Environmental Engineering

Fundamentals of Environmental Engineering

Assignment #1

Date handed out: September 8th, 2020

Date due: September 18th, 2020 (11:59 pm)

Student’s Name and ID #______________________________________

1. List the major disinfectants used for water disinfection processes. Describe how the disinfection by-products are formed briefly.

2. Write down the contaminants listed in both National Primary Drinking Water Regulations and National Secondary Drinking Water Regulations and their maximum contaminant levels.

3. The city A has a current population of 100,000 and the average daily water demand per person is 200 gallons per capita per day. Assuming that population growth is exponential over the 20-year period with the growth rate of 1.2%. (1) What is the population in 20 years? (Hint: Model 2. Uniform Percentage Method will be used). (2) Assume the daily water demand per capita is the same, what will be the average total day demand 20 years later? What will be the design capacity (gallon/day) for the new developed water treatment plant and distribution system with 20-year design period?

(Hint: the design capacity of treatment plant = maximum day capacity (180% × average day capacity); the design capacity of distribution system =maximum hour capacity (150 % ×max day capacity))

4. How many pounds does 5,000 gallons of water weigh?

5. A circular clarifier is 20 feet in diameter and 10 feet deep. How many gallons will the clarifier hold?

6. The total flow for 1 day at a plant was 3,335,000 gallons. What was the average gallon per minute (gpm) flow for that day?

7. Determine the chlorinator setting (lb/day) required to treat a flow of 5.5 MGD with a chlorine dose of 2.5 mg/L.

8. A total chlorine dosage of 10 mg/L is required to treat the water in a unit process. If the flow is 1.8 MGD and the hypochlorite has 65% available chlorine, how many lb/day of hypochlorite will be required?

9. Jar tests indicate that the best alum dose for a unit process is 20 mg/L. The flow to be treated is 1.8 MGD. Determine the gpd (gallon per day) setting for the alum solution feeder if the liquid alum contains 5.5 lb of alum per gallon of solution.

10. A settling tank receives a daily flow of 1 MGD. The influent contains 300 mg/L suspended solids, and the unit effluent contains 100 mg/L suspended solids. What will be the pumping rate (gpm) to remove the solids from the settling tank? Assume the solids content in the pumping line is 4%

Accumulation of solid in the reactor

= Solids in the Influent – (Solids in the effluent + Solids pumped)

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