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1、Technical NoteRemoval of organic compounds during treating printing and dyeing wastewater of different process unitsJ. Wang a,*, M.C. Long a, Z.J. Zhang a, L.N. Chi a, X.L. Qiao a, H.X. Zhu b, Z.F. Zhang ca College of En

2、vironmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China b Insitute of Light Industry and Food Engineering, Guangxi University, Nanning 530004, China c Shaoxing Wastewater Treatment Deve

3、lopment Co., Ltd., Shaoxing 312074, ChinaReceived 13 March 2007; received in revised form 1 October 2007; accepted 1 October 2007 Available online 13 November 2007AbstractWastewater in Shaoxing wastewater treatment plant

4、 (SWWTP) is composed of more than 90% dyeing and printing wastewater with high pH and sulfate. Through a combination process of anaerobic acidogenic [hydraulic retention time (HRT) of 15 h], aerobic (HRT of 20 h) and flo

5、cculation–precipitation, the total COD removal efficiency was up to 91%. But COD removal efficiency in anaerobic acido- genic unit was only 4%. As a comparison, the COD removal efficiency was up to 35% in the pilot-scale

6、 upflow anaerobic sludge bed (UASB) reactor (HRT of 15 h). GC–MS analysis showed that the response abundance of these wastewater samples decreased with their removal of COD. A main component of the raw influent was long-

7、chain n-alkanes. The final effluent of SWWTP had only four types of alkanes. After anaerobic unit at SWWTP, the mass percentage of total alkanes to total organic compounds was slightly decreased while its categories incr

8、eased. But in the UASB, alkanes categories could be removed by 75%. Caffeine as a chemical marker could be detected only in the effluent of the aerobic process. Quantitative analysis was given. These results demonstrated

9、 that GC–MS analysis could pro- vide an insight to the measurement of organic compounds removal. ? 2007 Elsevier Ltd. All rights reserved.Keywords: Alkane(s); Degradation; GC–MS; Industrial wastewater; Toxicity; Upflow a

10、naerobic sludge bed (UASB)1. IntroductionSecondary wastewater treatment plants (WWTPs) are being built rapidly throughout the world, especially in developing countries (Qian, 2000). However, toxicants in WWTP influent ma

11、y inhibit the biological activity of the activated sludge and cause treatment process upsets. For example, Jo ¨nsson et al. (2000) showed that 45–60% of the 109 Swedish WWTPs found received wastewater contain- ing i

12、nhibitory substances. WWTPs are designed to treat municipal and industrial wastewaters, which generally do not have an effect on the microorganisms involved in the biological treatment process. However, industrial wastes

13、contain inhibitory or toxic substances. With the develop- ment of industry, plant effluents become more complex mixtures for interactive effects chemicals. On the other hand, the inhibition mainly depends on the mode of

14、appli- cation and the biodegradability of the potential inhibitory compound. So, it is necessary to know which kind of main components has potential toxicity. Monitoring the toxicity of complex influent of WWTP can provi

15、de an early warning for the depressed perfor- mance of the microbial treatment process. And it is crucial that the realistic effects on biota of these complex industrial effluents must be estimated. Toxicity assessment m

16、ethods were used as microcalorimetry, titration bioassays, respi- rometry, the Microtox? assay, whole-cell sensors, and molecular-based biosensors and assays (Dalzell et al., 2002; Ren, 2004; Ren and Frymier, 2005). Howe

17、ver, in many cases it is unfortunate that there is no correlation0045-6535/$ - see front matter ? 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2007.10.001* Corresponding author. Tel.: +86 21 3420 078

18、4; fax: +86 21 5474 7368. E-mail address: wangjin100@sjtu.edu.cn (J. Wang).www.elsevier.com/locate/chemosphereAvailable online at www.sciencedirect.comChemosphere 71 (2008) 195–202were extracted by methylene dichloride i

19、nto acid, base and neutral fractions, and then qualitatively analyzed by USEPA Method 8270C (USEPA, 1996b) with an Agilent 6890/5973 GC–MSD (Mass Spectrometer Detector) equip- ment. Internal standard method was employed

20、for quanti- tative analysis. The analytical conditions were: a MSD, the capillary column model number was Agilent 19091S-433 which was made of quartz with nominal diameter of 0.25 mm, nominal film thickness of 0.25 lm an

