Optimization of Reactor Temperature for Continuous Anaerobic Digestion of Cow Manure: Bangladesh Perspective

Abstract

Converting organic waste into energy through anaerobic digestion is gaining popularity day by day. The reactor temperature is considered as one of the most vital factors for the digestion process. An experiment was conducted in the Biogas Laboratory of Green Energy Knowledge Hub at Bangladesh Agricultural University (BAU) to examine the influence of temperature on anaerobic digestion of cow-dung. Laboratory-scale continuous stirred tank reactors with a working volume of 15 L were operated for a 30-day retention time. The reactors were set at 20 °C, 25 °C, 30 °C, 35 °C, 40 °C and 45 °C, respectively to determine the effect of temperature on anaerobic digestion performance. Different parameters like total solids, volatile solids, pH, volatile fatty acids, ammonia nitrogen, total nitrogen, biogas production rate and methane concentration were examined. Among all the reactors, the reactor at 40 °C temperature produced maximum biogas (312.43 L/kg VS) and methane yields (209.70 L/kg VS), followed by the reactors at 35 °C and 30 °C, respectively. Statistical analysis of the obtained experimental results using Minitab® (State College, PA, USA) showed that the optimum process performance in terms of methane yield and volatile solid degradation is achieved at a reactor temperature of 35.82 °C.

Kinetic study and optimization of total solids for anaerobic digestion of kitchen waste: Bangladesh perspective

“…Final VFA value of KW of different TS contents was between 0.27 and 0.90 g/L. VFA concentrations over 3 g/L may lead to process failure and should be less than 2 g/L for proper AD (Nandi et al 2020). Low VFA level indicates favorable condition for biogas production.…”

“…It was because the temperature fluctuated during this period disturbing the activity of methanogens (Figure 1). A stable temperature is needed for optimum performance of AD (Nandi et al 2020). From 30 days, higher methane content was found, as the temperature was consistent.…”

“…Nevertheless, with increasing prices of oil, energy from renewable resources has become necessary to maintain the economic growth of the country. Currently the power generation capacity of the country is ∼20,000 MWe, only 1.37% of which comes from renewable sources (Nandi et al 2020). It is estimated that the country would require circa 34,000 MWe by the year 2030 to fulfil its demand (Nandi et al 2020).…”

“…Currently the power generation capacity of the country is ∼20,000 MWe, only 1.37% of which comes from renewable sources (Nandi et al 2020). It is estimated that the country would require circa 34,000 MWe by the year 2030 to fulfil its demand (Nandi et al 2020). On the other hand, the daily production of waste in the country is around 30,000 tons (Joshi 2020) of which kitchen waste (KW) comprises about 50-60% in urban areas (Mahmud et al 2016).…”

Effects of Seasonal Temperature Variation on Slurry Temperature and Biogas Composition of a Commercial Fixed-Dome Anaerobic Digester Used in Bangladesh

“…The methanogens are mainly effective in mesophilic and thermophilic regions where AD shows higher productivity. Previous studies on the effect of temperature on anaerobic digestion found higher methane yield in the mesophilic temperature range as compared to thermophilic condition [7,8]. Generally, a temperature range of 35-37 • C is suggested optimum for methane production in mesophilic conditions [9].…”