Fourth National Cyanobacterial Workshop
Formation of THMs and HANs during
bromination of Microcystis aeruginosa.
Ning Lu
[email protected]
Shanghai National Engineering Research Center of
Urban Water Resources
Sep. 23, 2014
Bromine-containing disinfectants, DBDMH (2,4-dibromo-5,5-dimethylhydantoin)
and BCDMH (bromo-3-chloro-5,5-dimethylhydantoin), are widely used for
recreational water and drinking water purification.
Bromide (Br-) in water could be oxidized to free bromine (Br2) by commonly
used disinfectants, such as chlorine or ozone.
Algae elevate TOC/TON in water, result in high formation risk of DBPs.
A brief introduction to Qingcaosha (Qcs) Reservoir
Investigation of bromide and algae in raw water from
Qcs Reservoir.
DBPs formation potential in Microcystis aeruginosa
solutions during bromination.
The largest reservoir as drinking water resource in China: 66.15 km2;
7,510,000 m3/d; available capacity: 524,000,000 m3/d
( 68 days continuous supply of drinking water for 13 millions people)
Costal: locates at Yangtz river estuary
Shallow: 2-14 m depth
.
bromide vs. conductivity & chloride,
respectively
90 μg/L
bromide in the influent and effluent
(2012-2013)
Outlet gate
Algae intensity of the influent and effluent (2013)
Synedra sp.
Cyclotella sp.
Tetrastrum elegans
Pediastrum duplex
Typical algae species in Qingcaosha reservoir
Microcystis in water samples
The ratio of Microcystis to all algae in water
samples (July, 2013- Nov, 2013)
solutions during bromination
Microcystis aeruginosa
solutions during bromination
Microcystis aeruginosa
Experimental setup: 25 ºC, 48 hr, dark conditions, amber bottles (glass),
10 mg/L disinfectants, 5 mgTOC/L algae solution. Free bromine was
prepared by AgNO3 -Br2 titration method (4 ºC).
BIF=0
BIF=3
Bromine
Incorporation
Factor
BIF=2.58
BIF=2.82
solutions during bromination
Microcystis aeruginosa
Experimental setup: 25 ºC, 48 hr, dark conditions, amber bottles (glass),
10 mg/L disinfectants, 5 mgTOC/L algae solution. Free bromine was
prepared by AgNO3 -Br2 titration method (4 ºC).
solutions during bromination
Microcystis aeruginosa
Microcystis aeruginosa
solutions during bromination
Toxicity=Σ(Ci/EC50i)i=1,n
Experimental conditions
HOBr 0.28mmol/L
HOCl 0.28mmol/L
HOCl 0.28mmol/L +Br0.14mmol/L
HOCl 0.14mmol/L +HOBr
0.14mmol/L
Cytotoxicity
pH=5
0.0173
pH=7
0.0606
pH=9
0.0418
pH=7
0.0007
pH=7
0.0243
pH=7
0.0533
Cytotoxicity EC50(mol/L): CF 9.1E‐3, BDCF 9.1E‐3, DBCF 5.2E‐3, BF 4.0E‐3, DCAN 5.8E‐5, TCAN 1.7E‐4, BCAN 8.4E‐6, DBAN 2.9E‐6.
Bromide and algae are the two main issues of Qingcaosha reservoir. Seawater
intrusion greatly elevates the bromide level.
Bacillariophyta is the dominant species in cold weather, while cyanophyta is
the dominant species in summer.
Brominated THMs and HANs were generated by applying bromine-containing
disinfectants to inactivate Microcystis aeruginosa.
The molar production of total THMs in free bromine disinfection was nearly
same as that of chlorine.
The presence of free bromine drastically elevated the cytotoxicity of the
formed disinfection by-products.
Thank you