过磷酸钙和双氰胺联用减少污泥堆肥温室气体及NH3排放

为研究添加剂过磷酸钙和硝化抑制剂双氰胺联用对脱水污泥高温好氧堆肥氨气和温室气体减排的影响效果,该文以脱水污泥和玉米秸秆为原材料,设置4个堆肥处理分别为:不添加任何添加剂作为对照(CK),只添加3.5%(湿基)过磷酸钙为SP3.5,在添加0.1%双氰胺基础上分别加入3.5%(湿基)过磷酸钙(SD3.5)和5.0%(湿基)过磷酸钙(SD5.0)控制材料,在60 L发酵罐中进行为期34 d好氧高温堆肥试验,监测堆肥过程中的温室气体、氨气排放速率及堆体总有机碳和总氮损失率。结果表明:添加过磷酸钙及硝化抑制剂双氰胺可以促进堆肥腐熟和提高堆肥品质,同时降低堆肥过程中的总氮损失、NH_3排放以及显著减少污泥堆肥总温室气体排放。2种添加剂联合使用使SD3.5和SD5.0处理氮素损失相比于CK处理减少10.92%和13.08%,总温室气体排放量比对照减少65.6%和74.8%。该研究可为污泥堆肥添加剂的选择以及污染气体的减排控制提供参考。

Combination of superphosphate and dicyandiamide decreasing greenhouse gas and NH3 emissions during sludge composting

To study the effects of superphosphate (SP) and nitrification inhibitor dicyandiamide (DCD) on NH3, N2O and CH4 emissions, an experiment of straw and sludge co-composting for 34 days was carried out. This research used 60 L sealed fermenter as composting reactor, raw sludge as basic composting material, corn stalk as porous material and set four composting treatments. The control check (CK) was the co-composting of straw and sludge without any additives. Other three treatments, SP3.5 treatment was only added with 3.5% superphosphate, SD3.5 and SD5.0 treatments were added with 0.1%dicyandiamide (DCD) besides the basic materials, with 3.5% superphosphate (SP3.5) and 5% superphosphate (SP5.0) , respectively, based on the wet weight of the materials. The results indicated that, during 34 days test, the combination use of SP and DCD additives can promote the decomposition of compost and improve the stability and maturity. The highest temperature of all treatments was greater than 70℃. The temperature higher than 50℃ of CK, SP3.5, SD3.5 and SD5.0 treatments lasted for 4, 4, 4 and 2 d respectively, which met the compost sanitation requirements. The germination indices of CK, SP3.5, SD3.5 and SD5.0 treatments were 103.21%±7.38%, 97.4%±4.50%, 120.31%±3.15% and 111.00%±2.70%, respectively. Statistical analysis data showed the germination indices of SD3.5 and SD 5.0 were significantly higher than those of other two treatments (P<0.05), which were promoted by 17.1% and 7.8% compared to CK.E4/E6 values of CK, SP3.5, SD3.5 and SD 5.0 treatments were 2.09±0.36, 2.20±0.26, 1.88±0.10 and 1.79±0.04, respectively. TheE4/E6 values of SD3.5 and SD 5.0 were decreased by10.0% and 14.4 % compared to CK. The EC value of all treatments used superphosphate and dicyandiamide were below 4 mS/cm, which could be biologically non-toxic. The total organic carbon losses of CK, SP3.5, SD3.5 and SD 5.0 treatments were 55.95%, 50.26%, 49.66% and 49.64%, respectively. The total organic carbon losses of treatments used additives were decreased by 11.2%-11.3%. Meanwhile, the total nitrogen losses of CK, SP3.5, SD3.5 and SD 5.0 treatments were 37.08%, 28.22%, 26.16% and 24.00%, respectively. The total nitrogen losses of treatments used additives were decreased by 10.92%-13.08%. The results showed that the CK had the peak value of gases emission among all treatments. NH3 and CH4 mainly occurred in the mesophilic and thermophilic phase of composting, process, while N2O occurred predominantly in the later period of composting. While combination use of superphosphate and dicyandiamide, the peak values of CH4, N2O and NH3emission were decreased. Besides, the cumulative emissions of CH4, N2O and NH3 also were decreased by 69.6%-82.6%, 88.1%-92.9% and 48.5%-52.8%, respectively. The global warming potentials of CH4 and N2O, on a 100-year time frame, were 25 and 298 times higher than that of CO2, respectively. The global warming potential value of CK, SP3.5, SD3.5 and SD5.0 were 170.11, 109.11, 58.47 and 42.94 kg/t. The combination use of superphosphate and dicyandiamide additives significantly mitigated total GHG emissions. The total greenhouse effects were decreased by 65.6%-74.8%.