Effect of aeration modes on the characteristics of composting emissions and the NH3 removal efficiency by using biotrickling filter

A pilot biotrickling filter (BTF) packed with ZX02 fibrous balls as packing material was tested for the treatment of ammonia (NH3) released from a composting plant of dairy manure. In order to investigate the effects of three compost aeration modes (mode Co-I, Co-II and In-II) on the NH3 removal efficiency, a field experiment was continuously carried out for more than eight months. The results demonstrated that under the intermittent aeration mode (In-II), the NH3 removal efficiency reached 99.2 +/- 0.1% when the inlet NH3 concentration was 7.5-32.3 mg m(-3) (9.8-42.5 ppmv). The maximum and critical elimination capacity of the biotrickling filter was 22.6 and 4.9 g NH3 m(-3) h(-1), respectively. The effluent concentration of NH3 was lower than 1.0 mg m(-3), which meets the first class discharge standards of GB14554-93. When the concentration of free ammonia in the trickling liquid was varied from 0.1 to 0.4 mg L-1, the nitrification yield was between 47.9% and 103.8%. In addition, the optimum liquid tricking velocity (LTV) of the biotrickling filter was 0.5 m(3) m(-2) h(-1) for low inlet concentrations and 2.2 m(3) m(-2) h(-1) for high inlet concentrations. Therefore, the use of the biotrickling filter for the compost under the third aeration mode (In-II) yielded an effective optimum NH3 removal and reduced the nitrogen loss in the compost. (C) 2011 Elsevier Ltd. All rights reserved.