Environmental Engineering Reference
In-Depth Information
System low rate
125 gpm
Contact time
1.6-4.34 min
Optimal contact time
3 min
Cubic feet of media
50 ft
3
EBCT in BVs
375 gal/BV
Density of media
40 lb/ft
3
Grams of media
910,428 g/50 ft
3
BV
Total gallons to exhaustion
18,750,000 gal
Total BV to exhaustion
50,000 BV
Total As removed/gal
0.0945 mg As/gal (jar test to
conirm)
Total As removed (mg)
1,771,875 mg As removed to
exhaustion
Total As removed (g)
1772 g As removed to
exhaustion
Total As removed (lb)
3.9 lb As removed to
exhaustion
Total As removed/ft
3
of media
0.078 lb As removed/ft
3
media
Total As removed/g of media
0.06 mg/g As removed/g of
media
Cost of treatment
TiO
2
price ($/lb)
$7.00 $/lb
Density
40 lb/ft
3
Cost ($/ft
3
)
$280/ft
3
Media cost ($/50 ft
3
)
$14,037
k-Gallon treated
18,750 kgal treated
Cost/kgal (does not include rebed)
0.75 $/kgal
9.5 Arsenic in the Food Supply
14
There is no question that water contamination (heavy metals, oxidizers such as perchlo-
rate) goes up the food chain. Rice ields irrigated with arsenic-contaminated irrigation
water allow inorganic arsenic to be adsorbed by the rice monocot plant and be disposed
of in the seed of the plant, better known as rice.
Three US lawmakers introduced a bill on September 21, 2012, to limit the amount of
arsenic allowed in rice and rice-based products, a legislator said. The move comes after
Consumer Reports
urged limits for arsenic in rice. Tests of more than 60 products, from
Kellogg's Rice Krispies to Gerber infant cereal, showed most had some inorganic arsenic,
a known carcinogen in humans.
The proposed RICE Act—Reducing Food-Based Inorganic and Organic Compounds
Exposure Act—requires the Food and Drug Administration to set a maximum level of arse-
nic in rice and food containing rice. Democratic lawmakers Rosa DeLauro of Connecticut,
