Organomineral fertilizer
By recycling food scraps, agricultural residues, animal manure and other biodegradable waste, this process reduces environmental pollution and promotes a circular economy. Indeed, the initiative, which is gaining ground in the agricultural sector, has the potential to revolutionize the global farming industry, reduce reliance on synthetic chemicals, and help address food security concerns.
One example of “waste into fertilizer” research is work being done at Australia’s University of Southern Queensland (UniSQ). Researchers have been trialing a raft of strategies to turn nutrient-rich animal waste into a bio-solution. UniSQ Centre of Agricultural Engineering (CAE) Director Professor Bernadette McCabe said the research was about offering solutions to the rapid rise of fertilizer prices. Over the last five years, a research team has been researching the agronomic benefits of biofertilizers. As part of this, the recent commission of a lab-scale granulator, funded by the Queensland Government’s Waste to Biofutures fund, the Fight Food Waste CRC and the University has expanded the research into the production of organomineral fertilizers.
“The granulator is a first of its kind in Australia and will enable the production of biofertilizers using various organic waste materials together with mineral fertilizers,” McCabe said.
The product, called an organomineral fertilizer or OMF granule, will have similar characteristics in terms of physical (particle density and diameter, size distribution), mechanical (particle strength) and aerodynamic properties to manufactured mineral fertilizers. Read more about this project, HERE.
Other research facilities are getting into the game as well. University of Illinois Urbana-Champaign (U. of. I) researchers show it’s possible and economical to prevent excess phosphorus from polluting downstream waterways, recycling that nutrient as a slow-release fertilizer. Researcher Hongxu Zhou used sawdust and lime sludge, byproducts from milling and drinking water treatment plants, respectively. They mixed the two ingredients, formed the mixture into pellets, and slow-burned them under low-oxygen conditions to create a “designer” biochar with significantly higher phosphorus-binding capacity compared to lime sludge or biochar alone. Importantly, once these pellets bind all the phosphorus they can hold, they can be spread onto fields where the captured nutrient is slowly released over time (read more HERE).
What “wastes” that are used are not just from organic sources. BiziSul Inc., a sulphur-based fertilizer products company in Blackfalds, Alberta, Canada, is getting nearly CA$2.6 million to set up a new manufacturing plant in central Alberta converting waste sulphur from oil and gas operations into a high-grade fertilizer.
Ryan Brown, BizSul Inc. director of business development, said the first products from their plant went to market last October.
"We sell a fair amount to the U.S. markets, the Midwest and the southern, mid- and northern Plains areas and the Pacific Northwest in Western Canada," he said.
The plant employs about 20 people and can ship 100,000 tonnes of fertilizer, mostly by truck, to its customers per year.
Brown said the company's products are ideal for crops that need high levels of sulphur replacement, such as canola, corn, cotton, sugar beet, alfalfa and potatoes. BiziSul produces a more sustainable, slow-release fertilizer that remains in the soil for a longer period of time.
Saving money, protectingthe environment For farmers, these new waste into fertilizers are not only environmentally friendly but also cost-effective, particularly in regions where access to traditional fertilizers is limited or where the cost of synthetic products is rising. Furthermore, the use of waste-derived fertilizers can improve soil quality by boosting microbial activity, increasing water retention, and reducing the need for excessive irrigation.
The success of waste-to-fertilizer technology also has the potential to alleviate the global waste crisis. According to the UN, an estimated 1.3 billion tons of food is wasted every year, much of which ends up in landfills, contributing to greenhouse gas emissions. By converting organic waste into fertilizer, these new technologies could help curb methane emissions while addressing both food waste and agricultural challenges.
Despite the promising prospects, challenges remain. Scaling up production to meet global demand for fertilizers will require substantial investment in infrastructure and technology. Additionally, regulatory frameworks must be established to ensure that waste-derived fertilizers meet safety and quality standards.
A consortium in Europe is tackling those challenges. In an ambitious stride towards promoting circular economy principles, the ReLEAF Consortium has officially signed the Grant Agreement 101156998 for a landmark project co-funded by CBE JU (Circular Bio-based Europe Joint Undertaking), UKRI (UK Research and Innovation) and SERI (Swiss State Secretariat for Education, Research and Innovation). This consortium, comprising 17 leading companies, technology developers, and research organizations from nine European countries, aims to revolutionize the bio-based fertilizer industry in alignment with the European Green Deal and the revised EU Bioeconomy Strategy.
