About usContact

BMP testingFruit, vegetables and their residues

Carrots (roots) — BMP: 4 studies, weighted mean 341 m³ CH₄/t VS

Carrot (roots) is a readily digestible vegetable waste rich in sugars and pectin fibre, with a low lignin content; available mainly in autumn and winter.

CH₄ ≈ 52 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo domdomegg / Wikimedia Commons, licence CC BY 4.0, source file; changes: cropping

Weighted mean
341m³ CH₄/t VS
Range
291–388m³ CH₄/t VS
Records
4studies
Publications
4sources
Temperatures
35 °C, 38 °C, 55 °Cof the test

Methane in biogas

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 (protein from total nitrogen (N 1 % DM × 6.25)) 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 4 studies

Weighted mean Individual records

BMP curves: Carrots (roots)Cumulative methane production over time for 4 records and the weighted mean of 341 m³ CH₄/t VS. 4 of the curves are model curves (first-order kinetics).0100200300400500051015202530time [d]m³ CH₄/t VSYan et al. (2021): 291 m³ CH₄/t VS (model curve)Buffiere et al. (2006): 388 m³ CH₄/t VS (model curve)Dubrovskis et al. (2018): 378 m³ CH₄/t VS (model curve)Kouas et al. (2017): 309 m³ CH₄/t VS (model curve)mean341

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 (341); 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

Download CSV
SourceBMP
m³ CH₄/t VS		TemperatureSampleCurve
Yan et al. (2021) DOI291—Carrot (Daucus carota var. Sativa) – Wholeend point (model curve)
Buffiere et al. (2006) DOI38855 °C · thermophilicCarrotend point (model curve)
Dubrovskis et al. (2018) DOI37838 °C · mesophilicCarrots (mono-fermentation)end point (model curve)
Kouas et al. (2017) DOI30935 °C · mesophiliccarrotend point (model curve)
Weighted mean341arithmetic mean 341, SD 49

Typical composition

Volatile solids (VS)
94.3 % DM (range 94.3–94.3)
Nitrogen
1 % DM
C/N ratio
39.7

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: BCBPD); dry matter: 0 determinations, volatile solids: 1 determination. C/N was calculated as the ratio of C and N content (% DM) from the same source. No DM in the sources – the calculator has to ask for a value.

Sources: Yan et al. (2021).

The composition of the raw material varies between batches — for plant calculations use an analysis of your own sample. The calculator inserts typical values automatically.

Process properties

Low confidence: the description is based on general characteristics of the substrate group, not on studies of this material. Treat it as a hint to be verified.

No published process studies

The literature we use does not describe the advantages or drawbacks of digesting this substrate beyond the BMP test results. Below are process characteristics assigned on the basis of the type of material — an editorial classification, not a study result.

easily degradable
sugars, starch, glycerol → fast hydrolysis and acidification (VFA), needs buffering
carbon-rich
high C/N → nitrogen deficiency; combine well with nitrogen-rich substrates
low in nitrogen
high C/N → nitrogen deficiency; combine well with nitrogen-rich substrates
poor in trace elements
poor in trace elements — mono-digestion requires supplementation
seasonal
seasonal availability — requires storage

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

Dosing

No source limits on the dose for this substrate.

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

Sources of the process data

  1. Co-fermentation of carrots, grain residues and potato chips
  2. Improvement of fruit and vegetable waste anaerobic digestion performance and stability with co-substrates addition
  3. Biochemical methane potential and biodegradability of complex organic substrates
  4. Compositional components and methane production potential of typical vegetable wastes
  5. Towards new indicators for the prediction of solid waste anaerobic digestion properties
  6. Robust assessment of both biochemical methane potential and degradation kinetics of solid residues in successive batches
  7. Lab-scale anaerobic digestion of cassava peels: the first step of energy recovery from cassava waste and water hyacinth
  8. Effects of size and thermophilic pre-hydrolysis of banana peel during anaerobic digestion, and biomethanation potential of key tropical fruit wastes
  9. Effect of particle size on biogas generation from biomass residues

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

What it is and where it comes from

The carrot (Daucus carota subsp. sativus) is an important root vegetable in Poland, grown on a large scale. Waste roots arise in sorting plants (crooked, damaged or atypically sized roots), in juice, frozen food and canning plants, and in trade. Carrot tops are described separately as a post-harvest waste.

Properties relevant to digestion

The carrot root consists mostly of water. In the dry matter, soluble sugars (sucrose, glucose, fructose), pectins, cellulose and hemicellulose dominate, and lignin is present in small amounts. The material is therefore readily available to bacteria, and hydrolysis proceeds quickly. The risk is overloading the system with acids and a fall in pH. Carrot contains carotenoids, but they are not a problem for digestion. Contaminants include soil and sand, which can settle at the bottom of the tank and require periodic removal.

How to read the spread of results

The dataset contains several records from several sources. Some records come from mesophilic conditions or with no temperature stated, and some from thermophilic conditions (55 °C). Differences may result from the variety, ripeness, condition of the roots, comminution (whole root versus pulp) and the way the sample was prepared. The substrate-to-inoculum ratio also has an effect: for a sugar-rich material, too high a dose can acidify the test. The spread therefore reflects the test conditions and the variability of the raw material.

In biogas plant practice

Carrot is a good supplement to the feed in the autumn-winter season. The roots should be shredded and mixed with a buffering material, e.g. slurry. Dosing should be gradual, with monitoring of volatile acids. Storage in clamps is possible for a short time, but rotten roots give off unpleasant odours. Waste from vegetable processing and trade is waste and requires the installation's permits, whereas material from the farm's own holding is treated according to the rules for agricultural products.

Because carrot is available mainly in autumn and winter, and its waste after storage becomes increasingly variable, good practice is to measure the dry matter of each delivery and adjust the dose to the current loading of the digester.

The advantages of carrot include the absence of significant inhibitors and the good predictability of the course of digestion, provided the dose is sensibly spread over time; its watery character remains a drawback, because of which one tonne of fresh matter yields relatively little energy.

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 = 0.245 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

  1. Yan, H.; Cai, F.; Wang, L.; Chen, C.; Liu, G. (2021). Compositional components and methane production potential of typical vegetable wastes. Environmental Science and Pollution Research 28(38), 54177–54186. DOI: 10.1007/s11356-021-15798-y DOI
  2. Buffiere, P.; Loisel, D.; Bernet, N.; Delgenes, J.P. (2006). Towards new indicators for the prediction of solid waste anaerobic digestion properties. Water Science and Technology 53(8), 233–241. DOI: 10.2166/wst.2006.254 DOI
  3. Dubrovskis, V.; Plume, I.; Straume, I. (2018). Co-fermentation of carrots, grain residues and potato chips. Engineering for Rural Development. DOI: 10.22616/erdev2018.17.n415 DOI
  4. Kouas, M.; Torrijos, M.; Sousbie, P.; Steyer, J.P.; Sayadi, S.; Harmand, J. (2017). Robust assessment of both biochemical methane potential and degradation kinetics of solid residues in successive batches. Waste Management 70, 59–70. DOI: 10.1016/j.wasman.2017.09.001 DOI

All sources of the site: bibliography.

Other substrates in the group “Fruit, vegetables and their residues”