Energy and exergy optimization of food waste pretreatment and incineration

With the aim of upgrading current food waste (FW) management strategy, a novel FW hydrothermal pretreatment and air-drying incineration system is proposed and optimized from an energy and exergy perspective. Parameters considered include the extracted steam quality, the final moisture content of dehydrated FW, and the reactor thermal efficiency. Results show that optimal working condition can be obtained when the temperature and pressure of extracted steam are 159 °C and 0.17 MPa, the final moisture content of dehydrated FW is 10%, and the reactor thermal efficiency is 90%. Under such circumstance, the optimal steam energy and exergy increments reach 194.92 and 324.50 kJ/kg-FW, respectively. The novel system is then applied under the local conditions of Hangzhou, China. Results show that approximately 2.7 or 11.6% (from energy or exergy analysis perspective) of electricity can be additionally generated from 1 ton of MSW if the proposed novel FW system is implemented. Besides, comparisons between energy and exergy analysis are also discussed.

     

高稳定性污泥蛋白发泡剂的发泡特性及应用研究

以污泥蛋白为实验材料,通过加入不同量的稳定剂GP-1,配制成高稳定性污泥蛋白发泡剂,并对高稳定性污泥蛋白发泡剂的发泡特性和影响因素进行研究。结果表明,以污泥蛋白10 mL、水90 mL、GP-1 0.4 g配方组合为研究对象,所制备的泡沫初始体积为770 mL,泡沫泌水时间大于15 h,泡沫半衰期大于64 h,泡沫综合发泡能力为2.2×10⁶ mL·min,泡沫的最佳搅拌时间为5 min,泡沫的泌水时间和泡沫的半衰期都是随着温度的上升而下降,在pH为3～13时泡沫稳定。经过对高稳定性污泥蛋白发泡剂发泡特性研究以及对水泥的胶凝时间、特性进行比较,研制出污泥蛋白泡沫混凝土发泡剂,并制备污泥蛋白泡沫混凝土块;结果表明,当污泥蛋白泡沫混凝土发泡剂的用量分别为0、6、6.8、7.6、8.4和9.2 mL,水泥为200 g时,制备泡沫混凝土块,其密度由2.07 g/cm³下降到0.34 g/cm³,体积由130 cm³ 上升到755 cm³;在泡沫混凝土块脱模后的第1 d、第7 d、第28 d分别称量他们的重量变化情况,结果表明,泡沫混凝土块第1 d和第7 d无重量变化,第28 d的重量明显减轻。该研究为污泥蛋白研制成为泡沫混凝土发泡剂,并应用于屋面隔热、保温建立前期基础。     

低温等离子体杀菌的实验研究

由于传统的化学水处理方式有化学成分残留和环境污染问题,因而迫切需要开发新型的水处理技术。本研究针对现有杀菌消毒方法的不足之处,利用低温等离子体进行杀菌处理的实验研究,对电压、水层厚度、气体种类及电极形式的影响进行考察。结果表明,低温等离子体用于杀菌不仅效果显著,而且使用方便、快捷、安全并无残留,因而适于饮用水或者生活污水的杀菌处理。     

Poplar plantation has the potential to alter the water balance in semiarid Inner Mongolia

Poplar plantation is the most dominant broadleaf forest type in northern China. Since the mid-1990s plantation was intensified to combat desertification along China's northwestern border, i.e., within Inner Mongolia (IM). This evoked much concern regarding the ecological and environmental effects on areas that naturally grow grass or shrub vegetation. To highlight potential consequences of large-scale poplar plantations on the water budget within semiarid IM, we compared the growing season water balance (evapotranspiration (ET) and precipitation (PPT)) of a 3-yr old poplar plantation (Kp₃) and a natural shrubland (Ks) in the Kubuqi Desert in western IM, and a 6-yr old poplar plantation (Bp₆) growing under sub-humid climate near Beijing. The results showed that, despite 33% lower PPT at Kp₃, ET was 2% higher at Kp₃ (228 mm) as compared with Ks (223 mm) in May–September 2006. The difference derived mainly from higher ET at the plantation during drier periods of the growing season, which also indicated that the poplars must have partly transpired groundwater. Estimated growing season ET at Bp₆ was about 550 mm and more than 100% higher than at Kp₃. It is estimated that increases in leaf area index and net radiation at Kp₃ provide future potential for the poplars in Kubuqi to exceed the present ET and ET of the natural shrubland by 100–200%. These increases in ET are only possible through the permanent use of groundwater either directly by the trees or through increased irrigation. This may significantly change the water balance in the area (e.g., high ET at the cost of a reduction in the water table), which renders large-scale plantations a questionable tool in sustainable arid-land management.     

