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This article appeared in a journal published by Elsevier. The attached
copy is furnished to the author for internal non-commercial research
and education use, including for instruction at the authors institution
and sharing with colleagues.
Other uses, including reproduction and distribution, or selling or
licensing copies, or posting to personal, institutional or third party
websites are prohibited.
In most cases authors are permitted to post their version of the
article (e.g. in Word or Tex form) to their personal website or
institutional repository. Authors requiring further information
regarding Elsevier’s archiving and manuscript policies are
This paper presents a brief review of the inter na tional sci en tific lit er a ture of poly bro mi nated diphenyl ethers (PBDEs) and poly bro-mi nated biphe nyls (PBBs) in sew age sludge and a sur vey of these com pounds in sew age sludge from 16 Aus tra lian waste wa ter treat-ment plants (WWTPs). This research was under taken because of con cerns raised by the Aus tra lian waste water indus try regard ing organic con tam i nants in sew age sludge, in par tic u lar the bro mi-nated flame retar dants (BRFs).
Due to the wide spread use of poly bro mi nated diphenyl ethers (PBDEs) as fire retar dants in a wide range of prod ucts and as a result of their chem i cal prop er ties, these com pounds have now accu mu-lated within many envi ron men tal com part ments. This includes the accu mu la tion of PBDEs within living organ isms, result ing in the expo nen tial increase in con cen tra tion in humans over the past 25
years (Nor én and Mei ronyte, 2000). The sci en tific evi dence over-whelm ingly sup ports the argu ment that PBDEs are can di dates for inclu sion in United Nations Envi ron ment Programme’s (UNEP) Stock holm Con ven tion on Per sis tent Organic Pol lu tants (POPs), i.e., they are envi ron men tally per sis tent (Law et al., 2006), capa ble of long-range atmo spheric trans port (Sch mid et al., 2007), bio ac cu-mu late (Harden et al., 2005) and are bio log i cally active (McDon ald, 2002). There fore, it is cru cial to know the lev els and envi ron men-tal fate of PBDEs. Sew age sludge is an impor tant medium requir ing mon i tor ing for chem i cal pol lu tion, as one of the respon si bil i ties of waste wa ter treat ment is to pre vent the (re)release of chem i cal pol-lu tants into the envi ron ment, and sew age sludge is an impor tant sink for POPs. The anal y sis of sew age sludge for POPs pro vides valu-able infor ma tion about chem i cal pol lu tion and the risk asso ci ated with the re-use of sew age sludge as bi os o lids for land appli ca tion.
PBDEs are a class of BFR that have been man u fac tured in three com mer cial for mu la tions, sold under the name of the prom i nent homo logue, i.e., pen ta BDE, oc ta BDE and deca BDE. These com-mer cial for mu la tions con tain many BDE cong en ers (BSEF, 2005). In many nations, the use of PBDE fire retar dants is being phased out – in par tic u lar, the pen ta BDE and oc ta BDE for mu la tions. Their use has been restricted in many parts of Europe, Japan, some states
Polybrominated diphenyl ethers and polybrominated biphenyls in Australian sewage sludge
Bradley Clarke a,b, Nichola Porter a,b,*, Robert Symons c, Philip Marriott a, Peter Ades d, Gavin Stevenson c, Judy Blackbeard b
a School of Applied Sci ences (Bld 3 Level 1), RMIT Uni ver sity, Mel bourne, Vic to ria, Aus tra liab Co-oper a tive Research Cen tre for Water Qual ity and Treat ment – Waste wa ter Pro gram, Mel bourne, Vic to ria, Aus tra liac National Mea sure ment Insti tute, Syd ney, NSW, Aus tra liad School of For est and Eco sys tem Sci ence, Uni ver sity of Mel bourne, Park ville, Vic to ria, Aus tra lia
a r t i c l e i n f o a b s t r a c t
Article history:
Received 7 March 2008
Received in revised form 29 May 2008
Accepted 3 June 2008
Available online 3 August 2008
This paper presents a brief review of the inter na tional sci en tific lit er a ture of poly bro mi nated diphenyl
ethers (PBDEs) and poly bro mi nated biphe nyls (PBBs) in sew age sludge and a sur vey of these com pounds
in sew age sludge from 16 Aus tra lian waste wa ter treat ment plants (WWTPs). The PBDE mean con cen tra-
tion in the Aus tra lian study was 1137 g kg¡1 dry weight (d.w.) (s.d. 1116) and ranged between 5 and 4
230 g kg¡1 d.w. The urban mean of 1308 g kg¡1 (s.d. 1320) and the rural mean of 911 g kg¡1 (s.d. 831)
are not sta tis ti cally dif fer ent and are sim i lar to lev els in Euro pean sludges. Prin ci pal com po nents anal y-
sis was per formed on the data set and revealed that 76% of the data var i a tion could be explained by two
com po nents that cor re sponded to over all con cen tra tion of the pen ta BDE and the deca BDE com mer cial
for mu la tions. An anal y sis of var i ance was per formed com par ing PBDEs lev els at three WWTPs over the
years 2005 and 2006, find ing dif fer ences between treat ment plants (BDE-47) but no sig nifi cant dif fer ence
in PBDE lev els in the years 2005 and 2006. Low lev els of BB-153 were detected in all sam ples of this sur-
vey (n = 16); mean 0.6 g kg¡1 d.w. (s.d. 0.5). This com pound has rarely been reported in any other study
of sew age sludges under taken outside Aus tra lia. This work high lights the need for a risk assess ment of
PBDEs in sew age sludge when used for land appli ca tion, tak ing into account typ i cal lev els found in Aus-
B. Clarke et al. / Chemosphere 73 (2008) 980–989 981
of the USA as well as in Aus tra lia (BSEF, 2005; NIC NAS, 2007). The man u fac ture and use of PBBs was largely curbed in the 1970s as a result of a seri ous human con tam i na tion inci dent in Mich i gan, USA (IPCS, 1994). Sim i lar to the PBDEs, PBBs were man u fac tured in three main com mer cial for mu la tions that was sold under the name of the prom i nent homo logue, i.e., hexa BB, oc taBB and de caBB (IPCS, 1994). The pro duc tion of PBBs has been phased out inter na tion ally with the last PBBs man u fac tured in France in 2000 (de Wit, 2002). How ever, the global demand for other BFRs con tin ues to grow sub-stan tially with the increas ing usage of organic poly mer mate ri als in con struc tion, elec tronic and com puter equip ment. The global mar ket for BFRs grew from 145000 ton nes in 1990 (Pet ti grew, 1994), to over 310000 ton nes in 2000 (BSEF, 2005).
