Evaluation of electrolysis for oxidative deodorization of hog manure

Abstract

Electrolysis was investigated as a method for the amelioration of odor from the supernatant phase of centrifuged liquid hog manure. Methods examined included the use of dual anodes to provide both oxidizing intermediates from water electrolysis and a sacrificial input of iron into solution to remove organic constituents of hog manure by coagulation. The most promising approaches used a ''dimensionally stable anode'' composed of tin dioxide coated on a base of titanium, and the newly developed material boron-doped diamond, which has an exceptional stability to both oxidizing and reducing electrolytic conditions. These anodes promote the formation of hydroxyl radicals which initiate oxidation of organic constituents of the manure.

Electrochemical Deodorization and Disinfection of Hog Manure

“…The correlation between TOC and the quality of manure odour was demonstrated previously (Bejan et al, 2005). This time, centrifuged manure was used in order to follow changes in TON values ( Figure 1) using a plug-flow reactor in simulated cascade mode.…”

“…Electrolysis also had a pronounced bactericidal effect, with anaerobic bacteria, in particular, reduced almost to zero after only one pass at both anodes (Figure 2), a result that is explicable by the evolution of molecular oxygen during electrolysis. The rationale for making this determination was our earlier observation that solutions electrolyzed to a near-odourless state could be stored for several weeks without redeveloping an off-odour, even though the solutions still contained a substantial residual TOC (Bejan et al, 2005).…”

“…Odour results from the action of anaerobic bacteria in the anoxic environments of the porcine gut and liquid manure tank, with the production of reduced sulphurand nitrogen-containing organic compounds. We previously showed (Bejan et al, 2005) that an electric current can ameliorate the odour of liquid hog manure, using electrochemical oxidation at anodes such as Ti/IrO 2 or boron-doped diamond (BDD), a novel electrode material known for stimulating the formation of reactive hydroxyl radicals under anodic polarization (Marselli et al, 2003;Panizza and Cerisola, 2004;Cañizares et al, 2004;Foti and Comninellis, 2004).…”

“…Our previous work employed a very small-scale "plug-flow" electrochemical reactor operated at flow rates in the range 1 mL min -1 (Bejan et al, 2005). The amelioration of odour quality correlated with the loss of Total Organic Carbon (TOC) from the solution, but no specific chemical marker was found to correlate with the change in odour.…”

Reduction of odorous compounds emissions from swine slurry by electrolytic treatments and copper addition

“…The anodic generation of oxygen is itself toxic to strictly anaerobic bacteria; moreover, hydroxyl radicals that are formed at certain electrodes are highly destructive to living cells and capable of causing damage to the cell membrane and their eventual rupture (Bejan et al, 2007). Hydroxyl radicals give way to radical chain auto-oxidation of the organic constituents of hog manure, with the first formed radical intermediates further oxidised by the molecular oxygen that is simultaneously evolved at the anode (Bejan et al, 2005;Bejan et al, 2007).…”