Biogas production from organic waste is an established sustainable energy solution, with anaerobic digestion (AD) serving as cornerstone technology. However, maximising biogas production and realising the full potential of biogas conversion necessitates a comprehensive understanding of feedstock composition and process KPI’s. This article explores the significance of soluble chemical oxygen demand (COD) monitoring and volatile solids (VS) or organic dry matter (oDM) analysis within total solids (TS) for optimising biogas production.

Specialising in biogas plant optimisation, ALPS Ecoscience is committed to maximising biogas production while ensuring operational efficiency and sustainability. Leveraging advanced technologies and innovative strategies, ALPS utilises COD monitoring as a performance indicator in anaerobic digestion process monitoring dashboards. This approach offers valuable insights into designing feedstock recipes and monitoring gas output, enhancing process control and production outcomes.

The Scientific case for COD and VS/oDM analysis

Traditionally, COD measurement has been pivotal in wastewater treatment, where liquid feedstock predominates. However, in the biogas sector, the focus is towards organic content in solid materials, often measured by VS or oDM within TS. While VS/oDM analysis provides insights into potential biogas conversion, integrating COD monitoring offers a more comprehensive understanding of feedstock characteristics and biogas conversion potential during digestion.

Scientific studies emphasise the importance of COD and VS/oDM analysis in predicting biogas production. For instance, research published in the Journal of Environmental Management highlights the correlation between COD concentrations and biogas yield in anaerobic digestion processes. Similarly, studies demonstrate the predictive value of VS/oDM analysis in determining biogas production potential. By combining COD monitoring and VS/oDM analysis in TS, operators can optimise biogas production processes and maximise gas output. These analytical techniques provide invaluable insights into feedstock composition, facilitating informed decisions regarding feedstock loading rates, HRT and process optimisation techniques. In valuable at lab and pilot scale advanced AD experiments as well as in full production.

The Operational Application of the Science

ALPS Ecoscience is dedicated to maximising biogas production efficiency while ensuring operational stability. Through our constant pursuit of improvement, we employ advanced technologies and innovative biological monitoring strategies to evolve biogas production for incremental conversion gains. One such advancement lies in the strategic utilisation of soluble COD monitoring as a key performance indicator within our biogas optimisation managed service data dashboard.

COD monitoring holds substantial value in both designing feedstock recipes for anaerobic digesters and monitoring gas output against feedstock loading. Here, ALPS has drawn from its wastewater industry experience, to offer new insights to the biogas sector, where the focus has primarily centred on the organic content of solid materials. Typically assessed via Volatile Solids (VS) or Organic Dry Matter (oDM) within Total Solids (TS).

TS/VS indicates proportion of organic material in dry matter and is a pivotal quality parameter of feedstock and the resultant gate fee. Yet, this measure alone does not directly correlate with final biogas output, as conversion efficiency is influenced by numerous factors. Therefore, a comprehensive approach involving multi-variate analysis and control is necessary.

Recognising the significance of integrating COD monitoring alongside traditional VS and oDM analysis, ALPS Ecoscience gains a deeper understanding of feedstock characteristics. By examining both oDM and COD, we attain a more nuanced insight into the total biogas conversion potential of the feedstock, enabling more precise process control and enhanced production outcomes.

The principle of anaerobic treatment of waste entails harnessing the capabilities of anaerobic bacteria to convert organic pollutants or COD into biogas within an oxygen-free environment. By monitoring COD levels, ALPS help operators anticipate biogas production levels and adjust process parameters accordingly. Elevated COD values signify a higher concentration of readily biodegradable compounds, thereby indicating greater gas production potential.

Key KPI’s in Maximising Biogas Production

ALPS Ecoscience harnesses advanced dashboard reports with dynamic content to monitor digester performance over time. The combined measures of soluble chemical oxygen demand (COD), total suspended volatile solids (TS/VS), and total volatile fatty acids (VFA) constitute a robust framework for evaluating fermentation efficiency. Soluble COD offers insights into the quantity of readily available organic compounds for microbial metabolism, reflecting the fermentable substrate concentration. TS/VS provides information on the organic matter content, indicating the degree of biomass accumulation or degradation. Additionally, total VFA levels serve as indicators of fermentation progress and product formation, reflecting the efficiency of organic matter conversion into valuable end products such as acids or alcohols or gas.

Integrating these metrics into ALPS digester dashboards allows for a comprehensive assessment of fermentation performance, facilitating adjustments to optimise conditions for enhanced gas yields and reduced digester instability. Monitoring changes in soluble COD, TS/VS, and total VFA over time enables fine-tuning of process parameters to achieve maximum efficiency in bioprocessing applications. By benchmarking, fermentation efficiency prior to optimisation clients can see the full thereby contributing to more sustainable and economically viable fermentation practices.

Data Analysis Highlights Improvement Opportunities

Leveraging data-driven insights empowers operators to make informed decisions and advance sustainable energy solutions.  COD monitoring adds invaluable insight and plays a pivotal role in optimising anaerobic digestion processes and unlocking the full potential of biogas conversion. By integrating soluble COD monitoring and VS/oDM analysis COD measurement into feedstock design and gas output optimisation strategies, biogas plant operators can maximise biogas production, enhance process efficiency, and bolster overall plant profitability. At ALPS Ecoscience, our motto is “Forward through Science” so we will persist in leveraging data analysis to discern patterns and trends within anaerobic digesters, thus better informing operational decisions and enhancing plant performance. What’s gratifying is seeing the direct relationship to increased biogas output from combining multiple performance metrics. In this instance the resulting insights are yielding performance improvements of 7% to 13% in a range of settings.

If you are interested in exploring an example of ALPS managed service data dashboard, to understand  how the insights help improve biogas output please get in touch here.

References:

Liu, C., Yuan, H., Wu, C., & Lü, F. (2016). Effect of organic loading rate on the performance, stability and microbial communities of anaerobic digestion treating swine wastewater. Journal of Environmental Management, 183, 231-239.
Taherzadeh, M. J., & Karimi, K. (2008). Pre-treatment of lignocellulosic wastes to improve ethanol and biogas production: A review. International Journal of Molecular Sciences, 9(9), 1621-1651.