PBDEs first gained prom i nence as potential haz ards in the late 1990s when the expo nen tial increase of PBDE lev els in Swed ish mother’s milk over a 25-year period, increas ing from 0.07 ng g¡1 lipid in 1972 to 4.02 ng g¡1 lipid in 1997 (Mei ronyte et al., 1999). In gen eral, the total PBDE con cen tra tions in humans have increased by a fac tor of »100 dur ing the last 30 years (Hites, 2004). This accu mu la tion of PBDEs in humans is caus ing con cern among sci-en tists and reg u la tory author i ties (Harden et al., 2005; Schec ter et al., 2006; Har rad and Porter, 2007; Schu hm ach er et al., 2007; She et al., 2007). The Aus tra lian Gov ern ment Depart ment of Envi-ron ment and Her i tage com mis sioned a study mea sur ing PBDE lev els in human milk sam ples col lected in 2002/2003. The mean con cen tra tion of PBDEs was 11 ng g¡1 expressed on a lipid basis and ranged between 6.0 ng g¡1 and 18 ng g¡1. On a world wide basis, the lev els of PBDE com pounds detected in breast milk are higher than those lev els observed in Europe and Japan but lower than those observed in North Amer ica and Can ada (Harden et al., 2005).
Assess ment of health risks asso ci ated with PBDE human accu-mu la tion and expo sure is com pli cated and to date has not been ade quately char ac ter ized. How ever the potential risks asso ci ated with expo sure to the most bio-active cong en ers (tri- to octa-BDE) include thy roid hor mone dis rup tion, neuro-devel op men tal defects and can cer (Darne rud et al., 2001; McDon ald, 2002). Sev eral stud-ies have shown that PBDEs share the gen eral prop erty of org ano-hal o ge nated com pounds in which in vivo expo sure of rodents results in reduc tion of serum total and free thy roid hor mone (thy-rox ine (T4)) lev els (McDon ald, 2002). The impli ca tions of altered thy roid hor mone func tion, par tic u larly dur ing early devel op ment, are pro found and have been hypoth e sized to lead to dis rupted brain devel op ment and per ma nent neu ro log i cal dam age (Le gler and Brou wer, 2003).
Cur rently there are no guide lines, either within Aus tra lia (NRMMC, 2004) or inter na tion ally (US EPA, 1999; Euro pean Com-mis sion, 2001), that reg u late or pro pose per mis si ble lev els of PBDEs or PBBs in sew age sludge for land appli ca tion. This arti cle sum ma rizes the sci en tific lit er a ture on PBDEs and PBBs lev els in sew age sludge and presents results of an Aus tra lian sew age sludge sur vey con ducted in 2006. All data reported are on dry weight (d.w.) basis unless otherwise stated.
2. His tor i cal lev els of PBDEs and PBBs in sew age sludge
There is a rel a tively small set of sci en tific lit er a ture that exam-ines the issue of PBDEs and PBBs in sew age sludge. The data sug gest that the use of PBBs has not resulted in the wide spread dis tri bu tion of PBBs in either the envi ron ment or in sew age sludge (de Wit, 2002). In con trast, the con cen tra tion of PBDEs in envi ron-men tal matri ces has increased dra mat i cally since mea sure ments were begun, and they are now found to be accu mu lat ing in most envi ron men tal com part ments, includ ing sew age sludge (de Wit, 2002). There have been com pre hen sive stud ies in Aus tra lia inves-ti gat ing PBDEs in envi ron men tal matri ces (Toms et al., 2006); how-
ever, there have been no stud ies focus ing spe cifi cally on sew age sludge. This review of the inter na tional body of work exam in ing PBDEs in sew age sludge should aid under stand ing the typ i cal lev-els of PBDEs in sludge, as well as the sources and envi ron men tal fate of these com pounds. PBDEs and PBBs are assumed to cir cu late within the envi ron ment in much the same way as other per sis tent hal o ge nated com pounds.
2.1. Poly bro mi nated diphenyl ethers
PBDEs were first detected in sew age sludge and other envi ron-men tal sam ples in 1979 from sam ples col lected near chem i cal man u fac tur ing sites in the USA (de Car lo, 1979). It was not until 1992 that the con cen tra tion of PBDEs was first reported. The con-cen tra tion of BDE-47 & -99, both com po nents of the pen ta BDE for mu la tion, were mea sured in Swed ish sludge (n = 2, 15 g kg¡1 and 19 g kg¡1, respec tively) (Nyl und et al., 1992). These lev els were sim i lar to those reported from Ger man sludges (n = 13), with a mean penta-BDE of 8.58 g kg¡1 and ranged from 0.22 to 17.13 g kg¡1 (Ha gen ma ier et al., 1992). The con sis tent pres ence of poly bro mi nated dib enzofu rans (PBDF) at rel a tively high con cen tra-tions (rang ing from 0.21 to 3.05 g kg¡1 and a mean of 1.17 g kg¡1) was reported, which are sim i lar to the con cen tra tions of the chlo-ri nated di ox ins and furans (Rap pe et al., 1998). They reported “a rea son ably good cor re la tion between the con cen tra tions of PBDFs and PBDEs” and sug gested that the PBDEs are the source of PBDFs observed in sludge. This is extremely impor tant and requires more research, as PBDFs share the same level of tox ic ity as the chlo ri-nated furans (IPCS, 1989, 1998).
The con cen tra tions reported in those Swed ish and Ger man sludges in 1992 is low when com pared to sludges ana lysed in the late nine ties from var i ous nations. For exam ple, the sludge sam ples col lected in Swe den in 1997–1998 (n = 3) reflect con cen tra tions of PBDEs in sludge more typ i cal of those in con tem po rary sludges con-tain ing a mean con cen tra tion of BDE-47 of 65 g kg¡1 and BDE-209 of 220 g kg¡1 (Sell strom et al., 1999; de Wit, 2002). These results show a higher bur den of BDE-209 com pared to the other cong en ers BDE-47 & -99, from the pen ta BDE for mu la tion. The dom i nance of BDE-209 was reported again in Swiss sludges (n = 8) (Koh ler et al., 2003). Also reported is the increase in con cen tra tion from an aver-age BDE-209 con cen tra tion of 220 g kg¡1 in 1993 to 1100 g kg¡1 in 2002, an increase of 560%.
