question answer
NAME ______________________________________
Industrial Wastewater Management (ESHS-614)
Homework Assignment #2
20 Points
1. Why/when do you think it might be important to calculate mass discharges rather than just referring to concentrations in a wastewater discharge? (2 points)
2. What are the differences and similarities (how they are measured, what they measure, etc.) between BOD, COD, and dissolved oxygen? (6points)
3. Perform the following calculations.
a. An iron-forming manufacturing process discharges 450,000 gals/day of wastewater containing 2.3 mg/L of iron. How much iron does the process discharge per day? (1 point)
b. In a food processing plant, wastewater is discharged to the sewer in two locations. At the first location, wastewater containing 435 mg/L BOD is discharged at a rate of 200,000 gals/day. At the second location wastewater is discharged at a rate of 90,000 gal/day and contains 650 mg/L of BOD. What is the total amount of BOD discharged to the sewer each day? (2 points)
c. A chemical manufacturing facility discharges 1.35 mgd of wastewater containing 600 lb/day of COD to the municipal sewer. The municipality wants to change its COD discharge limit to 50 mg/L. If it does this, will the chemical manufacturing facility be in compliance? By how much will its discharge concentration be above or below the new limit? (2 points)
4. The environmental manager at the Wepollute Chemical Company, which manufactures methylethylstuff (MES), an organic chemical, wants to develop a sampling and analysis plan in order to identify:
a. where their product, MES, is being discharged to the sewer (obviously, this is money down the drain); and
b. why there has been a dramatic increase in the amount of nickel being discharged to the POTW.
The three, parallel chemical manufacturing processes that each make MES discharge wastewater into the main industrial sewer system at a three different locations in the facility. (See the block flow diagram below.)These processes discharge suspended solids and nickel as well as MES into the sewer. The chemical plant operates two shifts, 5-days a week. During the day shift (7 am to 3 pm), all three production lines are operating. During the evening shift (3 pm to 11 pm), only one line (Line #2) is running. Develop a comprehensive sampling plan to meet the two objectives given above. Describe the goals of the sampling plan and indicate where you would collect samples, the type of samples you would collect (grab, composite or other), how you would collect the samples, and the sampling frequency and duration (1/day for 10 days, or perhaps once per hour for 5 days, or ??). Justify your answers. (7 points)
HELPFUL HINTS: Consider the variability that could occur in each line throughout the day and from day to day. Also, just because a line is not operating does not mean it is not discharging anything to the sewer. This includes weekends.
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Industrial Wastewater Management, Homework #2