| Title: | Zero-waste strategy of small wastewater treatment plants with integrated thermal treatment of generated solid wastes |
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| Authors: | ID Urbancl, Danijela (Author)
ID Hochenauer, Christoph (Author)
ID Zachl, Angelika Michaela (Author)
ID Fekonja, Nika (Author)
ID Petrovič, Aleksandra (Author)
ID Goričanec, Darko (Author)
ID Simonič, Marjana (Author) |
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| Files: |  1-s2.0-S0360544225043828-main.pdf (7,33 MB)
MD5: FC81DC026FC66FB6570ADC5AE05ED0BA
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| Language: | English |
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| Work type: | Article |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: | FKKT - Faculty of Chemistry and Chemical Engineering
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| Abstract: | The aim of the study was to analyse two small wastewater treatment plants (SWTPs) and compare their treatment performance with the aim of developing a zero-waste strategy. The analyses showed that the second wastewater treatment plant had a problem with an increased phosphorus concentration in the wastewater as well as fluctuations in nitrogen removal. One of the key aspects was the recovery of phosphorus in the form of struvite precipitated on zeolite, which can be used as a fertiliser due to its significant nutrient content. The main benefit of the same SWTP is the separate collection of cellulosic material (labelled as sample RS), which has the potential for reuse as biochar, while from the first SWTP the sludge sample (labelled as sample SS) was taken and torrefied for comparison with RS. Both samples were torrefied at 250 ◦C and 350 ◦C in nitrogen and carbon dioxide atmospheres. The RS products obtained in CO2 atmosphere at 350 ◦C showed the best biochar properties, as they had a higher heating value (HHV) and a higher C content. Elemental analysis showed that the carbon content in RS and SS increased from 43 to 65 % and from 35 to 39 %, respectively. Measurement of the HHV of the torrefied RS product showed an increase from 17 to 26 MJ/kg, while for SS it increased from 15 to 17 MJ/kg. The comprehensive combustion index and the EMCI index show higher values for the RS samples torrefied at 350 ◦C. The H/C and O/C ratios are favourable for these samples, as the high quality of torrefied biomass is associated with the highest prices on the market. According to the TGA and FTIR analysis, the type of torrefaction atmosphere, in contrast to the torrefaction temperature, has little influence on the subsequent use of the torrefied samples in combustion. The results show that the integration of torrefaction for biochar production with phosphorus recovery by struvite precipitation is an efficient solution for waste management in small wastewater treatment plants. |
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| Keywords: | wastewater treatment plant efficiency, torrefication, N2 atmosphere, CO2 atmosphere, solid biofuels, proximate and ultimate analyses, thermogravimetry |
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| Publication status: | Published |
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| Publication version: | Version of Record |
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| Submitted for review: | 28.02.2024 |
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| Article acceptance date: | 29.09.2025 |
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| Publication date: | 30.09.2025 |
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| Publisher: | Elsevier Ltd. |
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| Year of publishing: | 2025 |
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| Number of pages: | 13 str. |
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| Numbering: | Vol. 337 |
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| Source: | https://www.sciencedirect.com/journal/energy |
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| PID: | 20.500.12556/DKUM-95841  |
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| UDC: | 620.92/.98 |
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| ISSN on article: | 1873-6785 |
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| COBISS.SI-ID: | 252314627 |
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| DOI: | 10.1016/j.energy.2025.138740 |
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| Copyright: | © 2025 The Authors |
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| Publication date in DKUM: | 29.10.2025 |
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| Views: | 156 |
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| Downloads: | 13 |
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| Metadata: |    |
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| Categories: | Misc.
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