Evaluation of a plant material-based air purifier for removing H2S, NH3 and swine manure odour

Abstract

A plant material-based air purifier (PMAP) was evaluated for odour removal. Laboratory tests were performed using two identical chambers: one treated by PMAP, and one as the control. Swine manure, hydrogen sulphide (H2S) and ammonia (NH3) were tested as odour sources. The test was also conducted in a swine barn. Air samples were taken from test chambers and two rooms in the pig barn and analysed for H2S, NH3 and odour concentrations. When treated with PMAP, the H2S concentration in the sealed chamber was subject to exponential decay, with the decay constant ranging from 0.59 to 0.70 1/h. The H2S concentration was reduced from 20 to 3 ppm in 3 h and to 0.2 ppm in 7 h for H2S produced by chemical reaction, and from 0.4 to 0.02 ppm in 3 h for swine manure as the odour source. When an equal amount of ammonia solution was placed in the two test chambers, the NH3 concentration reached a peak value of 25 ppm in the chamber treated by PMAP, and 43 ppm in the control. The NH3 concentration in the treated chamber was reduced to 5 ppm in 3.5 h but stayed at 37 ppm in the control. The PMAP reduced the NH3 concentration from 38 to 10 ppm when swine manure was used as the odour source. The PMAP was capable of reducing swine odour in both laboratory and in-barn conditions. The reduction rate was at least 50%. The results from this research indicate the plant-based materials provide an alternative, environmentally friendly way for odour control. It is also shown that the mode of odour reduction by the PMAP was the removal of odour compounds, in contrast to odour masking, which occurs for most plant materials that have been used for odour control.