Slurry Smell Reduction-Trials

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AMMONIA (NH3) EMISSION FROM SLURRY TREATED WITH
COBIOTEX 500 IN COMPARISON TO NON-TREATED SLURRY IN A
CLOSED COWSHED IN THE NETHERLANDS

GJ Monteny and R. Scholtens IMAG. DLO VAGEMINGEN

Jean Penaud, November 12, 2001, COBIOTEX, France

TRIAL OBJECTIVE
Other than bad odour, the prolonged storage of slurry may generate the emission of gas containing ammonia (NH3) and nitrogen oxides(Nox), a source of pollution of the environment and a cause of acid rain. When inhaled, these gasses are toxic to both animals and humans. In 1997, R. Scholtens and associates have established that the emissions of ammonia per cow, raised on slats were 8.8 kg of NH3 over a period of 190 days per year. This has created the need to find ways to reduce the levels of ammonia emission from nitrogen contained in slurry. The purpose of this trial was to evaluate the effect of COBIOTEX 500 in slurry treatment to reduce ammonia (NH3) emissions.

TRIAL SET-UP
- Cowshed/animals: 80 cows and heifers on slats, covering 293.5m2 of floor surface over a 1.8 m deep slurry pit of 530m3 capacity
at J. Eggink-Laren GLD in the Netherlands
- Building: Closed shed, 8 meters high ceiling
- Milk Production: 7500 kg/cow per year
- Feeding:

    60-65% sun cured hay
    35-40% silage
    6 Kg concentrate per cow per day

- Water: available ad libidum
- Slurry Treatment: COBIOTEX 500, 120 gr/per animal per week spread over the slats.

METHODS TO MESURE NH3 EMISSIONS
- The emissions of ammonia (NH3) are measured from the concentration of NH3 in the air evacuated from the cowshed.
- The flow of air into the building was measured on the concentration of a tracer (SF6) that was injected at a constant volume at 3 locations above the feed troughs in the cowshed.
- 3 recording devices directly connected to a gas chromatograph were installed inside the building 4 m above floor level.
- The chromatograph and the recording pumps were controlled by a computer. Gas samples were collected and analyzed every 2 minutes. The results were recorded to measure the ammonia (NH3) given off during the various periods of data collection and were simulated to the reference standard 190 days of presence of the animals in a closed shed in the Netherlands.

EVALUATION OF PARAMETERS INFLUENCING AMMONIA PRODUCTION
- Temperatures inside and outside the building.

    *Temperature probe coupled to temperature recording devices installed inside the cowshed, 4 m above floor level.
    *Outside temperatures were obtained from the Weather Station of the Commune.
- Nitrogen in urine:
    *Urine samples were collected daily from 10 cows in the milking parlor, before milking and analyzed for:
    *Total Nitrogen
    *Urea
    *Ammoniac Nitrogen
    *Dry Matter
    *pH
- Nitrogen in slurry:
Slurry samples were taken to establish the ration of N in urine and the content of NH3 in slurry and analyzed for:
    *Total Nitrogen
    *Ammoniac Nitrogen
    *Total Phosphates
    *Dry Matter
    *pH
- Simulation of ammonia emission recording
The recording periods of ammonia (NH3) emission were divided into 6 periods in order to obtain a mathematical model:
    September 21-25, 1998 4 days Period “A”
    January 24-28, 1999 4 days Period “B1”
    January 28-31, 1999 3 days Period “B2”
    January 31-February 4,1999 4 days Period “C1”
    February 4-7, 1999 3 days Period “C2”
    February 7-11, 1999 4 days Period “D”
RESULTS
Refer to Tables I, II, III
CONCLUSIONS
This trial demonstrates the efficacy of COBIOTEX 500 in the treatment of slurry of cows kept in a closed shed to reduce NH3 emissions. There was a significant reduction of ammonia of up to 84.30%. This is in conformity with results obtained with COBIOTEX 500 in slurry treatment of pigs raised on slats.

Table I
Concentration of NH3 in the air and ammonia emissions from non-treated slurry

Measurement Period September 28, 1998 – February 11, 1999 >
Parameters A B1 B2 C1 C2 D
Emission of NH3 in gr/h 26.8 23.0025.30 27.00 18.10 16.80
Emission of NH3per day in gr 643.20 552.00 607.20 648.00 434.40 403.20
Emission of NH3 per cow per day in gr 8.04 7.08 7.78 8.31 5.57 5.17
Emission of NH3per cow over a period of 190 days in kg 1.528 1.345 1.478 1.579 1.058 0.982
Concentration of NH3 in the air in ppm 2.97 2.85 2.94 3.46 2.02 2.33

Table II
Reduction of the emissions of NH3 from slurry treated with COBIOTEX 500

Parameters Reference standards in the Netherlands Recordings of the trial at Egging
Air flow per cow per minute 400 to 900 m3 139 to 177 m3
Emission of NH3 calculated on the basis of parameters recorded per cow over 190 days. 8.80 Kg 4.03 Kg
Emissions of NH3 (standard or recorded) per cow over 190 days 8.80 Kg 1.38 Kg
Reduction in the emission of NH3 due to COBIOTEX 500 treatment of slurry in comparison to the Reference Standard in the Netherlands and to recorded measurements. 84.30% =100 - 1.38 x 100 / 8.80 65.75% =100 - 1.38 x 100 /4.03

Table III
Database for the simulation method of recordings for each period “A” to “D”

Parameters Period “A” Periods “B” to “D” Comments
Number of animals in the trial 80 78
Frequency of urine excreted per cow per day 10 10 Data from previous studies
Urea in urine (gr/l) 2.30 2.82 Average of analyzed samples
Temperature ° C inside the building 16.6 A 7.20
B1 9.40
B2 4.70
C1 9.10
C2 7.50
D 4.60		 Average of recorded temperatures
Slats surface per cow (m2) 3.68 3.77 Cowshed information
Air velocity over slats (meter/second) 0.05 0.05 As recorded
Slurry pit surface under slats per cow (m2) 3.68 3.77 Cowshed information
pH of urine collected on slats 8.60 8.60 Monteny et all - 1998
Total nitrogen in the upper layer of slurry in pits under the slats (grN/Kg) 1.08 1.12 Average of analyzed samples
Slurry temperature ° C in the upper layer of slurry in pit under the slats 16.60 A 7.20
B1 9.40
B2 4.70
C1 9.10
C2 7.50
D 4.60 		Identical to air temperatures inside the cowshed building
Air velocity in slurry pit under slats (meter/second) 0.01 0.01 As recorded

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