污水处理工业废水回用中英文对照外文翻译文献

1、Catalytic strategies for industrial water re-useAbstractThe use of catalytic processesi n pollution abatement 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,

2、1997. For water recovery 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. This paper will discuss some of the principles behind developing c

3、hemo-catalytic processes for water re-use. Within this context oxidative catalytic chemistry has many opportunities to underpin the development of successful processes and many emerging technologies based on this chemistry can be considered .Keywords: COD removal; Catalytic oxidation; Industrial wat

4、er treatment 1.IntroductionIndustrial water re-use in Europe has not yet started 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 rare.

5、 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 the most important fact about wastewater improvement avoid it completely if at all

6、possible! It is best to consider water not as a naturally available cheap solvent but rather, difficult to purify, easily contaminated material 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 p

7、rocess to keep the material where it should be contained 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 consequences for plant items if major

8、 flowsheet revision were required. Also avoidance may mean simply transferring the issue from the aqueous phase to the gas phase. There are advantages and disadvantagest o both water and gas pollutant abatement. However, it must be remembered that gas phase organic pollutant removal (VOC combustion

9、etc.,) is much more advanced than the equivalent water COD removal and therefore worth consideration 1. Because these aspects cannot be over-emphasised， a third step would be to visit the first two steps again. Clean-up is expensive, recycle and re-use even if you have a cost effective process is st

10、ill more capital equipment that will lower your return on assets and make the process less financially attractive. At present the best technology for water recycle is membrane based. This is the only technology that will produce a sufficiently clean permeate for chemical process use. However, the te

11、chnology cannot be used in isolation and in many (all) cases will require filtration upstream and a technique for handling the downstream retentate containing the pollutants. Thus, hybrid technologies are required that together can handle the all aspects of the water improvement process6,7,8.Hence t

12、he general rules for wastewater improvement are:Avoid if possible, consider all possible ways to minimise.Keep contaminated streams separate.Treat each stream at source for maximum concentration and minimum flow.Measure and identify contaminants over complete process cycle. Look for peaks, which wil

13、l prove costly to manage and attempt to run the process as close to typical values as possible. This paper will consider the industries that are affected by wastewater issuesa nd the technologies that are available to dispose of the retentate which will contain the pollutants from the wastewater eff

14、luent. The paper will describe some of the problems to be overcome and how the technologies solve these problems to varying degrees. It will also discuss how the cost driver should influence developers of future technologies.The industriesThe process industries that have a significant wastewater eff

15、luent are shown in Fig. 1. These process industries can be involved in wastewater treatment in many areas and some illustrations of this are outlined below.Fig. 1. Process industries with wastewater issues.RefineriesThe process of bringing oil to the refinery will often produce contaminated water. O

16、il pipelines from offshore rigs are cleaned with water; oil ships ballast with water and the result can be significant water improvement issues.ChemicalsThe synthesis of intermediate and speciality chemicals often involve the use of a water wash step to remove impurities or wash out residual flammab

17、le solvents before drying.PetrochemicalsEthylene plants need to remove acid gases (CO2, H2S) formed in the manufacture process. This situation can be exacerbated by the need to add sulphur compounds before the pyrolysis stage to improve the process selectivity. Caustic scrubbing is the usual method

18、and this produces a significant water effluent disposal problem.Pharmaceuticals and agrochemicalsThese industries can have water wash steps in synthesis but in addition they are often formulated with water-based surfactants or wetting agents.Foods and beveragesClearly use water in processing and COD

19、 and BOD issues will be the end result.Pulp and paperThis 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 much human society contributes to contaminate

20、d water and an investigation of the flow rates through municipal treatment plants soon shows the significance of non-process industry derived wastewater.The technologiesThe technologies for recalcitrant COD and toxic pollutants in aqueous effluent are shown in Fig. 2. These examples of technologies

21、2,6,8 available or in development can be categorised according to the general principle underlying the mechanism of action. If in addition the adsorption (absorption) processes are ignored for this catalysis discussion then the categories are:BiocatalysisAir/oxygen based catalytic (or non-catalytic)

