污水處理工業(yè)廢水回用中英文對照外文翻譯文獻

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.工業(yè)廢水回用的接觸反應策略摘要：無論從控制污染還是資源恢復的角度，接觸反應都是被廣泛應用并極具經(jīng)濟效益的。 在生物接觸反應理論以近于完善的今天，基于水資源恢復和回用的化學接觸反應技術正在逐漸興起。本論文將要探討化學接觸反應在水資源回用中的原理。 文章中闡述了氧化接觸反應化學在對新技術的鞏固和利用方面的用途是相當多

54、的。 明確來講，氧化還原催化作用和活性氧轉移氧化劑具有很多優(yōu)點。本文將涉及上述技術的設計。關鍵詞：COD 去除率 接觸反應工業(yè)廢水回用1緒論在歐洲，工業(yè)水回用尚未形成規(guī)模。然而，從歐洲氣候的長遠變化和越來越多的地上鑿洞及河流取水現(xiàn)象來預測，低價水將愈加稀少。由于水價的提高，研究水資源恢復及再利用的技術將成為可行的貿易運作方式。因此， 改善污水水質的研究將是未來關注的熱點。水不在是自然界的廉價溶劑，而是易于污染難于凈化的材料,一旦擴散到環(huán)境中將會侵入生物圈的各個部分。污染物僅僅是被置于錯誤地方的一種物質,因而,科研的目的就是將它們保存在安全無害的。避免和最小化是是污染物去處的前期步驟。當然,避免

55、在這樣一個任何變化都會導致嚴重結果的星球上是不可能具有選擇性的。另外， 所謂避免也指簡單的液相與氣相之間的轉化。液相與氣相污染物的消除都分別存在其利害關系。但值得注意的是，氣體污染物的去除的發(fā)展遠先進于水中COD 的去除。因此，液相中污染物的去除是值得關注的。由于研究不能面面俱到，第三步可以從前兩步驟中得到借鑒。徹底清潔是昂貴的， 即使你有一個成本高效的途徑，它仍然會降低資產(chǎn)回報和降低經(jīng)濟合理性目前， 水資源循環(huán)利用的最優(yōu)技術便是膜技術。它是唯一能夠利用化學工藝產(chǎn)生充分清潔滲透作用的技術。但是膜技術難以單獨運行，大都依賴于上向流過濾和處理向下流中含污染物的滯留物的技術。由此， 要在水質提高工藝

56、中做到面面俱到就要求多種工藝綜合運用。因此，廢水水質提高的大體規(guī)則如下：盡可能避免污染，考慮所有使污染最小化的措施。隔離受污染水體。源頭處理河水，高濃度低流量。在完整的處理周期中測量和鑒定污染物。找到運行管理費用的最高值，盡量 使其與常規(guī)費用相接近。本篇論文將要考慮到受污水影響的工業(yè)以及處理滯留物的技術，滯留物包括由污水管道排出的污染物。本文將要闡述需要克服的問題及解決問題過程中應用技術多樣化的程度。另外解釋了價格控制員如何影響未來技術的發(fā)展方向。2工業(yè)處理工業(yè)龐大的污水出流量。這些處理工業(yè)涉及污水處理的諸多領域，列舉一些示例如下：精練廠將原油送往煉油廠的過程中會對水體造成污染。無論是由海面鉆

57、探平臺引出的輸油管道被水沖刷干凈；還是儲油船的壓艙水都會帶來一系列水質改良問題?；瘜W藥品合成媒介或特殊化學藥品在烘干前常需大量清水沖掉雜質或殘余可燃性溶媒。石油化工產(chǎn)品乙烯車間需要去除生產(chǎn)過程中形成的酸性氣體。在通過高溫分解來提高加工選擇性之前添加硫化物更加劇了這一情形。慣常采用腐蝕性擦洗的辦法引發(fā)了大量廢水處理的問題。藥物和農用化學品這些工業(yè)在合成時需要沖洗步驟，包括以水為基礎的表面活性劑和濕介質。食品和飲料清潔工藝需水，產(chǎn)生BOD,COD。紙漿和造紙生產(chǎn)過程中大量用水-除了標準牛皮紙?zhí)幚砑垵{，漂白階段需要水合過氧化物和酶。所以充分了解人類社會活動怎樣對水質造成的污染是至關重要的，一份市政處理廠流速的調查顯示了未經(jīng)處理工業(yè)廢水的重要影響。3.處理技術去除出流水體COD 和污染物的處理技術如圖2 所示。這些可行的或處于發(fā)展中的工藝示例2,6,8依據(jù)大體的反映機理規(guī)則可被劃分為幾類。如果催化工藝中的吸附過程被忽略的話，則分類如下：生物催話作用以空氣/氧為基礎的接觸反應化學氧化無催化作用的化學藥劑氧化利用 _OH 或活性氧轉移的催化作用生物催化作用在市政污水處理中發(fā)揮了極佳的作用，為去除水中有機物提供了經(jīng)濟高效的途徑。在使用不同種類的細菌來增加技術的靈活性方面取得了很大進展。 一個遺留問題-怎樣處置脫水后的活性污泥。污泥量意味著這