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The role of micro-aeration-based processes for the valorisation of polluted sludge to value-added chemicals

Project description

Micro-aeration: breathing new life into sewage sludge

During wastewater treatment, almost all the water is purified and discharged. The residual semi-solid material that remains (i.e. sludge) is primarily non-toxic organic matter that can be used for the production of chemicals and energy carriers. Macronutrients and micronutrients in the sludge including nitrogen, phosphorous, potassium and iron also make sludge an excellent eco-friendly fertiliser. However, valorisation of sludge is complicated by the growing list and quantity of contaminants it contains – and our inability to remove them. With the support of the Marie Skłodowska-Curie Actions programme, the OXYCON project will use micro-aeration prior to conventional anaerobic fermentation/digestion to improve the degradation of selected organic micropollutants, removal of heavy metals and biotransformation of organic matter.

Objective

Industrial and municipal biological wastewater treatment plants (WWTP) generate vast amounts of sludge (SS) as a by-product. The total annual production of sludge currently surpasses 13 million tonnes of dry solids (DS) in the EU, even excluding sludge production from industrial on-site WWTP. Sewage sludge (SS) mainly contains non-toxic organic matter that can be converted to value-added compounds such as carboxylic acids, alcohols, and energy carriers. Furthermore, macronutrients such as nitrogen and phosphorus and micronutrients (e.g. potassium and iron) that are essential for crop growth are present as well, making sludge an interesting organic fertiliser. However, mainly depending on the composition of the wastewater and the pollutant’s biodegradability, SS typically contains various potential hazardous contaminants (OMP) such as adsorbable halogenated organic compounds (e.g. PFAS, AOX), phenols, sulfates, aromatics, active pharmaceutical ingredients (APIs) (e.g. antibiotics, endocrine disruptors), pathogens (viruses, bacteria, etc.), microplastics and heavy metals (HM). It is clear that there is an urgent need for technological strategies that tackle both the increasing presence of contaminants in sludge and allow efficient resource recovery from sludge. However, current alternative sludge management strategies fall short to properly respond to the growing demands of a sustainable society and unfortunately, a significant amount of sludge is incinerated or (even worse) landfilled.OXYCON will therefore explore the use of micro-aeration as an innovative technique to simultaneously (i) degrade selected OMP, (ii) remove HMs, and (iii) enhance carboxylic acid production as biobased chemical building block during (subsequent) anaerobic fermentation of the treated sludge. The potential of air will be researched via two different techniques: air-assisted ultrasonication and micro-aeration-based anaerobic fermentation.

Coordinator

KATHOLIEKE UNIVERSITEIT LEUVEN
Net EU contribution
€ 191 760,00
Address
OUDE MARKT 13
3000 Leuven
Belgium

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Region
Vlaams Gewest Prov. Vlaams-Brabant Arr. Leuven
Activity type
Higher or Secondary Education Establishments
Links
Total cost
No data