The project focuses on the systemic transformation of the industrial sectors involved in the bioeconomy towards achieving climate neutrality, enhancing biodiversity, combating pollution, and reducing reliance on fossil resources. Through innovative solutions, the consortium plans to integrate novel technologies, establish sustainable value chains, and create circular business models. This will not only contribute to environmental sustainability but also to economic growth by creating new green jobs, fostering collaborations, and developing partnerships.
ReLEAF’s objective is to valorize widespread bio-waste streams across Europe – including sewage sludge, fish processing waste, mixed food waste and agri-food residues – to produce safe, sustainable and efficient bio-based fertilizers (BBFs). These BBFs are designed to improve soil health and quality, close nutrient cycles within the food value chain, and reduce dependency on imported mineral fertilizers. The project’s ambition is to leverage existing supply chains and sales channels of the ReLEAF partners to commercialize the developed solutions and products within the EU and globally.
Structured in seven work packages, the ReLEAF project aims to optimize feedstock requirements and technologies for compound extraction and ingredient production, demonstrate fertilizer formulation and production technologies, and assess fertilizer efficiency, soil quality and product safety. Additionally, it will engage in exploitation and value chain co-creation to ensure circularity, conduct environmental, economic and social sustainability assessments, and carry out dissemination, communication and project management activities.
Through its comprehensive approach, ReLEAF aims to address significant challenges such as dependency on foreign supply chains and petroleum-based resources for fertilizer production, while promoting waste valorization and security of supply at a regional level. The project will demonstrate the effectiveness and replicability of BBFs in varying climate conditions and soil ecosystems across Europe, engage regional stakeholders through co-creation activities for widespread acceptance, and facilitate the rapid scale-up and industrialization of proposed technologies.
As the ReLEAF Consortium embarks on this transformative journey, it contributes not only to the “A Soil Deal for Europe” mission objectives but also expands the BBF knowledge base throughout the continent, paving the way for a more sustainable and circular bioeconomy.
In the meantime, researchers and companies continue to investigate and trial new fertilizer from waste projects. Read more aboutsome of those projects in the following pages. ●
Enter the University of Southern Queensland (UniSQ), which has been trialing a raft of strategies to turn nutrient-rich animal waste into a bio-solution.
UniSQ Centre of Agricultural Engineering (CAE) Director Professor Bernadette McCabe said the research was about offering real solutions to a global problem.
“Farmers are facing increasing input costs with the rapid rise of fuel and fertiliser prices,” McCabe said. “A significant influence on global fertilizer prices is the price of fossil fuels, particularly natural gas. Fossil fuels (and air) are the main input into nitrogen fertilizer production, and changes in global prices will be reflected in nitrogen fertilizer prices over time.”
McCabe said the use of biofertilizers brought not only potential economic benefits but also environmental outcomes since using organic waste to produce biofertilizers will reduce greenhouse gas emissions.
Over the last five years, a research team has been researching the agronomic benefits of biofertilizers.
As part of this, the recent commission of a lab-scale granulator, funded by the Queensland Government’s Waste to Biofutures fund, the Fight Food Waste CRC and the University has expanded the research into the production of organomineral fertilizers.
The product, called an organomineral fertilizer or OMF granule, will have similar characteristics in terms of physical (particle density and diameter, size distribution), mechanical (particle strength) and aerodynamic properties to manufactured mineral fertilizers.
“This is an important consideration in the design of the final product to enable field spreading with standard fertilizer spreading or pneumatic equipment,” McCabe said.
The research team will work with industry to develop the final product, which will have a suitable formulation to meet the nutritional requirements for crop and soil. ●
University of Southern Queensland Senior Research Fellow Dr Stephen Tait (Centre for Agricultural Engineering) using the lab-scale granulator. Photo: UniSQ
Denali, the U.S.’s leading recycler of organics, announced it has transformed over 10 billion pounds of organic byproducts into natural fertilizers.
This achievement positions Denali as the largest business of its kind in the U.S. The report also highlights the significant impact its services have had on food waste diversion, further enforcing the company’s crucial role in advancing the circular economy.
