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251.
252.
印钞废水属高浓度难降解有机废水,对环境污染严重。鉴于现有处理工艺出水普遍不达标的情况,通过对比实验确定了改进方案:超滤浓缩液离心出水在进入接触氧化池前,增加新的处理单元(Fenton氧化-混凝)。Fenton氧化最佳条件:FeSO4.7H2O投加量14 g/L,H2O2的投加量34 mL/L,初始pH值6.0,氧化反应时间1.5h,温度18.8℃;混凝过程最佳条件:PAC投加量4 g/L,PAM(5‰)投加量10 mg/L,pH值7。新增单元对废水中COD去除率接近80%,可生化性提高1.6倍,色度降低36%。 相似文献
253.
Tao Zhang Qiucheng Li Lili Ding Hongqiang Ren Ke Xu Yonggang Wu Dong Sheng 《环境科学学报(英文版)》2011,23(6):881-890
Chemical precipitation to form magnesium ammonium phosphate (MAP) is an effective technology for recovering ammonium
nitrogen (NH4
+-N). In the present research, we investigated the thermodynamic modeling of the PHREEQC program for NH4
+-N
recovery to evaluate the effect of reaction factors on MAP precipitation. The case study of NH4
+-N recovery from coking wastewater
was conducted to provide a comparison. Response surface methodology (RSM) was applied to assist in understanding the relative
significance of reaction factors and the interactive effects of solution conditions. Thermodynamic modeling indicated that the saturation
index (SI) of MAP followed a polynomial function of pH. The SI of MAP increased logarithmically with the Mg2+/NH4
+ molar ratio
(Mg/N) and the initial NH4
+-N concentration (CN), respectively, while it decreased with an increase in Ca2+/NH4
+ and CO3
2??/NH4
+
molar ratios (Ca/N and CO3
2??/N), respectively. The trends for NH4
+-N removal at different pH and Mg/N levels were similar to the
thermodynamic modeling predictions. The RSM analysis indicated that the factors including pH, Mg/N, CN, Ca/N, (Mg/N) (CO3
2??/N),
(pH)2, (Mg/N)2, and (CN)2 were significant. Response surface plots were useful for understanding the interaction effects on NH4
+-N
recovery. 相似文献
254.
Xinxin Wang Zhen Han Zhihui Bai Jingchun Tang Anzhou M Jizheng He Guoqiang Zhuang 《环境科学学报(英文版)》2011,23(11):1858-1864
The impact of petroleum on archaeal community in salinealkali soils was investigated, which will expand the knowledge of the archaeal population involved in the natural attenuation of hydrocarbons in extreme environments. 相似文献
255.
Effect of C/N ratio, aeration rate and moisture content on ammonia and greenhouse gas emission during the composting 总被引:3,自引:0,他引:3
Gaseous emission (N2O, CH4 and NH3) from composting can be an important source of anthropogenic greenhouse gas and air pollution. A laboratory scale orthogonal experiment was conducted to estimate the effects of C/N ratio, aeration rate and initial moisture content on gaseous emission during the composting of pig faeces from Chinese Ganqinfen system. The results showed that about 23.9% to 45.6% of total organic carbon (TOC) was lost in the form of CO2 and 0.8% to 7.5% of TOC emitted as CH4. Most of the nitrogen was lost in the form of NH3, which account for 9.6% to 32.4% of initial nitrogen. N2O was also an important way of nitrogen losses and 1.5% to 7.3% of initial total nitrogen was lost as it. Statistic analysis showed that the aeration rate is the most important factor which could affect the NH3 (p = 0.0189), CH4 (p = 0.0113) and N2O (p = 0.0493) emissions significantly. Higher aeration rates reduce the CH4 emission but increase the NH3 and N2O losses. C/N ratio could affect the NH3 (p = 0.0442) and CH4 (p = 0.0246) emissions significantly, but not the N2O. Lower C/N ratio caused higher NH3 and CH4 emissions. The initial moisture content can not influence the gaseous emission significantly. Most treatments were matured after 37 days, except a trial with high moisture content and a low C/N ratio. 相似文献
256.
The activities of CeO2 nanocubes calcined at different temperatures were tested for catalytic oxidation of o-xylene. Using CeO2 nanocubes as catalysts, complete catalytic oxidation of o-xylene was achieved below 210℃. The CeO2 nanomaterials were characterized by means of BET, X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). From the TEM images, all Ce02 nanocubes displayed cubic morphology irrespective of calcination temperature. The HRTEM images revealed that these nanocubes were enclosed by reactive {001}planes, which may contribute to the intrinsically catalytic property of o-xylene oxidation. The higher activity of Ce02 nanocubes calcined at 550℃ than those calcined at above 550℃ was attributed to their smaller crystallite size and larger surface area. The influences of reaction conditions were also studied, which found that a higher reaction temperature was necessary for complete catalytic oxidation of o-xylene at higher weight hourly space velocity (WHSV) and o-xylene concentration. 相似文献
257.
Polyaspartic acid (PASP) has been extensively studied in recent years as a green scale inhibitor. PASP was synthesized by thermal polycondensation of maleic anhydride and ammonium carbonate in this study. The optimal polycondensation reaction conditions were the raw material (maleic anhydride and ammonium carbonate) molar ratio of 1.0:1.2, the polymerization temperature of 180°C and reaction time of 2.0 hr. The results showed that PASP exhibits very good scale inhibiting performance. The inhibition rate was 95% for calcium carbonate and 90% for calcium sulfate by the application of 5 mg/L PASP. 相似文献
258.
259.
260.
密云水库流域2000-2005年植被覆盖度变化监测 总被引:1,自引:0,他引:1
植被是生态系统最重要的组成部分,而植被覆盖度是衡量地表植被状况的一个最重要的指标,是生态系统健康评价的前提和必要的基础。文章利用2000和2005年2个时相的Landsat 7 ETM+遥感影像为数据源,以BP神经网络法为植被覆盖度估算模型,计算了密云水库流域内不同时期的植被覆盖度,生成了该流域2个时相内的植被覆盖度图,以此分析密云水库流域植被覆盖度的时空变化。结果表明,从2000-2005年,密云水库流域内除无植被覆盖类型外(即水域部分),其余土地利用类型的植被覆盖度都呈增加趋势,其中以沙质地和耕地最为明显,分别增长了29.5%和27.3%,并且密云水库流域的平均植被覆盖度不高,尤其西部地区植被覆盖度较差,水土流失和土地沙化情况比较严重。 相似文献