外文翻譯--污水污泥處理濕地的重金屬分離和有機質(zhì)穩(wěn)定化（英文）

1、Ecological Engineering 37 (2011) 771–778Contents lists available at ScienceDirectEcological Engineeringjournal homepage: www.elsevier.com/locate/ecolengHeavy metal fractionation and organic matter stabilization in sewage

2、 sludge treatment wetlandsEleonora Peruzzi a,?, Grazia Masciandaro a, Cristina Macci a, Serena Doni a, Sandra G. Mora Ravelo b, Paolo Peruzzi c, Brunello Ceccanti aa National Council Research – Institute for Ecosystem St

3、udies (CNR-ISE), via Moruzzi 1, Pisa 56124, Italyb COLPOS, Km. 36.5 Carretera Mexico-Texcoco Montecillo Edo. de México 56230, Mexicoc ACQUE S.p.A., via Bellatalla 1, Pisa 56100, Italya r t i c l e i n f oArticle his

4、tory:Received 17 November 2009Received in revised form 31 May 2010Accepted 31 May 2010Available online 14 July 2010Keywords:Sludge treatment wetlandSludge stabilizationPyrolysisHeavy metal fractionationa b s t r a c tThe

5、 presence of heavy metals in sludge stabilized in a reed bed system may affect its use for agriculturalpurposes. However, the environmental impact of sludge depends on the availability and phytotoxicity ofthese heavy met

6、als.The aim of this research was to determine the effectiveness of a reed bed (Phragmites australis) sludgetreatment system in two urban wastewater treatment plants in Italy after a three-year period of oper-ation: (i) b

7、y estimating the process of sludge stabilization, following conventional and nonconventionalparameters related to the evolution of organic matter quality (water soluble carbon, dehydrogenase activ-ity, pyrolytic fragment

8、s); (ii) by following the heavy metal bioavailability in the sludge through theirfractionation. For heavy metal fractionation, the Community Bureau of Reference (BCR) was followed.The results showed that there was minera

9、lization and stabilization of sludge over time, suggestedby the decrease of about 35% in water soluble carbon and of about 60–80% of dehydrogenase activity.Moreover, significant values of benzene (17%), toluene (31%) and

10、 phenol (9%) were found at the end ofexperimentation in both treatment wetlands, highlighting the re-synthesis of humic-like matter.The results also showed that the content of heavy metals after 30 months was associated

11、with the lessmobile fractions of the sludge (more than 60% of total heavy metal content for almost metal), in particular,the fraction linked to the organic matter.© 2010 Elsevier B.V. All rights reserved.1. Introduc

12、tionThe treatment and disposal of sludge represents a bottleneck ofwastewater treatment plants all over the world due to environmen-tal, economic, social and legal factors. There is therefore a growinginterest in develop

13、ing technologies, such as sludge treatment wet-lands (TWs), to treat sewage sludge or biosolids with reduced costand low environmental impact.Sludge treatment wetlands have been successful since the late1980s in Europe (

14、Uggetti et al., 2010). They are an alternative tech-nology for municipal (Barbieri et al., 2003; Lienard et al., 1995;Nielsen, 2003) and agriculture sludge and slurries (Edwards et al.,2001).? Corresponding author. Tel.:

15、 +39 050 3152483; fax: +39 050 3152473.E-mail addresses: eleonora.peruzzi@ise.cnr.it (E. Peruzzi),grazia.masciandaro@ise.cnr.it (G. Masciandaro), cristina.macci@ise.cnr.it(C. Macci), serena.doni@ise.cnr.it (S. Doni), sgm

16、ora@colpos.mx (S.G.M. Ravelo),p.peruzzi@acque.net (P. Peruzzi), brunello.ceccanti@ise.cnr.it (B. Ceccanti).Sludge treatment wetlands, also known as sludge treatmentreed beds, are a combination of a traditional sludge dry

17、ing bedand natural wetland: Phragmites australis is directly planted in thedrying beds, where sludge is frequently applied. This technologyinvolves low construction costs, minimal daily maintenance, waterreduction conten

18、t and good stabilization of biosolids (Burgoon etal., 1997).P. australis is a tall annual grass with an extensive perennial rhi-zome and it is well suited to sludge dewatering (De Maeseneer,1997; Kim and Smith, 1997; Nas

19、sar et al., 2006), as it is extremelytolerant to variable environmental conditions and has a high evap-otranspiration rate (Chazarenc et al., 2003). It is also capable ofcreating aerobic micro sites near roots in an othe

20、rwise anaerobicenvironment of the sludge bed; this affords a rapid stabilization andmineralization of the sludge (Hardej and Ozimek, 2002). Indeed,aerobic conditions are maintained year-round and physical sur-face hinder

21、ing is prevented by roots (Kim and Smith, 1997). Thesludge–plant–microorganism system, in fact, is effective in stabiliz-ing sludge by means of two concomitant processes: mineralizationand humification of organic matter