In 2001, the total con cen tra tion of penta-BDEs in USA bi os o-lids ranged between 1100 and 2290 g kg¡1 and sug gested that the input was con sis tently high, regard less of the region and irre-spec tive of preliminary treat ment. These lev els are far higher than pre vi ously reported and exceeded those in Euro pean sludges by 10- to 100-fold. This was attrib uted to the much higher use of PBDEs, both the pen ta BDE and the deca BDE for mu la tions, within the USA. Unlike BDE-99, BDE-209 var ied widely among the bi os-o lids ana lysed rang ing from 84.8 to 4890 g kg¡1. Fur ther stud ies of PBDEs in USA sludges found a mean PBDEs con cen tra tion of 1540 g kg¡1 in 2002 (Hale et al., 2002) and max i mum con cen tra-tion of PBDE of 3 955 g kg¡1 in 2004 (North, 2004).
BDE-209 was the dom i nant PBDE in Span ish sludges (n = 6) col-lected in 2002, com pris ing >95% of the PBDE bur den. (Fa brel las et al., 2004). An indus trial sew age sludge sam ple from this Span ish study had a con cen tra tion of BDE-209 of 18032 g kg¡1 that is the high est reported to date. The total tri- to hexa-BDE lev els are low rel a tive to deca-BDE (5.3 and 177.3 g kg¡1, respec tively), but are sim i lar to con cen tra tions reported in other stud ies. The con cen tra-tion of PBDEs in Swed ish sludges ana lysed by the Swed ish EPA and reported by Law et al. (2006) again found that BDE-209 was the dom i nant spe cies. The con cen tra tion was highly var i able rang ing from 5.6 to 1000 g kg¡1 (Law et al., 2006). Con cen tra tions of the lower bro mi nated PBDEs were fairly sim i lar in all sew age sludge
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982 B. Clarke et al. / Chemosphere 73 (2008) 980–989
sam ples, indi cat ing dif fuse leach ing of these from prod ucts into waste wa ter streams (Law et al., 2006).
Knoth mea sured the con cen tra tion of PBDEs in 39 sludge sam-ples from dif fer ent stages of the WWTP pro cess from 11 municipal waste wa ter treat ment plants in Ger many, col lected from March 2002 to June 2003. The con cen tra tion of lower bro mi nated cong-en ers was fairly con sis tent, while the BDE-209 con cen tra tion once again var ied widely between 97 and 2217 g kg¡1 (mean 256 g kg¡1) and was again the most prevalent con ge ner detected (Knoth et al., 2007). No change in the tri- to hepta-BDE con ge ner pro file ratios was observed (% of total BDE-28, -47, -99, -153, -154, -183 with out -209) in sludge from dif fer ent stages of the waste water treat ment pro cess (primary sludge, sec ond ary excess sludge and de wa tered digested sludge), which sug gested that the deg ra-da tion of BDE-209 and other higher bro mi nated PBDEs to lower bro mi nated cong en ers did not occur.
Sludge sam ples col lected from 31 WWTPs in 26 cit ies in China report a low bur den of PBDEs (Wang et al., 2007). These lev els are about 10–100 times lower than those found in Europe and North Amer ica. PBDE lev els in sludge were not found to depend on the loca tion or treat ment capac ity of the WWTPs.
To sum ma rize, the major cong en ers pres ent in sew age sludge are BDE-47, -99 and -209 and the PBDE con cen tra tions are typ i-cally pres ent in the g kg¡1 to the low mg kg¡1 range. These cong-en ers rep re sent the major com mer cial for mu la tions of pen ta BDE (BDE-47, -99) and deca BDE (BDE-209), which appear to be the original source. The reported con cen tra tions of these cong en ers in the sci en tific lit er a ture is sum ma rised in Table 1.
2.2. Poly bro mi nated biphe nyls (PBBs)
The con cen tra tion of PBBs in sew age sludge has received little atten tion, pri mar ily because of the rel a tively low use of PBBs in man u fac tur ing. All the stud ies, except one (n = 4) that have inves-ti gated the lev els of PBBs in sludge, showed PBBs to be below the detec tion limit (de Car lo, 1979; de Boer et al., 2000, 2003). In 2000, PBBs were not detected in WWTP influ ent or e!u ent or other envi ron men tal sam ples ana lysed (de Boer et al., 2000). In 2003, de Boer et al. again ana lysed envi ron men tal sam ples for PBBs. This time they ana lysed the sam ples of in flu ents, e!u ents and sus pended par tic u late mat ter from a waste wa ter treat ment plant in the Neth er lands for BBs-15, -49, -52, -101, -153, -169 and -209 but these were, once again, below the detec tion limit (de Boer et al., 2003). The detec tion lim its for most PBBs were between <0.1 and <1 g kg¡1, but for BB-209 the detec tion lim its were gen er ally between <1 and <10 g kg¡1. This result is in agree ment with the neg li gi ble PBB pro duc tion in Europe over the past decades (de Boer
et al., 2003). BB-153, the main con ge ner in the hex ab ro mo bi phe-nyl com mer cial for mu la tion, was detected in Swed ish sludges in 2002, but unfor tu nately the results are pre sented on a wet weight basis mak ing com par i son impos si ble (Oberg et al., 2002). It was reported that BB-153 co-eluted with BDE-154. Ana lyt i cally, it has only been since the devel op ment of iso to pi cally labelled stan dards, and the advent of facil i ties with ultra-trace capa bil ity, using high-res o lu tion mass spec trom e try that the detec tion of PBBs has been pos si ble with a cer tain degree of cer tainty.
3. Sources of PBDEs in sew age sludge
Release of PBDEs into waste wa ter may occur dur ing their syn-the sis, dur ing incor po ra tion into poly mers or related fin ished prod ucts, dur ing their use and dis posal or recy cling of these prod-ucts, by cycling in the envi ron ment, or a com bi na tion of any of the above. As PBDEs are hydro pho bic, resis tant to deg ra da tion and widely used in prod ucts, it is log i cal to assume that some enter the waste wa ter treat ment plant pro cess and will sub se quently be con cen trated in high organic car bon-con tain ing sew age sludges. How ever, evi dence pub lished by de Boer et al. (2003) and North (2004) have indi cated that the com mon BDEs (-49, -99 and -209) are also pres ent in the WWTP e!u ent, or more spe cifi cally, the sus-pended organic mate rial.
