Cookies on Environmental Impact

Like most websites we use cookies. This is to ensure that we give you the best experience possible.


Continuing to use  means you agree to our use of cookies. If you would like to, you can learn more about the cookies we use.

Environmental Impact

From climate change to biodiversity loss - documenting human impacts on the environment

Environmental Impact is now available on our new platform, CABI Digital Library. Please note that this website will be discontinued in mid-December, and all access will be automatically redirected to CABI Digital Library.

Take a look at Environmental Impact on CABI Digital Library. 

News Article

Harnessing the power of urban algae for green energy

Algae offer solution to simultaneously treat wastewater and produce biofuel in India

Research into microalgae as a potential biofuel source has been ongoing for decades. However, attempts to harness the power of these single-celled phototrophs have repeatedly hit a brick wall: the cost of light, heat and nutrients required to produce sufficient algal biomass outweighs the profits generated. Eutrophication, or the overgrowth of algae due to anthropogenic nutrient inputs, is a common problem in polluted wastewater. Several decades ago, the algal turf scrubber was invented to remove nutrients and heavy metals from wastewater using algae. This system has since become a popular water filtration system for aquaria, although it has not yet been used for large-scale wastewater treatment. A number of researchers have now built upon this concept by attempting to use the system for an additional purpose: biofuel production.


To date, most experiments involving culturing algae in wastewater for biofuel have been carried out in temperate regions of the world, where sunlight levels and outdoor temperatures are unable to sustain the rapid algal growth needed for cost-effective biofuel production. However, a recent study in India has shown that the country’s tropical climate can boost algal productivity in wastewater sufficiently to overcome previous economic barriers and support a sustainable biofuel production system.


The team pumped domestic wastewater from a nearby residential area into a storage tank, before piping it continuously across a polyester mat which acted as a growth substrate, allowing the microalgae to self-seed. After 15 days, the algae were harvested for analysis. This experiment was carried out three times across different seasons: the Indian summer, monsoon season and winter. Species were identified using both live and desiccated samples. The total nitrogen, phosphorus and lipid content of samples was also measured. Lipids are particularly important for biofuel production, as they provide the key oil component of the fuel.


The researchers found that both nutrient removal and algal growth were faster and more efficient than in studies conducted in temperate or subtropical regions, such as the US and China. Diatom species dominated the algal community. Encased in a transparent silica shell, these algae are considered one of the most productive groups of microalgae on earth, making them a major focus of biofuel research. The researchers attributed the high productivity to this abundance of diatoms, as well as the high temperature, light and nutrient availability in the wastewater. Cyanobacteria and filamentous green algae were also detected in the samples, but these appearances were limited to certain seasons.


Before this technology can be used on a commercial scale however, several obstacles still remain. The composition and quantity of lipids present in algae samples must remain consistent throughout the year, and in this study, the lipid content fluctuated seasonally according to the changing weather. Inoculating the membrane with select species, such as high productivity diatom strains which produce desirable lipid types, may help to resolve this. However, open-air systems such as the setup used here are vulnerable to contamination from predatory zooplankton and invasive algae.


Although the system tested here is still far from being commercially viable, the significant benefits offered over traditional crop-based biofuel production systems make it a research effort worthy of further pursuit. The researchers ensured that materials used were durable and available locally, meaning there is potential for this solution to be applied in other tropical developing countries across the world. In addition, the growth mat can be orientated vertically and stacked, occupying minimal space and enabling the system to be used in urban areas.


Future research is likely to focus on overcoming the issues of contamination and consistent lipid output, as scientists slowly inch towards an algae-based solution for simultaneously treating wastewater and producing biofuels that can be scaled up for commercial use.


Reference: Marella, T. K., Datta, A., Patil, M. D., Dixit, S., & Tiwari, A. (2019). Biodiesel production through algal cultivation in urban wastewater using algal floway. Bioresource Technology, 280, 222-228. 10.1016/j.biortech.2019.02.031


To find over 500 similar records in the Environmental Impact database, use the following search terms: ("biofuel*" OR "bioenergy") AND "microalgae" AND "wastewater"