22、.Chemical oxidationWithout catalysis using chemical oxidantsWith catalysis using either the generation of _OH or active oxygen transfer. Biocatalysis is an excellent technology for Municipal wastewater treatment providing a very cost-effective route for the removal of organics from water. It is capa

23、ble of much development via the use of different types of bacteria to increase the overall flexibility of the technology. One issue 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

24、-use as a fertilizer can only use so much. The 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 because providing purer grades of oxyge

25、n 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 deliver reasonable rates of reaction. These plants become capital intensive as pressures (from _10 to 100 bar) are used. Th

26、erefore, although the running costs maybe low the initial capital outlay on the plant has a very significant effect on the costs of the process. Catalysis improves the rates of reaction and hence lowers the temperature and pressure but is not able to avoid them and hence does not offer a complete so

27、lution. The catalysts used are generally Group VIII metals such as cobalt or copper. The leaching of these metals into the aqueous phase is a difficulty that inhibits the general use of heterogeneous catalysts 7. Chemical oxidation with cheap oxidants has been well practised on integrated chemical p

28、lants. The usual example is waste sodium hypochlorite generated in chlor-alkali units that can be utilised to oxidise COD streams from other plants within the complex. Hydrogen peroxide, chlorine dioxide, potassium permanganate are all possible oxidants in this type of process. The choice is primari

29、ly determined by which is the cheapest at the point of use. A secondary consideration is how effective is the oxidant. Possibly the most researchedc atalytic area is the generation and use of _OH as a very active oxidant (advanced oxidation processes) 8. There are a variety of ways of doing this but

30、 the most usual is with photons and a photocatalyst. The photocatalyst is normally TiO2 but other materials with a suitable band gap can be used 9,10. The processes can be very active however the engineering difficulties of getting light, a catalyst and the effluent efficiently contacted is not easy

31、. In fact the poor efficiency of light usage by the catalyst (either through contacting problems or inherent to the catalyst) make this process only suitable for light from solar sources. Photons derived from electrical power that comes from fossil fuels are not acceptable because the carbon dioxide

32、 emission this implies far outweighs and COD abatement. Hydroelectric power (and nuclear power) are possible sources but the basic inefficiency is not being avoided. Hydrogen peroxide and ozone have been used with photocatalysis but they can be used separately or together with catalysts to effect CO

33、D oxidation. For ozone there is the problem of the manufacturing route, corona discharge, which is a capital intensive process often limits its application and better route to ozone would be very useful. It is important to note at this point that the oxidants discussed do not have sufficient inheren

34、t reactivity to be use without promotion. Thus, catalysis is central to their effective use against both simple organics (often solvents) or complex recalcitrant COD. Hence, the use of Fenton s catalyst (Fe) for hydrogen peroxide 11. In terms of catalysis these oxidants together with hypochlorite fo

35、rm a set of materials that can acthas active oxygen transfer (AOT) oxidants in tohf ea psrueistaebnlceec atalyst. Ifthe AOT oxidant is hypochlorite or hydrogen peroxide then three phase reactions are avoided which greatly simplifies the flowsheet. Cheap, catalytically promoted oxidants with environm

36、entally acceptable products of oxidation that do not require complex chemical engineering and can be produced efficiently would appear to offer one of the best solutions to the general difficulties often observed.Redox catalysis and active oxygen transferThe mechanism of catalytically promoted oxida

37、tion with hydrogen peroxide or sodium hypochlorite cannot be encompassed within one concept, however there are general similarities between the two oxidants that allows one to write a series of reactions for both (Fig. 3) 5. This type of mechanism could be used to describe a broad range of reactions

38、 for either oxidant from catalytic epoxidation to COD oxidation. The inherent usefulness of the reactions is that;The reactions take place in a two-phase system.High pressure and temperature are not required.The catalytic surface can act as an adsorbent of the COD to be oxidised effectively increasi

39、ng the concentration and hence the rate of oxidation.The simple mechanism shows the selectivity issue with this type of processes.T he oxidant can simply be decomposed by the catalyst to oxygen gas this reaction must be avoided because dioxygen will play no role in COD removal. Its formation is an e

