Aerobic treatment of liquid swine manure using polymer: Evaluation for ammonia emissions reduction and nitrogen retention

In the present study, the effectiveness of polymer (maleic-itaconic acid) on ammonia (NH3) emissions reduction and in retaining nitrogen (N) in fresh liquid swine manure (SM) was evaluated. The relationship between pH and NH3 emission was also determined. Different doses of polymer (namely Treatment 1 = T1 = 0.8 L polymer/ton of manure, Treatment 2 = T2 = 1.6 L polymer/ton of manure, Treatment 3 = T3 = 2.4 L polymer/ton of manure, and Treatment 4 = T4 = 3.2 L polymer/ton of manure) were added to the SM and its effects were observed for 30 d. The tests results showed significant reduction in pH for T1, T2, T3 and T4 compared to control (C). For the short term (up to 3d) T2, T3, and T4 showed significantly lower NH3 gas concentrations than C, however, for the long term (up to 10-20 d) only T4 continued to indicate significantly lower NH3 gas concentrations. Although numeric observations were reported for other treatments (T1, T2 and T3), no significant differences in NH3 gas concentrations were found. The NH3 emissions reductions were calculated in the range of 81-92%, 31-88%, −39-61%, 6-41%, −106% to −6% for the treatment period of 1, 3, 10, 20 and 30 d, respectively. The addition of polymer resulted in no significant difference in total ammonia nitrogen (TAN) and NO3−-N concentration. However, the addition of polymer had a significant influence on total Kjehldahl nitrogen (TKN) and soluble chemical oxygen demand (SCOD) concentration. The NH3 gas emissions strongly correlated with the manure pH (R2 = 0.911-0.999).