Effectiveness of a manure scraper system for reducing concentrations of hydrogen sulfide and ammonia in a swine grower-finisher room

The effectiveness of a manure scraper system for reducing the risk of barn worker and animal exposure to hydrogen sulfide (H2S) was evaluated by comparing gas levels in two swine production rooms, one with a manure scraper system installed (scraper) and the other with a conventional manure pit plug system (control). Measurements were done over four production cycles; during each 12-week cycle, gas concentrations were measured 4 to 5 times during weeks that conventional manure removal activities were performed in the control room, while the scraper system was operated daily in the scraper room. Daily removal of manure from the scraper room resulted in measured maximum H2S concentrations that were significantly lower (by 90%) compared to the control room. The type of manure removal system had no significant effect on ammonia (NH3) concentration and emission; during each trial, NH3 emission increased in both rooms over the 4 to 5 monitored weeks. The scraper system was also operated in two different modes. These tests revealed that NH3 production was reduced when all the manure was removed from the room compared to leaving the liquid portion on the pit floor surface, although the differences were not significant (p > 0.10). The estimated cost of including the scraper system in the construction and operation of a new barn is CDN$1.89 per pig sold, which is 35% less (on a per pig basis) than the cost of retrofitting an existing facility. The manure removal system tested was effective in reducing exposure of workers and animals to H2S, without significant adverse impact on NH3 production. However, given the highly variable nature of H2S production and dispersion within a room, care should always be taken when handling manure inside swine barns.