BMP testingWood and woody biomass

Lignin-rich hydrolysis residue — BMP: 2 studies, weighted mean 105 m³ CH₄/t VS

Hydrolytic lignin from birch is the solid residue left after wood hydrolysis, from which most of the readily available sugars have been removed, so it digests poorly.

CH₄ ≈ 52 % (estimate)

Published 31 October 2020Updated 29 October 20263 min readFeedstockData Editorial Team

Illustration: FeedstockData (AI, Google Gemini)

Weighted mean: 105m³ CH₄/t VS
Range: 85–125m³ CH₄/t VS
Records: 2studies
Publications: 2sources
Temperatures: 37 °Cof the test

Methane in biogas

≈51–54% CH₄

Medium methane content · ≈ 5.2 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (carbohydrate-dominated (no protein or fat characteristics)) and the yields of compound groups according to FNR.

How we calculate it and what the zones mean

Rating for biogas plants

not rated — editorial rating for biogas plants

Not rated: no dry matter or volatile solids in the data. We calculate the rating when the dry matter and volatile solids of the material are known.

Editorial rating per the methodology

Add to the co-digestion calculator CSV data

BMP curves from 2 studies

Weighted mean Individual records

Dashed lines are a model curve (first-order kinetics, B(t) = B₀·(1 − e^−kt)); the end point comes from the publication. All curves are model curves.

Cumulative methane production over the test [m³ CH₄/t VS]. The thick line is the weighted mean of all records (105); dots mark the end values given in the publications. Point at the chart to read values; click a legend item to hide or show a record.

Records and sources

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Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Mulat et al. (2018) DOI	125	37 °C · mesophilic	Hydrolysis lignin from birch (HL birch)	end point (model curve)
Costa et al. (2019) DOI	85	—	Lignin-rich residue from birch (LRR birch)	end point (model curve)
Weighted mean	105	arithmetic mean 105, SD 28

Process properties

fibrous
slowly degrading
carbon-rich
low in nitrogen
poor in trace elements
variable composition
editorial classification

Advantages

Methane potential in the database: weighted mean 105 m³ CH₄/t VS (median 105; range 85-125; 2 records from 2 sources).
A by-product of wood hydrolysis, available in large quantities at biorefineries; the set contains microbiological data from the study by Mulat 2018.

Drawbacks and risks

Lignin is practically non-degradable anaerobically; the result comes almost entirely from residual polysaccharides (review by Hendriks 2009).
Residues after hydrolysis may contain phenolic compounds and other degradation products, potentially inhibitory (a topic discussed in the study by Mulat 2018).

Co-digestion — what to combine it with, what to watch out for

combines well
group: Animal excreta (slurry, manure, poultry litter)
Excreta supply a diverse microflora and trace elements, easing adaptation.^[1][2]

Dosing

No source dose limits; in practice consider only as a limited additive after a BMP test and monitoring of volatile acids.

Introduce gradually, starting with a small dose and monitoring the process (e.g. FOS/TAC, pH, gas composition).

Practical requirements

Shred: shredding increases the surface available for degradation and speeds it up, but does not necessarily raise the final gas yield (FNR 2010, Ch. 3 “Triturado”).

Sources of the process data

The co-digestion calculator will assess a specific mixture containing this substrate.

What it is and where it comes from

Hydrolytic lignin is the solid fraction remaining after the hydrolysis of lignocellulose, once cellulose and hemicelluloses have been converted into sugars, for example in the production of second-generation ethanol or biochemicals. The dataset contains several records from birch wood: lignin from hydrolysis and a lignin-rich residue after steam explosion and hydrolysis. It is an industrial material, not an agricultural one, so it does not occur on the scale typical of biogas plants.

Properties relevant to digestion

By definition, the material consists mainly of lignin, a complex phenolic polymer that is degraded only to a negligible extent under anaerobic conditions. Methane is formed from residual, unseparated carbohydrates. Steam or acid treatment can generate inhibitory compounds (furfural, hydroxymethylfurfural, phenols), which at higher concentrations reduce the activity of microorganisms, although in the residue after hydrolysis their amount depends on washing. The nitrogen content is low. The material is hard and not very reactive, so size reduction is crucial.

How to read the spread of results

The dataset contains several records from different sources and processes, so the spread results from differences in the method of producing the residue: the degree to which sugars were separated, the intensity of the treatment (e.g. steam explosion) and the lignin content. The inoculum, temperature and test duration also have an effect. With so few records, a reliable typical range cannot be determined, and individual values reflect a specific process rather than the material "in general".

In biogas plant practice

Hydrolytic lignin is not used as a biogas plant substrate. In the technological model it is a waste from a biorefinery process, which is usually burned for energy recovery. Using it in digestion would make sense at most as an auxiliary component of a mix and after checking for the presence of inhibitors. Its legal status depends on its origin (industrial waste), and managing it requires an appropriate permit. The information in this dataset is indicative only.

For comparison with other lignocellulosic residues, it is important that lignin from a biorefinery is also a feedstock for further chemical processing and for solid fuel, which is usually more cost-effective than methane fermentation.

Before any attempt at digestion, it is worth carrying out an analysis of the composition (content of lignin, residual sugars and phenolic compounds) and a BMP test for the specific batch.

Methodology in brief

BMP is the amount of methane obtained from volatile solids (VS) in a batch test, given in m³ CH₄ per tonne of VS (numerically the same as NmL CH₄/g VS in the publications) and converted to normal conditions (0 °C, 101.325 kPa). The weighted mean gives each publication a total weight of 1, split equally between its results for the substrate — a paper testing twenty varieties does not outweigh a paper with a single sample. In inter-laboratory programmes the unit is the laboratory (total weight 1), and within it the weight of a test grows with the number of bottles (replicates). Results after pretreatment (e.g. thermal, chemical, enzymatic) are shown separately and are not included in the mean.

Solid lines are curves measured in the tests. Where a publication gives only the final result, we draw a first-order kinetic model, B(t) = B₀·(1 − e^−kt): only the end point comes from the publication, and the shape of the curve serves purely as visualisation — do not read the production on a particular day from it. For this substrate k = 0.039 d⁻¹ was assumed (median of rate constants k reported in the sources and/or fitted to the mean measured curves).

The statistics describe the spread of published results — a descriptive compilation, not a meta-analysis or a guarantee of plant yield.

Full methodology and correction policy

Bibliography

All sources of the site: bibliography.