科研之友
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摘要
Emission of ammonia (NH(3)) from lagoons or other similar animal manure holding structures not only degrades environmental quality but also lowers the fertilizer value of the liquid effluent. In general, NH(3) emissions from these facilities depend on the concentration of free NH(3) in the liquid (NH(3(aq)), which is a Junction of the dissociation of ammonium ions (NH(4)(+)). The dissociation of NH(4)(+) is dependent on manure properties, including temperature, pH, ionic strength, and total suspended solids (TSS) concentration. The dissociation constant of NH(4)(+) (K(d)) in flushed dairy manure was determined at a pH of 9, temperatures of 5 degrees C, 15 degrees C, 25 degrees C, and 35 degrees C, and total solids (TS) contents of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% w/w, and a regression model was obtained. The K(d) value increased by approximately 1.6x for every 10 degrees C rise in temperature. The data also indicated a logarithmic decay in K(d) with an increase in the concentration of TS in the liquid. The coefficient of determination (R(2)) of 0.97 for the nonlinear empirical model of K(d) as a function of both temperature and TS concentration demonstrated good fit to the experimental data. The K(d) values in the dairy manure with 1.5% TS were 117%, 87%, 61%, and 54% compared to the theoretical K(d) values in pure water-ammonium solutions at 5 degrees C, 15 degrees C, 25 degrees C, and 35 degrees C, respectively. Similar trends were observed at other TS concentrations, suggesting that the effects of solids were more significant at elevated temperatures. The results of this study emphasize the need for including both the TS concentration and the temperature in models of K(d) for liquid dairy manure, in addition to ensuring that the entire ranges of TS and temperature encountered in the region where the model will be used are covered.
- 出版日期2011-6
