云天化3#循环流化床锅炉项目技术经济分析

云天化股份公司在2004年建造了3#循环流化床锅炉，以煤代气。它可以缓解公司原料天然气的紧张状况，并能带来很大的经济效益。从技术经济的角度对该项目的技术先进性、可靠性及内部收益率、投资回收期、净现值等技术指标进行了分析。     

An improved method used for evaluating potential environmental pollution risk based on spatial distribution and density of farms

Environmental Science and Pollution Research - The livestock manure nitrogen load on farmland (LMNLF) is often used to assess the potential environmental pollution risk of livestock manure nitrogen...     

兰州市废旧手机产生量预测分析研究

手机普及率日益提高,随之产生的废弃量也日益增多,分别采用时间梯度模型、市场供给A模型、斯坦福(stanford)模型对兰州市2013年-2022年废旧手机的产生量进行了预测.结果显示,不同模型预测结果之间存在较大差异,市场供给A模型和斯坦福(Stanford)模型的预测结果比较接近,均大于时间梯度模型的预测结果,三种模型预测的兰州市2022年废旧手机的产生量分别为40.40万、46.67万和21.04万部.总体上看,兰州市废旧手机的产生量增长趋势较快.     

Occurrence and distribution of hexabromocyclododecane in sediments from seven major river drainage basins in China

The concentrations and geographical distribution of hexabromocyclododecane (HBCD) were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection (LOD) to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of HBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that γ-HBCD dominated in most of the sediment samples, followed by α- and β-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm 2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively.     

Formation of THMs and HANs during bromination of Microcystis aeruginosa

Bromine-contained disinfectants and biocides are widely used in swimming pools, recreational waters and cooling towers. The objective of this study was to evaluate the formation of thrihalomethanes (THMs) and haloacetonitriles (HANs) and their cytotoxicity in algae solutions during free bromine disinfection. Disinfection by-products formation potential experiments were conducted using model solutions containing 7 mg/L (as total organic carbon) Microcystis aeruginosa cells. Effects of free bromine dosage, pH and ammonia were investigated. The results showed that brominated disinfection by-products were the major products when free bromine was applied. The total THMs formed during bromination was much as that formed during chlorination, whereas HANs were elevated by using bromination instead of chlorination. Dibromoacetonitrice (C2H2NBr2 ) and bromoform (CHBr3 ) were the only detected species during free bromine disinfection. The production of C2H2NBr2 and CHBr 3 increased with disinfectant dosage but decreased with dosing ammonia. CHBr3 increased with the pH changing from 5 to 9. However, C2H2NBr2 achieved the highest production at neutral pH, which was due to a joint effect of variation in hydrolysis rate and free bromine reactivity. The hydrolysis of C2H2NBr2 was base-catalytic and nearly unaffected by disinfectant. Finally, estimation of cytotoxicity of the disinfected algae solutions showed that HANs formation was responsible for the majority of toxicity. Considering its highest toxicity among the measured disinfection by-products, the elevated C2H2NBr2 should be considered when using bromine-related algaecide.     

Life cycle comparison of hydrothermal liquefaction and lipid extraction pathways to renewable diesel from algae

Algae biomass is an attractive biofuel feedstock when grown with high productivity on marginal land. Hydrothermal liquefaction (HTL) produces more oil from algae than lipid extraction (LE) does because protein and carbohydrates are converted, in part, to oil. Since nitrogen in the algae biomass is incorporated into the HTL oil, and since lipid extracted algae for generating heat and electricity are not co-produced by HTL, there are questions regarding implications for emissions and energy use. We studied the HTL and LE pathways for renewable diesel (RD) production by modeling all essential operations from nutrient manufacturing through fuel use. Our objective was to identify the key relationships affecting HTL energy consumption and emissions. LE, with identical upstream growth model and consistent hydroprocessing model, served as reference. HTL used 1.8 fold less algae than did LE but required 5.2 times more ammonia when nitrogen incorporated in the HTL oil was treated as lost. HTL RD had life cycle emissions of 31,000 gCO₂ equivalent (gCO₂e) compared to 21,500 gCO₂e for LE based RD per million BTU of RD produced. Greenhouse gas (GHG) emissions increased when yields exceeded 0.4 g HTL oil/g algae because insufficient carbon was left for biogas generation. Key variables in the analysis were the HTL oil yield, the hydrogen demand during upgrading, and the nitrogen content of the HTL oil. Future work requires better data for upgrading renewable oils to RD and requires consideration of nitrogen recycling during upgrading.     

基于排队论的城市垃圾箱最佳间距研究

针对城市垃圾箱最佳间距的研究不够精细的现状,本文通过建立排队论模型得到了可供不同城市参考的城市垃圾箱最佳间距参数表。通过对部分城市街道的垃圾箱摆放间距情况进行实地调查,运用层次分析法将影响垃圾箱间距分布的多重因素转化为单因素;建立了基于指数分布的教学模型,利用排队论分析单因素状态下的垃圾箱间距分布,得到了求解城市垃圾箱最佳间距的一般方法。     

中国矿山地质环境恢复治理激励机制探索研究

目前,中国矿山地质环境恢复治理形势依然严峻,国家高度重视矿山地质环境恢复与治理工作,财政部、国土资源部不断加大矿山地质环境治理资金,但目前资金缺口仍然很大。文章通过梳理中国矿山地质环境恢复治理激励机制建设创新做法,总结各省开展矿山地质环境恢复治理"五结合"激励模式实践探索,并针对我们矿山地质环境治理目前存在的主要困难和问题提出了引入市场机制出台土地使用权,及尽快出台国家层面的鼓励政策等多方面的优惠政策等建议。     

表面活性剂辅助离子液体预处理稻秆的酶解动力学与结构变化分析

以稻秆为原料进行酶解研究,考察了纤维素酶和β-葡萄糖苷酶单独作用及协同作用对稻秆酶解还原糖产量的影响,以确定最佳酶体系,并研究在最佳酶体系中不同种类表面活性剂辅助离子液体对稻秆酶解的影响和动力学特征,最后通过稻秆成分分析、FTIR、XRD、SEM对预处理前后的稻秆结构、结晶性进行了分析比较.结果表明,纤维素酶与β-葡萄糖苷酶具有协同作用,而且在最佳酶体系中,与未处理稻秆及单独离子液体预处理相比,不同种类表面活性剂辅助离子液体预处理的稻秆在酶水解48 h时纤维转化率分别增加40%~85%、10%~31%,并且预处理对反应速率的提高有促进作用.     

动态膜-生物反应器处理城市污水的运行特性研究

考察了孔径108μm左右的不锈钢丝网动态膜组件处理城市生活污水的特性,并研究了出水水头和曝气强度对动态膜泥饼层形成的影响.结果表明,稳定运行情况下出水平均浊度1.2NTU,COD平均去除率90%,NH<,3>-N平均去除率97%,与传统膜-生物反应器处理效果接近.同时发现,在20、40mm的出水水头下,动态膜运行初期膜通量衰减规律均符合泥饼阻力模型.