污泥堆肥过程中氮素形态的变化

Transformation of nitrogen forms during co-composting of sewage sludge and wheat straw

以污水污泥(SS)为原料,小麦秸秆糠(WSB,粒径小于0.5cm)和小麦秸秆段(WSS,长度约3cm)为调理剂,采用强制通风静态好氧堆肥与自然通风好氧堆肥相结合的堆肥方法进行了为期120d的堆肥化处理,研究了堆肥化过程中各种氮素形态的变化特征.结果表明,在堆肥过程中,2次处理的堆温变化明显呈现出升温期、高温期和降温期3个阶段.在堆肥过程中,处理SS+WSB比处理SS+WSS的堆体升温快,高温期持续时间长,并且堆体的含水率也高.处理SS+WSB和处理SS+WSS的pH值分别从初始的8.74和8.06下降为6.69和6.18,TN含量分别从21.16g.kg-1和11.57g·kg-1增加到31.93g.kg-1和28.02g.kg-1,C/N比分别从23.39和22.90下降到15.31和13.75,水溶性总凯氏氮(TKN(W))含量降低幅度分别为70.43%和34.05%,NH4+-N含量分别从3.43g.kg-1和1.31g·kg-1下降到0.35g.kg-1和0.42g.kg-1,并且在2次处理中NH4+-N与pH达到最大值的时间相一致.处理SS+WSS比处理SS+WSB的高温持续时间短,NO3--N含量高,说明控制堆体的高温期持续时间,有利于硝化反应的进行.处理SS+WSB和处理SS+WSS的种子发芽指数(GI)在堆肥结束时分别为115.8%和97.52%,说明处理SS+WSB的腐熟情况明显优于处理SS+WSS.统计分析结果表明,添加不同形态的小麦秸秆作为调理剂对污泥堆肥中pH、NO3--N、GI、含水率、TN、水溶性凯氏氮(TKN(W))和NH4+-N含量变化的影响显著(p<0.05);对C/N比变化的影响不显著(p=0.125);2次处理中NH4+-N的含量对pH的影响均显著(p均为0.027).

The transformation of nitrogen forms during co-composting of sewage sludge and wheat straw was investigated in an aerated static pile composting system and a natural ventilation fermentation system.The raw material was sewage sludge（SS）conditioned with wheat straw bran（WSB,particle size less than 0.5 cm）or wheat straw sections（WSS,about 3 cm in length）.During the 120-day composting tests,significant changes of the temperature caused by the two treatments defined three stages including a warming period,high temperature period and cooling period for the compost pile.During the composting,the warming rate of Treatment SS＋WSB as well as its moisture content was higher than that of Treatment SS＋WSS,and the high temperature period of Treatment SS＋WSB was longer than that of Treatment SS＋WS.The pH of Treatment SS＋WSB decreased from 8.74 to 6.69 while the pH of Treatment SS＋WSS decreased from 8.06 to 6.18.The TN content of Treatment SS＋WSB and Treatment SS＋WSS increased from 21.16 g·kg^-1 and 11.57 g·kg^-1 to 31.93 g·kg^-1 and 28.02 g·kg^-1,respectively.The C/N ratios of Treatment SS＋WSB and Treatment SS＋WSS dropped from 23.39 and 22.90 to 15.31 and 13.75,respectively.The rates of TKN（W）loss in Treatment SS＋WSB and Treatment SS＋WSS were 70.43% and 34.05%,respectively.The NH4^＋-N and the pH reached their maximum values at the same time in the two treatments.In Treatment SS＋WSB and Treatment SS＋WSS,the NH4^＋-N concentration reduced from 3.43 g·kg^-1 and 1.31 g·kg^-1 to 0.35 g·kg^-1 and 0.42 g·kg^-1,respectively.Treatment SS＋WSS persisted at a high temperature for a shorter time and had a higher nitrate concentration than that of Treatment SS＋WSB,indicating that decreasing the sustained high-temperature period benefits the nitrification reaction.At the end of the composting,the GI（Germination Index）of Treatment SS＋WSB and Treatment SS＋WSS were 115.8% and 97.52%,respectively,showing that the maturity of the compost in Treatment SS＋WSB is greater than that of Treatment SS＋WSS.The statistical results showed that adding different forms of wheat straw as conditioners had very significant effect on the following indexes,pH,NO^3--N,GI,moisture content,TN,TKN（W）and NH4^＋-N（p 〈0.05）,however,it had no significant influence on the C/N ratio（p = 0.125）.During the composting period in both treatments,the content of NH4^＋-N had a significant effect on the pH of the compost（p =0.027）.