Calculat ed concent r at ions f or t he Basin GREAT- ER Simulat ions: Aire and Calder Basin I n- st r eam r emoval N ot e: 1Conduct ivit y- based dilut ion f act or of Melt ham W W T P ef f luent was 2. 94. 2Sit e E was excluded f r om t he die- away r at e calculat ions due t o t he high suspended solids cont ent indicat ing t hat r iver sediment was pot ent ially dist ur bed at t ime of sampling at t his sit e. ABST RACT The concent r at ions of Musk Ket one (MK) and Musk Xylene (MX) wer e det er mined in inf luent s and ef f luent s f rom t rickling f ilt er (TF) and act ivat ed sludge (AS) wast ewat er t reat ment plant s (WWTPs) in t he Aire Basin (Yorkshire, UK) in Sept ember 2000. Concent rat ions were also det ermined in t he river receiving t he ef f luent f rom t he TF plant . MK inf luent concent rat ions were 0. 37 μg/ l f or t he TF plant and 0. 75 μg/ l f or t he AS plant . MX inf luent concent rat ions were 0. 34 μg/ l f or t he TF plant and 0. 22 μg/ l f or t he AS plant . Af t er passage t hrough t he WWTPs, ef f luent concent rat ions were 0. 04 – 0. 06 μg/ l f or MK and 0. 01 – 0. 02 μg/ l f or MX. Removal rat es f or MK & MX respect ively were 90% and 95% in t he TF plant and 92% and 98% in t he AS plant . River concent r at ions r anged f r om 0. 002 μg/ l f or bot h MK and MX upst ream of t he ef f luent discharge t o 0. 024 μg/ l MK and 0. 007 μg/ l MX immediat ely downst ream of t he discharge (dilut ion f act or 2). Concent rat ions declined t o 0. 017 μg/ l MK and 0. 003 μg/ l MX at 3. 5 km downst ream. A preliminary est imat ion of in- st r eam r emoval r at e (via biot r ansf or mat ion, sor pt ion and/ or volat ilizat ion) in t his r iver was 0.071 h-1 f or MK and 0. 193 h- 1 f or MX. The concent rat ions report ed here are low relat ive t o hist orical levels. T his r ef lect s changing usage pat t er ns of nit r omusks in det er gent s wit hin t he EU. As t he st udy was conduct ed in t he ar ea cover ed by GREAT- ER (Geogr aphy- r ef er enced r egional exposur e assessment t ool f or Eur opean r iver s), t he measur ed concent r at ions and W W T P and in- st r eam r emoval r at es wer e used in t he model t o pr edict sit e- specif ic dist r ibut ion of nit r omusk concent r at ions in t he Air e Basin. STUDY OBJECTI VES T he cur r ent st udy was under t aken in or der t o bet t er under st and t he f at e of nit r omusks in t he aquat ic envir onment , including t heir r emoval dur ing wast ewat er t reat ment and in- st ream dissipat ion rat e. The dat a f r om t he st udy wer e used t o model t he concent r at ion dist r ibut ion of nit r omusks in a r eal r iver basin using GREAT- ER, a GI S- based exposure assessment model. Recent Analyses of Recent Analyses of N it r omusks N it r omusks in Sewage and River wat er in t he UK in Sewage and River wat er in t he UK D. D. Sabaliunas Sabaliunas (Proct er & Gamble, UK), S. F. Webb (Proct er & Gamble, Belgium), (Proct er & Gamble, UK), S. F. Webb (Proct er & Gamble, Belgium), S. S. Simonich Simonich (Procter & Gamble, USA) & W. S. (Procter & Gamble, USA) & W. S. Eckhof f Eckhof f (Procter & Gamble, USA) (Procter & Gamble, USA) I NTRODUCTI ON Musk Xylene (CAS 81- 14- 2) and Musk Ketone (CAS 81- 14- 1) are per f ume compounds employed in f r agr anced pr oduct s such as cosmet ics and household pr oduct s (e. g. det er gent s). Bot h mat erials are cur r ent ly subj ect t o r isk assessment under t he EU 3 rd priorit y list . Use of t hese mat erials has declined in recent years as a result of volunt ar y indust r y init iat ives. Use in Europe (1998) is report ed at 88 & 40 t onnes/ annum f or Musk Xylene and Musk Ket one respect ively. One of t he main rout es t hese chemicals ent er t he envir onment is via down- t he- dr ain disposal of consumer pr oduct s. T he concent r at ion and dist r ibut ion of nit r omusks in t he aquat ic envir onment ar e gover ned by r emoval r at es dur ing wast ewat er t r eat ment and subsequent par t it ioning, chemical and biological degr adat ion in sur f ace wat er s. RI VER AI RE BASI N T he River s Aire and Calder Basin is sit uat ed in Yorkshire, nort h of England. The River Aire drains t he cent r al Pennines and f lows sout h- east war d t hr ough W est Yor kshir e met r opolit an ar ea and t he Yor kshir e coalf ield, where it is joined by Calder, it s major t ribut ary. These areas are charact erized by a high densit y of populat ion, large number of small t ribut aries and medium t o small size wast ewat er t r eat ment plant s wit h dilut ions f act or s as low as 2. STUDY SI TES T wo wast ewat er t r eat ment plant s (W W T Ps) were select ed f or t he st udy. Cr of t on act ivat ed sludge (AS) plant sout heast of W akef ield ser ves t he populat ion of about 9,000 people wit h t he wast ewat er f low of approx. 