Denali’s recycling efforts produced enough natural fertilizer to support more than 100,000 acres of farmland and manufactured enough animal feed to nourish over 40,000 cattle across five U.S. states.
Food waste is one of many organic waste streams that Denali converts into valuable products as part of its mission. The company collects food waste from thousands of grocery stores and various food manufacturers, distribution centers, hotels, stadiums, universities and cafeterias across 48 states and Puerto Rico.
“Denali’s mission is to replenish the earth by repurposing waste,” said Denali CEO Todd Mathes. “Over the last several years we have invested in our business to deliver on this mission for our partners, the planet and society. Today, our dedicated team is driving the circular economy, by meaningfully reducing food waste and providing best-in-class solutions to our customers. Our 2023 sustainability reporting highlights our continued growth in impact as we help keep food waste and organics out of landfills.”
Denali also introduced ReCirculate, its compost and organic potting soil product made from food waste sourced from thousands of grocery stores. Starting January 2025, ReCirculate will be available for purchase in one cubic foot bags at participating retail locations across the U.S.
Most recently, Denali launched depackaging technology across the U.S., providing customers such as grocery retailers, municipalities, stadiums, restaurants and more, a way to collect and recycle wasted food items without having to manually separate organic contents from their packaging more easily. The depackaging technology automatically separates food from its packaging materials like plastic and cardboard, producing a cleaner stream of organic material that can be turned into animal feed, compost or converted into energy with anaerobic digesters. ●
In Urbana, Illinois, researchers at the University of Illinois Urbana-Champaign are pioneering a sustainable approach to fertilizer production that utilizes organic waste.
Through two innovative studies, the team has explored the potential of a fungal treatment to convert wastewater from hydrothermal liquefaction (HTL) into a viable fertilizer for agricultural crops.
Hydrothermal liquefaction is a process that transforms wet biomass, such as swine manure or food waste, into biocrude oil using high-temperature, high-pressure conditions. This process generates a byproduct known as hydrothermal liquefaction aqueous phase (HTL-AP), which typically contains valuable nutrients locked in organic forms that are not readily accessible to plants and may also contain toxic heavy metals.
Paul Davidson, an associate professor in the Department of Agricultural and Biological Engineering, explained, “While HTL-AP holds nutrients beneficial for fertilization, the organic nitrogen compounds need to be broken down into forms like ammonia or nitrate that plants can absorb, and toxic components must be removed.”
The first study, led by then-master’s student Vitória Leme, focused on employing Trametes versicolor, a type of white-rot fungus, to treat the HTL-AP. The results showed that treating the wastewater with this fungus for three days significantly increased the concentrations of nitrate and ammonia.
Following Leme’s graduation, undergraduate student Karla Lopez continued the research. In the second study, she combined the fungal treatment with a bacterial nitrification process to further convert ammonia into nitrate, achieving a 17-fold increase in nitrate concentration.
Lopez highlighted that optimal results were achieved when the microorganisms were maintained in water with a pH range of 6 to 7.5. She noted, “Our findings also suggest that the fungus not only aids in nutrient recovery but also plays a role in detoxifying the wastewater.”
Building on these promising outcomes, Davidson’s team is now exploring the use of this treated wastewater to grow hydroponic crops, aiming to establish a circular economy model that minimizes the need for long-distance transport of wet biomass. He envisions integrating this treatment system near swine farms or similar agricultural setups to streamline the process from waste generation to fertilizer application. ●
Vitória Leme working with fungal treatment under a biosafety hood.Insert: Fungus pellets in a petri dish. Photo: University of Illinois Urbana-Champaign
Bacterial communities in soil are as resilient to human urine as synthetic fertilizers – making recycling the bodily fluid as a fertilizer for agricultural crops a viable proposition, according to a new study.
Scientists discovered that, even when applied in high doses, one-year stored urine had little impact on soil bacterial communities and produced minimal change in soil pH and salinity.
However, the researchers did discover that urine fertilization increased the relative amounts of nitrifying and denitrifying groups compared to synthetic fertilizer – implying that more nitrogen oxides could be emitted when fertilizing with urine.
Publishing their findings in Applied Soil Ecology, the team of researchers from University of Birmingham and L'Institut Agro Montpellier, France, call for further studies on the long-term effects of urine fertilization – particularly regarding nitrogen oxide production and soil salinity.
