Value-Added Performance and Thermal Decomposition Characteristics of Dumped Food Waste Compost by Pyrolysis

Abstract

Food waste compost has a high Na content, which interferes with plant growth when used as a soil enhancer and therefore makes it difficult to use. And, compared to the amount of compost produced every day, the amount of consumption required in farms is smaller, and the rest is buried underground, which releases greenhouse gases and pollutes underground water. This research compared and analyzed thermal degradation behavior, calorific value, and gas spectrometry during the pyrolysis between food waste compost and sawdust to suggest producing food waste compost biochar by pyrolysis as a new alternative solution to utilize the massive amount of food waste compost. Biochar from pyrolysis of food waste compost had a high carbon content of 51% at 300 • C, and the carbon content decreased as the pyrolysis temperature increased. According to the thermogravimetric analysis (TGA) and derivative thermo-gravimetric (DTG) analysis results, compost showed the largest weight reduction from 240 • C to 365 • C. The weight reduction temperature ranges for compost and sawdust were quite similar. This occurred because food waste of the compost was degraded, but sawdust of compost remained nearly during the composting process. A gas chromatography and mass spectrometry (GC-MS) analysis found that the gases were fragments of fatty acids, protein, and hemi-cellulose. These results could also have been caused by degradation of microorganisms involved in the composting process, sawdust, and small fragments of food waste. In the calorific value of biochar, the highest value (24.33 kJ/g) was obtained 300 • C. At a low pyrolysis temperature, carbon fixation occurred easily since the food waste in compost was degraded by microorganism, and the volatilization of sawdust, which plays an important role in determining the calorific value, was also small. That is why the highest calorific value was shown at 300 • C, not 400 • C or 500 • C. Hence, it seems that food waste compost can be used as a promising alternative fuel at a low pyrolysis temperature, as other lignocellulosic refuse-derived fuels (RDF).

Effects of Pyrolysis Temperature and Retention Time on Fuel Characteristics of Food Waste Feedstuff and Compost for Co-Firing in Coal Power Plants

“…Compost has a lower chlorine content than feedstuff, as the compost is diluted during the washing process (water is added to the food waste to remove salt), and sawdust is added as a moisture-controlling agent. Since the main component of the discharged compost is sawdust [20], it exhibits similar chlorine behavior to other wood-based biomass studies. However, the feedstuff showed a different trend, with chlorine contents closer to the predicted values.…”

“…There was just a small difference in the carbon contents of the feedstuff and compost, even though carbon is decomposed by microorganisms during composting. This is because the sawdust that was added during composting and microorganisms grown during the decomposition of carbon are included in the compost and collectively released upon pyrolysis [20]. Table 3 shows the primary properties of the food waste compost and feedstuff samples after pyrolysis at different temperatures and retention times.…”

Thermogravimetry Applicability in Compost and Composting Research: A Review

“…For this reason, this study concluded that the pyrolysis of these composts did not seem to be a promising process due to the low values of superior calorific value and biochar. In another study, Lee et al [92] and Giwa et al [93] analyzed the thermal degradation behavior, calorific value and gas spectrometry during pyrolysis among compost from food waste. They concluded that these composts can be used as a promising alternative fuel.…”

Biomass Chars: Elaboration, Characterization and Applications II

“…Lee et al have studied an alternative for the recovery of food waste compost since the amount generated every day is higher than the amount consumed in farms [3]. Hence, authors have suggested producing biochar from food waste compost using pyrolysis processes.…”

“…The authors indicate that increased NaCl concentration in the samples inhibited cellulose and lignin decomposition, ultimately increasing the biochar yield by 2.7% for 20%-NaCl concentration. NaCl added in solution state exhibited templating effects, with maximum increase in the Brunauer-Emmett-Teller (BET) surface area and pore volume of 1.23 to 3.50 m 2 •g −1 and 0.002 to 0.007 cm 3 •g −1 , respectively, after washing. Adding a high concentration (20%) of NaCl reduced the BET surface area.…”