Ozone promoting organic nitrogen change to inorganic in anaerobic livestock wastewater

Ozone aeration may significantly change nitrogen form and availability in anaerobic swine wastewater, hence it is important to characterize the effect of ozone on nitrogen. In order to study the influences of ozone and aeration time on the nitrogen transformation and availability in anaerobic swine wastewater, an indoor experiment was conducted with self-designed ozone producer apparatus under five different durations of ozone aeration, 0, 10, 20, 40 and 60 min, respectively. Water samples were collected in different aeration time and different nitrogen forms were determined. The results showed that different durations of ozone aeration remarkably affected nitrogen contents and formations in wastewater system. Specifically, the content of total nitrogen, soluble Kjeldahl nitrogen, ammonium nitrogen, nitrite nitrogen and particulate organic nitrogen (PON) significantly declined by 10.11%, 6.75%, 17.90%, 98.81% and 89.33% (p < 0.05), respectively. On the contrary, the content of nitrate nitrogen and dissolved organic nitrogen increased by 613.85% and 459.85% at the end of 60 min (p < 0.05), respectively. The results suggested nitrogen form transformation and nutrient concentration change should be taken into consideration before reusing swine wastewater in irrigation.