Con stit u ents of pen ta BDE for mu la tion were detected in eleven sludges col lected from four dif fer ent regions of the USA. (Hale et al., 2001). The con cen tra tions (total of BDE-47, -99, -100, -153 and -154) were fairly con sis tent with con cen tra tions rang ing from 1100 to 2290 g kg¡1 despite dif fer ences in facil ity loca tion, indus-trial base and sludge sta bil iza tion pro cess. This sug gests that the source is domes tic in ori gin as it is con sis tently pres ent regard-less of region. In con trast, lev els of BDE-209 var ied sub stan tially between sam ples, rang ing between 84.8 and 4 890 g kg¡1, which sug gests that the source of this com pound is more random and derives from an indus trial or other var i able source. Another alter-na tive expla na tion is that BDE-209’s higher bio-de gra da bil i ty rel a-tive to other PBDEs (Bez ares-Cruz et al., 2004) may cause the high var i abil ity in con cen tra tion observed. The trend of con sis tent pen-ta BDE for mu la tion (BDE-47 & -99) con cen tra tions and highly var i-able BDE-209 con cen tra tions was observed in many other stud ies.
4. Meth ods
The aim of this research was to assess the typ i cal PBDE bur-den within Aus tra lian sew age sludges. To achieve this, two stud-ies were under taken. The first is a sur vey of the con cen tra tion of PBDEs in sew age sludge sam ples taken from 16 Aus tra lian WWTPs
Table 1
Con cen tra tion ( g kg¡1 dry weight) of PBDE-47, -99, -100 and -209 in sew age sludge from waste water treat ment plants reported in the English-lan guage peer reviewed
sci en tific lit er a ture
Coun try BDE-47 BDE-99 BDE-209 Ref er ence
Swe den 15, 15 19, 19 Nyl und et al. (1992)
Swe den 78, 80, 36 98, 100, 56 220, 270, 170 Sell strom et al. (1999)
USA 498, 754, 359, 525, 518, 673,
536, 605, 421, 686, 674
743, 1157, 513, 584, 714, 815, 516, 572, 391,
648, 613
308, 1460, 553, 84.8, 1940, 4890, 368 Hale et al. (2001)
Neth er lands 9.5, 11, 40 11, 14, 38 <180, 190, 8.6 de Boer et al. (2003)
Spain 83.6, 21.4, 28.3, 1.8, 49.8,
38.5
64.2, 23.4, 25.6, 37.6, 34.5, 5430, 756, 1203, 3591, 5837, 18632 Fa brel las et al. (2004)
China 5.0 (mean), 0.4 ! 58.7 4.5 (mean), <3.4 ! 69.7 68.5 (mean), <1 ! 1108.7 Wang et al. (2007)
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B. Clarke et al. / Chemosphere 73 (2008) 980–989 983
in 2006. The sec ond is an anal y sis of PBDE lev els in sew age sludge sam ples from three WWTPs over two suc ces sive years. PBDEs were quan ti fied using iso tope dilu tion inter nal stan dard high res-o lu tion gas chro ma tog ra phy/high res o lu tion mass spec trom e try (HRGC/HRMS). Anal y sis was under taken for the fol low ing PBDE cong en ers; BDE-17, -28&-33, -47, -49, -66, -77, -85, -99, -100, -119, -138&-166, -153, -154, -183, -184, -196, -197, -206, -207 and -209. The anal y ses were con ducted at the National Mea sure ment Insti-tute (NMI), Syd ney (Pym ble), Aus tra lia.
4.1. Sam pling meth od ol ogy
4.1.1. Aus tra lian sew age sludge sur vey 2006A sur vey of sew age sludge (n = 16) was con ducted with sam ples
col lected from each State and the North ern Ter ri tory of Aus tra lia dur ing 2006. Eight urban (pop u la tion >1000000) and eight rural (pop u la tion <300000) WWTPs were sam pled. Table 2 describes the treat ment pro cess for each of the par tic i pat ing WWTPs. Sew-age sludge sam ples were col lected by on-site work ers, who were pro vided with sam ple-kits con tain ing pre-cleaned amber-glass jars with Tefl on lined lids. Sam ples were sent via cou rier to NMI for anal y sis and freeze dried prior to sam ple treat ment.
4.1.2. Com par i son of PBDE lev els over timeThe con cen tra tion of PBDEs was mea sured in sludge sam ples
from three WWTPs (U6, U7 and U8), col lected in dupli cate, dur-ing the years 2005 and 2006. Sam ple col lec tion and anal y sis meth-ods were the same as for the Aus tra lian Sew age Sludge Sur vey described above.
4.2. Sam ple treat ment
Freeze dried sludge sam ples (20.0 g) were spiked with 10 l of mixed PBDE sur ro gate stan dards and were extracted into tol u ene using accel er ated sol vent extrac tion (Instru ment Model Dio nex ASE 100). The extracts were con cen trated using a Bu chi Syn core, which was used for con cen trat ing sam ples through out the extract cleanup pro cess. The extract was trans ferred into hex ane and then sub se quently treated with con cen trated sul fu ric acid for destruc-tive removal of organic mate rial. The extract was then treated for inor ganic and organic sul fur by acti vated cop per and sil ver nitrate clean-up tech niques, respec tively. A com mer cial auto mated
clean-up pro ce dure (Pow er Prep™ by Fluid Man age ment Sys tems, Wal tham, MA, USA) that employs acid and base mod i fied sil ica gels and basic alu mina col umn chro ma tog ra phy was used to remove inter fer ences from the sam ple extract. Extracts were con cen trated to dry ness under nitro gen and made up to 40 l with a PBDE inter-nal stan dard. Anal y ses were under taken for PBDEs and PBBs using iso tope dilu tion high res o lu tion gas chro ma tog ra phy – elec tron ioni sa tion – high-res o lu tion mass spec trom e try, with mon i tor ing of the fol low ing ions:
The ana lyt i cal pro ce dure was based upon stan dard US EPA meth-od ol o gies (US EPA, 2007).
