Danish Pig Research Centre: Annual Report 2010: Environmental TechnologyFriday, September 30, 2011
The 2010 annual report from the Danish Pig Research Centre outlines the latest research on pig house environmental management.
Testing of environmental technology
Pig Research Centre (PRC) participates in
the development and testing of environmental
technologies used by pig producers
to limit ammonia and odour emissions.
The aim is to ensure that these technologies
are efficient in terms of their environmental
impact as well as the economy in
A ‘technology list’ made by the Danish Environmental Protection Agency outlines the systems that have already been tested sufficiently (see the table), while PRC is continuously testing new products and technologies. A wide range of methods is available for reduction of ammonia emissions from pig houses whereas only few reduce odour emissions. Below, current investigations of new or improved environmental technologies are described.
Dorset air cleaner
Rotor A/S, a Danish ventilation company,
markets a biological air cleaner from the
Dutch company Dorset. The air cleaner
is approved for use in the Netherlands
and Germany, but foreign trials revealed
that the consumption of water and the
production of discharge water were too
high for the air cleaner to be used on pig
farms in Denmark.
The air cleaner was therefore modified and in 2009 set up on a Danish finisher farm where PRC tested its efficiency in reducing ammonia and odour over a year.
Data shows that both the consumption as well as the discharge of water were successfully reduced. The air cleaner also reduces emissions of both ammonia and odour under Danish production conditions. The results of the trial will be published in the autumn 2010.
Three-step air cleaner from SKOV A/S
For years, Danish pig producers have been using the Farm AirClean BIO system, a biological air cleaning system from SKOV A/S. Through trials, PRC has demonstrated that odour concentrations dropped by 30 per cent in the summer and by 50 per cent in the winter when ventilation air from pig houses was cleaned. Ammonia concentrations of 4-9 ppm were reduced to 1-2 ppm.
|Technology list of the Danish Environmental Protection Agency of approved environmental technologies and their efficiency in reducing ammonia and odour emissions from pig houses.|
|Reduced protein||15% if 10% less crude protein||0|
|Benzoic acid||1% per g/feed unit||0|
|Cooling of slurry||30%||0|
|Acidification of slurry||70%||0|
|Air cleaning with acid||90%||0|
|Biological air cleaning||70%||0|
SKOV A/S has improved the system to
increase the reduction in odour. The
controller was optimised and the washing
robot in the air cleaner modified. Furthermore,
a third filter element was installed,
ie. the air cleaner may consist of three vertical
cellulose filters if large odour reductions
are required. To ensure that all filters are evenly loaded with air, a perforated air
distribution board is fitted before the first
Recordings made in Germany in 2009 indicate that the air cleaner is improved in terms of odour reduction. PRC is now investigating the air cleaner to document the reduction in ammonia and odour and the costs of running the system on a Danish finisher farm.
Air cleaner from Munters A/S
In the summer 2009, PRC made a series of preliminary recordings of an air cleaning system developed by Munters A/S (previously Turbovent) that demonstrated a 90 per cent reduction in ammonia. The system
was subsequently modified by Munters
A/S, and is now ready for a comprehensive
test. The aim is to document its efficiency
in reducing ammonia emissions over a
long period of time and the costs of running
The air cleaner is constructed as a tube without filter elements. Nozzles at the bottom of the air cleaner sprinkle acidic water into the air stream whereby air is cleaned. A drip catch at the top of the system retains the acidic water in the air cleaner.
It remains to be clarified if acidic water is released with the exhaust air from such systems to potentially damage building parts. Part of the investigation of Munters’ system thus concerns the amount of acidic water released from air cleaner to the surrounding environment.
Cooling of inlet air
Odour emissions from pig houses are highest
in the summer when ventilation systems
run on maximum performance. In an
investigation of a ground cooling/heating
system from the Dutch company INNO+,
it was therefore determined whether
ammonia and odour emissions could be
reduced when the inlet air in a farrowing
house was warmed or cooled, respectively,
so that the ventilation rates in the housing
unit varied less. Over a year, the system
was capable of keeping the temperature
of the inlet air to the farrowing house
between 4.3 and 19.6 C° despite the fact
the outdoor temperatures ranged from -4
to +32 C°.
Odour emissions from the trial facility generally tended to be lower in the summer. However, on the hottest summer days, odour emissions from the trial facility were 39 per cent lower than from the control facility, which shows that cooling the inlet air may neutralize the release of very high odour emissions in warm weather. It was not possible to record a significantly lower ammonia emission over an entire year.
Ammonia and odour originate from slurry, and PRC investigated if the majority of these substances can be collected in air that is emitted through pit ventilation. If so, a large reduction in ammonia and odour emissions from pig houses will be possible by cleaning this air with an efficient air cleaner.
It was studied how much odour and ammonia
emission originates from pit ventilation
and ceiling exhaust, respectively, at a
pit ventilation capacity of 16 and 54 m3/h
per pig place, respectively. The remaining
ventilation air up to maximum output
(100 m3/h) was emitted through the
The results demonstrated that when 16 m3/h were sucked out through pit ventilation, 61 per cent of the overall odour emissions and 70 per cent of ammonia emissions from the pig house originated from the pit ventilation.
When 54 m3/h were sucked out trough pit ventilation, 90 per cent of odour emissions and 94 per cent of ammonia emissions were collected in the pit ventilation. Here the overall emissions of both odour and ammonia from the pig house were significantly higher than during pit ventilation at 16 m3/h, and higher than expected. The most realistic way forward is therefore setting pit ventilation at approx. 10-20 per cent of maximum capacity.
The working environment in the pig house was equally good with both settings evaluated on the basis of ammonia and odour concentrations in the room.
Frequent emptying of slurry pits
In 2009, PRC investigated whether it is
possible to reduce odour emissions from
pig houses with slurry systems by changing
the frequency of emptying of the pits.
In a trial section, slurry was emptied once a week, whereas it was emptied in the control section when the pits were full (40 cm). In the period June-November, 50 per cent lower odour emissions were recorded the day after the trial section was emptied compared with the control section. However, there was no significant difference in ammonia emission from the section regardless of emptying strategy.
The investigation is currently being repeated in the climate chambers at PRC’s Experimental Station Grønhøj where it is being studied for how long the reduced odour emissions last after emptying.
Infarm A/S is the only company with a
Technology Sheet on acidification of slurry
with 65-70 per cent reduction in ammonia emission
from pig houses.
In the summer 2010, the company Jørgen Hyldgård Staldservice A/S installed its first acidification system on a finisher farm where PRC will test the system.
|-||Go to our previous article on this report by clicking here.|