垃圾填埋场覆盖黄土的甲烷氧化能力及其影响因素研究

利用西安江村沟填埋场不同覆盖时间的临时覆盖黄土和新鲜黄土掺堆肥配置的土样,开展了甲烷氧化培养瓶试验,培养历时最长达22d,研究了不同覆盖时间的覆盖黄土和不同堆肥掺量的新鲜黄土的甲烷氧化能力,以及含水量对覆盖黄土甲烷氧化能力的影响,分析了甲烷氧化过程中各组分气体体积变化关系.研究结果表明:不同覆盖时间的覆盖黄土的甲烷氧化能力相差很大,覆盖3~5年的黄土最大甲烷氧化能力达26.05~53.95μg CH4/(g×h), 而未覆盖的新鲜黄土几乎没有甲烷氧化能力.在新鲜黄土中掺入堆肥,能有效提高其甲烷氧化能力,且在堆肥掺量小于50%时,土样的最大甲烷氧化能力与堆肥掺量呈正比例关系.含水量对覆盖土的甲烷氧化能力有很大影响,黄土甲烷氧化的最适宜含水量约为20% ~ 30%.在甲烷氧化过程中,甲烷氧化菌将CH4中约44%的碳氧化为CO2,其余碳转化为甲烷氧化菌胞内物质.实际工程中进行覆盖层设计时,需要根据填埋场实际产气量和覆盖层导气性确定与甲烷通量相匹配的甲烷氧化速率,进而合理确定堆肥掺量.     

果蔬类垃圾主发酵堆肥产物储放和利用的恶臭释放特征

鉴于目前尚缺乏主发酵堆肥产物储放和土地利用的恶臭风险评估数据,本文基于21 d恶臭释放潜力实验,描述了果蔬类垃圾主发酵堆肥产物在此过程中的恶臭释放源强特征,并据此评估其在储放和利用时的恶臭释放特征.结果表明,主发酵堆肥产物在实验过程中持续释放氨气、硫化物、苯系物和萜类物质,并以氨气为主;醇类物质、醛类物质的释放随时间逐渐减少,而酮类物质在整个过程中持续释放但释放量很少.通过模拟封闭环境和自然场地两个场景,本文从恶臭风险角度计算出在封闭环境中每平方米内可接受的主发酵产物的暂存或直接利用量,以及主发酵产物能够在自然场地中直接利用的使用量和最小防护距离要求.     

Changes in carbon fractions during composting and maturation of organic wastes

Seven mixtures from four organic residues—an aerobic sewage sludge, a city refuse, a peat residue, and a grape debris—were composted, and the changes undergone by their different carbon fractions during their composting and maturation were studied. In most cases a decrease in carbon fractions during the composting and maturation processes was observed. The extractable carbon, however, increased during maturation. Organic matter mineralization was greater in the composts with city refuse than in those with sewage sludge. The samples with peat residue showed the lowest decreases in carbon fractions. During maturation, an increase of humiclike fraction was observed, which was reflected by a decrease in the soluble carbon-precipitated carbon ratio at pH 2. Water-soluble carbon was the carbon fraction most easily degradable by microorganisms, and its amount correlated significantly with composting time in all the samples.     

Preparation and Biodegradation of Starch/Polycaprolactone Films

Starch granules were modified with trisodium trimetaphosphate (TSTP) and characterized by P³¹-NMR, FTIR and DSC. Seventy-micron films were prepared from modified starch and polycaprolactone blends by solvent casting technique. Three different types of films—PCL (100% polycaprolactone), MOD-ST/PCL (50% modified starch and 50% polycaprolactone blend) and NONMOD-ST/PCL (50% nonmodified starch and 50% polycaprolactone blends)—were prepared, and their thermal, mechanical, and morphologic properties were investigated to show the increased performance of PCL with the addition of starch and also the effect of modification. It was observed that with the addition of starch the Young's modulus of polycaprolactone was increased and became less ductile, whereas tensile strength and elongation at break values decreased. Biodegradation of these films was inspected under different aerobic environments with the presence of Pseudomonas putida, activated sludge, and compost. It was observed that whereas P. putida had almost no effect on degradation during 90 days, with the presence of activated sludge, considerable deformation of films was observed even in the first 7 days of degradation. In a compost environment, degradation was even faster, and all polymer films were broken into pieces within first 7 days of degradation and no film remained after 15 days.     

