Replacing Mineral Fertilisers with Certified Digestate
Increasing global demand for food dictates higher yields per hectare. Higher yields can often be achieved through increased fertiliser use. However, reliance on traditional mineral fertilisers not only raises concerns about decreasing worldwide reserves, but it also results in negative environmental impacts from consumption of fossil fuels required for mineral fertiliser production.
One solution to mitigate increased demand for mineral fertilisers is to use digestate from anaerobic digestion. Once organic waste, such as manure and food waste, has been digested in an anaerobic digester to produce biogas, what remains is a digestion residue, known as ‘digestate’. Digestate is rich in plant nutrients, has excellent fertiliser qualities and has great potential worldwide as a sustainable alternative to mineral fertilisers.
Despite its potential, the use of digestate as fertiliser has been limited in many countries due to unfamiliarity of the product, as well as insufficient confidence in its quality and safety. To increase confidence in digestate as a fertiliser, a quality assurance certification system is required that inspects digestate along the chain from raw material to finished product. Such a certification system not only increases confidence in digestate use, but would ensure that certified digestate is free of heavy metals, organic pollutants, bacteria such as Salmonella, and weed seeds.
One such national quality standards for digestate is Sweden’s RAPPORT B2009: Certification Rules for Digestate (ISSN 1103-4092), which lays out the requirements for certification, technical requirements and requirements for continuous control of certified digestate. This certification, based on prevailing standards and on the requirements of Swedish Waste Management, takes its principles from European regulation 1069/2009, and guidelines and advice about storage, digestion and composting from the Swedish Environmental Protection Agency. The certification rules are also regularly up-dated through decisions taken by the management committee.
For more information about quality assurance certification systems for digestate, or if you have any questions regarding biomass renewable energy, please contact us.