Odour and odorant emission estimation of dredged sediment

Transcription

1 Odour and odorant emission estimation of dredged sediment Xinguang Wang 1, Jing Guan 1, Gautam Chattopadhyay 1, Greg Britton 2, Michael Wright 3, Kate Panayotou 2, Todd Dickinson 4 and Richard M. Stuetz 1 1- Water Research Centre, The University of New South Wales, Australia 2 Worley Parsons, North Sydney, Australia 3 GHD, Sydney, Australia 4 Warringah Councils, Australia

2 Overview Introduction Methodology Results and Discussions Conclusions

3 Review Dredging is a periodical action in many ports, channels, rivers, and lakes in the world. 248x10 6 yd 3 from US Army Corp of Engineers built and managed channels 100,000 m 3 of fine sediment from UK s estuaries in order to maintain navigation routes 400 billion m 3 was estimated to be dredged in Netherlands between billion m 3 is heavily polluted.

4 Well-known Dredging in Australia Newcastle Harbour New South Wales Botany Bay New South Wales Townsville Harbour Queensland Brisbane River Queensland

5 Possible Pollutants - Reported Hydrocarbons PAHs (polycyclic aromatic hydrocarbons) PCBs (Polychlorinated Biphenyls) HCB (Hexachlorobenzene) DD Odour H 2 S VOCs

6 Two Sites Investigated in this Study Extension of shipping channels in Newcastle, NSW Manly Lagoon, NSW

7

8 Manly Lagoon Dredging Sites

9 Dredging

10 Emission Test on the Barge

11 Odour Pens

12 Emission Test Manly Lagoon

13 Sampling and Analysis Methods Odour Tedlar bag Olfactometry analysis H 2 S Absorbing solution HACH analysis PAHs XAD2 tube GC-MS analysis VOCs: - Charcoal tube solvent extraction GC-FID - Tenax TA TD-GC-MS

14 Emission calculation The specific odour, H 2 S, VOCs, and PAHs emission rates were calculated based on the equation: ER x = Q A where, ER x - specific odour, H 2 S, VOCs, and PAHs emission rate, OU/s.m 2 ; mg/min.m 2 ; µg/s.m 2 ; µg/min.m 2 ; C x - odour, H 2 S, VOCs, and PAHs concentration, OU/m 3 ; mg/l; µg/l; µg/l; Q - flow rate of purging gas, m 3 /s; C x A - inner surface area of the flux hood, m 2

15 Results Odour and H 2 S Dredging Site Situation Odour Emission Rate (OU/s m 2 ) H 2 S Emission Rate (mg/min m 2 ) Newcastle Harbour Dredging Dredging/Loading/Unloading Cement Stabilisation Geobag Dewatering n/a Site Manly Lagoon Dredging Site 3 Site Site

16 Odour and H 2 S results Odour emission rates 3.357~ OU/s m 2 H 2 S emission rates ~ mg/min m 2

17 PAH results Compounds Emission range (μg/min m 2 ) Emission average (μg/min m 2 ) Naphthalene Acenaphthylene Acenaphthene Fluorene Phenanthrene Anthracene

18 PAH results 6 of 16 target PAH compounds were detected Heavier members of PAHs are less volatile and are not usually found in the vapour phase.

19 VOC results No VOC detected in charcoal sorbent tube samples indicating charcoal tube sampling and analytical methodology is not effective for detecting VOC emissions from flux hood emission test. 19~37 VOCs were detected from Manly Lagoon dredged materials with the emission rates varied from 0.01 to μg/s m 2 Tenax TA sampling + TD-GC-MS is an effective methodology for VOCs determination

20 Emission reduction of treatment Geobag dewatering - H 2 S reduced 2~7% - Odour reduced 85% - Naphthalene: 44~90%; Acenaphthylene: 39~85%; Acenaphthene: 54~85%; Fluorene: 57~93%; Phenanthrene: 70~98% Cement stability - Odour reduced 78%

21 Conclusions Odour and H 2 S emission rates varied from to OU/s m 2, and from to mg/ min m 2, respectively from the dredged samples. Odour and H 2 S emission rates of Manly Lagoon dredged materials were higher than those of Newcastle Harbour dredged materials. 6 of 16 targeted PAHs were detected and PAHs with high molecular weight were not detected as they are less volatile. Using Geobag dewatering could reduce odour, H2S, and PAHs emissions by 85%, 39~98%, and 2~7%, respectively. Odour emission rates decreased by 78% when cement stability treatment was employed for treatment. Tenax sorbent tube sampling followed by TD-GC-MS analysis was the preferred method for determination of VOCs from flux hood simulation tests.