Impacts of Chromium from Tannery Effluent and Evaluation of Alternative Treatment Options

The paper has focused on the challenges/impacts of tannery effluent and evaluates the alternative treatment options used to treat, recover or recycle chromium from the waste water. The paper was done entirely on secondary data by consulting literature sources including scientific journals, chapters of books, conference report papers and websites. The results of this review paper indicated that chromium is highly toxic and carcinogenic to human beings, animals, plants and the general environment (soil and water sediment). It is found out that chrome is the primary threat when ever tanning industry comes in to practice. Though many treatment options were evaluated to prevent its consequence on the environment, neither of them could achieve to treat or recover chrome 100%. Treatment options are either;inef-ficient, complicated, energy demanding, costly or applicable to a certain parts of the world due to technology or skilled man power demand. Therefore, to tackle this serious challenge stringent environmental regulation with law enforce-ment has to be exercised to use better treatment system which is widely applicable. Polluters must also know the envi-ronmental cost of their industry and treated according to polluter pay or precautionary principles. Moreover, the gen-eral public has to be aware of it and all concerned organizations and governments has to work hand in hand to reach zero discharge level or at least to attain the EPA chrome discharge

Efficiency of locally available filter media on fluoride and phosphate removal for household water treatment system

Since conventional water treatment is not affordable in developing countries,looking for locally available and alternative treatment options is mandatory.Removal of fluoride and phosphate can be achieved by designing appropriate filtration media from different materials such as sand,calcined clay,pumice,scoria and bone char.This study was designed to determine the removal efficiency of these locally available filter media with respect to detention time and pH.The filtration apparatuses(tank)were filled separately with stone,gravel with grain size 0.6-4.75 mm and 40 cm deep,sand(ES=0.15-0.35 mm and UC=1.5-3),calcined clay,pumice,scoria and bone char with grain size 0.25-0.5 inch.Water samples were prepared using glass bottles with fluoride concentrations of 6 and 8 mg/l and phosphate concentration of 4 mg/1.Laboratory analysis was carried out before and after filtration to determine the removal efficiency of each medium.It was found that the highest removal of fluoride was achieved by bone char(89.65%),followed by pumice(82.4%).However,bone char has rather increased the concentration of phosphate by 63.8%.Sand was the most efficient media to remove phosphate,managing to remove by 70%.Therefore,it is an attractive option to use these locally available,environmental friendly and appropriate technologies for efficient removal of both fluorine and phosphate at the household or community water treatment level.

卫星观测在全球细颗粒物浓度长期暴露评估中的应用

[背景]十余年的卫星观测提供了全球细颗粒物（PM2.5）人群暴露趋势和大小的信息。[目的]利用多个卫星的测量值推断的PM：5浓度，建立和改进大气PM2.5质量和趋势的全球暴露评估。[方法]结合3个卫星反演的PM25源数据，得出1998-2012年10km×10km尺度上全球PM2．5估计值。对每一个源数据，通过GEOS—Chem化学物运输模型把气溶胶光学厚度总柱反演与近地面PM2.5联系起来，以表示当地的气溶胶光学性能和垂直廓线。从文献中收集210个全球基于地面的PM2.5观测值，用北美和欧洲之外其他地区的测量值来评估基于卫星的估计值。[结果]1998--2012年，全球人口加权的大气PM25浓度每年增加0．55gg／m3（95％CI：0．43～0．67）（2．1％／年；95％CI：1．6％-2．6％）。尽管在一些发达地区PM2.5减少，但在一些发展中地区PM2．s的增加推动了这一全球性的变化。在东亚，PMzs水平高于世界卫生组织（WHO）第一个中期目标35μg／m3的人口比例从1998--2000年的51％上升到2010---2012年的70％。相比之下，北美高于WHO空气质量指南10μg/m3的人口比例，从1998--2000年的62％下降到2010---2012年的19％。北美及欧洲以外地区的卫星反演估计值和地面测量值之间存在关联（r=0．81；n=210；斜率=0．68）。卫星反演的估计值偏低，提示真实的全球浓度可能更高。[结论]卫星观测值提供了大气PM2.5浓度的全球性长期变化的新认识。从这项研究中获得的PM2.5的卫星反演估计值和地面观测值可供公众使用。

卫星观测在全球细颗粒物浓度长期暴露评估中的应用(续完)

测量仪器、测量方法以及测量位置的差异会制约我们从已公开发表的文献中推导PM2.5浓度的变化趋势,并会影响其与卫星反演值等需要计算地区权重的数据的可比较性。尽管如此,补充材料图S4～S6显示的北京、新德里和科威特三个城市从文献中获取的PM2.5浓度实测值与图5的卫星反演估计值的比较仍然具有重要意义。Hyvarinen等（2010）于2007—2010年对新德里进行研究,数据显示卫星反演的年均PM2.5浓度偏低，可能由冬季卫星观测增加所致。