2.2 Pre-treatment Technologies of Anaerobic Fermentation
17
Fig. 2.4 Influences of different hydrothermal hydrolysis pre-treatments on total sugar and reducing
sugar
activity of microorganisms directly affected biotreatment efficiency. Therefore, the
increase of content of saccharide substance in liquid phase of kitchen wastes has
important influences on the subsequent anaerobic fermentation.
2.2.1.4 Effects of Hydrothermal Pre-treatment on Organic Carbon
With increasing hydrothermal temperature and prolonging treatment time, the content of organic carbon in liquid phase constantly rose. After adding 40% of water
and being treated for 70 min at 200 °C, the contents of total organic carbon (TOC)
and chemical oxygen demand (COD) reached the highest of 23.7 and 109.7 g/L,
which raised by 1.67 and 1.39 times in comparison with the control group without
pre-treatment. Furthermore, the lowest ratio of volatile solid (VS)/total solid (TS)
in solid phase was 69.04%, which decreased by 15.43% compared with the control
group without pre-treatment. VS/TS is an important index to measure the transformation of solid organic matter into liquid phase of kitchen wastes. As shown in
Fig. 2.5, the changes of VS/TS after hydrothermal treatment was negatively correlated with TOC and COD and as heating time prolongs and temperature rises, the
less the water was added, the more significant the reduction of VS/TS. Obviously,
after hydrothermal hydrolysis pre-treatment, solid substances in kitchen wastes were
constantly liquefied, dissolved and transferred to the liquid phase, which provided
more nutrition substrates with high homogenisation for anaerobic fermentation.
17
Fig. 2.4 Influences of different hydrothermal hydrolysis pre-treatments on total sugar and reducing
sugar
activity of microorganisms directly affected biotreatment efficiency. Therefore, the
increase of content of saccharide substance in liquid phase of kitchen wastes has
important influences on the subsequent anaerobic fermentation.
2.2.1.4 Effects of Hydrothermal Pre-treatment on Organic Carbon
With increasing hydrothermal temperature and prolonging treatment time, the content of organic carbon in liquid phase constantly rose. After adding 40% of water
and being treated for 70 min at 200 °C, the contents of total organic carbon (TOC)
and chemical oxygen demand (COD) reached the highest of 23.7 and 109.7 g/L,
which raised by 1.67 and 1.39 times in comparison with the control group without
pre-treatment. Furthermore, the lowest ratio of volatile solid (VS)/total solid (TS)
in solid phase was 69.04%, which decreased by 15.43% compared with the control
group without pre-treatment. VS/TS is an important index to measure the transformation of solid organic matter into liquid phase of kitchen wastes. As shown in
Fig. 2.5, the changes of VS/TS after hydrothermal treatment was negatively correlated with TOC and COD and as heating time prolongs and temperature rises, the
less the water was added, the more significant the reduction of VS/TS. Obviously,
after hydrothermal hydrolysis pre-treatment, solid substances in kitchen wastes were
constantly liquefied, dissolved and transferred to the liquid phase, which provided
more nutrition substrates with high homogenisation for anaerobic fermentation.