1,400 m 3 / day, and Melt ham t rickling f ilt er (TF) plant sout h of Hudder sf ield ser ves t he populat ion of 8, 000 people wit h t he wast ewat er f low of approx. 4,100 m 3 / day. T he lat t er plant oper at es t wo consecut ive series of t rickling f ilt ers, i. e. t he level of wat er t reat ment is equivalent t o t ert iary t reat ment . Bot h plant s r eceive municipal wast ewat er only. T he Melt ham plant discharges int o Mag Brook, t he 3. 5- km sect ion of which below t he dischar ge point was used f or river wat er die- away st udy. SAMPLI NG One- day (24 h) hour ly composit e samples of inf luent , primary ef f luent and f inal ef f luent were collect ed at each wast ewat er t reat ment plant . The river wat er die- away st udy was car r ied out by f ollowing a wat er plug using t he Rhodamine WT dye wit h f luor escent det ect ion. Triplicat e grab river wat er samples were t aken at dist ances 20 m, 0. 5 km, 1, 5 km and 3. 5 km downst r eam f r om t he ef f luent dischar ge point at t he t ime of t he peak f luor escent dye concent r at ion. Anot her set of wat er samples was t aken about 50 m upst r eam f r om t he wast ewat er plant dischar ge point . GREAT - ER River Aire and t hree relat ed river basins (Calder, Went and Rot her ) are modelled in GREAT - ER, t he Geogr aphy- Ref er enced Regional Exposur e Assessment T ool f or Eur opean River s. GREAT - ER is an envir onment al model developed by ECET OC (Eur opean Cent r e f or Ecot oxicology and T oxicology of Chemicals) and ot hers on behalf of ERASM. GREAT- ER combines envir onment al models and GI S t echniques t o pr edict and visualize t he concent r at ion of down- t he- dr ain chemicals in Eur opean r iver basins (Schowanek et al. , 2001). SAMPLE PROCESSI NG AND ANALYTI CAL Wastewater and river water samples were preserved wit h 3% (v/ v) f ormalin, ext ract ed and analysed wit h GC/ MS as described in Simonich et al. (2001). Limits of quant if icat ion wer e 2 ng/ l f or MX and 1 ng/ l f or MK in inf luent and 1 ng/ l and 0. 7 ng/ l respect ively in ef f luent . DI SCUSSI ON T he r esult s demonst r at e t hat bot h Musk Xylene and Musk Ket one ar e ext ensively r emoved dur ing wast ewat er t r eat ment wit h f ur t her r apid loss f r om t he wat er column in surf ace wat ers. The WWTP removal rat es (>90%) are in line wit h t he r esult s f r om ear lier P & G st udies (Simonich et al. 2000) where the measured removal of Musk Xylene in Act ivat ed Sludge averaged 98. 7% and in Trickling Filt er averaged 90. 9 %. Musk Ket one averaged 82.6% and 80.3% respect ively. T he relat ive lower removal of Musk Ket one is repeat ed here. Measur ed inf luent and ef f luent concent r at ions ar e lower t han hist or ical Eur opean levels (e. g. , Eschke et al. 1994). This undoubt edly ref lect s t he known decrease in use of t hese mat erials (especially in det ergent s) during the 1990s. The Musk Xylene in- stream removal rate (0. 193 h- 1) was comparable t o or even higher t han t he rat e of BOD decay (0. 16 h- 1). The in- st ream removal rat e f or Musk Ket one was lower (0. 071 h- 1). These rat es ref lect all pot ent ial loss mechanisms (biot r ansf or mat ion, sor pt ion or volat ilisat ion). The lower die- away rat e f or Musk Ket one t oget her wit h t he lower wast ewat er t r eat ment r emoval r at e account s f or t he higher measur ed and pr edict ed concent r at ions of t his mat er ial in sur f ace wat er s r elat ive t o Musk Xylene. In Mag Br ook, t he measur ed concent r at ions of nit r omusks wer e sever al- f old higher t han t hose pr edict ed by t he GREAT- ER model. This may part ially be explained by a low river- f low rat e at t he t ime of t he st udy (early Sept ember 2000) compar ed to t he year- round dist r ibut ion of f low r at es used in t he Mont e Car lo simulat ions of t he GREAT - ER. T he GREAT - ER calculat ed aver age concent r at ion of Musk Xylene and Musk Ket one in t he Aire Basin were in t he range of 0.5 - 1 ng/ l and 1 – 4 ng/ l depending upon t he cat chment weighing met hod. For per spect ive, t he PN EC f or Musk Xylene is 1. 