重庆沼气肥养分物质和重金属状况研究

Contents of Selected Nutrients and Heavy Metals in Biogas Slurry

本文对重庆地区沼气肥的基本性状、养分物质含量、毒性重金属及其污染状况进行了研究。结果表明,沼气肥的pH值范围为中性到微碱性。沼气肥养分和重金属含量及变异主要受发酵原料的影响。沼液全量和水溶性氮磷钾养分平均含量均以K>N>P,沼渣则以P高于N、K。沼液的中、微量元素平均含量为Ca>Mg>Fe>Zn>Cu>Mn,沼渣则为Ca>Fe、Mg、Mn>Cu、Zn。沼液毒性重金属的平均含量为全As>Cr>Cd>Pb>Hg,而沼渣则为全Cr>As>Pb>Cd>Hg。沼气肥重金属含量的变异很大,以猪粪发酵而成的沼气肥(沙坪坝区)毒性重金属含量(除As外)均低于以猪粪+农作物废弃物为发酵原料的沼气肥(涪陵区),且毒性重金属的变异也较小。除Pb外沼液毒性重金属均存在不同超标现象,并以As较严重。沼渣的毒性重金属含量均在允许范围内,农用安全性高。

In the present study, we analyzed basic characters, contents of nutrients and heavy metals in biogas slurry and dregs collected from Chongqing. The results showed that the pH of the slurry were either neutral or light-alkalinity. Contents of both nutrients and heavy metals were changeable and affected by raw material used. The average contents of nutrients in slurry were found to be in an order： K 〉 N 〉 P, exception of P, which in dregs was higher than K and N. The order of the average content of middle-micronutrient in slurry from high to low was Ca,Mg,Fe,Zn,Cu and Mn and in dregs was Ca 〉 Fe, Mg, Mn 〉 Cu, Zn. The average contents of heavy metals in slurry were in a range of： total As 〉 Cr 〉 Cd 〉 Pb 〉 Hg and in dregs total Cr 〉 As 〉 Pb 〉 Cd 〉 Hg, respectively. The contents and variation of heavy metals in the slurry fermented with pig manure were lower than others except for the content of arsenic. The contents of heavy metals exceeded limitations in the studied slurries except lead. In addition, arsenic was in highest contents. However, there was little risk for dregs in our study.