CE 311 Environmental Engineering I
Dr. Kauser Jahan, P.E.
Fall 2006
ASSIGNMENT # 2: Mass Balance
DUE DATE: Monday September 25, 2006
Problems from textbook: 3-4, 3-5
3. An industrial flow of 12 L/min has a solids concentration of 80 mg/L. A solids
removal process extracts 960 mg/min of the solids from the flow without affecting
the liquid flow. What is the percent recovery of the solids?
4. A 10 MGD wastewater treatment plant has a suspended solids concentration
of 80 mg/L. If the plant discharges into the Delaware river (Upstream Flow 3
MGD, Upstream Suspended Solids 5 mg/L), what is the suspended solids
concentration in mg/L downstream after the plant discharge?
Wastewater Plant
Delaware River
(b) If the New Jersey regulatory agency allows a suspended solids
concentration of 30 mg/L in the downstream reach of the river, what
concentration of suspended solids in mg/L can the wastewater treatment
plant discharge?
5. Jahan Textile Company discharges waste containing 20 g/L of red dye from
vats at a rate of 900 Gallons per minute. The color intensity is too great and the
state regulatory agency has ordered the company to reduce the color to 80 mg/L
in the discharge. The company has discovered that the least expensive method
is to dilute the current 20 g/L waste stream with drinking water and produce an
80 mg/L dye waste.
What is the flowrate in GPM of the drinking water that needs to be added for
the necessary dilution?