40、xpensive waste of reagent with oxygen gas ($20/Te) compared to the oxidant ($400 600/Te). To be cost competitive with alternative processes redox catalysis needs excellent selectivity.Technology mappingThe technologies so far described can be mapped 12 for their applicability with effluent COD conce

41、ntration (measured as TOC) and effluent flow rate (m3 h-1). The map is shown in Fig. 4. The map outlines the areas where technologies are most effective. The boundaries, although drawn, are in fact fuzzier and should be only used as a guide. Only well into each shape will a technology start to domin

42、ate. The underlying cost model behind the map is based on simple assertions at high COD mass flows only air/oxygen will be able to keep costs down because of the relatively low variable cost of the oxidant. At high COD concentrations and high flows only biological treatment plants have proved themse

43、lves viable of course if done at source recovery becomesa n option. At low flows and low COD levels redox AOT catalysis is an important technology the Synetix Accent 1 process being an example of this type of process (see Fig. 5 for a simplified flowsheet). The catalyst operates under very controlle

44、d conditions at pH 9 and hence metal leaching can be avoided (5 ppb). The activity and selectivity aspects of the catalyst displayed in Fig. 3 can be further elaborated to look at the potential surface species. This simple view has been extended by a significant amount of research 3,4,5. Now the mec

45、hanism of such a catalyst can be described in Fig. 6. The key step is to avoid recombination of NiO holes to give peroxy species and this can be contrasted with the hydrogen peroxide situation where the step may be characterized as oxygen vacancy filled. From both recombination will be facilitated b

46、y electronic and spatial factors. The range of application of the process is outlined below. From laboratory data some general types of chemical have been found suitable sulphides, amines, alcohols, ketones, aldehydes, phenols, carboxylic acids, olefins and aromatic hydrocarbons. From industrial tri

47、als recalcitrant COD (nonbiodegradable) and sulphur compounds have been successfully demonstrated and a plant oxidising sulphur species has been installed and is operational.4. ConclusionsWastewater treatment processes are in the early stages of development. The key parameters at present are effecti

48、veness and long term reliability. Many processes operating are in this stage, including the redox Accent TM is a trademark of the ICI Group of Companies. catalysis systems. However,once proven, redox catalysis offers many advantages for COD removal from wastewater:The low capital cost of installatio

49、n.Simple operation that can be automated.Flexible nature of the process can be easily modified to meet changing demands of legislation.Hence it will be expected to develop into an important technology in wastewater improvement.AcknowledgementsThe author is grateful to Jane Butcher and Keith Kelly of

50、 Synetix for discussions on this paper. ReferencesR.J. Farrauto, C.H. Bartholomew, Fundamentals of Industrial Catalytic Processes, Blackie Academic and Professional, 1997. F.E. Hancock / Catalysis Today 53 (1999) 3 9 9J.N. Horan, Biological Wastewater Treatment Systems; Theory and Operation, Chiches

51、ter, Wiley, 1990.F.E. Hancock et al., Catalysis Today 40 (1998) 289.F. King, F.E. Hancock, Catal. Today 27 (1996) 203.J. Hollingworth et al., J. Electron Spectrosc., in press.F. Luck, Environmental Catalysis, in: G. Centi et al. (Eds.), EFCE Publishers, Series 112, p. 125.D. Mantzavinos et al., in:

52、Vogelpohl and Geissen (Eds.), in: Proceedingso f the Conference on Water Science and Technology, Clausthal-Zellerfeld, Germany, May 1996, J. Int. Assoc. Water Quality, Pergamon, 1997.R. Venkatadri, R.W. Peters, Hazardous Waste Hazardous Mater. 10 (1993) 107.A.M. Braun, E. Oliveros, Water Sci. Tech.

