Pyrolysis and gasification of meat-and-bone-meal: Energy balance and GHG accounting

Meat-and-bone-meal (MBM) produced from animal waste has become an increasingly important residual fraction needing management. As biodegradable waste is routed away from landfills, thermo-chemical treatments of MBM are considered promising solution for the future. Pyrolysis and gasification of MBM were assessed based on data from three experimental lab and pilot-scale plants. Energy balances were established for the three technologies, providing different outcomes for energy recovery: bio-oil was the main product for the pyrolysis system, while syngas and a solid fraction of biochar were the main products in the gasification system. These products can be used – eventually after upgrading – for energy production, thereby offsetting energy production elsewhere in the system. Greenhouse gases (GHG) accounting of the technologies showed that all three options provided overall GHG savings in the order of 600–1000 kg CO₂-eq. per Mg of MBM treated, mainly as a consequence of avoided fossil fuel consumption in the energy sector. Local conditions influencing the environmental performance of the three systems were identified, together with critical factors to be considered during decision-making regarding MBM management.     

阻燃剂对棉布和地毯热解燃烧性能的影响研究

研究了氢氧化铝和三聚氰胺氰尿酸盐对棉布和地毯热解和燃烧行为,考察了阻燃剂添加量对棉布和地毯点燃时间、热解速度和火焰持续时间的影响,并利用锥形量热仪测定了添加阻燃剂前后材料在点燃时间、热释放速率、质量损失速率和CO释放速率的变化,结果表明海水中添加10%的Al(OH)3和MCA可显著降低棉布和地毯的热解速度及热释放速率.     

Tar-free fuel gas production from high temperature pyrolysis of sewage sludge

Pyrolysis of sewage sludge was studied in a free-fall reactor at 1000–1400 °C. The results showed that the volatile matter in the sludge could be completely released to gaseous product at 1300 °C. The high temperature was in favor of H₂ and CO in the produced gas. However, the low heating value (LHV) of the gas decreased from 15.68 MJ/N m³ to 9.10 MJ/N m³ with temperature increasing from 1000 °C to 1400 °C. The obtained residual solid was characterized by high ash content. The energy balance indicated that the most heating value in the sludge was in the gaseous product.     

Removal and recycling of copper from aqueous solutions using treated Indian barks

Removal of copper from aqueous solutions containing 100–1000 ppm, using different Indian bark species, was performed on laboratory scale. The percentage removal of metal ions depends on the solution pH, bark species and time. The efficiency of copper removal by the used raw barks increases with a rise of solution pH and reaches a maximum of about 65–78% around pH 4–5. However, the decontaminated aqueous solutions were colored due to the dissolution of soluble organic compounds contained in the raw bark. This increases the biological and chemical oxygen demand (BOD and COD) of the solutions as well as the total organic carbon content (TOC). For this reason, raw bark should be treated either by chemical or biological means. Such treatment will allow the extraction of the soluble organic compounds and increase the chelating capacity and efficiency of the treated bark. Depending on the pH value, the chelating efficiency of treated barks is about 1.2–2.2 times that of the raw ones. Moreover, the retention capacity of the Indian treated bark varies from about 42–51 mg/g of dry bark. It is equal to or higher than that of common European species. About 1.8 mols of H₃O⁺ are released, by the treated barks, for every mol of chelated copper ions. Moreover, scanning electron microscopy (SEM) observations show uniform distribution of metal ions throughout the copper saturated bark. Infra red (IR) spectra suggest that the copper ions are chelated to hydroxyl and/or carboxyl functional groups of organic compounds contained in the treated bark. It seems that the interaction of the copper ions with the bark follows a cation exchange mechanism. This hypothesis is supported by elution experiments that allow recovery of about 99% of the contained copper. The retention capacity of the treated bark is almost constant after five cycles of chelation–elution, suggesting that the ‘life time cycle' is sufficiently long for continuous industrial application. The spent copper loaded barks can either be incinerated or pyrolysed. It generates solids containing either ≈80% of CuO or ≈14% of Cu°, respectively. Such materials can be used either in the secondary or primary copper production, thus offering a friendly environmental solution of effluents' treatment. The suggested process can be used as an alternative to the classical technologies for effluent decontamination. It is also efficient for polishing effluents treated by other methods.     

