Reduction of Particulate Matter and Ammonia by Spraying Acidic Electrolyzed Water onto Litter of Aviary Hen Houses: A Lab-scale Study

Particulate matter (PM) concentrations are high in aviary hen houses due to accumulation of litter on the floor and hen activities on it. Spraying agent such as acidic electrolyzed water (AEW) to mitigate PM levels and disinfect houses has been reported, and higher spray dosage will reduce PM to a lower level. However, spraying higher dosage of AEW may generate higher levels of ammonia (NH₃) due to increase in litter moisture content (LMC). Lab-scale experiments were conducted to assess the effect of AEW spray dosage and pH value on PM and NH₃ emissions from litter of aviary hen houses. Three spray dosages of 25, 50, and 75 mL [kg dry litter]^-1d^-1 and three pH values of 3, 5, and 7 at a free-chlorine concentration of 200 mg L^-1 were tested. Spraying was done within 10 min once a day for 5 consecutive days. A no-spray regimen was used as the control. Four dynamic emission chambers (DEC's) located in an environmentally-controlled room were used for the evaluation. The results showed that higher spray dosages of AEW led to lower PM emissions. Specially, spraying dosages of 25, 50, and 75 mL [kg dry litter]^-1d^-1 reduced PM levels by (mean±SD) 71±3%, 81±1%, and 89±1%, respectively, immediately after spraying. The PM reductions were still significant after 24h of spraying, averaging 57±4%, 71±5%, and 83±1%, respectively. There was no significant difference (P=0.30-0.43) in reduction efficacy among the PM sizes (i.e., PM₁, PM_2.5, PM₄, PM₁₀, and total suspended particulates). For NH₃ emissions, spraying 75 mL [kg dry litter]^-1d^-1 generated 5-6 times NH₃ emissions as compared to 25 mL [kg dry litter]-¹ d^-1 due to difference in LMC (22.6% vs. 13.0%). Meanwhile, spraying AEW with pH7 yielded 2-3 times higher NH₃ emissions than AEW with pH3 at the same dosage. Ammonia emissions of all the spray treatments were found to be higher than those of the control, albeit no significant difference between control and the 25 mL [kg dry litter]^-1d^-1 dosage at pH3 and pH5 (P=0.81, P=0.47). Pearson correlation coefficients between NH₃ and spray dosage (0.82) and pH value (0.46) indicated that the spray dosage is more linearly correlated to NH₃ emissions than pH value (P<0.05). The results suggest that use of 25 mL [kg dry litter]^-1d^-1 dosage at a pH3 seems to be a prudent combination to control PM levels without causing the undesired elevation in NH₃ emissions in the litter-based aviary hen houses. This lab-based finding provides the basis for the future field verification test.