4.3. Instru men tal tech nique
Quan ti fi ca tion was per formed on an Ag i lent 6890 gas chro-mato graph that was cou pled to a Thermo Finn i gan MAT 95XL HRMS. The col umn used was a DB-5 col umn (J&W Sci en tific) 10 m £ 0.1 mm £ 0.1 m. One mi cro li tre of sam ple extract was injected using the splitless method with an injec tor temp of 280 °C. The tem per a ture pro gram employed was an ini tial tem per a ture of 120 °C held for 2 min, a ramp rate of 15 °C min¡1 from 120 to 230 °C fol lowed by a 5 °C min¡1 increase from 230 °C to the final tem per-a ture of 320 °C that was held for 5 min utes. Helium was used as a car rier gas with con stant flow mode of 0.4 ml min¡1. The trans fer line was main tained at 280 °C. Elec tron ioni sa tion (EI) mode was used with an elec tron energy of 70 eV, fil a ment cur rent of 0.7 mV, and ion source at 240 °C. The elec tron mul ti plier volt age was set to pro duce a gain of 106.
4.4. Mate rial, stan dards and reagents
Pes ti cide grade sol vents were pur chased from Merck and were tested for con tam i na tion prior to use. Pow er Prep™ col umns (acid and base mod i fied sil ica gels and basic alu mina) were pur chased from Fluid Man age ment Sys tems, Wal tham, MA, USA.
Iso tope dilu tion was per formed using stan dard com pounds pur-chased from Wel ling ton Lab o ra to ries Inc., Guelph, Ontario, Can ada. Sur ro gate Stan dard: BFR-LCS-STK; Cal i bra tion Stan dard: BFR-CVS; Recov ery Stan dard: BFR-ISS-STK.
Table 2
Aus tra lian sew age sludge sur vey 2006 – type of treat ment pro cess and source of waste wa ter
WWTP Pop u la tiona Treat ment method Source
U1 4297000 Anaer o bi cally digested and freshly de wa tered. Ser vices res i den tial and indus trial areas.
U2 1811000 Acti vated sludge, de wa tered. Com po si tion indus trial and domes tic.
U3 1139000 Acti vated sludge. Dis solved air-flo ta tion fil tra tion. Mix ture of domes tic and indus trial and some
ground wa ter run off.
U4 1139000 Inte grated fixed-film acti vated sludge. Mix ture of domes tic and indus trial and some
ground wa ter run off.
U5 3850000 Acti vated sludge plant. Anaer o bi cally digested primary and sec ond ary sludge.
De wa tered in sludge dry ing pans. Stock piled for >3 years.
Indus trial and domes tic
U6 1508000 Mes o philic anaer o bic diges tion, cen tri fuge dewa ter ing, 110 ml day¡1. Mainly domes tic »2% indus trial input.
U7 1508000 Acti vated sludge. Mechan i cally de wa tered. Chem i cally sta bi lized (lime). 60 ml day¡1. Mainly domes tic, »5% indus trial.
U8 1508000 Mes o philic anaer o bic diges tion, cen tri fuge dewa ter ing. 120 ml day¡1. Mainly domes tic »9% indus trial input
R1 142000 Stored in a lagoon for 6 months. De wa tered by cen tri fuge and stock piled for 4 months. 92% domes tic 8% trade waste.
R2 106000 Lagoon. De wa tered by vac uum fil tra tion. Domes tic and light indus trial.
R3 27000 Acti vated sludge. De wa tered. Domes tic source.
R4 35000 Aer o bic diges tion. De wa tered. Domes tic and light indus trial.
R5 202000 Chem i cally sta bi lized with lime. Domes tic and indus trial
R6 52000 De wa tered and chem i cally sta bi lized (lime). Mainly domes tic.
R7 5000 Acti vated sludge and lagoon pro cess. Land dried. Domes tic and abat toir
R8 14000 Oxi da tion treat ment pond. Solar dried. Domes tic and Indus trial
a Pop u la tion refers to the pop u la tion of the town/city and not just the feed ing pop u la tion of the WWTP; U = urban (pop u la tion >1000000), R = rural (pop u la tion
<300000).
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984 B. Clarke et al. / Chemosphere 73 (2008) 980–989
4.5. Qual ity assur ance/qual ity con trol
Inter nal stan dard iso tope dilu tion quan ti fi ca tion was under-taken within this study. This employs the use of 13C12 labelled sur-ro gates and inter nal stan dards. The 13C12 sur ro gates (13C12 BDE-28, -47, -77, -99, -100, -126, -153, -183, -197, -205, -207, -209, BB-153) are added to the sam ple prior to extrac tion and are car ried through all the lab o ra tory oper a tions. The inter nal stan dards (13C12 BDE-79, -139, 180, 206) were added just prior to anal y sis by HRGC-EI-HRMS. Both the recov ery of the sur ro gate and inter nal stan dard response are then used in the quan ti fi ca tion of the native BDEs.
Pro ce dural blanks were per formed in each batch of anal y ses. All glass ware was placed in a fur nace over night at 450 °C and rinsed with sol vent before use. Each batch of dis pos able equip ment such as Pow er Prep™ col umns were checked prior to use for PBDE con-tam i na tion. The limit of detec tion (LOD) was set as the limit of quan ti fi ca tion (LOQ) and was deter mined as three times the blank amount.
The anal y sis of the higher bro mi nated BDEs, par tic u larly BDE-209, is recog ni sed as being di" cult because it can degrade dur ing the ana lyt i cal pro cess (Co vac i et al., 2003). Using a short thin-film cap il lary col umn, reg u larly chang ing the injec tion liner, and using a low source tem per a ture min i mized the potential for deg ra da tion of BDE-209.
The lab o ra tory is accred ited by the National Asso ci a tion of Test-ing Author i ties (NATA) and has par tic i pated suc cess fully in four inter na tional inter-lab o ra tory stud ies.
4.6. Co-elut ing cong en ers
Co-elu tion of cong en ers BDE-138 and -166 is a com mon prob-lem (Kory tar et al., 2005; US EPA, 2007). There fore a pre cau tion ary approach was taken with BDE138/BDE166 and was reported as a co-elu tion.
