BMP testingFruit, vegetables and their residuessingle study (2 samples)
Rambutan pulp — BMP: 2 studies, weighted mean 316 m³ CH₄/t VS
Rambutan pulp is a fruit waste rich in simple sugars and almost devoid of lignin; fresh and spoiled pulp were tested, with a very similar result.
Photo Frank Schulenburg / Wikimedia Commons, licence CC BY-SA 4.0, source file; changes: cropping
- Weighted mean
- 316m³ CH₄/t VS
- Range
- 309–323m³ CH₄/t VS
- Records
- 2single study (2 samples)
- Publications
- 1source
- Temperatures
- 35 °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 (carbohydrate-dominated (no protein or fat characteristics)) and the yields of compound groups according to FNR.
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.
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 (316); 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| Source | BMP m³ CH₄/t VS | Temperature | Sample | Curve |
|---|---|---|---|---|
| Sanjaya et al. (2016) · 1 DOI | 309 | 35 °C · mesophilic | Fresh ripe rambutan pulp | end point (model curve) |
| Sanjaya et al. (2016) · 2 DOI | 323 | 35 °C · mesophilic | Rooten rambutan pulp | end point (model curve) |
| Weighted mean | 316 | arithmetic mean 316, SD 10 | ||
Typical composition
- Dry matter (DM)
- 14% (range 9.4–18.6)
Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 2 determinations, volatile solids: 0 determinations.
Sources: 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
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
Co-digestion — what to combine it with, what to watch out for
- combines well
substrates: nitrogen-rich — e.g. Pig slurry, Poultry manure, Waste activated sludge (secondary sludge), Chlorella vulgaris, Nannochloropsis salina
A nitrogen-rich co-substrate balances the low C/N of fruit and vegetable waste (Bouallagui et al. 2009).[1]
- combines well
substrates: high alkalinity (buffer) — e.g. Cattle manure, Pig slurry, Cattle slurry, Duck slurry, Rumen and digestive tract content
Co-digestion of easily degradable substrates with dairy slurry increased the methane yield relative to slurry alone.[2]
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
- Improvement of fruit and vegetable waste anaerobic digestion performance and stability with co-substrates addition
- Biochemical methane potential and biodegradability of complex organic substrates
- Mesophilic batch anaerobic digestion from fruit fragments
- Effects of size and thermophilic pre-hydrolysis of banana peel during anaerobic digestion, and biomethanation potential of key tropical fruit wastes
- 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 (Nephelium lappaceum) is a tropical fruit grown in South-East Asia. The edible pulp surrounds the seed and is covered with a hairy skin. In processing (preserves, juices) the pulp is a valuable product, and the skin and seeds remain as waste, although fruit that fails quality requirements is also sometimes waste. In Poland rambutan occurs only as an imported fruit, so the practical significance is small.
Properties relevant to digestion
The pulp contains a lot of water, simple sugars (sucrose, glucose, fructose), organic acids and pectins, with a very low content of lignin, protein and fat. Such a composition means very easy and rapid hydrolysis. The risk is acidification of the digester at high dosing or a short retention time, as well as spontaneous fermentation during storage. The material does not require milling, but requires a buffer in the form of manure, slurry or sludge.
How to read the spread of results
The dataset contains several records from one study: fresh and spoiled pulp, with very similar results. This means that in this study spoilage did not change the methane potential per volatile solids, although the composition and rate of degradation probably change. A single study does not, however, yield a rule for other batches. The result is affected by the variety, maturity, sample preparation and inoculum.
In biogas plant practice
Rambutan pulp is a typical waste of fruit processing in the tropics. It can be introduced into co-digestion with manure or sludge, at a moderate share, spread over time. Because it spoils easily, it is not stored for long. Under Polish conditions it has no practical significance, but the data help to assess the behaviour of similar, readily fermentable fruit wastes. In processing practice the pulp is sometimes mixed with skin and seeds, so the proportions of the fractions in a batch must be known before the dose is determined.
Given the similar result for fresh and spoiled fruit, it can be cautiously assumed that waste batches of pulp are suitable for digestion, provided the system is not overloaded with acids; the key, however, is rapid use of the material.
The conclusions of this study should be applied cautiously to other tropical fruits, because although they have a similar sugar composition, they differ in acidity, fibre content and the presence of secondary compounds, which affect the degradation kinetics.
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.
Bibliography
- 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”
Cauliflower leaves and stems — BMP: 8 studies, weighted mean 336 m³ CH₄/t VS
336 m³ CH₄/t VS weighted mean from 8 studies
neutral — editorial rating for biogas plants68 %
Spinach — BMP: 2 studies, weighted mean 227 m³ CH₄/t VS
227 m³ CH₄/t VS weighted mean from 2 studies
≈58 %
Tropical tubers (sweet potato, Chinese yam) — BMP: 2 studies, weighted mean 280 m³ CH₄/t VS
280 m³ CH₄/t VS weighted mean from 2 studies
good — editorial rating for biogas plants≈52 %
Potato peels — BMP: 5 studies, weighted mean 234 m³ CH₄/t VS
234 m³ CH₄/t VS weighted mean from 5 studies
neutral — editorial rating for biogas plants≈56 %