A New Method For Reduction Of NH3 Emissions From Pig Housing Systems By Adding Sulphuric Acid To Slurry

Effects of adding sulphuric acid to slurry by flushing the waste pits were studied in a commercial finishing unit with four identical sections. Each section included 300 pigs on fully slatted floors. Waste pits in two control sections had a pull-plug system installed for removal of slurry. The other two sections had a new developed and patented waste handling system using a sulphuric acid treatment.

In the new system the slurry was treated with sulphuric acid in a storage tank outside the building. At the bottom of the tank concentrated sulphuric acid was added at a ratio of approximately 5 kg per tons of slurry. This reduced the pH to about 5.5. Simultaneously slurry was aerated by injecting compressed air to prevent the sulphate-ion changing into noxious hydrogen sulphide. Slurry pits were flushed 6 times daily with sulphuric acid treated slurry.

Ammonia emission was measured continuously to evaluate emission rates from control and experimental sections. Odour emission was calculated from two point measurements per batch when pigs weighed 40, 60 and 80 kg. In addition data on performance and health of the pigs were collected. The technical performance of the new developed slurry system was evaluated as well.

Measurements indicate that ammonia emission can be reduced by approximately 70%. At the same time field
experiments shows a much higher utilization of the nitrogen in the acid treated slurry compared with non-treated slurry.