50 percent of phosphorous from wastewater.

The researchers conducted experiments at a wastewater treatment plant in Texas using 12 open tanks that

were continuously supplied with filtered wastewater from the plant's clarifiers, which remove suspended

solids from sewage.

A range of environments were tested in each tank. Some were monocultures of oil-rich algal strains, while

others contained mixed cultures. Some tanks contained fish that preyed upon algae-eating zooplankton.

Earlier research had suggested that a variety of algal species might perform better in open tanks and that fish

might prevent yields being affected by algae-eating zooplankton, explained study co-author Evan Siemann, a

professor of biosciences at Rice University.

However, this study showed prolific algal growth in all 12 tanks. Monocultures were not invaded by other

algal species, and the presence of fish did not affect any variables.

"Our results are likely to be very encouraging to algae producers because the case they would prefer --

monocultures with no fish and no cross-contamination -- was the case where we saw optimal performance,"

Siemann said.

Writing in the journal Algae, Siemann and study lead author Meenakshi Bhattacharjee said their results

indicated that algae can be grown in open tank bioreactors using wastewater as a nutrient source. Moreover,

the stable productivity of monocultures suggests that this may be a viable production method to procure algal

biomass for biodiesel production.