絮凝剂对模拟餐饮泔水中乳化油破乳效果的研究

餐饮泔水中的油脂会抑制厌氧发酵过程,干扰后续产甲烷潜势和餐厨废弃物资源化利用效率。针对餐饮泔水中乳化油的破乳问题,以模拟餐饮泔水为研究对象,采用絮凝工艺对废水进行处理,分别选取聚合氯化铝、聚合硫酸铁、硫酸铝、氯化铁、硫酸铁五种絮凝类破乳剂,并以单因素试验和响应曲面法对破乳条件进行优化。试验结果表明,选取聚合氯化铝作为破乳剂,投加17mg/L,搅拌时间100 s,搅拌转速为260 r/min,可以获得最佳破乳效果,搅拌时间与搅拌转速之间交互作用明显。投加量对试验结果的影响最大,在餐饮泔水破乳效果中起主导作用。

改土归流后生计方式的变化及对生态环境的影响——以湘西土家族地区为例

改土归流之后,清政府实施的鼓励农耕、移民等政策,引发了湘西土家族地区的生计方式转变,即由传统的农林渔采等并行方式向以农耕为主的方式转变。这导致了资源利用方式与所处生态环境的背离,诱发了森林资源遭破坏、生物品种减少、水旱灾害频发等生态后果。这一历史过程表明,生态环境蜕变的原因并不单是利用过度的问题,也与资源利用方式上的失误紧密相关联。

Characterization of nanoscale iron and its degradation of 2,4-dichlorophenol

Nanoscale iron was detected by TEM, X-ray diffraction and X-ray photoelectron spectroscopy. It was found that the size of the nanoscale iron particles is in the range of 30?40 nm according to TEM image, and it contains abundant Fe3O4 as passivating layers on the surface of the core-shell structure. To improve its performance, dilute HCl was used for the removal of the passivating layers, and the degradation of 2,4-dichlorophenol (2,4-DCP) was measured for the nanoscale iron samples treated and untreated. Experimental results demonstrated that the removal of 2,4-DCP by untreated nanoscale iron is mainly due to the adsorption of 2, 4-DCP by nanoscale iron, and there are no degradation products detected by HPLC in the process. However, excellent dechlorination of 2,4-DCP was gained by HCl-treated nanoscale iron, and 2-chlorophenol, 4-chlorophenol and phenol were detected during the process. It was concluded that dechlorination is the key reaction pathway for the degradation of 2,4-DCP by activated nanoscale iron, and phenol is found to be the main product.

Remobilization of heavy metals during the resuspension of Liangshui River sediments using an annular flume

The release and transport of heavy metals(Ni,Cr,Cu and Pb) from Liangshui River sediments into the overlying water column during the resuspension event were determined using an annular flume with a velocity ranging from 0.15 to 0.35 m/s.It is shown that the suspended particulate matters(SPM) increased as much as nearly 25 times from 165 to 4220 mg/L as the velocity increased.Heavy metals showed an increase in dissolved phase as the velocity increased due to their desorption from the SPM.Acid-soluble heavy metals increased as the velocity increased,indicating that part of the heavy metals transformed from stable phase to labile phase during resuspension.Heavy metal concentrations in the SPM on volume normalization increased by approximately 2-6 times.However,on the mass weighted basis they decreased,approaching the bulk-sediment contents at high velocity,due to the "particle concentration effect".The distribution coefficients(K D) of heavy metals were higher at slower velocity during the sediment resuspension,which could be attributed to the decrease of fine particles(silt/clay fraction) during resuspension.

Dechlorination of 2,4-dichlorophenol by nickel nanoparticles under the acidic conditions

Metal nanoparticles are effective for remediation of contamination with a range of compounds including chlorinated organics.However,the sorption process of the passivation oxide layers on the metal nanoparticle surfaces may result in incomplete degradation of contaminants.This phenomenon can be prevented by an acidic washing procedure or reaction in an acidic medium.In this paper,nickel nanoparticles manufactured via the carbonyl powder process were analyzed using scanning electron microscopy,transmission electron microscopy,X-ray diffraction and energy-dispersive X-ray spectroscopy.The sorption and degradation of 2,4-dichlorophenol (2,4-DCP) by nickel nanoparticles under acidic conditions was then investigated.Transmission electron microscopy and XRD results showed that the nickel nanoparticles range in size from 10 to 20 nm,and a thin passivation layer of NiO is present on the surface.This oxide layer can be removed by pretreatment washing with acidic solutions.It was indicated that dechlorination was the key reaction pathway for degradation of 2,4-DCP by nickel nanoparticles under acidic conditions.The main degradation products were 4-Chlorophenol,2-Chlorophenol,and Phenol,and among these,Phenol was dominant.The acidic medium promoted degradation by providing an appropriate pH,and H+ may be involved in the reaction.Dechlorination of 2,4-DCP by nickel nanoparticles under the acidic condition follows the second order kinetic model,and the rate constants at 298,306,316 K are 0.02,0.2 and 0.3 (g L h)-1,respectively.

论计算机软件在舞台美术LED视频制作中的取舍

LED视频因其具有色彩丰富、变化简单快捷、视觉冲击力强等优点,早已广泛出现在各类电视综艺节目及晚会之中,同时也被观众熟知和接受。而群众文化的精品打造,同样也离不开LED视频的辅助。一、群众文化舞美设计的特点群众文化有独特的属性,因而群众文化舞美的设计也不同于一般艺术作品的舞美设计思路,舞美设计思路上也要有所变化。