53、35 (1997) 17.D. Bahnemann et al., Aquatic and surface photochemistry, Am. Chem. Soc. Symp. Ser. (1994) 261.J. Prousek, Chem. Lisy 89 (1995) 11.工业废水回用的接触反应策略摘要：无论从控制污染还是资源恢复的角度，接触反应都是被广泛应用并极具经济效益的。 在生物接触反应理论以近于完善的今天，基于水资源恢复和回用的化学接触反应技术正在逐渐兴起。本论文将要探讨化学接触反应在水资源回用中的原理。 文章中阐述了氧化接触反应化学在对新技术的巩固和利用方面的用途是相当多

54、的。 明确来讲，氧化还原催化作用和活性氧转移氧化剂具有很多优点。本文将涉及上述技术的设计。关键词：COD 去除率 接触反应工业废水回用1绪论在欧洲，工业水回用尚未形成规模。然而，从欧洲气候的长远变化和越来越多的地上凿洞及河流取水现象来预测，低价水将愈加稀少。由于水价的提高，研究水资源恢复及再利用的技术将成为可行的贸易运作方式。因此， 改善污水水质的研究将是未来关注的热点。水不在是自然界的廉价溶剂，而是易于污染难于净化的材料,一旦扩散到环境中将会侵入生物圈的各个部分。污染物仅仅是被置于错误地方的一种物质,因而,科研的目的就是将它们保存在安全无害的。避免和最小化是是污染物去处的前期步骤。当然,避免

55、在这样一个任何变化都会导致严重结果的星球上是不可能具有选择性的。另外， 所谓避免也指简单的液相与气相之间的转化。液相与气相污染物的消除都分别存在其利害关系。但值得注意的是，气体污染物的去除的发展远先进于水中COD 的去除。因此，液相中污染物的去除是值得关注的。由于研究不能面面俱到，第三步可以从前两步骤中得到借鉴。彻底清洁是昂贵的， 即使你有一个成本高效的途径，它仍然会降低资产回报和降低经济合理性目前， 水资源循环利用的最优技术便是膜技术。它是唯一能够利用化学工艺产生充分清洁渗透作用的技术。但是膜技术难以单独运行，大都依赖于上向流过滤和处理向下流中含污染物的滞留物的技术。由此， 要在水质提高工艺

56、中做到面面俱到就要求多种工艺综合运用。因此，废水水质提高的大体规则如下：尽可能避免污染，考虑所有使污染最小化的措施。隔离受污染水体。源头处理河水，高浓度低流量。在完整的处理周期中测量和鉴定污染物。找到运行管理费用的最高值，尽量 使其与常规费用相接近。本篇论文将要考虑到受污水影响的工业以及处理滞留物的技术，滞留物包括由污水管道排出的污染物。本文将要阐述需要克服的问题及解决问题过程中应用技术多样化的程度。另外解释了价格控制员如何影响未来技术的发展方向。2工业处理工业庞大的污水出流量。这些处理工业涉及污水处理的诸多领域，列举一些示例如下：精练厂将原油送往炼油厂的过程中会对水体造成污染。无论是由海面钻

57、探平台引出的输油管道被水冲刷干净；还是储油船的压舱水都会带来一系列水质改良问题。化学药品合成媒介或特殊化学药品在烘干前常需大量清水冲掉杂质或残余可燃性溶媒。石油化工产品乙烯车间需要去除生产过程中形成的酸性气体。在通过高温分解来提高加工选择性之前添加硫化物更加剧了这一情形。惯常采用腐蚀性擦洗的办法引发了大量废水处理的问题。药物和农用化学品这些工业在合成时需要冲洗步骤，包括以水为基础的表面活性剂和湿介质。食品和饮料清洁工艺需水，产生BOD,COD。纸浆和造纸生产过程中大量用水-除了标准牛皮纸处理纸浆，漂白阶段需要水合过氧化物和酶。所以充分了解人类社会活动怎样对水质造成的污染是至关重要的，一份市政处理厂流速的调查显示了未经处理工业废水的重要影响。3.处理技术去除出流水体COD 和污染物的处理技术如图2 所示。这些可行的或处于发展中的工艺示例2,6,8依据大体的反映机理规则可被划分为几类。如果催化工艺中的吸附过程被忽略的话，则分类如下：生物催话作用以空气/氧为基础的接触反应化学氧化无催化作用的化学药剂氧化利用 _OH 或活性氧转移的催化作用生物催化作用在市政污水处理中发挥了极佳的作用，为去除水中有机物提供了经济高效的途径。在使用不同种类的细菌来增加技术的灵活性方面取得了很大进展。 一个遗留问题-怎样处置脱水后的活性污泥。污泥量意味着这