1. If 8000m3/d of wastewater from an industry has a BOD5 of 190 mg/L and k = 0.17 per day (base 10)
a. How much oxygen (kg/day) is required to satisfy the BOD demand of this waste, assuming 1 kg of oxygen is to be supplied per kilogram of the ultimate BOD in the waste
b. What is the population equivalent of the waste (based on BOD5)
2. A 5000-m3/day wastewater plant discharges to a river with a minimum drought flow of 137.7 m3/min (immediately upstream from the outfall)
a. What total allowable BOD5 (kg/day) could be discharged in the river after initial dilution must not exceed 1 mg/L and no upstream pollution is occurring?
b. What degree of treatment (% BOD satisfied) does this represent, assuming the plant influent to have a BOD5 of 250 mg/L
3. During recent winters there has been considerable criticism of the practice of dumping salt-laden snow from the streets into rivers and lakes for disposal. What problems are caused by this? (minimum of 4) Should the practice be prohibited? What alternatives are available? How would they resolve these problems
4. Calculate the surface area and depth of an "ideal" settling tank to remove all 10um spherical particles (SG = 2.65) from 1000 m3 of wastewater per day and provide a detention time of at least 1 Hr
5. From the information given, wastewater is made up of many different constituents, which one in your opinion creates the greatest risks to human habitation? Natural habitation? Which ones are reasonably inert? Is treatment the only way to prevent these elements from entering the wastewater stream?
Part II
1. Discuss methods that can allow you personally to reduce water consumption. Does individual consumption rates for a community compare to industrial uses?
2. Desalination seems to be the key to unlocking the vast supply of ocean water for our use. Explain, why it is unlikely that desalination - even if costs can be brought down to those of most municipal water supplies, will ever be widely used in irrigation, the world's most common water use. Note that seawater contains between 18,000 to 35,000 mg/L of salt.
3. Water has unique properties that are different from those of any other liquid. It is the universal solvent and has a high heat capacity, high heat of vaporization, a large temperature difference between its boiling point and its freezing points and a maximum density at 4 degrees C. Explain how these 5 characteristics are important in our environment?