Title: Occurrence and Sources of Bromate in the Chlorinated Tap Drinking Water in Metropolitan Manila, Philippines

Homer C. Genuino and Maria Pythias B. Espino

LIST OF SUPPLEMENTAL INFORMATION

Fig. S1Schematic diagram of the water treatment processes at the Balara Water Treatment Plants 1 and 2

Fig. S2Schematic diagram of the University of the PhilippinesSewage Treatment Plant operations indicating the two sampling points

Table S1 Monthly data from October 2006 to June 2007 for the average of rainfall (mm) and temperature (oC) reported by the Philippine Atmospheric, Geophysical and Astronomical Services Administration

Table S2Average levels of residual chlorine in tap drinking water in the distributionsystem serviced by Manila Water Company, Incorporated (MWCI) (data were obtained from the Central Laboratory report of MWCI submitted to MWSS)

Table S3Average levels of residual chlorine in tap drinking water in the distribution system serviced by Maynilad Water Services Incorporated (MWSI) (data were obtained from the Central Laboratory report of MWSI submitted to MWSS)

Table S4 Step-by-step calculation of the mass balance on bromate and hypochlorite analyses of wastewaterfrom University of the Philippines Sewage Treatment Plant (calculations adopted from the work of Weinberg et al. (2003))

Fig.S1

Fig.S2

Table S1


Sampling time
/ Sampling location / Reported average rainfall in mm / Reported average
temperature in oC
October 2006 / Quezon City a / 212.2 / 27.5
Manila b / 199 / 28.4
November 2006 / Quezon City / 88.7 / 27.8
Manila / 70.9 / 29.1
December 2006 / Quezon City / 76.8 / 27.1
Manila / 107.7 / 28.2
January 2007 / Quezon City / 2.2 / 26.6
Manila / 1.2 / 27.3
February 2007 / Quezon City / trace / 26.2
Manila / 10.5 / 27.9
March 2007 / Quezon City / 21.6 / 27.9
Manila / 28 / 29.2
April 2007 / Quezon City / 25.8 / 29.7
Manila / 27.2 / 30.3
May 2007 / Quezon City / 23.6 / 30.6
Manila / 20.5 / 29.4
June 2007 / Quezon City / 67.8 / 27.5
Manila / 73.1 / 28.3

a PAGASA weather station science garden, Agham Road, Diliman, Quezon City

b Port Area, Intramuros, Manila

Table S2

City or municipality / Average concentration of residual chlorine in mg L-1
October 2006 / November 2006 / December 2006 / January
2007 / February 2007 / March 2007 / April 2007

Makati / 0.54 / 0.65 / 0.79 / 0.67 / 0.68 / 0.64 / 0.70
Mandaluyong / 0.61 / 0.65 / 0.73 / 0.72 / 0.70 / 0.73 / 0.75
Manila / 0.60 / 0.64 / 0.71 / 0.70 / 0.66 / 0.73 / 0.76
Marikina / 0.82 / 0.78 / 0.82 / 0.83 / 0.90 / 0.93 / 0.93
Pasig / 0.71 / 0.84 / 0.80 / 0.94 / 0.90 / 0.75 / 0.75
Pateros / 0.69 / 0.75 / 0.82 / 0.81 / 0.97 / 0.69 / 0.72
Quezon City / 0.70 / 0.73 / 0.79 / 0.79 / 0.85 / 0.89 / 0.86
San Juan / 0.68 / 0.68 / 0.77 / 0.75 / 0.74 / 0.76 / 0.79
Taguig
/ 0.60 / 0.71 / 0.78 / 0.78 / 0.88 / 0.71 / 0.72

Table S3

City or municipality / Average concentrationof residual chlorine in mg L-1
October 2006 / November 2006 / December 2006 / February 2007 / March 2007 / April 2007

Caloocan / 0.91 / 1.01 / 0.99 / 1.00 / 0.95 / 0.89
Las Piñas / 0.85 / 0.89 / 0.94 / 0.90 / 0.90 / 0.85
Makati / 0.97 / 0.86 / 0.82 / 0.74 / 0.79 / 0.68
Malabon / 0.94 / 0.97 / 0.93 / 0.82 / 0.85 / 0.81
Manila / 0.89 / 0.88 / 0.85 / 0.95 / 0.90 / 0.88
Navotas / 0.99 / 0.93 / 0.88 / 0.75 / 0.82 / 0.81
Novaliches / 1.14 / 1.08 / 1.05 / 1.22 / 1.22 / 1.10
Parañaque / 0.86 / 0.87 / 0.95 / 0.82 / 0.89 / 0.83
Pasay / 0.88 / 0.81 / 0.79 / 0.77 / 0.82 / 0.75
Quezon City / 0.98 / 1.04 / 1.02 / 1.08 / 1.08 / 1.00
Valenzuela
/ 0.97 / 0.99 / 0.98 / 0.86 / 0.91 / 0.86

Table S4

Parameter and calculation
/ Result
Average concentration (n=3) of bromate in calcium hypochlorite feedstock / 6645 mg L-1
Average concentration (n=3) of free chlorine in calcium hypochlorite feedstock
(determined using the standard method for free chlorine) / 146 g L-1
µg BrO3- / g free chlorine
[ (6645 mg L-1 × 1000) / (146 g L-1) ] / 45514 µg g-1
Hypochlorite dose
(provided bythe University of the Philippines Sewerage Treatment Plant) / 7.0 mg L-1
Predicted bromate concentration
(hypochlorite dose in mg L-1) ×(bromate concentration in µg g-1) / (free chlorine in feedstock inμg g-1)
[ (7.0 mg L-1 × 45514 µg BrO3- per gramof free chlorine) / (1000) ] / 319 µg L-1
Average concentration (n=3) of bromate in thewastewater samplefrom the effluent tanka / 342 µg L-1
Mass balance
(measured bromate concentration / predicted bromate concentration) × 100%
[ (342 µg L-1 / 319 µg L-1) × 100% ]
/ 107%

aobtained from the January 2007 data