Co-author Manon Rumeau, from the University of Birmingham, commented: "Our research highlights the potential of recycling human urine to enhance agricultural sustainability, reduce wastewater pollution, and decrease reliance on synthetic fertilizers. Stored urine can be safely applied to a plant-soil system without negatively impacting the soil microbiome."
Fresh urine is composed of 95 percent water with the remaining five percent made up of amino compounds, such as urea or creatinine, organic anions and inorganic salts making it a source of bioavailable nutrients and micronutrients for plant growth.
There has been great interest inre-using human urine as a crop fertilizer, but – until the publication of this study – more understanding was required on how urine can affect soil functions and microbial communities.
Scientists fertilized a spinach crop with two different doses of a source-separated and stored human urine – comparing these with a synthetic fertilizer treatment and a water treatment without fertilization, conducted across four soil tanks in greenhouse conditions.
After 12 months of storage, urine had a depleted microbiome but contained few common strains of urine. Thus, storing urine for several months, with the resulting increase in its pH value (about 9 rather than 6.5 for fresh urine) and its free ammonia concentration is considered sufficient to inactivate most human pathogenic bacteria and break down extracellular DNA.
Soil bacterial communities were resistant to urine fertilization with only three percent of groups of organisms impacted. The urine's high salt concentration had little discernible effect on the bacterial community. ●
Trials have been conducted on spinach
In a first-of-its-kind field study, University of Illinois Urbana-Champaign (U. of. I) researchers show it’s possible and economical to prevent excess phosphorus from polluting downstream waterways, recycling that nutrient as a slow-release fertilizer.
“Phosphorus removal structures have been developed to capture dissolved phosphorus from tile drainage systems, but current phosphorus sorption materials are either inefficient or they are industrial waste products that aren’t easy to dispose of. This motivated us to develop an eco-friendly and acceptable material to remove phosphorus from tile drainage systems,” said study author Hongxu Zhou, who completed the study as a doctoral student in the Department of Agricultural and Biological Engineering (ABE), part of the College of Agricultural, Consumer and Environmental Sciences and The Grainger College of Engineering at U. of I.
Zhou and his co-authors used sawdust and lime sludge, byproducts from milling and drinking water treatment plants, respectively. They mixed the two ingredients, formed the mixture into pellets, and slow-burned them under low-oxygen conditions to create a “designer” biochar with significantly higher phosphorus-binding capacity compared to lime sludge or biochar alone. Importantly, once these pellets bind all the phosphorus they can hold, they can be spread onto fields where the captured nutrient is slowly released over time.
Leveraging designer biochar’s many sustainable properties, the team tested pellets in working field conditions for the first time, monitoring phosphorus removal in Fulton County, Illinois, fields for two years. Like the majority of Midwestern corn and soybean fields, the experimental fields were fitted with subsurface drainage pipes. This drainage water flowed through phosphorus removal structures filled with designer biochar pellets of two different sizes. The team tested 2-3 centimeter biochar pellets during the first year of the experiment, then replaced them with 1 cm pellets for the second year.
Both pellet sizes removed phosphorus, but the 1-centimeter pellets performed much better, reaching 38 to 41 percent phosphorus removal efficiency, compared with 1.3 to 12 percent efficiency for the larger pellets.
The result was not a surprise for study co-author Wei Zheng, who said smaller particle sizes allow more contact time for phosphorus to stick on designer biochar. Zheng, a principal research scientist at the Illinois Sustainable Technology Center (ISTC), part of the Prairie Research Institute at U. of I., has done previous laboratory studies showing a powdered form of designer biochar is highly efficient for phosphorus removal. But powdered materials wouldn’t work in the field.
“If we put powder-form biochar in the field, it would easily wash away,” Zhou said. “This is why we have to make pellets. We have to sacrifice some efficiency to ensure the system will work under field conditions.”
After showing the pellets are effective in real-world scenarios, the research team performed techno-economic and life-cycle analyses to evaluate the economic breakdown for farmers and the overall sustainability of the system.
The cost to produce designer biochar pellets was estimated at US$413 per ton, less than half the market cost of alternatives such as granular activated carbon ($800-$2,500 per ton). The team also estimated the total cost of phosphorus removal using the system, arriving at an average cost of $359 per kilogram removed. This figure varied according to inflation and depending on the frequency of replacing pellets – two years appeared to be the most cost-effective scenario.
