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Sustainable cleaning agent and organic fertilizer recovery from sewage sludge

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Cleaning products and fertilisers produced from sewage sludge

Wastewater sewage sludge production is continuing to increase around the world due to population growth and urbanisation. Hence, the treatment and handling of sewage sludge are among the greatest challenges facing small and medium-sized wastewater treatment plants both in Europe and globally.

Climate Change and Environment
Industrial Technologies

Existing solutions for sewage sludge are focused on exploitation of the calorific value or organic matter. However, in many cases, like incineration and landfilling, much of the value contained within the sludge is lost. This situation is exacerbated by the lack of available commercial technologies that can extract valuable components from sewage sludge while neutralising its toxicity. The EU-funded reNEW project addressed these challenges by sustainably recovering valuable ingredients that are locked in the sludge. The process involves biological transformation of the material into a liquid that contains volatile fatty acids (VFAs) and valuable macro- and micronutrients like nitrogen (N) phosphorus (P) and potassium (K). In addition to recovering useful products, the process also reduces the volume of the processed biosolids by almost 50 %.

Valuable products recovered

These products represent important market value. “Extracted VFAs form the basis for an acetic cleaning agent, which is targeted at both the home consumer and professional markets. The NPK forms a humic acid-rich liquid fertiliser and the organic matter improves soil properties like tilth, friability, fertility and water-holding capacity to optimise plant growth,” says Sunny Bhasin, inventor and CEO of coordinating company UTB Envirotec, one of central Europe’s leading wastewater and water treatment engineering services. According to Bhasin, the core of the technology is based on improvements in the fermentation and distillation processes. “This allows us to recover essential ingredients like VFAs, micro- and macroelements, and humic and fulvic acids that are otherwise locked in the sludge and lost forever,” he explains.

Economic and environmental benefits

The reNEW project will exploit the new process, rolling it out across Europe. “We aim to scale up our process to an industrial scale and commercialise both valuable products: the environment-friendly cleaner based on VFA and fertilisers based on NPK. Our target is to create a techno-economic framework in which the return on investment for the reNEW process installation would be less than 3 years,” Bhasin points out. Key project results include the validation of the technology and the recovery of essential acids and nutrients that are the main ingredients in the new products. reNEW technology will therefore make an immense contribution to the circular economy, as it valorises undesired waste products of wastewater treatment. Furthermore, it has a carbon footprint of zero on the environment. “Our vision is that wastewater produced by cities can be cleaned of products that can be recovered over and over again,” Bhasin concludes. “Our next focus for this versatile raw material will be on bioplastics.”

Keywords

reNEW, sewage sludge, wastewater, organic fertiliser, volatile fatty acids (VFA), macroelement, microelement, cleaning agent, biological transformation

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