(368b) An Electrochemical Method to Remove Aqueous Sulfide from Swine Manure

Authors: 
Wang, Y., University of Minnesota
Lin, H., University of Minnesota
Hu, B., University of Minnesota
Sulfide is synthesized by sulfur reducing bacteria during the anaerobic degradation of swine
manure. The year-long pit storage of swine manure allows the accumulation of sulfide, which
eventually results in a high risk of hydrogen sulfide (H 2 S) releasing to the air during the manure
pumping. H 2 S is an extremely hazardous and toxic gas; and a number of casualties have been
reported due to H 2 S poisoning in the past several years. In order to minimize the sulfide level in
swine manure and create a safe working environment, an effective way is presented in this
study. By applying a certain voltage onto low carbon steel electrodes partially immersed in the
swine manure storage, a 90% or above sulfide removal can be achieved after 1 to 2 weeks
treatment. In our experiment, the optimal voltage was investigated to be 0.7 V, which allowed
the majority removal of sulfide, and meanwhile a guarantee of less electrode material
consumption. The effects of potential parameters, including manure solid content, electrode
surface area, distance between electrodes, treatment temperature, biogas composition in the
reactor headspace, and sulfide recovery after shutting down the power, were investigated. This
electrochemical treatment has shown a significant aqueous sulfide removal from swine manure.
Optimization based on mentioned parameters can further improve the treatment feasibility in
reality.