Undeniably, it sounds like a smart business to first help the client to get rid of various bi-products to later sell back the valuable components to the same customer.

“Really so smart and simple, it is not in all situations, but in concrete terms, we are helping to create systems to recycle plant nutrients out of something that is often considered waste and ensure that industry will benefit again,” says Jan Nystedt , CEO of Biototal AB.

“For us, it is currently a big deal to take care of biological waste products arising from biogas production. The waste product, called digestate, is rich in nutrients and we sell about 300,000 tonnes of it to farmers, ” Nystedt continues. “They are building more and more biogas plants in the country and at the same time there is increasing interest in bio-fertilizers. We are the largest distributor of bio-fertilizer in Sweden, but as it stands currently, agriculture’s demand is higher than supply.”

Biototal works with digestate, a waste product from the production of biogas in the Swedish agricultural industry.

Biototal works with digestate, a waste product from the production of biogas in the Swedish agricultural industry.

“We see ourselves as a link in the cycle between city and country. We can help with knowledge on design of facilities to extract valuable materials from bi-products, we convey bio-fertilizers and sludge for agriculture, and we have many connections with the food industry and other industries about how to create environmental benefits from waste,”says Nystedt .

Bio-fertiliser

For Swedish farmers are bio-fertilizers relatively new. The digestate is formed when the biogas is produced from a substrate consisting of organic material. Here it can be anything from manure, slaughterhouse waste, food waste, sewage sludge and other biological waste products.

During the digestion process, the substrate -energy methane (biogas), consists of carbon and hydrogen. At the same time in the organic substrate a number of organic and inorganic there are compounds that do not produce biogas. The product is called digestion and is composed of water, organic materials, microorganisms and various nutrients. The texture is similar to the liquid manure from cattle and pigs.

“We prefer to call it digestate. It is a “green fertilizer” because it contains nutrients like nitrogen, phosphorus, potassium and sulphur, as well as essential micro-nutrients and organic matter,” says Nystedt . “A part of the nitrogen in the manure is produced in the form of ammonium, which is a result of the digestion process. The high proportion of ammonia makes a digestate a fertilizer with a fast nitrogen effect. It means that the nitrogen will be quickly used.”

As a result of the digestion process, the content of organic materials in the digestate is lower than in manure. According Biototal, this is an advantage because the organic material is more stable, it offers the advantage that the content is increased and the soil structure is improved.

Quality assurance systems

Digestate must not contain contaminants such as heavy metals, pathogens, drug residues and pesticides. It is therefore important that the bi-products submitted to digestion are not contaminated. Careful sorting is a prerequisite for a successful end result.

In Sweden, there is a certification system where biogas plants can voluntarily oversee and certify the production of bio-fertilizer. The certification process examines the entire chain from raw material to final product and the levels of a number of pollutants are monitored regularly. Among other requirements, the Salmonella bacteria may not occur in the digestate. The certification also requires that staff be regularly trained in safety awareness. The purpose of certification is to help increase customer confidence in the digestate.

Upstream and downstream in the value chain

The content of the digestate from various plants and production batches shifts. It is therefore important to the farmer that the digestate can be characterized with respect to nutrient content and a number of other physical and chemical parameters.

“In Biototal, we work both upstream and downstream in the value chain,” said Nystedt . “Downstream, we create a close cooperation with the customer, where we put ourselves into the whole business to provide optimal solutions. The basis for this work is a tool that we call “value added calculation.” The tool provides a good overview of bilateral and residual value of the products from an agronomic, environmental and economic perspective.”

“Upstream, we work to ensure the quality of the organic material to be digested. Of particular interest is to minimize the pollutants in sewage sludge. Among other things, we conduct development work with Käppalaförbundet , which is a major player in wastewater treatment, and the common goal is that sludge will become an accepted and valuable fertilizer product . In this context, the certification system REVAQ for quality assurance of sewage treatment is important. We have the expertise to help smaller wastewater treatment plants with working upstream with their clients as a stepping stone to become certified by REVAQ.”

The article was published in December 2013