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BMP testingFruit, vegetables and their residues

Other cucurbit vegetables (bitter melon, luffa, wax gourd, chayote, horned melon) — BMP: 5 studies, mean 274 m³ CH₄/t VS

Other cucurbit vegetables (bitter melon, luffa, ash gourd, chayote, kiwano) are five species from several studies; the result depends on the species and the part of the fruit used.

CH₄ ≈ 55 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Joydeep / Wikimedia Commons, licence CC BY-SA 3.0, source file; changes: cropping

Weighted mean
274m³ CH₄/t VS
Range
208–367m³ CH₄/t VS
Records
5studies
Publications
3sources
Temperatures
35 °Cof the test

Methane in biogas

Medium methane content · ≈ 5.5 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 3.2 % 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 5 studies

Weighted mean Individual records

BMP curves: Other cucurbit vegetables (bitter melon, luffa, wax gourd, chayote, horned melon)Cumulative methane production over time for 5 records and the weighted mean of 274 m³ CH₄/t VS. 5 of the curves are model curves (first-order kinetics).0100200300400051015202530time [d]m³ CH₄/t VSYan et al. (2021) · 1: 208 m³ CH₄/t VS (model curve)Yan et al. (2021) · 2: 217 m³ CH₄/t VS (model curve)Yan et al. (2021) · 3: 220 m³ CH₄/t VS (model curve)Zhao et al. (2016): 241 m³ CH₄/t VS (model curve)Kouas et al. (2017): 367 m³ CH₄/t VS (model curve)mean274

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 (274); 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) · 1 DOI208—Bitter melon (Momordica charantia) – Wholeend point (model curve)
Yan et al. (2021) · 2 DOI217—Luffa (Luffa aegyptiaca) – Wholeend point (model curve)
Yan et al. (2021) · 3 DOI220—Wax gourd (Benincasa hispida) – Wholeend point (model curve)
Zhao et al. (2016) DOI241—Horned melon (Cucumis metuliferus) – Shellend point (model curve)
Kouas et al. (2017) DOI36735 °C · mesophilicchayoteend point (model curve)
Weighted mean274arithmetic mean 251, SD 66

Typical composition

Volatile solids (VS)
91.9 % DM (range 90–95)
Nitrogen
3.2 % DM
C/N ratio
14.4

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: 4 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. (2021); Zhao et al. (2016).

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
acidic
low pH of the substrate (silages, stillage, whey, fruit)
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
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
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.

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

Sources of the process data

  1. Improvement of fruit and vegetable waste anaerobic digestion performance and stability with co-substrates addition
  2. Biochemical methane potential and biodegradability of complex organic substrates
  3. Compositional components and methane production potential of typical vegetable wastes
  4. Bio-energy conversion performance, biodegradability, and kinetic analysis of different fruit residues during discontinuous anaerobic digestion
  5. Robust assessment of both biochemical methane potential and degradation kinetics of solid residues in successive batches
  6. Effects of size and thermophilic pre-hydrolysis of banana peel during anaerobic digestion, and biomethanation potential of key tropical fruit wastes
  7. 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 cucurbit family (Cucurbitaceae) includes many plants grown as vegetables. Besides the common pumpkins, courgettes and cucumbers, the set includes bitter melon (Momordica charantia), luffa, ash gourd (Benincasa hispida), chayote and kiwano (Cucumis metuliferus). Most are grown in Asia and warm regions. In Poland they are niche plants or imports, and the waste arises mainly on farms, in shops and in processing.

Properties relevant to digestion

Cucurbit fruits consist largely of water, and the dry matter contains sugars, pectins and fibre, with a small share of lignin. As a result they are readily available to bacteria. Bitter melon contains bitter compounds (cucurbitacins, momordicin), and mature luffa forms a fibrous structure from which sponges are made. Kiwano peel is thicker and more fibrous than the flesh. The low dry matter content means a low energy concentration in the fresh material.

How to read the spread of results

Different species from several studies have been gathered under a single name, so the spread is natural. Some of the records relate to whole fruit and some only to the peel, which further affects the value. Variety, ripeness, seed content, particle size and test temperature all matter (for some records it is not given in the compilation). For planning, the result for the specific species should be used, not the average for the whole group.

In biogas plant practice

Cucurbits are used in biogas plants as a seasonal supplement, especially as waste from processing and wholesale markets. Shredding (especially of seeds and hard peels), mixing with a substrate of higher dry matter and pH control are recommended. Exotic species of this group rarely reach biogas plants in quantities that allow planning, so the literature results are of mainly comparative significance.

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. Zhao, C.; Yan, H.; Liu, Y.; Huang, Y.; Zhang, R.; Chen, C.; Liu, G. (2016). Bio-energy conversion performance, biodegradability, and kinetic analysis of different fruit residues during discontinuous anaerobic digestion. Waste Management 52, 295–301. DOI: 10.1016/j.wasman.2016.03.028 DOI
  3. 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”