【作者】 席晓黎；

【导师】 郭夏丽；

【作者基本信息】 郑州大学 ， 环境科学， 2013， 硕士

【摘要】 随着污水处理率的提高,剩余污泥产量迅速增加,由于缺乏合理有利的处置技术,大量污泥堆积造成二次污染。污泥中氮、磷、钾等含量丰富,农用是最有效的资源化利用方式,但是污泥中的重金属等有毒有害物质限制了其在土地中的利用。污泥生产堆肥和制备活性炭是比较理想的资源化利用方式,本论文以剩余污泥为原料制备生物质炭,考察了其对重金属Cr(VD和Cu(Ⅱ)的吸附效果,在此基础上,利用制备的生物质炭和高温固体菌剂进行污泥堆肥,探讨其对堆肥中氮素损失、腐熟时间及重金属钝化的影响,主要研究结果如下：(1)以Cr(Ⅵ)吸附容量为衡量指标,优化出生物质炭的最佳制备工艺条件为：炭化温度500℃、活化剂H28O4浓度40%、浸渍比例1：1、浸渍时间8h、炭化时间30min。红外光谱分析表明制备的生物质炭表面具有羟基、羧基、内酯基等基团及Si-O-C结构。(2)通过单因素实验优化了生物质炭对Cr(Ⅵ)和Cu(Ⅱ)的吸附条件。在25℃、pH1.0、生物质炭投加量1.4gL-1的条件下,生物质炭对Cr (Ⅵ)的最大吸附容量为61.3mgg-1；吸附容量随着pH的降低而增加；热力学分析⊿HH0>0、⊿G0>0,说明生物质炭对Cr(Ⅵ)的吸附是吸热过程,吸附不能自发进行；在35℃、pH5.6、生物质炭投加量0.4g L-1条件下,生物质炭对Cu(Ⅱ)的最大吸附容量为136.5mgg-1。生物质炭对Cr(Ⅵ)和Cu(Ⅱ)的吸附动力学均可以用二级动力学方程拟合,说明吸附以化学吸附为主,Langmuir等温线拟合说明生物质炭表面较为均匀,吸附为单分子层吸附。(3)添加不同含量的污泥基生物质炭进行污泥好氧静置堆肥,结果表明,添加生物质炭可以减少堆肥中氮素的损失,生物质炭保氮效果与添加量成正比,添加8%生物质炭处理中氮素损失率为25%,相对于对照处理的44.3%,保氮效果显著。生物质炭和高温腐熟菌剂均可以加快堆肥升温速率,提高堆肥温度,加快堆肥腐熟。生物质炭的添加可以降低堆肥中重金属的生物有效性,添加量为8%时,不稳定态铬和铜所占的比例分别下降了10%和1.3%,对照处理中不稳定态铬比例下降了4%,不稳定态铜反而升高了2%,重金属生物有效性的降低可能与生物质炭表面的羟基、羧基等基团有关,这些基团之间以氢键构成网络,与重金属离子或者重金属氧化物相互作用,达到吸附钝化重金属的效果。更多还原

【Abstract】 With the increasing number of wastewater treatment plants, more and more municipal sewage sludge is produced. Due to the lack of reasonable and effective disposal technologies, large amounts of sewage sludge accumulated caused secondary pollution. Since sludge is rich in nitrogen, phosphorus, potassium and other elements, the agricultural use is the most effective way of its resource utilization, but the toxic and hazardous substances such as heavy metals in the sludge limit its application in the land. So there is an urgent need for a safe disposal option. In this thesis, for this reason, the adsorption of bio-charcoal from sewage sludge on Cr (Ⅵ) and Cu (Ⅱ) was explored and the influence of bio-charcoal on nitrogen loss, maturity time and heavy metal bioavailability during the sludge composting was also discussed. The main conclusions were showed as follows:(1) Based on the adsorption capacity of Cr (Ⅵ), the conditions of bio-charcoal preparation were optimized. The results were as follows:the activation temperature of500℃、40%of the concentration of H2SO4、impregnation ratio of1:1、impregnation time of8h、carbonization time of30min. According to the analysis of IR spectra, there may be hydroxy1、carboxy1、lactone and structure of Si-O-C on the surface of bio-charcoal.(2) The adsorption conditions of bio-charcoal on Cr (Ⅵ) and Cu (Ⅱ) was optimized through single factor experiments. The maximum adsorption capacity of bio-charcoal on Cr (Ⅵ) was61.3mg g-1under the condition of25℃、pH1.0and dosage of1.4g L’1. The adsorption capacity increased with the decrease of pH. The thermodynamic analysis of△H0>0and△G0>0illustrated that the adsorption of bio-charcoal on Cr (Ⅵ) was an endothermic process and didn’t occurre spontaneously. The maximum adsorption capacity of bio-charcoal on Cu (Ⅱ) was136.5mg g-1under the condition of35℃、pH5.6and dosage of0.4g L"1. The adsorption of bio-charcoal on Cr (Ⅵ) and Cu (Ⅱ) were fitted well with second-order kinetics, which indicated that the adsorption was mainly chemical. The fitting of Langmuir isotherm showed that the surface of bio-charcoal was uniform and the adsorption was monolayer.(3) The sludge composting results indicated that the additive bio-charcoal in the compost could reduce the loss of total nitrogen and the effect was proportional to the amount of bio-charcoal added. The inhibition of nitrogen losses was most significant with8%bio-charcoal added. After40days of composting the nitrogen loss rate was25%in compost with8%bio-charcoal and was44.3%in control compost. The amendment of bio-charcoal and thermophilic bacteria could speed up the compost heating rate, improve the temperature and accelerate the composting. The incorporation of bio-charcoal into the sludge composting material could inhibit the bioavailability of heavy metals in the compost. The proportion of chromium and copper in the unstable state decreased10%and1.3%, separately, in compost with8%bio-charcoal. However, in the no bio-charcoal amendment control, the proportion of copper in the unstable state increased2%and the proportion of chromium in the unstable state only decreased4%. This may be assigned to hydroxyl, carboxyl and other groups on bio-charcoal surface. The network structure formed through hydrogen bonds between these groups and the reaction between surface groups and metal ions or heavy metal oxides could reduce bioavailability of heavy metals.更多还原