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BMP testingFruit, vegetables and their residues

Other leafy and stem vegetables (bok choy, amaranth, garlic chives, garlic shoots, water dropwort, toon sprouts, zucchini and turnip leaves) — BMP: 8 studies, mean 253 m³ CH₄/t VS

Other leafy and stem vegetables (pak choi, amaranth, garlic, water dropwort, Chinese toon, turnip and courgette) are eight materials from several studies with different plant parts.

CH₄ ≈ 58 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

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

Weighted mean
253m³ CH₄/t VS
Range
129–378m³ CH₄/t VS
Records
8studies
Publications
3sources
Temperatures
35 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.8 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 4.6 % 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 8 studies

Weighted mean Individual records

BMP curves: Other leafy and stem vegetables (bok choy, amaranth, garlic chives, garlic shoots, water dropwort, toon sprouts, zucchini and turnip leaves)Cumulative methane production over time for 8 records and the weighted mean of 253 m³ CH₄/t VS. 8 of the curves are model curves (first-order kinetics).0100200300400500051015202530time [d]m³ CH₄/t VSYan et al. (2017) · 1: 129 m³ CH₄/t VS (model curve)Yan et al. (2017) · 2: 130 m³ CH₄/t VS (model curve)Yan et al. (2017) · 3: 164 m³ CH₄/t VS (model curve)Yan et al. (2017) · 4: 183 m³ CH₄/t VS (model curve)Yan et al. (2017) · 5: 228 m³ CH₄/t VS (model curve)Cai et al. (2019) · 1: 178 m³ CH₄/t VS (model curve)Cai et al. (2019) · 2: 378 m³ CH₄/t VS (model curve)Gunaseelan (2004): 314 m³ CH₄/t VS (model curve)mean253

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 (253); 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. (2017) · 1 DOI129—Chinese toon sprout (Toona sinensis) – Sproutend point (model curve)
Yan et al. (2017) · 2 DOI130—Amaranth wood (Amaranthus tricolor)end point (model curve)
Yan et al. (2017) · 3 DOI164—Celery (Oenanthe javanica)end point (model curve)
Yan et al. (2017) · 4 DOI183—Leek (Allium tuberosum)end point (model curve)
Yan et al. (2017) · 5 DOI228—Garlic (Allium sativum) – Shootend point (model curve)
Cai et al. (2019) · 1 DOI178—Zucchini (Cucurbita pepo) – Leafend point (model curve)
Cai et al. (2019) · 2 DOI378—Bok choy (Brassica chinensis var. Chinensis)end point (model curve)
Gunaseelan (2004) DOI31435 °C · mesophilicTurnip Leavesend point (model curve)
Weighted mean253arithmetic mean 213, SD 89

Typical composition

Volatile solids (VS)
79.4 % DM (range 65.2–94.8)
Nitrogen
4.6 % DM
C/N ratio
7.2

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: BCBPD, MY-D); dry matter: 0 determinations, volatile solids: 8 determinations. 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. (2017); Cai et al. (2019); Gunaseelan (2004).

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.

dilutes the feed (low DM)
low dry matter, dilutes the feed
seasonal
seasonal availability — requires storage
poor in trace elements
poor in trace elements — mono-digestion requires supplementation
variable composition
high variability of composition between batches

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

Dosing

No source limits on the dose for this substrate.

Sources of the process data

  1. Improvement of fruit and vegetable waste anaerobic digestion performance and stability with co-substrates addition
  2. Study on biomethane production and biodegradability of different leafy vegetables in anaerobic digestion
  3. Prediction of methane production performances based on determination of organic components for different vegetable wastes
  4. Biochemical methane potential of fruits and vegetable solid waste feedstocks
  5. Effects of size and thermophilic pre-hydrolysis of banana peel during anaerobic digestion, and biomethanation potential of key tropical fruit wastes
  6. 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

This entry combines leafy and stem vegetables that do not have separate entries: pak choi, Chinese spinach (Amaranthus tricolor), garlic chives, garlic shoots, water dropwort (Oenanthe javanica), Chinese toon shoots, and courgette and turnip leaves. These are plants grown in Asia and Europe, and the waste arises during harvesting, sorting and cleaning. Some of them (pak choi, turnip, courgette) are also grown in Poland, though on a small scale.

Properties relevant to digestion

The green tissues of leafy plants have a low lignin share, high moisture and a lot of protein, which makes them readily digestible, but also increases the risk of ammonia release when such materials predominate in the ration. Vegetables from the brassica and allium families contain sulphur compounds from which hydrogen sulphide is formed. In large quantities this can worsen biogas quality and burden desulphurisation. Chinese toon shoots contain specific aromatic compounds, and the stems of older plants contain more fibre.

How to read the spread of results

The records relate to eight different plants from several studies. The species and the plant part (leaf, shoot, whole plant) play the largest role, followed by growth stage, harvest date, shredding, sample drying and test conditions. For most records the temperature is not given in the compilation. Such diversity means that the result for one species is not representative of the others.

In biogas plant practice

Leafy vegetable residues are an occasional additive to the mix, especially on horticultural farms and at processing plants. Supply is seasonal and the material spoils quickly, so it should be used promptly or ensiled. It should be dosed so as not to overload the system with nitrogen, and H₂S should be monitored with sulphur-rich materials. Profitability depends on distance and scale, and the decision should be based on a BMP test.

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.; Zhao, C.; Zhang, J.; Zhang, R.; Xue, C.; Liu, G.; Chen, C. (2017). Study on biomethane production and biodegradability of different leafy vegetables in anaerobic digestion. AMB Express 7(1), 27. DOI: 10.1186/s13568-017-0325-1 DOI
  2. Cai, F.; 1. Biomass Energy and Environmental Engineering Research Center, College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China; Yan, H.; Zhang, R.; Liu, G.; Chen, C.; 2. Department of Biological and Agricultural Engineering, University of California, Davis, CA 95616, USA (2019). Prediction of methane production performances based on determination of organic components for different vegetable wastes. International Journal of Agricultural and Biological Engineering 12(3), 154–159. DOI: 10.25165/j.ijabe.20191203.4705 DOI
  3. Gunaseelan, V. (2004). Biochemical methane potential of fruits and vegetable solid waste feedstocks. Biomass and Bioenergy 26(4), 389–399. DOI: 10.1016/j.biombioe.2003.08.006 DOI

All sources of the site: bibliography.

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