초록
<P><B>Abstract</B></P> <P>Anaerobic digestion (AD) technology is one of the best eco-friendly waste-to-energy processes. Hence the trend of biogas production shows considerable ranges of fluctuations in entire digestion period. This study analyzes the daily substance conversion dynamics, biomethane production and changes in microbial community structure. The results show that in the first peak of biogas production during 1st up to 4th days of the digestion period, CO<SUB>2</SUB> was the dominant component. However, the daily methane production (DMP) reveal accelerated increment starting from day 8 up to the peak point on day 13 (462.11 mL/d). The concentration of acetic acid covered 21.80% up to 62.00% of the total VFAs in the first 10 days of digestion period. On the other hand, the accumulation of propionic acid is in the range of 1735.70 mg/L- 2893.12 mg/L in between day 5–15, which is beyond the inhibition level (1000 mg/L) but the system didn't stop biogas production. The distribution of bacterial family such as <I>Clostridiaceae_1</I>, <I>Prevotellaceae</I>, <I>Enterobacteriaceae</I> and <I>Peptostreptococcaceae</I> are the dominant group at early stage as compared to composition in remaining stages except <I>Enterobacteriaceae</I> which have marginally high abundance in lowest biogas production point. The archaeal genus <I>Methanosaeta</I> is dominant among the samples collected at early stages (65.66%–77.22%). However, the <I>Methanobacterium</I> is predominant (34.88%–59.40%) in samples obtained at late stages of AD period. On the other hand, the distribution of <I>Methanosarcina</I> is comparable in the first three samples (S1(16.60%), S2(22.21%) and S3(20.38%)) than the stable stage (S4 (6.7%)). This study demonstrates the detailed conditions at fluctuating and constant biogas production periods, which would benefit future researchers working in similar area.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Continuous changes in reactor were studied during anaerobic digestion of rice straw. </LI> <LI> Fluctuation in biogas production was related with rate of conversion and stability. </LI> <LI> Butyric and propionic acids produced were fully converted before day 17 of AD time. </LI> <LI> The abundance of bacterial and archaeal taxa varied at every fluctuation points. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>