油泥热解废水处理工艺中试应用

针对油泥热解废水高含油、高氨氮、高COD、难处理的问题,使用GC-MS定性分析发现污水含有52种有机物;采用“预处理+芬顿氧化+生化+芬顿氧化+BAF”工艺处理油泥热解废水,连续6天检测各单元处理后的水质,结果表明：通过预处理、芬顿氧化、生化、二次芬顿、BAF等步骤,可使油泥热解废水中COD浓度＜150 mg/L、NH4+-N浓度＜25 mg/L、石油类＜10 mg/L,满足《污水综合排放标准》GB8978-1996中二级排放标准要求。酸性条件下使用膨润土作吸附预处理,对热解废水中COD、石油类的去除率分别可达60%、72%~75% 。氨氮主要在生化单元去除,膨润土吸附和芬顿氧化对氨氮的去除效果不明显。本文为油泥处理后衍生的废水提供了新的处理思路,对油泥全流程无害化处理有一定参考和借鉴意义。     

Analysis of products from the pyrolysis and liquefaction of single plastics and waste plastic mixtures

Waste plastics in the form of two examples of real world municipal solid waste plastics and a simulated mixture of municipal waste plastics were pyrolysed and liquefied under moderate temperature and pressure in a batch autoclave reactor. In addition, the five main polymers which constitute the majority of plastics occurring in European municipal solid waste comprising, polyethylene, polypropylene, polystyrene, polyethylene terephthalate and polyvinyl chloride were also reacted. The plastics were reacted under both a nitrogen (pyrolysis) and hydrogen pressure (liquefaction) and the yield and composition of products are reported. The hydrocarbon gases produced were mainly methane, ethane, propane and lower concentrations of alkene gases. A mainly oil product was produced with the mixed plastic waste with significant concentrations of aromatic compounds, including single ring aromatic compounds. The composition of the oils and gases suggested that there was significant interaction of the plastics when they were pyrolysed and liquefied as a mixture compared to the results expected from reactions of the single plastics.     

水生植物热解生物油对中肋骨条藻的抑制作用

将芦竹、芦苇、香蒲3种湿地常见水生植物分别在250、300、400、500、600 ℃下进行热裂解,研究热解所得生物油对中肋骨条藻的抑制作用.结果表明,3种水生植物在不同温度下所得的15种热解生物油对中肋骨条藻生长均表现出一定的抑制作用,且随着生物油浓度的增加,抑制作用呈增强趋势.同种植物热解温度不同,所得热解生物油的抑制效果具有一定差异,芦苇及香蒲400 ℃下热解生物油对中肋骨条藻的半数效应浓度EC50(Median Effect Concentration)分别为0.82、0.85 mg · L-1,抑藻效果最强.芦竹以300 ℃热解生物油的抑制效果最强,其EC50为1.29 mg · L-1.不同植物所得热解生物油对中肋骨条藻的抑制能力不同,抑藻活性顺序为芦苇＞香蒲＞芦竹.经GC-MS分析可知,芦竹300℃下热解生物油甲基化后主要成分有苯、苯酚类物质及少量酮类和酯类,其中,2-甲氧基苯酚含量最高,生物油中抑藻活性物质尚需进一步研究.本研究可为湿地植物生物质高价值利用、赤潮藻控制提供科学依据.     

废轮胎热解油脱色工艺研究

为解决废旧轮胎热解油颜色过深和存在异味而无法直接利用问题,文章采用活性炭对热解油吸附脱色工艺,将液相中含有的杂质、色素、异味等舍弃物吸附于活性炭表面上,以达到精致的目的。试验表明:热解油活性炭吸附脱色技术的最佳工艺条件为炭粒度550~1 700μm、脱色温度为室温、吸附时间为300 min、振荡频率为150 r/min。并证明了平2均孔径、中孔孔容积和中孔比表面积为26.4、0.307 m L/g和280 m/g的烟煤基活性炭对热解油具有很好的脱色能力。     

Analysis of good practices,barriers and drivers for ELTs pyrolysis industrial application

Boosting of eco-innovative solutions for End of Life Tyres (ELTs) management, under the principles of the EU Resource Efficiency Roadmap and the Waste Framework Directive, can not only diminish the environmental hazards and the consequent societal cost, but also result to the establishment of a novel perception regarding ELTs; thus, a valuable stock of resources that can be exploited. Despite the extensive scientific research of the previous years on ELTs depolymerisation via pyrolysis highlighting its eco-innovative characteristics, the use of pyrolysis to process scrap tyres has not yet achieved a broad commercial success, with economic viability and product standardization to constitute the primary impediments. More specifically, pyrolysis was not applied to an extensive industrial scale so far, due to deficient market analysis, legislative barriers, economic instability and sometimes public acceptance. All the above issues are addressed by the present study. Modifications on current EU legislation can prevent or reduce delays or derailment of efforts on pyrolysis, through its differentiation from incineration. The attainment of economic viability could be realized through the valorization of the pyrolytic char towards activated carbon production for environmental depollution applications; needless to say, the penetration on niche and well-organised markets is more than essential.