21、d length of 30 m packed with 5% phenyl methyl siloxane; front inlet was splitless; total flow was 4.3 ml min?1; and the temperature for the gasification compartment was 280 ?C. The temper- ature control program registere

22、d initial 40 ?C, retaining for four min, then increasing to 300 ?C with an increment of 8 ?C min?1, total run time was 46 min; the temperature for MS quad was 150 ?C and for MS ion source was 230 ?C, electron energy was

23、70 eV, resulting in electron multiplier voltage was 2105.9 V, scan parameters were 35–500 lm. Compounds were identified from their molecu- lar fragmentation and quantified from the peak area of their major fragment ions,

24、 according to the instrument library (NIST 98.L) database.3. Results3.1. Performance of the treatment at SWWTPThe anaerobic acidogenic reactor (anaerobic baffled reactor) with total volume of 200000 m3 at SWWTP had 3–3.5

25、 g SS l?1 (2.3–2.6 g VSS l?1). The reactor was kept at HRT of 15 h. The aerobic reactor (aerobic plug flow reac- tor) with total volume of 270000 m3 at SWWTP had 2.5– 3 g SS l?1 (2.1–2.5 g VSS l?1). The reactor was kept

26、at HRT of 20 h. According to the indices [determined accord- ing to Monitoring Methods (Editorial Board of Environ- ment Protection Bureau of China, 2002)] were obtained from the operation of practical engineering projec

27、t of SWWTP over the year 2005–2006. The average COD con- centration of raw influent was 1340 mg l?1, and that of anaerobic effluent still remained 1283 mg l?1 at SWWTP. The value of effluent from aerobic unit was 234 mg

28、l?1. The total COD removal efficiency was 91% after floccula- tion–precipitation. Final effluent could be discharged below the discharging limit, and the majority of COD was removed by the aerobic process unit, while the

29、 removal efficiency of anaerobic acidogenic was very low. The ABR (anaerobic baffled reactor) of SWWTP is an anaerobic bio- membrane reactor with many stirrers. Its stirrers tangled with its padding gradually. One year a

30、fter the operation, the ABR became short circuit and its removal efficiency of COD became very low.3.2. Performance of the pilot-scale UASB reactorThe pilot-scale UASB was inoculated with landfill anaerobic sludge after

31、one year of digestion. Fig. 2 summa-rizes the variations in influent and effluent COD concentra- tion of the UASB reactor working for 400 d. The wastewater treated in the UASB was practical wastewater of SWWTP. It can be

32、 seen from Fig. 2 that, there was 35% COD reduction in UASB. COD decreased on the average from 1340 to 869 mg l?1. The values of pH, sulfides/H2S, and volatile fatty acids (VFAs) had only very little change between influ

33、ent and effluent of anaerobic acidogenic reac- tor at SWWTP. However, the pH of UASB decreased aver- age 1.51; VFAs decreased from average 174 to 126 mg l?1expressed in acetate, and the mean increase of sulfides includin

34、g H2S was 105 mg l?1. However, the concentration of H2S should be very low and had no inhibition on the anaerobic process because H2S would transform to sulfides under high alkalinity and pH value in the influent and ana

35、erobic effluent. The COD of terephthalic acid (TA) accounted for 40– 60% total COD of SWWTP’s wastewater. TA was readily biodegradable under aerobic conditions while relatively difficult to be decomposed under anaerobic

36、conditions (Guan et al., 2003). In addition, the printing and dyeing wastewater contained lots of toxic compounds with high pH (9.14–10.21) and high sulfate concentration (about 500 mg l?1). Further, the HRT of 15 h was

37、short which was controlled by the future renovation of the equalization ponds at SWWTP, the diminished COD of 471 mg l?1should be better and steady result of the reactor.3.3. GC–MS analysisIn order to further investigate

38、 the removal of different organic compounds and their biodegradability in different process units, GC–MS analysis was performed. The chro- matograms of practical influent and effluent at SWWTP are shown in Figs. 3 and 4a

39、 and the effluent of the UASB reactor is presented in Fig. 4b. The further details of organic components are presented in Tables 1 and 2.60 120 180 240 300 360 4206009001200150018002100COD (mg l -1)Time (d)InfluentEfflue

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