Flash BMP® : Calibration for the Biochemical Methane Potential of solid organic waste using Near Infrared Spectroscopy (NIRS)

Significance of the Topic

Managing solid organic waste is critical for environmental protection and resource recovery. Converting these wastes into biogas through anaerobic digestion provides renewable energy while reducing landfill volume. Assessing the biochemical methane potential (BMP) of waste streams is essential to optimize digester performance and predict gas yields.

Objectives and Study Overview

The Flash BMP approach aims to develop a rapid, noninvasive method to estimate BMP using near infrared spectroscopy NIRS. Key goals include:

• Replacing the standard 30 day biological BMP assay with a fast spectroscopic assessment
• Enhancing industrial anaerobic digester monitoring by providing near real time substrate characterization

Methodology

Solid waste samples spanning green waste, agricultural residues, energy crops, agroindustrial byproducts, municipal solid waste and sludge were freeze dried and finely ground. Reference BMP values were obtained using a conventional batch fermentation test over 30 days. Near infrared spectra were collected on prepared samples, and a calibration model was constructed linking spectral features to reference methane yields.

Used Instrumentation

The core analytical tool was a near infrared spectrometer covering the relevant absorbance bands for organic matter. Sample preparation required a freeze dryer and a mill to ensure uniform particle size. No additional consumables were needed for spectral acquisition.

Results and Discussion

The NIRS based Flash BMP method achieved:

• Measurement turnaround in under 2 days from sample prep
• Representative sampling across diverse waste types
• A robust calibration database of 500 samples covering 20 to 700 ml CH4 per gram volatile solids
• Prediction accuracy comparable to the reference test with errors of 15 to 20 percent

The model demonstrated validity across multiple substrate categories, highlighting its versatility for industrial applications.

Practical Benefits and Applications

Integrating Flash BMP offers several advantages:

• Significant reduction in analysis time and labor
• Elimination of reagent costs and frequent biological assays
• Rapid screening of feedstock mixtures to optimize digester loading
• Improved process control by providing timely methane potential data

Future Trends and Applications

Emerging directions in spectroscopic BMP assessment include:

• Portable and inline NIR sensors for continuous feed monitoring
• Machine learning algorithms to refine prediction accuracy
• Expansion to novel waste streams such as industrial liquids and mixed biomasses
• Integration with digital platforms for real time process optimization

Conclusion

Flash BMP using NIRS provides a fast, cost-effective alternative to traditional BMP assays. With a comprehensive calibration and validated performance across waste types, this method supports enhanced anaerobic digestion management and promotes sustainable waste valorization.

References

• Angelidaki I Alves M Bolzonella D Borzacconi L Campos JL Guwy AJ Kalyuzhnyi S Jenicek P van Lier JB Defining the biomethane potential BMP of solid organic wastes and energy crops a proposed protocol for batch assays Water Sci Technol 2009 59 5 927 934
• Lesteur M Bellon Maurel V Gonzalez C Latrille E Roger JM Junqua G Steyer JP Alternative methods for determining anaerobic biodegradability A review Process Biochem 2010 45 4 431 440