Turning wastewater into fertilizer is feasible and could help to make agriculture more sustainable: Researchers lifecycle analysis of nitrogen reclamation from wastewater shows a viable path forward

The wastewater draining from massive pools of sewage sludge has the potential to play a role in more sustainable agriculture, according to environmental engineering researchers at Drexel University. A new study, looking at a process of removing ammonia from wastewater and converting it into fertilizer, suggests that it’s not only technically viable, but also could help to reduce the environmental and energy footprint of fertilizer production — and might even provide a revenue stream for utilities and water treatment facilities.

A Sustainable Nitrogen Source

The production of nitrogen for fertilizer is an energy-intensive process and accounts for nearly 2% of global carbon dioxide emissions. In the last several years researchers have explored alternatives to the Haber-Bosch nitrogen production process, which has been the standard for more than a century. One promising possibility, recently raised by some water utility providers, is gleaning nitrogen from the waste ammonia pulled from water during treatment.

“Recovering nitrogen from wastewater would be a desirable alternative to the Haber-Bosch process because it creates a ‘circular nitrogen economy,'” said Patrick Gurian, PhD, a professor in the College of Engineering who helped lead the research, which was recently published in the journal Science of the Total Environment. “This means we are reusing existing nitrogen rather than expending energy and generating greenhouse gas to harvest nitrogen from the atmosphere, which is a more sustainable practice for agriculture and could become a source of revenue for utilities.”

A Cleaner Way to Clean

Under the Clean Water Act of 1972 municipal water treatment facilities have been challenged to meet water quality standards for water that they discharge into waterways. Increasingly ammonia is seen as both a concern for aquatic environments as elevated levels of ammonia can result in overgrowth of vegetation in streams and rivers which can endanger fish species. The options for removing ammonia are generally time and space consuming and can be energy-intensive undertakings.

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