1 μg/ l (AF 50 2 chronic NOECs) and 6. 3 μg/ l f or Musk Ket one (AF 10 3 chronic NOECs). CONCLUSI ONS § Observed nit r omusk r emoval dur ing wast ewat er t r eat ment cor r esponds t o pr eviously r epor t ed r at es. § I nf luent and ef f luent concent r at ions ar e lower t han hist or ical obser vat ions in Eur ope. T his r ef lect s known decr eases in t he use of t hese mat er ials in cosmet ics and especially det er gent s. § I nst ream removal rat es are 0. 193 h- 1 and 0. 071 h- 1 f or Musk Xylene and Musk Ket one respect ively. RESULT S Wast ewat er t reat ment removal Melt ham TF BOD (mg/ l) Or ganic car bon (mg/ l) Suspended solids (mg/ l) LAS (mg/ l) NM (mg/ l) I nf luent 204 151 228 3.18 MX 0.34 MK 0.37 Pr imar y ef f luent 55.3 33.2 56 2.88 MX 0.18 MK 0.26 Final ef f luent 2.7 5.88 14 0.016 MX 0.02 MK 0.04 Pr imar y r emoval (%) 72.9 78 75.4 9.4 MX 47 MK 30 T ot al r emoval (%) 98.7 96.1 93.9 99.5 MX 95 MK 90 Cr of t on AS BOD (mg/ l) Or ganic car bon (mg/ l) Suspended solids (mg/ l) LAS (mg/ l) NM (mg/ l) I nf luent 262 126 166 1.71 MX 0.22 MK 0.75 Pr imar y ef f luent 230 142 120 2.4 MX 0.09 MK 0.42 Final ef f luent 4.1 21.4 14 0.029 MX 0.01 MK 0.06 Pr imar y r emoval (%) 12.2 0 27.7 0 MX 59 MK 44 T ot al r emoval (%) 98.4 83 91.6 98.3 MX 98 MK 92 Conduct ivit y Suspended solids (mg/ l) BOD (mg/ l) Or ganic car bon (mg/ l) NM μS/ cm Dilut ion MX (ng/ l) MK (ng/ l) Site A (50 m ) 175 - 10 3.9 6.36 2 2 Site B (20 m ) 352 Start 1 9 3.6 9.28 7 24 Site C (0.75 km ) 282 1.25 7 2.4 7.53 7 24 Site D (1.5 km ) 293 1 6 2.2 7.07 4 20 Sit e E (3.5 km )2 316 1 51 3.1 5.95 3 17 Die away rat e B- D (h- 1) N/A 0.14 0.16 0.09 0.193 0.071 GREAT - ER Simulat ions: concent r at ion pr of ile Concent r at ion (ng/ l) C sim (mean) ± SD C sim (90%) ± SD W eight ed by volume (loaded st r et ches only MX 0.53 ± 0.41 MK 2.86 ± 2.22 MX 0.76 ± 0.60 MK 4.41 ± 3.44 W eight ed by lengt h (loaded st r et ches only) MX 1.01 ± 0.10 MK 4.23 ± 0.46 MX 1.50 ± 0.16 MK 6.82 ± 0.73 W eight ed by f low increment (all st ret ches) MX 0.47 MK 2.62 MX 0.67 MK 4.06 I nitial MX 3.71 MK 9.82 REFEREN CES Eschke et al. , 1994. Analyt ik und Bef unde kunst licher N it r omuschus- Subst anzen in Oberf lachen- und Abwasser n sowie Fischen aus des Einzugsgebeit der Ruhr. Vom W asser Vol. 83, 373- 383. Simonich et al., 2000. Trace analysis of f ragrance mat erials in wast ewat er and t reat ed wast ewat er. Envir onment al Science and T echnolology, Vol. 34, 959- 965. Schowanek, D. et al., 2001. GREAT- ER: a new t ool f or management and risk assessment of chemicals in river basins. Cont r ibut ion to GREAT - ER # 10. Water Science and T echnology, Vol. 43, pp 179- 185. Cont act : Darius Sabaliunas, e- mail: Sabaliunas. D@pg. com Musk Xylene Musk Ket one Musk Xylene Musk Ket one 0 2 4 6 8 0 50 100 River Lengt h (km) Concent r at ion (ng/ l) Bot h simulat ions assume UK usage of appr ox. 4 t onnes per annum or 65 mg per capit a per year back- calculat ed f r om inf luent levels. 0 20 40 60 80 100 120 0 50 100 150 200 Time (minut es) Concent r at ion Loss (%) BOD Musk Xylene Musk Ket one W ast ewat er t r eat ment r emoval is based upon obser ved r at es f r om Melt han and Cr of t on W W T Ps. I n- st r eam r emoval is assumed to be as obser ved in Mag Br ook Example of concent r at ion prof ile (Mag Brook – Holme – Calder – Aire) f or Musk Ket one Csim(90%) BOD Organic carbon Suspen ded solids LAS Musk Xylene Musk Ketone Crofton Meltham 70 75 80 85 90 95 100 Removal, % N O O O N O O N O O N O O N O O Loss of Musk Ket one, Musk Xylene and BOD f r om sit e B t o D. Gr aphic r epr esent at ion of BOD, or ganic car bon, suspended solids, LAS, Musk Xylene and Musk Ket one r emoval r at es. AIRE CALDER