Preliminary trials of in situ ammonia stripping from source segregated domestic food waste digestate using biogas: effect of temperature and flow rate.

Batch experiments to remove ammonia from food waste digestate were set up, and preliminary runs undertaken. These experiments were based on gas stripping in a heated column reactor; the effects of different temperatures (35, 55 and 70 degrees C) and gas flow rates (0.125, 0.250 and 0.375 L(biogas)L(digestate)(-1)min(-1)) were considered using biogas as the stripping gas. At 35 degrees C, an increase in the ammonia removal rate by approximately 4.5 times was observed when the flow rate increased from 0.125 to 0.375 L(biogas)L(digestate)(-1)min(-1). At 55 degrees C, and flow rates of 0.250 and 0.375 L(biogas)L(digestate)(-1)min(-1), ammonia removal of 3.46 and 9.38%day(-1), respectively, were achieved. The highest values of removal of ammonia were reached at 70 degrees C: 18.4 and 10.4%day(-1), for 0.250 and 0.375 L(biogas)L(digestate)(-1)min(-1) flow rates, respectively.