The input of nutrients is essential for food production – but nutrient leaching from soils causes pollution and euthropication. EkoBalans completes the cycles by removing harmful substances from waste and residual streams and refining the nutrients into fertilizer.
”I have always been interested in circular concepts and recycling of natural resources. In order to grow food, nitrogen, phosphorus and other nutrients are needed. They are mostly distributed in the form of commercial fertilizers, which are based on limited, mined resources. The extraction process affects the environment and consumes fossil fuels. Effluents from farms and sewages are rich in these nutrients, but they often go to waste and cause euthrophication instead of being recycled”, says Gunnar Thelin, founder and business developer of the greentech company EkoBalans, and former researcher at Lund University.
Nutrients: from pollution to profit
Gunnar Thelin’s research at Lund University focused on plant nutrition, nutrient balances in forestry, and ash recycling. As Gunnar focused on the subject of nutrient rich residues he was amazed by the contradiction between unutilized phosphorus resources in society and the discussions about decreasing phosphorus resources and possible future food shortages. He became increasingly concerned about the poor handling of natural resources in the society.
”As a society, we are not very good at husbanding phosphorus, potassium and nitrogen. The nutrients leach from landfills and from agricultural soils, causing euthrophication of waters. They end up in the domestic waste from homes and restaurants. When we eat, nutrients pass through our digestive systems and are flushed out in the sewage. Large amounts of phoshorus are accumulated in the sludge at sewage treatment plants, but often accompanied by heavy metals, drug residues and other contaminants. Instead of mining for virgin materials, we should find a way of harvesting them from waste and effluents”, Gunnar Thelin says.
”Our overall solution is to take care of the effluent in a way that is sustainable for our customers and for the environment. It solves the problem of volume and nutrient overloading for our customers, and closes the loop by bringing nutrients back to agriculture where they belong. We extract the nutrients, separate them from the harmful substances and refine them into a fertilizer product comparable to conventional, non-recycled fertilizers. They can be used to grow food without any investments in new technology. They are excellent for closed loop gardens”.
A circular solution
”Our patented technologies turn the cost of effluent management into a profit. We have solutions for sustainable recycling of phosphorus and nitrogen from the food industry, biogas facilities, farms, sewage treatment plants and other operations that generate nutrient-rich effluents”, Gunnar Thelin says.
”eco:P is our phosphorus recycling technology. The process can be used at a sewage treatment facility, for instance, to recover the substance from the water. Sludge that has been drained after undergoing anaerobic digestion (decomposition by microorganisms) has a high phosphorus concentration. It is fed into a fully automated eco:P plant, which is neatly contained in a 40-feet high cube container. The plant can treat up to 300 m3/d with a phosphorus reduction capacity of 90 percent.
First, the pH in the phosphorus rich water is increased through air stripping. With addition of magnesium, phosphorus precipitates as struvite micro crystals in a semi-batch reactor process.
The struvite is a very clean product, free from the pollutants such as cadmium and other heavy metals that may occur in the sludge. The micro crystals have good plant availability”.
”The eco:P process and our nitrogen extraction process eco:N allow us to recover phosphorus and nitrogen from various effluents. Both processes can recover nutrients efficiently from sources that otherwise have low recovery rates, in the food industry, biogas production and agriculture. One of the key advantages is the fact that nutrients are extracted in a very clean form”.
”Some effluents are particularly polluted, and the eco:S process was developed to separate these. The residue is drained, then pyrolyzed (treated at high temperature in an anaerobic environment). The process removes more than 90 percent of the cadmium, 99 percent of the mercury, and about 50 percent of lead and zinc. Pathogens and other organic substances are completely eliminated. Phosphorus and other nutrients remain in the final product, which is a soil enhancing biocoal”.
A paradigm shift
”It is still common in the industry to associate effluents and residues only with problems and costs. I believe that a paradigm shift is about to happen; the circular economy concept is changing the tune. Our separation technology makes it possible to harvest resources from waste without unreasonable costs. This allows operations to profit from their residues. In a wider perspective, the phosphorus and nitrogen recovery could be combined with other processes to generate biogas and clean water from the effluents as well”, Gunnar Thelin says.
”I am largely optimistic, but there are a few dark clouds. For instance, public sewage treatment plants currently have an obligation to prevent euthrophication. But why not commission them to also make sure that the nutrients are safely returned to forests and agricultural land, without contaminants?”, Gunnar suggests.
The article was published in December 2017.