BMP testingFruit, vegetables and their residuessingle study (4 samples)

Pomegranate fruit and processing wastes — BMP: 4 studies, weighted mean 376 m³ CH₄/t VS

Pomegranates as a substrate are peels, pomace, seeds and spoiled fruit from a single study; the result depends on the fraction, because peel and flesh differ in composition.

CH₄ ≈ 52 % (estimate)

Published 19 August 2025Updated 29 October 20263 min readFeedstockData Editorial Team

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

Weighted mean: 376m³ CH₄/t VS
Range: 312–430m³ CH₄/t VS
Records: 4single study (4 samples)
Publications: 1source
Temperatures: 35 °Cof the test

Methane in biogas

≈51–54% CH₄

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.

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

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 (376); 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
Gunaseelan (2004) · 1 DOI	312	35 °C · mesophilic	pomegranate peels	end point (model curve)
Gunaseelan (2004) · 2 DOI	342	35 °C · mesophilic	pomegranate whole rotten fruit	end point (model curve)
Gunaseelan (2004) · 3 DOI	420	35 °C · mesophilic	pomegranate pressings	end point (model curve)
Gunaseelan (2004) · 4 DOI	430	35 °C · mesophilic	pomegranate rotten pulpy seeds	end point (model curve)
Weighted mean	376	arithmetic mean 376, SD 58

Typical composition

Volatile solids (VS): 92 % DM (range 86.8–97.2)

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 0 determinations, volatile solids: 4 determinations. No DM in the sources – the calculator has to ask for a value.

Sources: 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.

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

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

What it is and where it comes from

Pomegranate (Punica granatum) is grown in a warm climate, including in Asia and the Mediterranean basin. Waste arises in juice production (pomace, peels and seeds) and as fruit rejected because of spoilage. The dataset contains four fractions from a single study: peels, whole spoiled fruit, pomace and spoiled seeds with flesh.

Properties relevant to digestion

The flesh and juice contain sugars, so they ferment readily. The peel is rich in tannins, which bind proteins and can inhibit enzymes and bacteria, slowing the process at large doses. The seeds are hard and contain oil and lignin, so they degrade more slowly. The reaction of the fruit is acidic, which requires pH control in mono-digestion.

How to read the spread of results

The records describe different fractions of the same fruit, and the differences between them originate in composition, not in measurement. Because they all come from a single study and a single temperature, it is not known how the results would behave in other laboratories. The variety, the degree of ripeness or spoilage, the ratio of peel to flesh and size reduction all have an effect.

In biogas plant practice

Pomegranate in Poland is not a mass waste; it appears in the processing of exotic fruit. It is best treated as a component of a mix of fruit waste in a limited proportion because of the tannins. It is worth size-reducing the seeds and increasing the dose gradually, monitoring pH and volatile fatty acids. Pomace may also be utilised by other routes (polyphenol extraction, feed), which affects its availability.

In practice the value of the result for pomegranate depends on which waste fraction the processor delivers. Pomace after juicing will contain more peels and seeds than rejected fruit, and this changes both the rate of degradation and the risk of inhibition by tannins. It is therefore sensible to commission a BMP test for the actual mixture of fractions, and not for a single, cleaned part of the fruit.

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

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.