BMP testingAnimal excreta (slurry, manure, poultry litter)

Duck slurry — BMP: 6 studies, weighted mean 395 m³ CH₄/t VS

Duck slurry is a rarely studied material rich in nitrogen and water from duck rearing; results from several sources differ greatly, and the risk is ammonia.

rating: neutral CH₄ ≈ 55 % (estimate)

Published 27 September 2024Updated 29 October 20263 min readFeedstockData Editorial Team

Photo MiNe (sfmine79) from Taipei, Taiwan / Wikimedia Commons, licence CC BY 2.0, source file; changes: cropping

Weighted mean: 395m³ CH₄/t VS
Range: 135–551m³ CH₄/t VS
Records: 6studies
Publications: 2sources
Temperatures: 30 °C, 38 °Cof the test

Methane in biogas

≈52–56% 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 % DM × 6.25; in manure part of the N is ammonium nitrogen)) 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 (21 m³ CH₄/t); process risk: protein / nitrogen. Handling costs: sand, stones, shells.

Why? Rating factors

Potential per tonne 0

±0potential 21 m³ CH₄/t fresh matter (BMP 395 × DM 6.2 % × VS 84 %)

Process stability +0.5

−1protein / nitrogen: risk of ammonia inhibition at higher shares
+1.5high alkalinity — stabilises the pH of the mixture

Handling and costs −0.5

−0.5sand, stones, shells — sediment in the digester

Total points: 0 · 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 6 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 (395); 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
Lallement et al. (2023) DOI	551	38 °C · mesophilic	duck slurry	end point (model curve)
Vedrenne et al. (2008) · 1 DOI	135	30 °C · mesophilic	duck slurry	end point (model curve)
Vedrenne et al. (2008) · 2 DOI	172	30 °C · mesophilic	duck slurry	end point (model curve)
Vedrenne et al. (2008) · 3 DOI	255	30 °C · mesophilic	duck slurry	end point (model curve)
Vedrenne et al. (2008) · 4 DOI	310	30 °C · mesophilic	duck slurry	end point (model curve)
Vedrenne et al. (2008) · 5 DOI	320	30 °C · mesophilic	duck slurry	end point (model curve)
Weighted mean	395	arithmetic mean 290, SD 147

Typical composition

Dry matter (DM): 6.2% (range 6.2–6.2)
Volatile solids (VS): 84 % DM (range 84–84)
Nitrogen: 3 % DM
C/N ratio: 14

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

Sources: Lallement et al. (2023).

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

high alkalinity (buffer)
nitrogen-rich
dilutes the feed (low DM)
sand and sediment
variable composition
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 potential in the Substraty.pl BMP set: weighted mean 394.8 m³ CH₄/t VS (SD 147.4; 6 records, 2 sources).
High alkalinity and ammonium N: a buffer for acidic substrates (Rajagopal et al. 2013).

Drawbacks and risks

Waterfowl excreta contain a lot of N (uric acid -> NH3): risk of free ammonia inhibition, especially at higher temperature and pH (Rajagopal et al. 2013; Abouelenien et al. 2010).
BMP data from several sources differ strongly: set the dose after analysis.

Co-digestion — what to combine it with, what to watch out for

combines well
substrates: carbon-rich — e.g. Wheat straw, Maize silage (whole crop), Cereal straw (unspecified), Willow (short rotation), Cardboard and paperboard
Carbon substrates lower the ammonia risk by improving the C/N.^[1][2]
caution
substrates: protein-rich — e.g. Food waste, Municipal sewage sludge (mixed), Poultry manure, Organic fraction of municipal solid waste, Grass clippings
Additional protein -> NH3 threshold exceeded.^[1]

Dosing

No source threshold. Monitor NH4-N and pH, combine with carbon substrates.

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

Practical requirements

ABP cat. 2 (Art. 9 of Reg. 1069/2009): manure, slurry and digestive tract content may be digested without prior sterilisation if the authority does not recognise a risk of spreading a serious transmissible disease (Art. 13(e)(ii)); in that case a minimum of 70 °C for a minimum of 60 min applies (Reg. 142/2011, Annex V Ch. III Section 1), and where they are the only material of animal origin in the installation, the authority may approve other requirements (Section 2 point 3).
Provide for removal of sand and heavy contaminants: sand is often strongly bound to organic matter and is released only in the digester, and sediments reduce its usable capacity, so a scraper or bottom drain is needed (FNR 2010, Ch. 3).

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

Duck slurry is a mixture of duck excreta, water and feed residues from rearing carried out in unbedded systems or with minimal bedding. Ducks use and foul a lot of water, so the excreta are liquid. In Poland duck rearing is located mainly in a few regions, so the raw material is available only in specific places. The dataset contains samples from several studies, tested mainly under mesophilic conditions, with several records coming from a single series at a lower temperature.

Properties relevant to digestion

Bird excreta contain a lot of nitrogen, including uric acid, which breaks down to ammonia. Combined with low dry matter, this gives a liquid substrate with a high concentration of ammonium nitrogen and a high buffering capacity. Free ammonia can inhibit methanogenic archaea, particularly at higher temperature and at large doses. The slurry may contain feathers, sand and feed residues. The content of readily available carbohydrates is limited, so the potential depends on the undigested components of the feed.

How to read the spread of results

The range of results in the dataset is very wide, which reflects the variability of this material: the slurry depends on the feed, the age of the birds, the amount of water and the method of storage. Differences in methodology also have an effect: temperature (several records at a lower temperature), the substrate-to-inoculum ratio, adaptation of the inoculum to ammonia and test length. High values may concern samples rich in undigested feed residues, and low ones diluted or long-stored material. With a limited number of sources, a reliable typical range cannot be determined.

In biogas plant practice

Duck slurry is suitable for co-digestion with carbon-rich materials (silages, straw, plant waste), which lower the ammonia concentration. When planning the dose, ammonium nitrogen and pH must be monitored. It is a natural fertiliser on the farm, and in the context of ABP a Category 2 material, which may be used in a biogas plant under the conditions set out in EU and national regulations. Detailed requirements should be confirmed with the veterinary authority.

For comparison with cattle slurry, duck material has a higher nitrogen concentration and less fibre, which changes the character of the risk: it is limited not by lignin but by ammonia.

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 = 0.393 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.