環(huán)境工程畢業(yè)設(shè)計外文翻譯--工業(yè)廢水回用的接觸反應(yīng)策略_第1頁
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1、中文 中文 3452 字出處: 出處:Catalysis today, 1999, 53(1): 3-9 Catalytic strategies for industrial water re-useF.E. HancockSynetix, Billingham, Cleveland, TS23 1LB, UKAbstractThe use of catalytic processes in pollution ab

2、atement and resource recovery is widespread and of significant economic importance [R.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional,1997.]. For water rec

3、overy and re-use chemo-catalysis is only just starting to make an impact although bio-catalysis is well established [J.N. Horan, BiologicalWastewater Treatment Systems; Theory and Operation, Chichester, Wiley, 1990.]. Th

4、is paper will discuss some of the principles behind developing chemo-catalytic processes for water re-use. Within this context oxidative catalytic chemistry has many opportunities to underpin the development of successfu

5、l processes and many emerging technologies based on this chemistry can be considered .Keywords: COD removal; Catalytic oxidation; Industrial water treatment1.IntroductionIndustrial water re-use in Europe has not yet star

6、ted on the large scale. However, with potential long term changes in European weather and the need for more water abstraction from boreholes and rivers, the availability of water at low prices will become increasingly ra

7、re. As water prices rise there will come a point when technologies that exist now (or are being developed) will make water recycle and re-use a viable commercial operation. As that future approaches, it is worth stating

8、the most important fact about wastewater improvement– avoid it completely if at all possible! It is best to consider water not as a naturally available cheap solvent but rather, difficult to purify, easily contaminated m

9、aterial that if allowed into the environment will permeate all parts of the biosphere. A pollutant is just a material in the wrong place and therefore design your process to keep the material where it should be – contain

10、ed and safe. Avoidance and then minimisation are the two first steps in looking at any pollutant removal problem. Of course avoidance may not be an option on an existing plant where any changes may have large consequence

11、s for plant items if major flowsheet revision were required. Also avoidance may mean simply transferring the issue from the aqueous phase to the gas phase. There are advantages and disadvantages to both water and gas pol

12、lutant abatement. However, it must be remembered that gas phase organic pollutant removal (VOC combustion etc.,) is much more advanced than the equivalent water COD removal and therefore worth consideration [1]. Because

13、these aspects cannot be over-emphasised,a third step scrubbing is the usual method and this produces a significant water effluent disposal problem. 2.4. Pharmaceuticals and agrochemicals These industries can have water w

14、ash steps in synthesis but in addition they are often formulated with water-based surfactants or wetting agents. 2.5. Foods and beverages Clearly use water in processing and COD and BOD issues will be the end result. 2.6

15、. Pulp and paper This industry uses very large quantities of water for processing – aqueous peroxide and enzymes for bleaching in addition to the standard Kraft type processing of the pulp. It is important to realise how

16、 much human society contributes to contaminated water and an investigation of the flow rates through municipal treatment plants soon shows the significance of non-process industry derived wastewater. 3. The technologies

17、The technologies for recalcitrant COD and toxic pollutants in aqueous effluent are shown in Fig. 2. These examples of technologies [2,6,8] available or in development can be categorised according to the general principle

18、 underlying the mechanism of action. If in addition the adsorption (absorption) processes are ignored for this catalysis discussion then the categories are: 1. Biocatalysis 2. Air/oxygen based catalytic (or non-catalytic

19、). 3. Chemical oxidation 1. Without catalysis using chemical oxidants 2. With catalysis using either the generation of _OH or active oxygen transfer. Biocatalysis is an excellent technology for Municipal wastewater treat

20、ment providing a very cost-effective route for the removal of organics from water. It is capable of much development via the use of different types of bacteria to increase the overall flexibility of the technology. One i

21、ssue remains – what to do with all the activated sludge even after mass reduction by de-watering. The quantities involved mean that this is not an easy problem to solve and re-use as a fertilizer can only use so much. Th

22、e sludge can be toxic via absorption of heavy metals, recalcitrant toxic COD. In this case incineration and safe disposal of the ash to acceptable landfill may be required. Air based oxidation [6,7] is very attractive be

23、cause providing purer grades of oxygen are not required if the oxidant is free. Unfortunately, it is only slightly soluble in water, rather unreactive at low temperatures and, therefore, needs heat and pressure to delive

24、r reasonable rates of reaction. These plants become capital intensive as pressures (from _10 to 100 bar) are used. Therefore, although the running costs maybe low the initial capital outlay on the plant has a very signif

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