基于批式呼吸计量法的溶解性COD组分划分

利用批式好氧呼吸计量法结合溶解性慢速水解COD(S_H)水解动力学拟合提出了溶解性COD(SCOD)的组分划分方案.上海2个污水处理厂进水的SCOD组分划分结果表明,A厂沉砂池出水(典型生活污水)的SCOD中含有43.5%～58.6% S_H、 21.8%～35.2%易生物降解COD(S_S)和15.4%～30.9%溶解性惰性COD(S_I); B厂沉砂池出水(长距离输送的合流制污水)SCOD中含有34.5%～45.2% S_H、 29.3%～37.7% S_S和25.6%～31.2% S_I. 9组不同水样的试验拟合结果表明,一级动力学能够很好地描述S_H的水解过程,A厂和B厂进水S_H的水解速率常数分别为28.00～39.77 d^-1和26.48～29.52 d^-1.该组分划分方案能够实现S_S积分区域的理论划分,并消除溶解性微生物产物对S_I测定的影响.     

工业燃煤链条炉细粒子排放特征研究

链条燃煤锅炉是当前我国工业锅炉的最主要应用炉型,其容量占到了工业锅炉总容量的85%,是重要的大气污染物排放源之一.本研究在3个地区选取了5种典型容量的链条炉,应用自行设计的二级稀释系统现场测试其细粒子（PM_2.5）和各种气态污染物的排放特征.结果表明,链条炉烟气中的PM_2.5质量粒径呈单峰或双峰分布,第1个峰值在0.14 μm处,第2个峰值在1 μm后;湿法除尘和旋风除尘对PM_1.0的细粒子仍具有有效的去除效率;在相同或相似除尘控制技术的条件下,PM_2.5的排放水平随锅炉容量的增大而减小.在PM_2.5中,SO^2-₄是最丰富的离子,质量分数在20%～54%范围内;C是最丰富的元素,质量分数在7.5%～31.8%之间,其次是S,质量分数为8.4%～18.7%.采用碳平衡法计算得出PM_2.5、NO_x和SO₂的排放因子分别为0.046～0.486 　g·kg^-1、 1.63～2.47　g·kg^-1、 1.35～9.95　g·kg^-1,这为建立我国的工业锅炉排放清单及大气污染来源分析提供了必要的基础数据.     

Influence of driving cycles on exhaust emissions and fuel consumption of gasoline passenger car in Bangkok

The influence of different driving cycles on their exhaust emissions and fuel consumption rate of gasoline passenger car was investigated in Bangkok based on the actual measurements obtained from a test vehicle driving on a standard chassis dynamometer. A newly established Bangkok driving cycle (BDC) and the European driving cycle (EDC) which is presently adopted as the legislative cycle for testing automobiles registered in Thailand were used. The newly developed BDC is constructed using the driving characteristic data obtained from the real on-road driving tests along selected traffic routes. A method for selecting appropriate road routes for real driving tests is also introduced. Variations of keyed driving parameters of BDC with different driving cycles were discussed. The results showed that the HC and CO emission factors of BDC are almost two and four times greater than those of EDC, respectively. Although the difference in the NOx emission factor is small, the value from BDC is still greater than that of EDC by 10%. Under BDC, the test vehicle consumes fuel about 25% more than it does under EDC. All these differences are mainly attributed to the greater proportion of idle periods and higher fluctuations of vehicle speed in the BDC cycle. This result indicated that the exhausted emissions and fuel consumption of vehicles obtained from tests under the legislative modal-type driving cycle (EDC) are significantly different from those actually produced under real traffic conditions especially during peak periods.     

Optimization of gasoline hydrocarbon compositions for reducing exhaust emissions

Effects of hydrocarbon compositions on raw exhaust emissions and combustion processes were studied on an engine test bench. The optimization of gasoline hydrocarbon composition was discussed. As olefins content increased from 10.0% to 25.0% in volume, the combustion duration was shortened by about 2 degree crank angle ( CA), and the engine-out THC emission was reduced by about 15%. On the other hand, as aromatics content changed from 35.0% to 45.0%, the engine-out NOx emissions increased by 4%. An increment in olefins content resulted in a slight increase in engine-out CO emission, while the aromatics content had little e ect on engine-out total hydrocarbon (THC) and CO emissions. Over the new European driving cycle (NEDC), the THC, NOx and CO emissions of fuel with 25.0% olefins and 35.0% aromatics were about 45%, 21% and 19% lower than those of fuel with 10.0% olefins and 40.0% aromatics, respectively. The optimized gasoline compositions for new engines and new vehicles have low aromatics and high olefins contents.     

