Algae-based Wastewater Treatment

Microalgae are favorable wastewater treatment agents due to their ability to absorb nutrients and convert them to biomass. During the brewery wastewater treatment, nitrogen, phosphorus, and other nutrients present in the wastewater are adequately absorbed by microalgae for their growth. Microalgae, through their photosynthetic activities, freely release oxygen which is utilized by bacteria in the wastewater. Microalgae also fix CO2 by assimilating HCO3 from CO2 via respiration. Until recently, the application of microalgae in wastewater treatment had only been restricted to the laboratory. Raceway ponds and photobioreactor technologies have been applied in microalgae wastewater treatment, including brewery wastewater. Raceway ponds are semi- circular at the two ends, with a shallow open system. The system has paddle wheels that provide continuous mixing of the microalgae in the wastewater for nutrients and sunlight. Different microalgae can effectively treat the range of industrial wastewater. However, total suspended solids (TSS) in industrial wastewater restrict the efficiency of treatment by microalgae. To overcome this challenge, our company has developed a technology that effectively removes the TSS from the industrial wastewater and makes it suitable for the cultivation of microalgae. Hence, we can support different industries in treating their wastewater and make the treated water useful for cultivating value-added microalgae.

Potential of Microalgae in Wastewater Treatment

The cost of maintaining microalgae growth in wastewater is lower than that of conventional wastewater treatments. Organic loads found in the brewery wastewater is suitable for the growth of microalgae, thereby making it an extremely attractive means for sustainable and low-cost wastewater treatment. Several species of microalgae can capture nutrients from wastewater. The capital cost of this process is less expensive as compared to conventional wastewater treatment processes.

Low Energy Requirement
Microalgae release oxygen as a byproduct during wastewater treatment, and aerobic bacteria use this to degrade the remaining organic loads further. This reduces the energy cost compared to the cost of mechanical energy for aeration during conventional waste water treatment. Approximately 1 kWh of electrical power is needed to remove 1 kg of BOD in the activated sludge process. During this process, 1 kg of fossil carbon dioxide is produced from power generation. Microalgae do not require any energy input to remove 1 kg of BOD from brewery wastewater and produce 1 kWh of electric power through methane production byalgal biomass.

Reductions in Sludge Formation
The primary objective of every wastewater treatment plant is to reduce or eliminate sludge. Conventional wastewater treatment is characterized by the use of large amounts of chemicals. Substantial use of chemicals may result in the formation of sludge. This produces hazardous solid wastes which must be disposed of in the environment. Microalgae wastewater treatment requires no chemical additives, and sludge is accumulated in the form of algal biomass.

Greenhouse Gas Emissions Global warming is of great concern worldwide. CO2 mitigation has been strategically tackled in two ways; chemically and biologically. Chemical approaches involve separation, transporting, and sequestration. These approaches are energy-consuming and costly; therefore, there is a need for alternative cost-effective and sustainable means to curb the threat. Microalgae are an emerging biotechnological approach to mitigating CO2 , and about 2,000,000 species are useful for CO2 sequestration. Fixation of CO2 through photoautotrophic algal culture can decrease CO2 in the atmosphere. Approximately microalgae fix 183 tons of carbon dioxide to produce 100 tons of biomass. Microalgae grow more rapidly than other terrestrial plants due to their ability to capture solar energy more efficiently revealed that Microalgae have much higher growth rates and CO2 fixation abilities than conventional forestry, agricultural, and aquatic plants.

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