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BMP testingFruit, vegetables and their residues

Rambutan peel — BMP: 3 studies, weighted mean 99 m³ CH₄/t VS

Rambutan skin is a fibrous fruit waste with highly variable results, containing tannins and phenolic compounds that can modify the course of digestion.

rating: neutralCH₄ ≈ 52 % (estimate)

Published Updated 3 min readFeedstockData Editorial Team

Photo Shagil Muzhappilangad / Wikimedia Commons, licence CC BY-SA 4.0, source file; changes: cropping

Weighted mean
99m³ CH₄/t VS
Range
33–203m³ CH₄/t VS
Records
3studies
Publications
2sources
Temperatures
35 °Cof the test

Methane in biogas

Low 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 0.9 % 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

neutral — editorial rating for biogas plantsNo clear advantages — worth charging a fee for accepting it

Potential per tonne of fresh matter: low, but limited by the poor degradability of the organic matter (28 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer, slow degradation.

Why? Rating factors

Potential per tonne 0

  • ±0potential 28 m³ CH₄/t fresh matter (BMP 99 × DM 29.4 % × VS 96.6 %); low degradability of VS (BMP 99 m³ CH₄/t VS) — points capped

Process stability 0

  • 0no factors

Handling and costs −1

  • −0.5fibres, floating layer — shredding and intensive mixing
  • −0.5slow degradation — long retention time

Total points: −1 · thresholds: ≥ 2.5 very good, ≥ 1 good, below — neutral; negative with cumulative process risk.

Editorial rating per the methodology · confidence of the rating: low · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 3 studies

Weighted mean Individual records

BMP curves: Rambutan peelCumulative methane production over time for 3 records and the weighted mean of 99 m³ CH₄/t VS. 3 of the curves are model curves (first-order kinetics).050100150200250051015202530time [d]m³ CH₄/t VSZhao et al. (2016): 33 m³ CH₄/t VS (model curve)Sanjaya et al. (2016) · 1: 126 m³ CH₄/t VS (model curve)Sanjaya et al. (2016) · 2: 203 m³ CH₄/t VS (model curve)mean99

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 (99); 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
Zhao et al. (2016) DOI33—Rambutan (Nephelium lappaceum) – Shellend point (model curve)
Sanjaya et al. (2016) · 1 DOI12635 °C · mesophilicRooten rambutan peelend point (model curve)
Sanjaya et al. (2016) · 2 DOI20335 °C · mesophilicFresh ripe rambutan peelend point (model curve)
Weighted mean99arithmetic mean 121, SD 85

Typical composition

Dry matter (DM)
29.4% (range 23.6–35.1)
Volatile solids (VS)
96.6 % DM (range 96.6–96.6)
Nitrogen
0.9 % DM
C/N ratio
56.1

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: BCBPD, MY-D); dry matter: 2 determinations, volatile solids: 1 determination. C/N was calculated as the ratio of C and N content (% DM) from the same source.

Sources: Zhao et al. (2016); Sanjaya 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

  • fibrous
  • slowly degrading
  • seasonal
  • variable composition
  • dilutes the feed (low DM)
  • editorial classification

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.

Advantages

  • Methane yield in the compendium: median 126 (range 33–203) m³ CH₄/t VS, 3 records from 2 papers (weighted mean 99).

Drawbacks and risks

  • Rambutan waste (chopped) gave a lower yield than ground banana peel (Odedina et al. (2017))

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. Biochemical methane potential and biodegradability of complex organic substrates
  2. Bio-energy conversion performance, biodegradability, and kinetic analysis of different fruit residues during discontinuous anaerobic digestion
  3. Mesophilic batch anaerobic digestion from fruit fragments
  4. Effects of size and thermophilic pre-hydrolysis of banana peel during anaerobic digestion, and biomethanation potential of key tropical fruit wastes
  5. Improvement of fruit and vegetable waste anaerobic digestion performance and stability with co-substrates addition
  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

Rambutan skin (Nephelium lappaceum), covered with characteristic hairs, is the largest part of the mass of waste in processing the fruit. It arises at preserving plants, juice production and on farms. In Poland rambutan is an imported fruit, so this substrate matters above all as a comparative material from the literature.

Properties relevant to digestion

The skin is more fibrous than the pulp: it contains cellulose, hemicellulose and pectins, as well as lignin in moderate amounts. It is rich in polyphenols, including tannins, which can bind proteins and may limit the activity of microorganisms and hydrolytic enzymes. The content of simple sugars is lower than in the pulp, so the risk of rapid acidification is smaller, although the presence of organic acids lowers the pH. Size reduction eases access to the fibre, but does not remove the effect of polyphenols.

How to read the spread of results

The dataset contains several records from several sources, and the spread of results is exceptionally large here: values from different studies differ significantly. This results from the fact that the skin is a heterogeneous material; the polyphenol and fibre content depends on the variety, maturity and condition of the fruit (fresh or spoiled skin), as well as on the degree of size reduction, sample preparation and the inoculum. With such great disagreement the results must be treated cautiously.

In biogas plant practice

Rambutan skins can supplement the feed at tropical plants, usually together with manure or other fruit wastes. Size reduction and a moderate share in the mixture are recommended because of the tannins. Storage in a moist state quickly leads to moulding. Because of the high variability of results, each new batch should be tested with a BMP test before it becomes a permanent element of the recipe.

In practice a cautious approach consists in starting with a small share of skins in the feed and observing pH, volatile acids and gas production, and only after several weeks of stable operation increasing the dose, if the process does not object.

Because of the large spread of results and the presence of polyphenols, rambutan skin is a good example of a material for which a literature average does not replace a test of your own; only a series of trials with a local batch makes it possible to estimate the real yield.

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. 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
  2. Sanjaya, A.P.; Cahyanto, M.N.; Millati, R. (2016). Mesophilic batch anaerobic digestion from fruit fragments. Renewable Energy 98, 135–141. DOI: 10.1016/j.renene.2016.02.059 DOI

All sources of the site: bibliography.

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