污泥生物炭中氮硫行为及环境效应研究进展

污泥生物炭中氮硫元素含量高,其氮硫行为和环境效应对全球气候变化的影响不容忽视。以往的研究中,研究者往往以富碳生物炭作为主要研究对象,关注碳对全球气候变化的行为和功效,而对氮硫元素的作用关注不够。本文从原始污泥基本性质到其热解过程,再到生物炭的老化,逐步对污泥生物炭整个生命周期内氮硫的行为及其环境效应研究进行综述,并对未来应注重开展的研究方向进行展望,为生物炭中氮硫元素固定、释放及与之关联的环境效应和温室气体排放控制研究提供理论基础。分析表明,污泥中氮元素含量普遍高于硫元素,且热解过程中氮比硫更容易转移至气相产物。氮硫元素随热解温度的增加,在三相产物中的分配都是炭中持续减少,油中先增后减,气中一直增加。高温（＞800℃）条件下,气相中的氮含量高于固相,而硫元素则仍然主要存在于固相中。污泥生物炭老化及其环境效应研究表明,污泥生物炭氮硫元素与土壤的相互作用及其温室效应问题在今后的研究中应引起重视。     

基于离散元法的秸秆生物炭接触参数标定

为获取秸秆生物炭的离散元仿真参数,采用仿真分析与物理试验相结合的方法对生物炭接触参数进行标定。通过Placket-Burman试验筛选出生物炭离散元显著性影响参数,最陡爬坡试验确定显著性影响参数的最佳范围,Box-Behnken试验确定3个显著性影响参数分别为炭-炭滚动摩擦系数0.097、 JKR表面能0.018 J/m²、炭-钢滚动摩擦系数0.256。进行堆积角试验与其Rocky离散元仿真结果对比表明,所确定的参数误差为2.33%,满足仿真分析参数设定要求。     

生物炭吸附重金属污染物的研究进展

生物炭作为新型吸附剂,其物理化学特性以及其对环境中的重金属污染物的吸附固定被广泛研究。本文主要对生物炭的表征、特性以及其对重金属污染物的吸附固定的机理研究进展进行综述,并扼要对生物炭的研究方向进行了展望,为未来生物炭的应用提供一定的思路。通过文献总结,我们发现重金属在生物炭上的吸附机理的研究仍然存在矛盾之处;生物炭本身重金属毒性的释放研究是未来生物炭还田应用的研究方向;利用化学手段对生物炭进行化学修饰,以提高其吸附的有效性和针对性是在节能环保的前提下,未来生物炭发展的新方向。     

自组装构筑MgO改性生物质炭及其磷吸附性能研究

为了提升MgO改性生物质炭的磷吸附能力,文章以花生壳为载体,利用碱式碳酸镁前驱体自组装-热解技术制备了结构有序的花瓣状MgO改性生物质炭吸附剂(FMgO-BC)。采用SEM,EDS,XRD,IR和TG表征了制备的FMgO-BC的物相结构与表面形貌,并研究了水解温度和Mg;浓度对FMgO-BC吸附性能的影响。研究结果表明,当水解温度为80℃,Mg²⁺浓度为0.6 mg/L时,FMgO-BC的吸附性能最优。文章还探究了FMgO-BC在不同pH值和加入量条件下的等温吸附模型和吸附动力学,研究结果表明,FMgO-BC的磷吸附动力学符合准二级动力学方程,等温吸附模型符合Langmuir等温吸附方程,理论最大吸附量为2221.89 mg/g,优于目前报道的MgO改性生物质炭的磷吸附性能。     

Energy recovery and economy aspects of steam-explosion pretreatment in waste phytomass management

Steam-explosion pretreatment allows lowering of the natural resistance of plant material to subsequent biodegrading processes, such as anaerobic fermentation. This is achieved by a complex of cavitation forces that disintegrate rigid lignocellulose structures and liberate labile organic matter during a quick release of phytomass from a steam-pressurized reactor back to the atmospheric pressure. Hydrolyzing reactants or catalysts may increase the effect; however, the management of chemicals raises financial and environmental concerns. The current state of knowledge was reviewed to identify promising designs and reengineering that would enable subsequent transfer into the commercial scale in order to reverse the current trend of phytomass waste management – landfilling. In an effort to achieve profitability, it has been concluded that further development should focus on a deeper interconnection of the apparatus with associated technology units, reuse of waste heat from the subsequent biogas combustion, widening the range of processing parameters, reuse of nutrients, and utilization of the ballast organic matter.     

An investigation of drum granulation of post-pyrolysis washed biochar

Biochar, unwashed and washed with a solution of Triton and hydrogen peroxide, was wet drum granulated using molasses binder solutions. Unwashed biochar was very hydrophobic and granulation proceeded through forming liquid marbles and layering. Washing reduced the hydrophobicity of the biochar. The effectiveness of the wash depended on the biochar source; it significantly reduced the hydrophobicity of biochar from woodchips and moderately reduced the hydrophobicity of biochar from flower digestate. Therefore, washed biochar from woodchips was granulated using a hydrophilic mechanism, while washed biochar from digestate was granulated according to a combination mechanism of liquid marbles collapsing and then coalescing. The change in granulation mechanism produced stronger and denser granules with higher yields of granules in the 1–4 mm optimal size range. Washing and then granulating biochar created a product that could be further tailored for optimal soil amendment.     

炭化工艺对脱水沼渣炭理化性质的影响

以一级脱水沼渣为原料,通过热重-红外联用分析其失重行为及热解气相产物的组成,采用单因素试验方法,考察炭化温度、升温速率、保温时间对沼渣炭的得率、理化性质的影响。结果表明：360～480℃区域为热解的主要阶段。随着温度的升高,炭得率、挥发分含量降低,灰分含量增加,固定碳含量在700℃最高（18.37%）;随着升温速率提高,灰分、固定碳含量提高,炭得率及挥发分含量降低;随着保温时间的延长,炭得率逐渐降低,对灰分、挥发分、固定碳影响不显著;原料及炭热值较低;重金属Cd和Pb含量低于“有机-无机复混肥料”标准限值（GB 18877—2009）;Hg和Cr含量较低,符合肥料用有害重金属元素限值标准,而有益于植物生长的元素Mn和Zn含量较高,本研究为减量化处理复杂沼渣提供了理论依据。