It is also well known that there is co-elu tion on a DB-5 col umn between BB-153 and BDE-154 (Sta ple ton, 2006) There fore the use of elec tron cap ture detec tor, neg a tive-ion chem i cal ioni sa tion and low-res o lu tion mass spec trom e try detec tors can lead to an over esti ma tion of either com pound. The HRGC-EI-HRMS method used in this study over comes these lim i ta tions by care ful selec tion of the respec tive quan ti fi ca tion and con fir ma tory ions for labelled sur-ro gates and native com pounds, as well as oper at ing the mass spec-trom e ter at high res o lu tion (R > 10000), thereby ensur ing accu rate iden ti fi ca tion and quan ti fi ca tion. The ions selected for the 13C12 BB-153 sur ro gate and the native BDE-154 rep re sent [M+2¡2Br]+and [M+6¡2Br]+, respec tively (Cer tifi cate of Anal y sis sup plied by Wel-ling ton Lab o ra to ries). These ions are less abun dant (<65%) than the [M+4¡2Br]+ ions but can be mass resolved from one another with an instru ment res o lu tion of >10000. This approach has been val i-dated by anal y sing cer ti fied stan dards, pro ce dural blanks and sam-ples con tain ing high BB-153 and BDE-154 lev els.
4.7. Sta tis ti cal anal y sis
Prin ci pal com po nents anal y sis (PCA) was per formed to ana lyse the rela tion ship among the PBDE cong en ers using the soft ware pack age NTSYSpc ver sion 2.20 (Exe ter Soft ware). The raw con cen-tra tion data for each com pound were stan dar dised to a mean of zero and a stan dard devi a tion of one, and the PCA was con ducted on the cor re la tion matrix of the stan dar dised data. Val ues below the detec tion limit were assumed to be zero for this anal y sis.
In the study of var i a tion in PBDEs over time, anal y sis of var i-ance (ANOVA) was used to test whether there were effects of year, WWTP or a year by WWTP inter ac tion. WWTP effects were con sid-ered to be fixed while year and the inter ac tion were con sid ered as hav ing random effects, so the sig nifi cance of the WWTP effects
was tested against the inter ac tion. A log a rithm trans for ma tion was required to sta bi lise resid ual var i ance for some cong en ers.
5. Results and dis cus sion
5.1. Aus tra lian sew age sludge sur vey 2006
5.1.1. Poly bro mi nated diphenyl ethersThe con cen tra tion of PBDEs as mea sured in the 16 sew age
sludge sam ples is sup plied in Table 3. An esti mate of the error asso ci ated with each ana lyt i cal mea sure ment has been cal cu lated by the rel a tive error of dupli cate sam ples mea sured as part of the time study. BDE-47, -99 & -209 con cen tra tions found in this sur vey are com pared with inter na tional lev els in Fig. 1a and b.
Exam i na tion of the cor re la tion matrix revealed that there were three primary groups of com pounds, with cor re la tions high among cong en ers within groups and low between groups. The first two groups con tained cong en ers that are rep re sen ta tive of the pen ta-BDE and deca BDE for mu la tions. The basis for group sep a ra tion is that the indi vid ual cong en ers in each group are highly cor re lated with one another; they are the reported con stit u ents of the com-mer cial for mu la tion and are pres ent in sim i lar ratios to those reported in the for mu la tions. The ratio of the prin ci pal cong en ers of the pen ta BDE for mu la tion BDE 47:99 + 100:153 + 154 have a ratio of 41:51:8 which is sim i lar to the reported ratio of 40:45:6 (Sjö din et al., 1998). The prin ci pal cong en ers of the deca BDE for mu la tion BDE 209:206 + 207 + 208, reported to have a ratio of 97 ¡ 98:0.3 ¡ 3 were found in an over all ratio of 93:7 (Alaee et al., 2003).
The first two prin ci pal com po nents explained 76% of the var i a-tion within the sam ple set. PCA1 was pri mar ily rep re sen ta tive of the aver age con cen tra tion of com po nents in the pen ta BDE for mu-la tion (BDE-47, -49, -66, -77, -85, -99, -100, -119, -139, -140, -153, -154) explain ing 50% of sam ple var i a tion and PCA2 cor re sponded to rep re sen ta tive cong en ers of the deca BDE for mu la tion (BDE-201, -203, -206, -207, -208 and -209), explain ing an addi tional 26% of the sam ple var i a tion. The third com po nent explained 13% of the data var i a tion; how ever, it was con cluded that this com po nent was not mean ing ful, as it cor re sponded mainly with var i a tion in cong-en ers that were at or below their detec tion lim its (BDE-171, -180, -184 and -191). Given the high cor re la tions within for mu la tions, the con cen tra tion of PBDEs could be rea son ably sum ma rised by the con cen tra tion of three dom i nant cong en ers, BDE-47 and BDE-99 rep re sent ing the pen ta BDE for mu la tion and BDE-209 rep re sent ing the deca BDE for mu la tion. A plot of PCA1 vs PCA2 (i.e. pen ta BDE vs deca BDE for mu la tions) does not reveal any obvi ous trends, such as asso ci a tions with size of town (pop u la tion) or in dus tri ali sa tion (Fig. 2).
If the PBDEs in sew age sludge were derived mainly from domes-tic prod ucts one would expect there would be con sis tency in the rel a tive con cen tra tions of PBDEs regard less of region. Using BDE-47 and BDE-99 as rep re sen ta tives of the pen ta BDE for mu-la tion this pro posal is con firmed; the mean of BDE-47 and BDE-99 is 136.5 g kg¡1 (s.d. 112 g kg¡1) and 138 g kg¡1 (s.d. 116), respec tively. There fore it is sug gested that the primary source of the pen ta BDE for mu la tion in Aus tra lian sew age sludge is largely domes tic. Con cen tra tion of the deca BDE for mu la tion, on the other hand is highly var i able (mean BDE-209 715 g kg¡1, s.d. 981), con-sis tent with pre vi ous reports in the sci en tific lit er a ture (Hale et al., 2001), sug gest ing a less uniform source than the domes tic envi ron-ment. Var ied indus trial appli ca tions could explain the var i a tion observed.
Among the sam ples, two are quite unusual. These are urban WWTP U5 and rural WWTP R7. The urban WWTP U5 has an atyp i-cally high BDE-209 con cen tra tion. Sew age sludge may be sta bi lized for bi os o lids using a vari ety of meth ods and this ele vated con cen-tra tion may be a result of the method used at this WWTP, i.e., longer
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Table 3
Con cen tra tion of PBDE cong en ers and PBB-153 g kg¡1 dry weight in Aus tra lian sew age sludge sur vey con ducted in 2006; U = Urban (Pop. >1000000), R = Rural (Pop. <300000)
a Does not include half detec tion limit. b The stan dard error asso ci ated with rep li cate sam pling and ana lyt i cal mea sure ment cal cu lated from five rep li cate sam ples as part of the time series study. c Mean con cen tra tion of rep li cate sam ples.
