A low-cost deodorizing spray net device for the removal of ammonia emissions in livestock houses

Abstract Ammonia (NH3) originating from high-intensity pig farms has caused a global air pollution problem. In this study, a deodorizing spray net device (DSND) is designed, which is inexpensive and achieves a good deodorizing effect. The DSND comprises a steel frame, three spray layers, two 12-needle nylon mesh layers and a backflow device. The device exerts the least impact on the wind speed at a given pig farm when installed at a distance of 2.5 m from blower fans. The device reaches an NH3 reduction rate of 73 %. To further reduce operating costs, microbial liquid is collected and sprayed in cycles according to the peak pig farm NH3 emissions. After two microbial liquid recycling steps, the NH3 reduction rate still reaches 71 %. The construction cost of the device is $3200, and the annual operation cost reaches $2600. Through microbial diversity determination and redundancy analysis (RDA), we find that the reasons for the higher NH3 reduction rate of the device may include the higher dust removal rate and both the higher denitrifying bacterial abundance and lower pH and electrical conductivity (EC) values of the sprayed microbial liquid. The device provides a practical solution to resolve the NH3 problem in mechanically ventilated livestock housing system.