Specification and Classification of Pelletised Dried Sewage Sludge: Identifying Its Key Properties as a Renewable Material for Enabling Environmentally Non-Harmful Energy Utilisation

Vesna Mislej () and Barbara Novosel
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Vesna Mislej: JP Vodovod Kanalizacija Snaga d.o.o., Vodovodna cesta 90, 1000 Ljubljana, Slovenia
Barbara Novosel: Faculty of Chemistry and Chemical Technology, University of Ljubljana, p.p. 537, Večna pot 113, 1000 Ljubljana, Slovenia

Sustainability, 2022, vol. 14, issue 22, 1-24

Abstract: Renewable active sludge is a smart material for wastewater treatment and the protection of surface water bodies. The generated pellets (dried and pelletised dehydrated anaerobically stabilised excess sludge) are produced in a quantity of 31.4 ± 5.6 g dry matter (DM) per one Population equivalent (PE) calculated to COD (PE COD ) in one day. As pellets are combustible material, their energy utilisation must reach the sustainable development goals (SDGs)—a bridge must be created between “treated sewage sludge as the tool to remove pollutants and nutrients from wastewater” and “preparation of the valuable material as a solid recovered fuel (SRF) that meets customer-specific requirements”. Technical Report CEN/TR 15508 and Technical Standard EN ISO 21640 set up methods for specifying and classifying pellets as an SRF. In the last eleven years (2010–2021), pellets’ net calorific value (NCV) is 13.0 ± 0.7 MJ kg −1 as received (ar). In 2021, the 80th percentile of the Hg/NCV ratio was 0.079 mg Hg MJ −1 . In 2010–2021, the annual amount of Hg transferred to stakeholders reduced by 64.3% m/m—from 10.1 kg to 3.67 kg. The halogen contents of the pellets do not threaten corrosion to the incineration facility. Stable pellets’ energy potential and perspective ash composition for critical raw materials recovery qualify pellets as a specific waste stream and a renewable material for SRF production.

Keywords: alternative solid recovered fuel classification; pelletised sewage sludge; pollution prevention; renewable material; sustainable energy production (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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