Photodegradation and Biodegradation Study of a Starch and Poly(Lactic Acid) Coextruded Material

To simulate the behavior of agricultural mulch coextruded poly(lactic acid)(PLA)/starch films, two stages were carried out. The first was an ultraviolet treatment (UV) at 315 nm, during which glass transition temperature T_g, weight, and molecular weight (MW) decreased and a separation between PLA and starch phase was observed. For the second stage, the mineralization of the carbon of the material was followed using the ASTM (D 5209–92 and 5338–92) and ISO/CEN (14852 and 14855) standard procedures. To measure the biodegradability of polymer material, the assessment of the carbon balance allowed determination of the distribution between the carbon rate used to the biomass synthesis or the respiration process (released CO₂), as well as the dissolved organic carbon into the culture medium and the carbon in the residual insoluble material. The influence of the nature of the medium and the standardized procedures on the final rate of biodegradation was investigated. Whatever the standardized method, the biodegradation percentage was significantly stronger in liquid medium (92.4–93.4) than on inert medium (80–83%). In the case of the compost process, only released CO₂ was measured and corresponded to 79.1–80.3%.     

沸石在猪粪堆肥过程中保氮效果研究

通过设置未添加、添加5%、10%和15%沸石4个处理,试验研究了不同沸石添加量对猪粪、米糠堆肥的保氮效果.结果表明:添加沸石可以降低堆体的pH和水溶性NH4+-N含量,减少NH3的挥发损失;与对照处理相比,添加5%、10%、15%沸石处理可将N损失率分别降低12.33%、35.53%、47.32%;但沸石的添加量达到15%时,其堆体保持高温(≥55℃)的时间及平均堆温均较对照处理低,不利于堆肥的顺利进行,而添加5%、10%沸石处理的堆温较为合理.综合以上各项指标,研究认为沸石的适宜添加量为10%左右.     

生物滤池净化城市生活垃圾BMT发酵恶臭气体的研究

针对城市生活垃圾BMT过程中的恶臭气体,以堆肥为填料,在现场进行了生物滤池处理研究,分别测定了臭气的成分、臭气中TVOC浓度变化的规律、滤池的净化效率、填料中有机质、全氮、全碳、全磷和pH等特征,以及填料菌落数的变化. SPME-CC-MS的分析结果表明,恶臭气体中的主要有机污染物包括苯系物、萜烯和烷烃;臭气中TVOC浓度在发酵初期较大,而后逐渐减少,变化范围为68.3×10-6～3.3×10-6(体积分数),滤池净化效率范围为31,5%～84,8%;在4个月的运行过程中,填料中有机质、总氮、总碳、总磷的含量基本上保持在比较稳定的数值,而水溶性总氮增加了53.7%.水溶性总磷减少了19.6%,填料的pH值在初始经历了一个升高阶段后稳定在7.8左右;填料中细菌和霉菌的数量呈上升趋势,而酵母菌和放线菌的数量呈下降趋势,分别为初始填料的3.1、3.4、0.04、0.07倍.     

猪粪中土霉素环境风险及好氧降解技术研究进展

针对国内规模化养猪场饲料及猪粪中土霉素的高残留量的现状,综述了国内外关于畜禽粪便中土霉素研究的现状。文章首先介绍了畜禽粪便中土霉素的应用和残留情况,然后探讨了土霉素存在于环境中对微生物、植物和动物的生态毒性,最后结合国内外现有畜禽粪便处理技术优缺点的评价．对好氧堆肥技术应用于高土霉素残留猪粪的无害化处理以及应该注意的一些问题提出了建议。     

SACT-B污泥快速堆肥工艺及冬季运行效果

以唐山西郊污水处理厂污泥堆肥工程为例,讲述了SACT-B污泥快速堆肥工艺的特点以及在冬季运行的效果:整个工艺过程依靠污泥处理专用设备(主要包括链条式翻堆机、固体曝气系统等非标设备)和采用定时定量曝气的方式来运行,并对污泥堆肥的效果进行评判,评判方法参考腐熟度评价系统指标中的物理性质(含水率、温度、颜色、气味等)、化学指标(挥发性固体、C/N比等)及生物指标(种子发芽率),最终评判结果证明冬季SACT-B工艺处理污泥效果良好。     

菌渣、鸡粪联合堆肥工艺研究

对以菌渣、鸡粪为主要原料的静态条垛式好氧堆肥工艺进行了研究.结果表明在1次发酵过程中,温度维持在55 ℃以上的时间均超过7 d.堆肥结束时,堆体温度恢复到略高于室温水平,含水率下降15%左右,pH值为7.8左右,总氮含量损失了13.8%～15%,并且主要发生在1次发酵阶段.本文通过对各参数的测定和分析发现,菌渣和鸡粪通过添加酵素菌进行30 d左右好氧发酵,即可获得高质量的堆肥产品,对堆肥工程有指导作用.