The life cycle analysis showed the system – including returning spent biochar pellets to crop fields and avoiding additional phosphorus and other inputs – could save 12 to 200 kilograms of carbon dioxide-equivalent per kilogram of phosphorus removed. Zhou says the benefits go beyond nutrient loss reduction and carbon sequestration to include energy production, reduction of eutrophication, and improving soils.
“At the moment, there's no regulation that requires farmers to remove phosphorus from drainage water. But we know there are many conservation conscious farmers who want to reduce nitrate and phosphorus losses from their fields,” said co-author Rabin Bhattarai, associate professor in ABE. “If they’re already installing a woodchip bioreactor to remove nitrate, all they’d have to do is add the pellets to the control structure to remove the phosphorus at the same time. And there’s something very attractive about being able to reuse the pellets on the fields.”
The study, “Exploring the engineering-scale potential of designer biochar pellets for phosphorus loss reduction from tile-drained agroecosystems,” is published in Water Research. ●
Researchers at UNSW Sydney (Australia) have developed a zero-emissions system using a solar panel that turns nitrate wastewater into ammonium nitrate for use in fertilization.
UNSW Scientia Professor Rose Amal, collaborating with Professor Xiaojing Hao, and their teams developed a way to generate ammonium ions from nitrate-containing wastewater using only a specially designed solar panel that works like an artificial leaf.
The process is known as photoelectrocatalytics (PEC) and utilizes a nano-structured thin layer of copper and cobalt hydroxide on the panel that acts as a catalyst to assist the chemical reaction needed to produce ammonium nitrate from wastewater.
The research was published in a paper in the Journal of Energy and Environmental Science.
The research team, which includes lead author of the paper Chen Han, and Dr. Jian Pan (a DECRA Fellow) have built a 40cm2 artificial leaf system on the roof of Tyree Energy Technologies building at UNSW which has been able to produce ammonium ions that can satisfy 1.49m2 of cropland.
The results encourage development of the size of the system in pursuit of creating ammonia without the associated greenhouse gas emissions.
“Traditional ammonia production requires high temperatures – around 400 to 500 degrees Celsius – and high pressure, historically necessitating the use of fossil fuels,” said Amal from the School of Chemical Engineering. “This system works at ambient conditions and just uses sunlight to produce ammonium from nitrate-containing wastewater, which is an important chemical used in fertilizer.
“We think this new technology could be implemented on a relatively small scale in agricultural locations to produce ammonium onsite, which would decentralize the production process and further reduce CO2.emissions that are associated with the transportation process,” added Amal.
In a real leaf, photosynthesis is the way that plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar. In this new photoelectrocatalytic process, the solar panel is acting like an artificial leaf to use sunlight, and nitrate-containing wastewater to create ammonium nitrate.
“We are combining photovoltaics’ expertise from UNSW's School of Photovoltaics & Renewable Energy Engineering, and our expertise in chemical engineering, to take nitrate waste and turn it into an important commodity in the form of ammonia,” said Han. “We’ve developed a very efficient catalyst with some special nanostructures and incorporated that with a traditional silicon solar panel which results in a highly effective process. Our findings provide a clean, efficient and cost-effective solution for utilising solar energy and chemical wastes to produce ammonia and other value-added products.
“You do not need a high concentration of ammonia in fertilizer so we believe the amounts of ammonia we are producing using our system make it a viable application in the real world, although we definitely still have some ways to further improve it,” added Han.
The researchers hope that the generation of the ammonium from the wastewater will allow the processed water to be used to irrigate crops and further help them to grow.
“It’s important to acknowledge that the wastewater we convert isn’t coming directly from municipal waste or runoff – it still needs to be processed first to filter out the organic matters and particulates,” said Amal. “But we are hopeful that once we have generated ammonium from the nitrate wastewater, the treated water can then be put into irrigation.”
Amal is keen for further collaboration and involvement with potential industry partners to further develop the process into a fully viable commercial system. “Industry partners would help us scale up this device, and we definitely would like to utilise a full-scale, traditionally sized solar panel for our application,” she said. ●
Artificial leaf system developed at UNSW to create ammonia from wastewater using onlythe sun.
Photo: Chen Han/UNSW
