Preliminary Technical and Economic Analysis of Alkali and Low Temperature Thermo-alkali Pretreatments for the Anaerobic Digestion of Waste Activated Sludge
| Autor: | Gerardo Scibilia, Alberto Cerutti, Mariachiara Zanetti, Eugenio Lorenzi, Giuseppe Campo, Barbara Ruffino, Giuseppe Genon |
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| Rok vydání: | 2016 |
| Předmět: |
Alkali
Environmental Engineering 020209 energy Anaerobic digestion Waste activated sludge Pre-treatments Low-temperature Economic feasibility 02 engineering and technology 010501 environmental sciences 01 natural sciences Methane chemistry.chemical_compound Biogas 0202 electrical engineering electronic engineering information engineering Economic analysis Waste Management and Disposal 0105 earth and related environmental sciences Waste management Renewable Energy Sustainability and the Environment Chemistry Alkali metal Pulp and paper industry Activated sludge Yield (chemistry) |
| Zdroj: | Waste and Biomass Valorization. 7:667-675 |
| ISSN: | 1877-265X 1877-2641 |
| DOI: | 10.1007/s12649-016-9537-x |
| Popis: | Waste activated sludge (WAS) contains various organic and inorganic substances that should be treated for a safe disposal. Anaerobic digestion is the most widely accepted method for stabilizing WAS. This work presents preliminary results concerning the technical and economic feasibility of alkali and hybrid thermo-alkali pretreatments for the improvement of WAS anaerobic digestion. Chemicals used for pretreatments were NaOH and Ca(OH)2, with doses in the range of 0.04–0.2 g alkali/g TS. The same substances were used for hybrid pretreatments at low temperature (70 and 90 °C). Test outcomes demonstrated that NaOH was a more performing chemical in sludge disintegration and COD liberation than Ca(OH)2. NaOH showed good performances already at low doses (0.08 g NaOH/g TS) with disintegration rates in the order of 20 %. Thermal effect improved alkali performance, in fact the biogas yield increased of 13.2 and 26.8 % when samples were treated respectively at 20 and 70 °C with 0.04 g NaOH/g TS for 90 min. However, until nowadays economic issues (mainly the cost of chemicals for alkali pretreatments and pH conditioning) have limited the real-world applications of alkali and hybrid pretreatments. The preliminary economic analysis performed in this work demonstrated that, if the pretreatment was carried out with a dose of alkali of 0.08 g NaOH/g TS, only an increase in the methane yield in the order of 60 % could offset the cost of chemicals. On the other hand, if the alkali dose was of only 0.04 g NaOH/g TS, increases in the methane yields in the order of 15–20 % were sufficient. |
| Databáze: | OpenAIRE |
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