This package determines the concentrations of individual volatile fatty acids and related organic acids in samples from anaerobic digestion systems. The package includes acetic acid, lactic acid, propionic acid, butyric acid, isobutyric acid, valeric acid and isovaleric acid.

 

Volatile fatty acids are important intermediate products formed during the microbial degradation of organic matter. Under stable digester conditions, these acids are subsequently converted by other microbial populations into biogas, principally methane and carbon dioxide. Their concentrations and relative proportions therefore provide valuable information on the balance between acid production and acid consumption within the digestion process.

 

An accumulation of VFAs can indicate that acid-forming microorganisms are producing intermediates more rapidly than they can be converted by methanogenic microorganisms. This may occur because of organic overloading, temperature changes, nutrient deficiencies, inhibitory compounds, inadequate mixing or other process disturbances. Elevated concentrations of particular acids, especially propionic and butyric acids, can provide an early indication of digester stress before a substantial reduction in methane production becomes apparent.

 

Speciation provides more detailed information than a single total-VFA result. The relative concentrations of acetic, propionic, butyric, valeric and branched-chain acids can help identify changes in the dominant degradation pathways and support the investigation of process instability. Lactic acid is also determined because its accumulation may be associated with rapid fermentation of readily degradable feedstocks or an imbalance in the microbial conversion process.

 

The analysis is suitable for digester contents, digestates, process liquids and other outputs from anaerobic digestion systems. It can be used for routine process monitoring, feedstock trials, troubleshooting, comparison of operating conditions and assessment of changes following process interventions.

Constituents Determined

For every constituent determined via wet-chemical analysis each sample is analysed in duplicate and we provide the compositional data for each replicate along with the average value and the standard deviation between the duplicates. Our analytical protocols typically provide results with a high level of precision, as detailed here.

Examples of the data reports generated can be viewed on the Celignis Database. Please log on to the guest account using email "test@celignis.com" and password "celignis".

Click here to place an order for determining Volatile Fatty Acids (VFAs) Speciation.

Sample Weight Requirements

Under nornal conditions there is a minimum requirement of 5g of sample for this analysis package with a recommended weight of 10+g of sample.

However, it may be possible for us to undertake the anaysis with lower quantities than the minimum specified above. Please email us at info@celignis.com to find out.