An approach to the fluctuation mechanism of ecotone

In this paper,the relationship among land productivity,population pressure and the fluctuation mechanism of ecotone is analyzed,taking coumties and banners of southeast Inner Mongolia plateau as an example,which is the most fragile part in the farming and husbandry interleaving belt of north China due to its severe desertification degree and low level of economic development.The Cv for the total output value of agriculture decreases from southeast to northwest,with the same rule as which the overloading population cumulated distributes,and both indicators have close relation with the high linear coefficient of 0.83.These reveal the fluctuation mechanism for ecotone:fluctuation of the level of economic development is a scientific and practical measure both to weakness degree and to instability of ecotone,because it is a synthesized response to the variation of climate as well as irrational land uses,which reinforce and magnify the fluctuation.In detail,the heavier the population overloading,the severer the grassland reclamation,the stronger the dependence of regional productivity on rainfall,the lower the level of economic development,the rougher the fluctuation of ecotone,but the weaker the PRED system.     

Mg2+ improves biomass production from soybean wastewater using purple non-sulfur bacteria

Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria (PNSB). This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg²⁺ under the light-anaerobic condition. Results showed that with the optimal Mg²⁺ dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L, and biomass yield also was improved by 60%. Chemical Oxygen Demand (COD) removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg²⁺ could promote the content of bacteriochlorophyll in photosynthesis because Mg²⁺ is the bacteriochlorophyll active center, and thus improved adenosine triphosphate (ATP) production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials (biomass yield) and COD removal, leading to more biomass production. With 10 mg/L Mg²⁺, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.     

Sewage sludge disintegration by high-pressure homogenization: A sludge disintegration model

High-pressure homogenization (HPH) technology was applied as a pretreatment to disintegrate sewage sludge. The effects of homogenization pressure, homogenization cycle number, and total solid content on sludge disintegration were investigated. The sludge disintegration degree (DDCOD), protein concentration, and polysaccharide concentration increased with the increase of homogenization pressure and homogenization cycle number, and decreased with the increase of sludge total solid (TS) content. The maximum DDCOD of 43.94% was achieved at 80 MPa with four homogenization cycles for a 9.58 g/L TS sludge sample. A HPH sludge disintegration model of DD_COD= kN^aP^b was established by multivariable linear regression to quantify the effects of homogenization parameters. The homogenization cycle exponent a and homogenization pressure exponent b were 0.4763 and 0.7324 respectively, showing that the effect of homogenization pressure (P) was more significant than that of homogenization cycle number (N). The value of the rate constant k decreased with the increase of sludge total solid content. The specific energy consumption increased with the increment of sludge disintegration efficiency. Lower specific energy consumption was required for higher total solid content sludge.     

Effects of WOx modification on the activity, adsorption and redox properties of CeO2 catalyst for NOx reduction with ammonia

A series of WO₃/CeO₂ (WOx/CeO₂) catalysts were synthesized by wet impregnation of ammonium metatungstate on a CeO₂ support. The resulting solid acid catalysts were characterized by X-ray diffraction (XRD), UV-Vis spectroscopy (UV-Vis), Raman spectroscopy (Raman), in-situ Fourier transform infrared spectroscopy (in-situ FT-IR) of ammonia adsorption, NH₃-TPD, H₂ temperature-programmed reduction (H₂-TPR), NH₃/NO oxidation and activity measurements for NOx reduction by NH₃ (NH₃-SCR). The results show that polytungstate (WOx) species are the main species of tungsten oxide on the surface of ceria. The addition of tungsten oxide enhances the Brönsted acidity of ceria catalysts remarkably and decreases the amount of surface oxygen on ceria, with strong interaction between CeO₂ and WOx. As a result, the N₂ selectivity of NH₃ oxidation and NH₃-SCR at high temperatures (> 300℃) is enhanced. Therefore, a wide working temperature window in which NOx conversion exceeds 80% (NOx conversion > 80%) from 200 to 450℃, is achieved over 10 wt.% WOx/CeO₂ catalyst. A tentative model of the NH₃-SCR reaction route on WOx/CeO₂ catalysts is presented.     

UASB+生物接触氧化工艺处理饮料废水

介绍采用升流式厌氧污泥床反应器(UASB反应器)+生物接触氧化工艺处理饮料废水的工艺设计和运行效果。运行结果表明:此工艺能有效处理饮料废水,COD、BOD5平均去除率分别达95.8%和98.1%,出水水质达DB 61/224—2006《陕西省渭河水系污染物排放标准》的一级排放标准。     

模糊综合评判法在渭河水质评价中的应用研究

渭河是陕西省的第一大河流,准确的水质评价是治理渭河水体污染的重要前提。本文采用模糊变换原理和最大隶属度原则,运用模糊综合评判法对渭河潼关吊桥断面2012年的监测数据进行了全面评价。结果表明该断面春、夏、秋、冬四个季度的水质污染级别分别为:Ⅴ类(严重污染)、Ⅰ类(未污染)、Ⅳ类(重污染)和Ⅴ类(严重污染),主要污染物为NH3-N。与传统的单因子评价法相比,该方法能更全面合理地反映水质情况。     

家用洗涤剂中特征污染物的检测及潜在风险研究

家用洗涤剂的特征污染物磷与表面活性剂随废水排入环境水体造成水体溶解氧下降、富营养化,破坏水生生态环境。从北京市三个具有代表性的市场购买洗衣液、洗衣粉、洗衣皂和洗洁精四种形态的家用洗涤剂共40个样本,并对其中磷与阴离子表面活性剂(LAS)含量进行检测。结果显示,所有衣用洗涤剂总P2O5含量均小于1.1%,符合无磷洗涤剂国家标准(GB/T 13171.2-2009);而LAS含量差异较大,范围为6.9%~31.4%,基本趋势是洗洁精洗衣液洗衣粉;经估算,洗涤等量衣物,洗衣液的LAS排放量比洗衣粉高49.1%,北京市每年家用洗涤剂LAS产生量至少为1.23万吨;经检测蓟运河北京段水样,61.5%的样点水样中LAS含量达到III类水质标准,但局部地区污染仍较为严重,污染风险不可忽视。     

台湾的环境与生态危机及解决思路--从石门水库淤积事件谈起

石门水库在桃园县,桃园县位于台湾省西北部,西北临台湾海峡,东北邻台北县,西南与新竹县、东南与宜兰县交界。全县面积1220平方千米。人口约135万。过去县内遍植桃树,开花时缤纷馨郁,全县如一个大花园。有“桃仔园”之称,后来设县正名为桃园。全县地形分为滨海平原、丘陵台地和高山地形三大部分,是台湾主要水稻产区之一,产量居全省第四位。     

危险化学品活性反应危害及混配危险的规则研究(Ⅱ)

第四类芳香烃 活性特点: 芳香烃化合物的分子里至少含有6个碳原子,并且含氢的比例较脂肪类化合物少得多,为共轭环状结构,非常稳定.     

过程工业安全仪表系统的等级评定

介绍了安全整体性要求级别、安全联锁系统评定的内容、安全联锁系统评定的程序以及确定安全仪表联锁系统等级的方法,并介绍了安全保护层分析在安全联锁系统评定中的应用.