22、(Peruzzi et al., 2009). However,0925-8574/$ – see front matter © 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.ecoleng.2010.05.009E. Peruzzi et al. / Ecological Engineering 37 (2011) 771–778 773Table 2Chemica

23、l characteristics (means and deviation standard) of the influent sludge in TW 1 and TW 2. pH; total solids (TS) (g/L); volatile solids (VS) (%); total nitrogen (TN) (% dw); total organic carbon (TOC) (% dw); heavy metalt

24、otal content (mg dw/kg).pH TS (g/L) VS (%) TN(% dw) TOC(% dw) Cr(mg/kg dw) Cu(mg/kg dw) Ni(mg/kg dw) Cd(mg/kg dw) Pb(mg/kg dw) Zn(mg/kg dw)TW 1 (Colle di Compito) 6.7 ± 0.8 1.6 ± 0.3 96.4 ± 1.2 8.7 ±

25、1.4 79.2 ± 5.9 70 ± 18 357 ± 121 32 ± 17 <3 143 ± 26 905 ± 203TW 2 (Pittini) 7.1 ± 0.5 1.3 ± 0.4 97.9 ± 0.8 9.9 ± 1.3 83.3 ± 5.4 25 ± 12 301 ± 98 23

26、77; 15 <3 37 ± 19 510 ± 106(Ceccanti et al., 2007; Marinari et al., 2007). A ratio of the peaks’relative abundances was determined as an index of energetic reser-voir AL/AR (aliphatic to aromatic compounds,

27、the former are thesum of acetic acid, furfural and acetonitrile, the latter the sumof benzene, toluene and phenol). This index evaluates the labileand stable parts of organic matter. In addition, a numeric index ofsimila

28、rity (Sij) between the relative abundances (I) of the homol-ogous peaks (k) in two pyrograms (i and j) was calculated asfollows: Sij = (? (Ii/Ij)k)/n with Ii < Ij, and n is the number of thepeaks. The index of similar

29、ity Sij compares a pair of pyrogramswithout discriminating peaks. The index varies in the range of0–1: the higher the value, the greater the similarity. However,three conventional levels, high (0.75–0.85), middle (0.70–0

30、.75)and low (0.60–0.70) have been suggested for the characteriza-tion of heterogeneous materials such as soil organic matter andcompost (Ceccanti et al., 2007).The procedure for fractionation differentiated the sludge he

31、avymetals into four fractions:1. Exchangeable fraction associated with carbonated phase(Fraction 1). Metals are adsorbed on the sludge components andFe and Mn hydroxides. This is the most mobile fraction potentiallytoxic

32、 for plants.2. Reducible fraction associated with Fe and Mn oxides(Fraction 2). Heavy metals are strongly bound to these oxidesbut are thermodynamically unstable in anoxic and acidicconditions.3. Oxidisable fraction boun

33、d to organic matter (Fraction 3). Itis well known that metals may be complexed by natural organicsubstances. These forms become soluble when organic matter isdegraded in oxidising conditions. This fraction is not conside

34、redto be bioavailable and mobile because the metals are incorporatedinto stable high molecular weight humic substances, which releasesmall amounts of metals very slowly.4. Residual fraction (Fraction 4). The residual sol

35、ids mainly con-tain primary and secondary solids that occlude the metals in theircrystalline structures. It is considered to be unextractable and in aninert form.For heavy metal fractionation the Community Bureau of Ref-

36、erence (BCR) method was followed (Mocko and Waclawek, 2004):heavy metals are divided into acid-soluble/exchangeable, reducibleand oxidisable fractions, while the residual fraction was obtainedby difference between the to

37、tal element concentration in thesludge and the sum of concentrations of all extracted fractions.The sequential extraction procedure was carried out step by stepas follows: (1) 40 ml CH3COOH 0.11 M per 1 g of dry sample w

38、asshaken overnight at a temperature of 25 ?C; the extraction mix-ture was centrifuged (3000 rpm for 30 min) and the supernatantwas transferred. The residue was washed with distilled water,shaken and centrifuged, and the

39、supernatant was discarded. (2)40 ml of NH2OH·HCl (adjusted to pH = 2 with HNO3) was added tothe residue and extracted overnight. Then the same proceduresof step one were followed. (3) 10 ml of H2O2 8.8 M was addedto

40、 the residue and digested for 1 h at 25 ?C; 10 ml of H2O2 8.8 Mwas added for 1 h at 85 ?C in a water bath; the solution was evap-orated to few milliliter and the residue was extracted overnightwith 50 ml of CH3COONH4 1 M

41、 (adjusted to pH = 2 with HNO3) at atemperature of 25 ?C. Then the same procedures of step one werefollowed. The heavy metal concentration analysis was performedby atomic absorption spectrometry using a ContrAA300 (Analy

42、ticalJena) spectrometer with air/acetylene flame.All results reported in the text are the means of determina-tions made on five replicates for Colle di Compito TW 1, on sixreplicates for Pittini TW 2 and on five replicat