An industry is illegally discharging tetrachloroethene (also called tetratchloro

Question

An industry is illegally discharging tetrachloroethene (also called tetratchloroethylene, perchloroethylene, or PCE) into a river. The concentration in the river at the point of discharge is 0.05 mg/L. A drinking water treatment plant (DWTP) is located 8.5 km downstream. The water velocity in the river is 0.25 km/day. A. What is the hydraulic residence time of the river between the discharge point and the DWTP? If PCE degrades with a first-order rate constant k = 0.1 d-1, what is the PCE concentration at the DWTP at steady state? The oral potency factor for PCE is 5.1 Times 10-2 (mg/kg-d)-1 (text. Table 4.9). If a 70 kg person drinks 2 L of the water from the DWTP every day, is the lifetime cancer risk greater than 1 in one million? Assume no removal of PCE in drinking water treatment.

Explanation / Answer

hydaulic residence time = capacity / discharge

let us assume dia of pipe = 150 mm A= 3.14*d^2/4 = 0.0176

q= A * v = 0.0176 * 0.25 * 10^3/24*60*60 = 0.00289 m^3/s

capacity = A * l = 0.0176 * 0.00289 = 0.0000509 m^3

t = 56.779 sec

c = c1 e^-(kt) = 0.00017

Here c1 is initial concentration

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---