A Swedish environmental cleantech company has become the first in the world to develop a commercially viable method for recycling nitrogen from wastewater to solid form.
EkoBalans, based in Lund, has announced the new technology, called eco:N. This is a completely new and unique process for extracting ammonium nitrogen from water as solid ammonium sulphate. This crystallized product can then be processed into fertilizers and used in agriculture.
“This is a revolution in water purification”, says Erik Kvarmo, CEO of EkoBalans. “The eco:N process creates a solid product containing 21% nitrogen. This can then be mixed with other recycled nutrients to make a more complete fertilizer.
“By recycling wastewater to extract the nitrogen and phosphorus, we can make fertilizers in a way that is far less damaging to the environment than the production of artificial ones”, he explains.
Up to now, the most common way to recover nutrients from wastewater and use them to fertilise soil is to spread sludge onto arable land. Dewatered digestate or sludge contains almost all the phosphorus that is separated at a treatment plant. EkoBalans has a process called eco:S in which the phosphorus in the sludge is recycled as sludge biochar, which is free of cadmium and other pollutants.
Nevertheless, only about 15% of the nitrogen in wastewater ends up in the digested and dewatered sludge. This means that the practice of sludge spreading only makes use of a small proportion of the total available nitrogen as fertilizer.
Profitable for both companies and the environment
A recent Swedish government enquiry proposed minimum requirements for the recycling of phosphorus from wastewater. The recycling of nitrogen is likewise important. “This is because both the production of conventional nitrogen fertilizer and biological nitrogen cleaning at WWTPs creates high greenhouse gas emissions,”, explains Gunnar Thelin, founder and development manager at EkoBalans.
“With our new method of recycling nitrogen from wastewater, things are much different. Now, the agriculture industry, biogas plants and treatment plants can achieve better sustainability and profitability. This has benefits both for their own operations and for society as a whole”.