A river with a flowrate (Q) of 850 cfs (cubic feet per second) has a total dissolved solids (TDS, think table salt in water) concentration of 55 mg/L. An industry discharges a water stream with a TDS concentration of 2,500 mg/L into the river and the two streams are well mixed. If the maximum TDS concentration allowed in the river is 250 mg/L, the system is at steady state, and there are no other TDS inputs, answer the following: a) What is the maximum allowable wastewater flow from the industry (in cfs)? b) If the 250 mg/L TDS level is met downstream, what percent of the TDS comes from the industry?
A river with a flowrate (Q) of 850 cfs (cubic feet per second) has a total dissolved solids (TDS, think table salt in water) concentration of 55 mg/L. An industry discharges a water stream with a TDS concentration of 2,500 mg/L into the river and the two streams are well mixed. If the maximum TDS concentration allowed in the river is 250 mg/L, the system is at steady state, and there are no other TDS inputs, answer the following:
a) What is the maximum allowable wastewater flow from the industry (in cfs)?
b) If the 250 mg/L TDS level is met downstream, what percent of the TDS comes from the industry?
Given,
Flow rate of river, Q = 850 cfc= 850 ft3/sec
TDS of river, say C =55 mg/L
TDS of discharge from the industry, say Ci = 2500 mg/L
a) Let the flow rate of the industrial discharge be Qi (cfs).
The resultant TDS for the mixture of the river and the industrial discharge, say Cr can be given as:
Also, according to the given problem, the maximum allowable TDS = 250 mg/L.
Therefore, the maximum allowable wastewater flow from the industry = 73.667 cfs.
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