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Energy efficiency of dry sewage sludge before and after low-temperature microwave pyrolysis
| Content Provider | Semantic Scholar |
|---|---|
| Author | Racek, Jan Chorazy, Tomáš Novák, V. Čáslavský, J. Hlavínek, Petr |
| Copyright Year | 2018 |
| Abstract | This paper deals with current applied research focused on energy efficiency from dry sewage sludge (SS) before and after microwave pyrolysis (MP) of SS at AdMaS Research Centre in the Czech Republic. The issue of sewage sludge (SS) treatment at wastewater treatment plants is one of the important topics in the European Union (EU) and also in the Czech Republic (CR). Disposal of SS has received significant attention mainly due to new strict regulation of the SS landfilling and direct application in agriculture. The society is looking for a new method of waste recycling, material and energy use closely connected with “Circular Economy”. MP as a thermal treatment of SS is a suitable solution in the EU. The products of MP are biochar, pyrolysis oil and pyrolysis gas (Syngas). These MP products should not be classified as a waste but as a resource representing a solution under the terms of the circular economy: carbon footprint reduction, energy use and for many other applications. Current applied research is carried out at different conditions. First in a laboratory and second in two full-scale appliances using MP units operating at a low temperature less than 300 °C and a low pressure 800 hPa with 3 kW magnetrons with 2.45 GHz. At present, the basic and most common way of dry SS treatment is an incineration using an exothermic reaction the product of which is a thermal energy. The experiments were performed at different samples of dried SS and the biochar as an outcome from MP was tested for contribution tests. All MP products can be used energetically as an alternative to fossil fuels for incineration, cogeneration or combustion engines. The results were compared with literature for dried SS before MP execution and for biochar after MP execution. The contribution tests carried out by the laboratory MP unit reported higher difference energy efficiency 2.88 MJ.kg than before MP process than tests from small full-scale unit. Admittedly, the small fullscale with the difference 1.05 MJ.kg after MP process has its value closer to simulating real conditions at WWTP. This difference responds different SS, the heterogeneity of SS, few measurements and is influenced by different device. In a view of the current situation of disposal routes for SS, the compact MP unit with dryer (CMPUD) of SS was design and described by 3 stages for energy efficiency and other use. The Stage 3 considers the use of biochar in agriculture and it represents solution with a positive impact on the environment. The MP as an eco-friendly treatment of SS with products may represents a solution in terms of circular economy. Pyrolysis gas and pyrolysis of MP will be energy used. Biochar after MP process will be energy used and after the challenges of the present used in agriculture is assumed. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://uest.ntua.gr/naxos2018/proceedings/pdf/NAXOS2018_Racek(b)_etal.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
