The Paris Agreement on Climate Change intends to hold the global average temperature increase below 2°C. Many researchers believe that carbon capture and utilization methods will be necessary in order to achieve this goal. An increasing amount of data indicates that wastewater treatment plants may offer opportunities for carbon capture and emissions reductions.
There are many ways to remove carbon dioxide (CO2) from the atmosphere. Several of them, as outlined in a report from the Intergovernmental Panel on Climate Change, involve extracting carbon out of air or power plant flue gas using membrane separation or adsorption technologies.
Wastewater treatment plants have been identified as large-scale greenhouse gas emitters. While some of these emissions are derived directly from treatment processes such as nitrogen and phosphate removal and sludge management, others are the product of natural off-gassing.
Scientists today are experimenting with a concept that replaces the typical microbes used to treat wastewater with microbes that feed on CO2. In theory then, wastewater from industrial processes could be pumped into tanks where microbes would consume CO2 and produce valuable chemicals like ethanol, offering an additional revenue stream for treatment facilities.
“The wastewater treatment plant would become a refinery,” Princeton University environmental engineer Zhiyong Jason Ren told WIRED. “You take this CO2 waste, you take wastewater, then using all these technologies you convert it into something.” This course of action builds upon the widespread belief that in order for carbon capture to be considered a viable solution, it needs to be either mandated through policy reform or made profitable.
Ren and his colleagues recently published their research in a Nature review of potential carbon capture techniques in wastewater treatment.
Beyond carbon-consuming microbes, another carbon capture concept used in wastewater treatment plants involves treating sludge and converting it into highly concentrated fertilizers that can be sold to farmers and returned to the earth via agricultural applications.
Utilities such as DC Water are currently producing potent fertilizer products from treated solid waste. The materials are processed using a thermal hydrolysis process and digesters, which uses heat, pressure, and bacteria to eliminate pathogens.
What are your thoughts on incorporating carbon capture methods at wastewater treatment plants? Has your organization considered adopting either of these methods?
