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. 2020 Sep 28;6(9):e05036. doi: 10.1016/j.heliyon.2020.e05036

Figure 2.

Figure 2

The anaerobic monodigestion (AMD) of the biological hydrolysis- (BH-P) and NaOH-pretreated (NaOH-P) rice straw (RS) under freshwater (FW) and thalassic (TH) conditions, showing the (a) cumulative biogas production, (b) methane production rate, and (c) AMY (n = 3, error bar = s.d.). The BH-P was performed for 3 days using the hydrolytic bacteria (HB) inoculum that was developed for FW and TH conditions. The NaOH-P was performed for 5 days by adding 3% (w/w) NaOH pellet to feedstock and mixing distilled water and seawater for FW and TH conditions, respectively. The measurement of the (a) cumulative biogas production and (b) methane production rate of the TH BH-P of 100 % U (Image 5), 75U:25RS (Image 6), 50U:50RS (Image 7), 25U:75RS (Image 8), and 100% RS (Image 9) was done until biogas production stopped. The (c) AMY (Image 10) of the TH BH-P 100% RS, TH NaOH-P 100% RS, FW BH-P 100% RS, and FW NaOH-P 100% RS was compared to the theoretical methane yield (TMY, Image 11) of RS, while indicating the salinity (Image 12) of the AMD batch digesters (n = 3, error bar = s.d.). The AMY and TMY were computed using Eqs. (1) and (3), respectively. The results showed that BH-P was better than NaOH-P under both conditions (P = 0.008). However, the AMY of TH BH-P was comparable to FW BH-P (P = 0.182), resulting in the utilisation of TH BH-P in anaerobic co-digestion (ACD).