Acute effects of chlorpyryphos-ethyl and secondary treated effluents on acetylcholinesterase and butyrylcholinesterase activities in Carcinus maenas

The acute effects of commercial formulation of chlorpyrifos-ethyl (Dursban(r)) and the secondary treated industrial/urban effluent (STIUE) exposure on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities in hepatopancreas and gills of Mediterranean crab Carcinus maenas were investigated. After 2 d of exposure to chlorpyriphos-ethyl, the AChE activity was inhibited in both organs at concentrations of 3.12 and 7.82 μg/L, whereas the BuChE was inhibited only at higher concentration 7.82 μg/L of commercial preparation Dursban(r). The exposure of crabs to Dursban(r) (3.12 μg/L) showed a significant decrement of AChE activity at 24 and 48 h, whereas the BuChE was inhibited only after 24 h and no inhibition for both enzymes was observed after 72 h. Moreover, a significant repression of AChE activity was observed in both organs of C. maenas exposed to 5% of STIUE. Our experiments indicated that the measurement of AChE activity in gills and hepatopancreas of C. meanas would be useful biomarker of organophosphorous (OP) and of neurotoxic effects of STIUE in Tunisia.     

Cover crop effects on nitrous oxide emission from a manure-treated Mollisol

Agriculture contributes 40–60% of the total annual N₂O emissions to the atmosphere. Development of management practices to reduce these emissions would have a significant impact on greenhouse gas levels. Non-leguminous cover crops are efficient scavengers of residual soil NO₃, thereby reducing leaching losses. However, the effect of a grass cover crop on N₂O emissions from soil receiving liquid swine manure has not been evaluated. This study investigated: (i) the temporal patterns of N₂O emissions following addition of swine manure slurry in a laboratory setting under fluctuating soil moisture regimes; (ii) assessed the potential of a rye (Secale cereale L.) cover crop to decrease N₂O emissions under these conditions; and (iii) quantified field N₂O emissions in response to either spring applied urea ammonium nitrate (UAN) or different rates of fall-applied liquid swine manure, in the presence or absence of a rye/oat winter cover crop. Laboratory experiments investigating cover crop effects N₂O emissions were performed in a controlled environment chamber programmed for a 14 h light period, 18 °C day temperature, and 15 °C night temperature. Treatments with or without a living rye cover crop were treated with either: (i) no manure; (ii) a phosphorus-based manure application rate (low manure): or (iii) a nitrogen-based manure application rate (high manure). We observed a significant reduction in N₂O emissions in the presence of the rye cover crop. Field experiments were performed on a fine-loamy soil in Central Iowa from October 12, 2005 to October 2, 2006. We observed no significant effect of the cover crop on cumulative N₂O emissions in the field. The primary factor influencing N₂O emission was N application rate, regardless of form or timing. The response of N₂O emission to N additions was non-linear, with progressively more N₂O emitted with increasing N application. These results indicate that while cover crops have the potential to reduce N₂O emissions, N application rate may be the overriding factor.     

超声波在低声能密度下处理污泥的实验研究

文章采用超声波在0.014W/mL、0.025W/mL、0.031W/mL、0.035W/mL四个声能密度水平下,作用时间在0～60min范围内对生活污水厂污泥进行处理。研究结果表明:在低声能密度下,超声波处理污泥45min可以使可溶性化学需氧量(SCOD)溶出率超过10%,同时可以使污泥中氨氮的含量降到5mg/L左右。     

竹炭吸附去除糖蜜酒精废水中COD的研究

通过实验研究了竹炭类型、粒度、投加量、吸附时间以及初始浓度等因素对竹炭吸附去除糖蜜酒精废水中COD效果的影响。结果表明,高温竹炭的吸附效果优于中温竹炭;竹炭粒径越小,废水COD去除效果越好;废水COD去除率随着吸附时间的增大而增加;废水的初始COD浓度越小,COD去除率越大。正交实验表明,废水中COD的去除的最佳条件为,在选用粒度为65～80目的高温竹炭条件下,投加量为1.5g/50mL,水样稀释1倍,振荡时间为1.5h。     

不同土壤对垃圾沥滤液净化效能研究

通过土柱模拟实验比较了不同土壤对垃圾沥滤液中高浓度污染物NH4+-N和COD的去除效率。结果表明不同类型土壤对垃圾沥滤液的处理效果有明显差异。紫色土对沥滤液NH4+-N的去除效率可达到95%以上,COD去除率较低;腐殖土对COD去除率最高,出水NH+4-N含量随pH值的上升迅速下降;与腐殖土相比,黄壤对NH+4-N的去除效果较高,对COD的去除率较低。随进水次数增加,土柱对渗滤液中污染物的去除效率明显降低。     

生物渗滤池运行参数优化研究

实验针对间歇投配污水的生物渗滤池处理生活废水的一些基本运行参数进行了优化研究。通过对生物渗滤池的出水量、不同填料性质、不同填料粒径以及不同进水水质与污染物(COD)去除率影响的研究,证实该系统的水力负荷与污染物去除率成反向关系,即当水力负荷减少时,污染物去除率会相对增加;研究还表明选用粒径为0.9～2mm自然河沙作为系统填料时,系统COD去除率较高,这时填料不易被堵塞且即使堵塞也较易恢复;运用生物渗滤池处理城市生活污水能使处理后污水COD达到城镇污水处理厂出水排放标准的一级标准。提高污水中营养物质的配比以及采用多级生物渗滤池联用,能高效处理高浓度污水,甚至使出水达标排放。