中国东南沿海地区耕地资源保护与可持续利用

我国东南沿海地区具有优越的地理区位和气候条件,加上地区开发历史悠久,已成为中国经济最发达的地区之一。然而,近十多年来,由于经济以超常规速度发展,第二,三产业的发展速度,第二,三产业的发展速度大幅度加快,人多地少的矛盾日益突出,导致耕地面积不断萎缩,耕地质量不断下降。利用率和产出率显著滑坡,滥占耕地,占而不用及闲置浪费的现象相当普遍。以浙江省乐清市为例,近年来耕地以平均每年１．２％的速率在减少,目前     

SBR系统中活性污泥内源呼吸速率的研究

在SBR污水处理系统中应用呼吸速率测定仪对活性污泥的呼吸速率进行测定,探讨了污泥浓度和温度对内源呼吸速率的影响.对大量的比内源呼吸速率数据进行处理后发现,在混合液温度基本不变的基础上,内源呼吸速率与污泥浓度变化趋势一致,即比内源呼吸速率与污泥浓度无关;而温度对比内源呼吸速率的影响十分显著.这些结论为呼吸速率成为SBR工艺的控制参数提供了基础.     

利用成组生物测试评估某城市典型污水处理工艺

设计了一组基于生物标记物的生物测试方法,并用于评价某城市4个典型污水处理工艺对水中痕量有毒有机物的去除效果.测试方法包括检测芳烃(Ah)受体效应物质生物毒性的EROD(7-乙氧基-3-异吩噁唑酮-脱乙基酶)试验、类雌激素效应物质的重组基因酵母生物毒性试验和遗传毒性物质的SOS/umu试验.结果表明,4个典型的城市污水处理工艺对Ah受体效应物质、类雌激素效应物质和遗传毒性物质都有一定的去除效果,其中A2/O处理工艺对3类物质的去除效果最明显;空气曝气活性污泥工艺对直接遗传毒性物质的去除效果较好,但对Ah受体效应物质的去除效果一般,倒置A2/O处理工艺和氧化沟处理工艺也能够较好地去除这3类物质,两种处理工艺效果相当.采用成组生物标记物方法可以对城市污水中的痕量有毒有机物进行毒性筛选或测试,适用于水处理工艺的风险评价.     

重碳酸盐碱度对电吸附设备除盐性能影响的研究

为了系统地考察重碳酸盐碱度对电吸附设备除盐性能的影响,利用小型电吸附模块对含有不同重碳酸盐碱度的原水水质进行处理.实验结果表明,随着其含量从170 mg/L增加到400 mg/L,电吸附设备的除盐率明显下降.通过对起始工作电流降低这一变化作理论分析,认为重碳酸盐碱度在电吸附模块内部积存结垢是影响电吸附设备除盐性能的重要原因,并通过实验证实其与钙离子共同作用导致了结垢.     

Research on low emission MSW gasification and melting system

In order to eliminate secondary pollution caused by municipal solid waste (MSW) incineration, a MSW gasification and melting process is proposed. The process is expected to reduce the emission of pollutants, especially heavy-metals and dioxins. In this paper, the combustible components of MSW and simulated MSW were gasified in a lab-scale fluidized bed at 400°C–700°C when the excess air ratio (ER) was between 0.2 and 0.8. The experimental results indicated that the MSW could be gasified effectively in a fluidized bed at approximately 600°C–700°C when excess air ratio was 0.2–0.4. The melting characteristics of two typical fly ash samples from MSW incinerators were investigated. The results indicated that fly ash of pure MSW incineration could be melted at approximately 1,300°C and that of MSW and coal co-combustion could be melted at approximately 1,400°C. When temperature was over 1,100°C, more than 99.9% of the dioxins could be decomposed and most of the heavy-metals could be solidified in the slag. Based on the above experiments, two feasible MSW gasification and melting processes were proposed for low calorific value MSW: (1) sieved MSW gasification and melting system, which was based on an idea of multi-recycle; (2) gasification and melting scheme of MSW adding coal as assistant fuel. __________ Translated from Environmental Science, 2006, 27(1): 69–73 [译自: 环境科学]     

炼油废水处理技术进展

描述了炼油废水的产生及特点,介绍了几种水处理技术,并对炼油废水处理技术的发展趋势进行了展望。