Chemical treatment
Nutrient Removal and Recovery from Digestate: A Review of the Current Knowledge
Digestate is a byproduct of anaerobic digestion, which can be considered waste or a product of potential use for the chemical industry or agriculture. In either case, the digestate must usually be treated prior to being disposed of or valorized. This review describes digestate processing technologies and their specific characteristics. Nutrient recovery and removal from digestate can be achieved through mechanical, physicochemical or biological processes. Available and potential digestate treatment techniques are presented. The complexities of the technologies available, legislation, the agronomical value of the digestate and the economic value of the process mean a decision support tool is required to help managers choose the best digestate processing technology. To ensure adequate analysis, the whole biomethanization project should be integrated in the use of these decision support tools. The objectives and limits of some of the currently available tools are analyzed at the end of this review.
Nutrient recovery from digestate: Pilot test experiments
A pilot-scale study tested several technologies to treat biogas digestate— the residue from anaerobic digestion of dairy, animal, and some crop wastes—so that nutrients can be recovered and the material can be reused. The digestate was processed through microfiltration, ultrafiltration, reverse osmosis, selective electrodialysis, and UV/ozonation. Early filtration steps removed over 80% of solids and large organic molecules, while reverse osmosis removed nearly all remaining dissolved substances, producing clean water suitable for reuse. Selective electrodialysis recovered over 95% of ammonium and potassium and about 55% of phosphate, 75% of which was turned into struvite, a valuable fertilizer.
Nutrient-recovery-from-digestate-Pilot-test-experiments.pdfVALUEWASTE opens its pilot plant in Murcia: sustainable technologies for the valorisation of biowaste in EU cities
The VALUEWASTE project has opened a pilot plant in Cañada Hermosa, Murcia (Spain) to demonstrate sustainable technologies for the valorisation of urban biowaste. The facility processes the brown bin organic fraction through sorting, anaerobic digestion and digestate separation into solid and liquid fractions. From the liquid digestate, the plant recovers nutrients such as struvite and ammonium sulphate, which are used to produce high-value fertilisers. The solid fraction is transformed into protein-rich biomass through black soldier fly larvae cultivation. The pilot plant is part of an integrated circular-economy approach that converts municipal biowaste into valuable products, fertilisers, proteins and energy, while reducing waste and supporting sustainable urban resource management.
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Digestate Valorization: Turn Waste into Premium Organic Fertilizer & Energy
The article explains how digestate — the wet by-product of anaerobic digestion — is being transformed from a bulky waste into a premium organic fertiliser and energy source. It highlights multiple upgrade technologies such as mechanical dewatering, thermal drying, pelletisation, struvite precipitation and water recycling, allowing facilities to recover nitrogen, phosphorus, potassium and also reuse water.
It emphasises both the economic benefits (reduced disposal costs, revenue from energised processes, premium pricing for processed products) and the environmental advantages (lower greenhouse gas emissions, less reliance on synthetic fertilisers, conservation of finite resources, improved water quality) of such valorisation paths.
The article suggests the future of digestate lies in its integration into circular-economy models: waste becomes input for high-value outputs, helping to close nutrient loops while enhancing sustainability.
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Valorisation of digestate: Characteristics, products, processes and potential
Anaerobic digestion (AD) is an important technology for renewable energy production and waste management, but it also generates large volumes of digestate that must be effectively managed to realize its full sustainability potential. This review examines the key characteristics of digestate and how they influence opportunities for its valorisation into useful products. It assesses current technologies, including separation methods and advanced processing pathways, and discusses their technical and economic implications. Policy and regulatory considerations are also highlighted. Overall, the review provides guidance for researchers, industry stakeholders, and policymakers working to advance circular economy strategies.
Valorisation-of-digestate-Characteristics-products-processes-and-potential.pdf