Anaerobic co-digestion: Current status and perspectives

Karki, Renisha; Chuenchart, Wachiranon; Surendra, K.C.; Shrestha, Shilva; Raskin, Lutgarde; Sung, Shihwu; Hashimoto, Andrew G.; Khanal, Samir Kumar

doi:10.1016/j.biortech.2021.125001

Cited by 257 publications

(112 citation statements)

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“…The microbial degradation is impacted by various factors such as inoculum, substrate, experimental and operational conditions [9,10]. The anaerobic co-digestion is a process of treating more than one organic wastes in a suitable proportion and is known to improve process efficacy by balancing nutrients, diversifying microbial population and lowering toxins, balancing alkalinity, etc., and has been studied extensively [10][11][12][13]. The mono-digestion of animal manures is sometimes prone to process failures due to nutrient imbalance for the microbes owing to their low C/N ratios.…”

Section: Introductionmentioning

confidence: 99%

“…The traditional management strategies have been to use it for feeding and bedding for the animals or composting, followed by addition to the soil as humus. The presence of microbial pests (verticillium wilt in particular) and pesticide residues, low heating value [19] in energy production limit the recycling options of CGT [12,13]. However, the urgency to lower fossil fuel consumption had the scientists investigating agro-industrial wastes such as CGT as potential renewable energy sources [22].…”

Section: Introductionmentioning

confidence: 99%

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Optimizing anaerobic co-digestion of goat manure and cotton gin trash using biochemical methane potential (BMP) test and mathematical modeling

Kaur

Kommalapati

2021

SN Appl. Sci.

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Anaerobic co-digestion is widely adopted to enhance process efficacy by balancing the C/N ratio of the feedstock while converting organic wastes to biomethane. Goat manure (GM) and cotton gin trash (CGT) were anaerobically co-digested in triplicate batch bioreactors. The process was optimized and evaluated utilizing mathematical equations. The liquid fraction of the digestate was analyzed for nitrate and phosphate. The co-digestions with 10 and 20% CGT having the C/N ratios of 17.7 and 19.8 yielded the highest and statistically similar 261.4 ± 4.8 and 262.6 ± 4.2 mL/gvs biomethane, respectively. The biodegradability (BD) of GM and CGT was 94.5 ± 2.7 and 37.6 ± 0.8%, respectively. The BD decreased proportionally with an increase in CGT percentage. The co-digestion having 10% CGT yielded 80–90% of biomethane in 26–39 d. The modified Gompertz model-predicted and experimental biomethane values were similar. The highest synergistic effect index of 15.6 ± 4.7% was observed in GM/CGT; 30:70 co-digestion. The concentration of nitrate and phosphate was lower in the liquid fraction of digestate than the feedstocks, indicating that these nutrients stay in the solid fraction. The results provide important insights in agro-waste management, further studies determining the effects of effluent application on plants need to be conducted.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimizing anaerobic co-digestion of goat manure and cotton gin trash using biochemical methane potential (BMP) test and mathematical modeling

Kaur

Kommalapati

2021

SN Appl. Sci.

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“…The anaerobic co-digestion (AcoD) process has been widely studied as an alternative to overcome some of the drawbacks of mono-digestion, by combining at least two different substrates. This type of operation provides an opportunity to compensate for the nutrient imbalance, increase the organic load rate, enhance system stability, improve buffering capacity, and create positive synergies on microorganisms [10][11][12][13]. Overall, through AcoD, the production and composition of biogas can be improved [10].…”

Section: Introductionmentioning

confidence: 99%

“…Overall, through AcoD, the production and composition of biogas can be improved [10]. Furthermore, one of the most relevant advantages of AcoD is the possibility of simultaneously using several residues generated by the same industry [12], as in the tomato industry, or managing seasonal residues with others of continuous production (e.g., sewage sludge). This is one of the reasons why the publication of scientific papers regarding AcoD increased by about 121% (data recorded on the web of science platform) since 2016.…”

Section: Introductionmentioning

confidence: 99%

“…So, the optimization of the composition blend in the AcoD is of high relevance. The synergetic effect of AcoD has been evaluated through the co-digestion performance index (CPI) by several authors [12,14,15]. This parameter corresponds to the ratio of ultimate methane potential of co-digestion and the weighted average of the ultimate methane potential of mono-digestion of each substrate.…”

Section: Introductionmentioning

confidence: 99%

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Bioenergy Production through Mono and Co-Digestion of Tomato Residues

et al. 2021

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The agro-industry of tomato generates three types of residues: ripe rotten tomato (unfit for consumption) (RT), green (unripe) tomato (GT), and tomato branches including leaves and stems (TB). These materials are commonly wasted or used as feed for livestock. Energy production through anaerobic digestion is an alternative way to manage and simultaneously valorise these materials. Initially, the operating conditions of mono anaerobic digestion were investigated using RT. Thus, a design of experiments based on a two-level fractional factorial design with resolution V was performed to determine the factors that affect biochemical methane potential (BMP). The substrate to inoculum ratio (SIR), total volatile solids concentration (VSt), working volume (WV), presence of nutrients (Nu), and the pre-incubation of the inoculum (Inc) were investigated. The results showed that SIR is the most important factor. The maximum BMP for RT was 297 NmLCH4/gVS with SIR = 0.5; tVS = 20 g/L; WV = 20%; no pre-incubation and the presence of nutrients. Using these optimum operating conditions, co-digestion was investigated through a mixture design approach. The substrates RT and GT presented similar BMP values, whereas TB led to a significantly lower BMP. Indeed, when high concentrations of TB were used, a significant decrease in methane production was observed. Nonetheless, the highest BMP was achieved with a mixture of 63% RT + 20% GT + 17% TB, with a production of 324 NmLCH4/gVS, corresponding to a synergetic co-digestion performance index of about 1.20. In general, although the substrate RT generates the highest BMP, the mixture with GT did not impair the methane yield. Overall, the co-digestion of tomato residues must be conducted with SIR close to 0.5 and the content of tomato branches in the reaction mixture should be kept low (up to 20%).

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