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0
200
400
600
800
1000
1200
1400
Sweden(Nylund1992)
Sweden(Sellstrom
1999)
U.S.A.(Hale, 2001)
Netherlands(de
Boer,2003)
Spain(Fabrellas
2004)
Germany(Hamm2004)
U.S.A.(North 2004)
Sweden(Law, 2006)
Germany(Knoth,2007)
China (Wang2007)
Australia(Clarke2008)
Conc
entra
tion u
g kg-1
d.w.
BDE-47 BDE-99
0
1000
2000
3000
4000
5000
6000
Sweden(Nylund1992)
Sweden(Sellstrom
1999)
U.S.A.(Hale, 2001)
Netherlands(de
Boer,2003)
Spain(Fabrellas
2004)
Germany(Hamm2004)
U.S.A.(North 2004)
Sweden(Law, 2006)
Germany(Knoth,2007)
China (Wang2007)
Australia(Clarke2008)
Conc
entra
tion u
g kg-1 d.
w.
BDE-209
a
b
Fig. 1. A com par i son of the major PBDE cong en ers g kg¡1 dry weight (a) BDE-47, -99 and (b) BDE-209 from the Aus tra lian sur vey and the English peer reviewed sci en tific
lit er a ture. The graphs rep re sent the mean con cen tra tion and the error bars express the range reported. Note: the con cen tra tion of BDE-209 (18 632 g kg¡1 d.w.) reported in
one sludge from the Span ish sur vey 2004 was excluded from this pre sen ta tion as it was con sid ered an anom a lous sam ple.
prep a ra tion time (three years). Over time there is a loss of organic mate rial which may result in the con cen tra tion of the PBDEs on the remain ing organic mate rial, assum ing no losses through bio deg ra-da tion, phys i cal break down or atmo spheric losses. The other nota-ble fea ture of the sam ple from U5 is the low bur den of the pen ta BDE for mu la tion cong en ers, which sug gests losses of these com pounds due to above mech a nisms leav ing the BDE-209 to accu mu late pref-er en tially. Sim i larly, sludges from treat ment plants R1 and R8, both lagoon pro cesses that degrade organic mate rial over time, have the sec ond and fourth high est PBDE con cen tra tions in this study. Regard less of whether or not BDE-209 has been con cen trated in the sam ples from U5, its con tin ued ele vated con cen tra tion in sew-age sludge that has been aged for three years, con tra dicts lab o ra-
tory evi dence of the faster deg ra da tion of BDE-209 com pared to the other lower bro mi nated cong en ers (Bez ares-Cruz et al., 2004; Eri ks son et al., 2004). This con tra dic tion over the per sis tence of BDE-209 was found also in a 2005 Swed ish field trial that found ele vated lev els of PBDEs, includ ing BDE-209 (2200 g kg¡1 com-pared to the con trol of 0.75 g kg¡1) twenty years after the last use of PBDEs at that site, and found no evi dence of the pho to de bro min-a tion of BDE-209 in the soils stud ied (Sell strom et al., 2005). Future anal y sis should also include total organic car bon mea sure ments as well as dry weight mea sure ments to enable the con cen tra tion of PBDEs to be stan dar dised against total organic car bon.
Another unusual sam ple is rural WWTP R7, which has almost no PBDE bur den. This is an anom aly both within the cur rent
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sam ple set and the inter na tional lit er a ture. If the source of pen ta-BDE for mu la tion cong en ers is domes tic, one would expect there to be sim i lar con cen tra tions in all sludges regard less of region of waste wa ter treat ment pro cess. WWTP R7 is a small com mu nity that ser vices an abat toir and it is pos si ble that this treat ment plant pro cesses large vol umes of ani mal waste, which may have low ered the PBDE con cen tra tion by dilu tion.
To pro vide a con text in which to assess the mag ni tude of these PBDE bur dens they have been com pared to the con tam i na tion lim its for the poly chlo ri nated biphe nyls (PCBs). In Aus tra lia, the National guide lines are con tam i na tion limit 1 of 200 g kg¡1 (restricted land appli ca tion) and con tam i na tion limit 2 of 1000 g kg¡1 (unsuit able for land appli ca tion) (NRMMC, 2004), which are sim i lar to those in sev eral Euro pean nations (Euro pean Com mis sion, 2001). If it were appro pri ate to trans late these guide lines directly from the PCB con tam i na tion lim its to a PBDE con tam i na tion limit, then all sam-
ples, except WWTP R7, would be unsuit able for unre stricted land appli ca tion. Fif teen of the six teen sam ples had a PBDEs greater than 200 g kg¡1 and 7 of the 16 sam ples con tained PBDEs greater than 1000 g kg¡1. At this time no con tam i nant lim its have been pro posed for PBDEs and the practice of sew age sludge land appli ca tion has not stopped in the USA and many other nations despite higher PBDE bur dens than those observed in Aus tra lia. The PBDE lev els found in Aus tra lian sludges are sim i lar to those found in Euro pean sludge sam ples and ten to one hun dred times greater than lev els of PBDEs in Euro pean soils; PBDEs 0.065–12 g kg¡1 (Hass a nin et al., 2004). If the con cen tra tion of PBDEs in Aus tra lian soils are sim i lar to Euro pean lev els then it is likely that land appli-ca tion of sludge would increase the PBDE bur den found in soils.
To sum ma rise, the mean con cen tra tion of PBDEs in this Aus-tra lian sur vey was 1137 g kg¡1 (s.d. 1116). When com par ing the urban mean of 1308 g kg¡1 (s.d. 1320) and the rural aver age of 911 g kg¡1 (s.d. 831) there is little var i a tion and the dif fer ence is not sig nifi cant at the 95% con fi dence level. The PBDE con cen tra-tions reported in this study are sim i lar to those reported in the inter na tional sci en tific lit er a ture. Prin ci pal com po nents anal y sis revealed that this data set could be reduced to two primary com-po nents reflect ing the pen ta BDE and deca BDE for mu la tions and these two for mu la tions can be suit ably rep re sented by the dom i-nant cong en ers BDE-47, -99 and BDE-209, respec tively.
