BMP testingFruit, vegetables and their residues

Tomatoes — BMP: 7 studies, weighted mean 291 m³ CH₄/t VS

Tomatoes (fruit) are a watery greenhouse and processing waste, rich in sugars and organic acids, with seeds and skin of higher lignin content.

CH₄ ≈ 55 % (estimate)

Published 3 September 2024Updated 29 October 20263 min readFeedstockData Editorial Team

Photo Jeffery Martin / Wikimedia Commons, licence CC0 1.0, source file; changes: cropping

Weighted mean: 291m³ CH₄/t VS
Range: 210–384m³ CH₄/t VS
Records: 7studies
Publications: 5sources
Temperatures: 35 °C, 38 °Cof the test

Methane in biogas

≈53–57% CH₄

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 3.3 % 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 7 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 (291); 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
Yan et al. (2021) DOI	218	—	Tomato (Solanum lycopersicum) – Whole	end point (model curve)
Aybek et al. (2017) DOI	372	—	Tomato	end point (model curve)
Shin et al. (2011) DOI	210	38 °C · mesophilic	Tomato	end point (model curve)
Gunaseelan (2004) · 1 DOI	211	35 °C · mesophilic	tomato whole rotten	end point (model curve)
Gunaseelan (2004) · 2 DOI	384	35 °C · mesophilic	tomato whole rotten	end point (model curve)
Kouas et al. (2017) · 1 DOI	347	35 °C · mesophilic	tomato	end point (model curve)
Kouas et al. (2017) · 2 DOI	373	35 °C · mesophilic	tomato	end point (model curve)
Weighted mean	291	arithmetic mean 302, SD 84

Typical composition

Volatile solids (VS): 92.5 % DM (range 88.1–98.1)
Nitrogen: 3.3 % DM
C/N ratio: 13.8

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: 3 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); 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

Tomato (Solanum lycopersicum) is an important vegetable in Polish greenhouse and field production. Waste fruit arises at sorting plants, on greenhouse farms (fruit failing standards, split, out of date) and in processing, where tomato pomace arises alongside the fruit. This entry concerns whole fruit, not pomace.

Properties relevant to digestion

The fruit contains about ninety-five per cent water. The dry matter is dominated by sugars (glucose and fructose), organic acids (citric, malic), pectins and protein. Seeds and skin contribute fibre and a more poorly degradable fraction, with lignin and fat in the seeds. The material is readily degradable, and the low pH of the fruit and rapid acid formation can acidify the digester when there is no buffer. In batches of green fruit the glycoalkaloid tomatine is present, but at typical doses it is not considered a significant inhibitor. Sand may come from soil in field harvesting.

How to read the spread of results

The dataset contains several records from several sources, some without a stated temperature, some mesophilic. They describe market fruit, greenhouse waste and spoiled fruit. The spread results from varietal differences, degree of ripeness, share of seeds and skin, size reduction and the condition of the fruit. Spoilage changes the composition: part of the sugars is consumed and fermentation products appear. The inoculum and the substrate-to-inoculum ratio are additional sources of variability.

In biogas plant practice

Tomatoes are best dosed as an addition to slurry or silage, which provide buffer and dry matter. Size reduction is necessary, because seeds and skin may form layers. Storage in warm conditions quickly leads to spoilage, so batches are used as they arrive. Waste from processing and trade is waste, and its acceptance requires appropriate authorisations; own waste from a greenhouse farm may be treated as an agricultural product. Large seasonal deliveries should be spread over time to avoid pH fluctuations.

It happens that tomato waste contains remnants of strings, clips and pieces of film from greenhouse cultivation; such contaminants must be removed before size reduction so as not to damage pumps and cause agitator failures.

It is good practice to mix tomato waste with material of high dry matter, for example maize silage or straw, which improve the structure of the feed and reduce the risk of too sudden a drop in pH.

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

All sources of the site: bibliography.