5.2. Poly bro mi nated biphe nyls
The find ing of BB-153 in all sam ples was unex pected (mean 0.6 g kg¡1, s.d. 0.5) and, as far as is known, there are no indus tries uti liz ing the hex ab ro mi nat ed biphe nyl com mer cial (hexa BB) for mu-la tion in Aus tra lia. In terms of his tor i cal use, it is unclear whether this com pound was ever used in Aus tra lia. The ubiq uity of BB-153 strongly sug gests that it was in a com mon prod uct, such as auto-mo biles or widely used domes tic prod ucts. How ever, the use of hexa BB in Aus tra lia would be sur pris ing con sid er ing it was banned from many Western nations in the 1970s fol low ing the Mich i gan con tam i na tion disas ter. It is likely that BB-153 was imported in an unknown prod uct, which was com monly used and widely dis-trib uted. A more con cern ing hypoth e sis is that this chem i cal is extremely per sis tent in the envi ron ment and has been sub ject to long-range atmo spheric trans port.
Table 4
Con cen tra tion of PBDEs g kg¡1 dry weight in sew age sludge mea sured at three WWTPs (U6, U7 and U8) in the years 2005 and 2006
Fig. 2. Prin ci pal com po nent anal y sis of PBDEs in Aus tra lian sew age sludge sur vey
con ducted in 2006. Plot of PCA1 vs PCA2, pri mar ily rep re sent ing pen ta BDE and
deca BDE com mer cial for mu la tions, (A) score plot and (B) load ing Plot.
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5.3. Var i a tion of PBDE lev els over time
An ANOVA was per formed on the con cen tra tion of the three com po nents BDE-47, -99,-209 as well as PBDEs at three WWTPs from the same city (U6, U7 and U8) over two years (2005 and 2006). From the cor re la tion matrix (R) and prin ci pal com po nents anal y sis pre vi ously per formed, PBDE cong en ers were sep a rated into groups that have been iden ti fied as the pen ta BDE and deca BDE for mu la-tions. Given the high cor re la tions within for mu la tions, it is appro-pri ate to con duct an anal y sis of var i ance on just the dom i nant cong en ers rep re sen ta tive of each viz. BDE-47&-99 and BDE-209.
PBDEs was also ana lysed. Other cong en ers were mea sured and the raw data are pro vided in Table 4.
In all three cases there was a sig nifi cant WWTP by year inter ac-tion indi cat ing that dif fer ences in con cen tra tion existed between the WWTPs but the mag ni tudes of these dif fer ences var ied depend-ing on the year of mea sure ment. There were also sig nifi cant dif fer-ences between WWTPs for BDE-47. The con cen tra tion of BDE-47 was sig nifi cantly lower at U7 (60 g kg¡1) than at the other two plants (U6 213 g kg¡1, U8 285 g kg¡1) and, while the dif fer ences in the con cen tra tions of BDE-99, -209 and PBDEs are not sta tis ti-cally sig nifi cant they were also lower at U7, com pared to U6 and U8 (Table 4). There were no over all sig nifi cant dif fer ences between years or WWTPs for either BDE-209 or PBDEs. The sim i lar result for BDE-209 and PBDEs is not sur pris ing as BDE-209 is the most abun dant con ge ner. These find ings dem on strate that WWTPs from the same city can have vary ing con cen tra tions of PBDEs. A more com pre hen sive data set over a longer period of time would improve this anal y sis.
6. Con clu sion
A sur vey of Aus tra lian sew age sludge in 2006 found the PBDE mean con cen tra tion to be 1137 g kg¡1 d.w. (s.d. 1 116), with little dif fer ence between the urban (mean 1308 g kg¡1, s.d. 1320) and the rural (mean 911 g kg¡1, s.d. 831) sam ples. The PBDE lev els in Aus tra lian sew age sludge reported in this study are sim i lar to PBDE lev els reported in the inter na tional sci en tific lit er a ture. Fif teen of the six teen sam ples con tained PBDE greater than 200 g kg¡1 and seven were higher than 1000 g kg¡1. The PBDE bur den found in Aus tra lian sludge is far higher than the lev els reported in Euro-pean soils. There are no pub lished data avail able on PBDEs in Aus tra lian soils but if it is assumed that they have a sim i lar PBDE bur den to Euro pean soils, then sludge land appli ca tion is likely to increase the PBDE lev els in soil. A risk assess ment of PBDEs in sew-age sludge land appli ca tion, tak ing into account typ i cal PBDE con-cen tra tion in Aus tra lian soils, should be under taken.
Both the pen ta BDE and deca BDE for mu la tions appear to pass through the WWTP sys tem unchanged. The con cen tra tion of pen-taB DEs was found to be fairly con sis tent in con cen tra tion in the sludges sur veyed, sug gest ing domes tic sources, whereas the deca-BDE for mu la tion was found to be var i able, which is best explained by dif fer ent indus trial inputs. Fur ther research is sug gested to clar-ify the sources of these com pounds in WWTPs.
The find ing of BB-153 in all sam ples ana lysed in this sur vey of sludges was unex pected as they are rarely ana lysed or detected in inter na tional research. The results dem on strate that PBBs are extremely envi ron men tally per sis tent, capa ble of long-range atmo-spheric trans port and are widely dis trib uted within the Aus tra lian envi ron ment, albeit in low con cen tra tions.
This is the first arti cle to com pre hen sively focus on PBDEs and BB-153 in Aus tra lian sew age sludge and the first to pro vide a review of the inter na tional lit er a ture spe cifi cally on PBDEs and PBBs in sew age sludge. We have iden ti fied the issue of PBDEs in Aus tra lian sew age sludge as a potential prob lem for sew age sludge land appli ca tion and the need for fur ther research to
ascer tain the risks to human health and the envi ron ment from this practice.
Acknowl edge ments
The authors would like to acknowl edge the water treat ment author i ties that kindly sup plied sam ples and per mit ted the data anal y sis to be released pub licly. BC grate fully acknowl edges the finan cial sup port of Waste wa ter Pro gram of the Coop er a tive Research Cen tre for Water Qual ity and Treat ment, the Water Cor-po ra tion of Western Aus tra lia and the Vic to rian Depart ment of Human Ser vices.
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