Environmental Engineering

Question 1 Not yet answered Marked out of 0.10 P Flag question The Figure below show the typical Water Treatment Unit Processes and Their Arrangement. These processes are typically used for treatment of: Influent from surface water Screen Oxidant/ disinfectant PH control Particulate material Coagulant Rapid mix Water return from filter waste washwater recovery system and solids dewatering Flocculation/ sedimentation Solids to dewatering O Water with high levels of dissolved constituents O Air pollution O Ground water O Surface water Polymer Oxidant disinfectant Granular filtration Filter waste washwater Clear-well storage Effluent to distribution system Filter washwater Water processing Solids processing

Chemicals toxic to humans by Ingestion could contaminate the food chain or drinking water.

Problem 5. World reserves of chromium are about 800 million tons, and current usage is about 2 million tons per year. If growth in demand for chromium increases exponentially at a constant rate of 2.6 percent per year, how long would it take to use up current reserves? Suppose the total resource is five times current reserves; if the use rate continues to grow at 2.6 percent, how long would it take to use up the resource?

5. a) Convert 12 mg/L of Fe(OH)2+ to unit of M. b) What is the oxidation number of Fe in Fe(OH)2+?

39) Lining the bottom of a landfill with a thick tough plastic barrier is a good way to address problems related to methane production. 3) settling. ) incomplete decomposition. -) groundwater contamination.

Problem 4. The ultimate BOD of a river just below a sewage outfall is 50.0 mg/L and the DO is at the saturation value of 10.0mg/L. The deoxygenation rate coefficient is 0.30 day" and the reaeration rate coefficient, k, is 0.90 day". The river is flowing at 48.0 miles/day. The only source of BOD is this outfall. A. Find the critical distance downstream at which DO is a minimum. B. Find the minimum DO. C. If a wastewater treatment plant is to be built to treat the sewage, what fraction of the BOD would have to be removed to assume a minimum of 5.0 mg/L downstream?

3. For a town with a population of 224,752 citizens, a new sanitary sewer line is being designed with an average flow rate of 85 gallons per capita per day (GPCD). Five primary clarifiers are being planned, each with a 70 ft. diameter. The residence time for the wastewater in each clarifier is 1.8 hours. What is the depth of each clarifier?

3. (10 points) The National Ambient Air Quality Standards (NAAQS) limit the maximumhourly average concentration of ground-level ozone to 235 µg/m³. Convert this standardvalue to ppmv. Assume pressure is 1 atm and temperature is 20°C.

4. A rapid sand filter has four cells with the following dimensions: Length=10 ft, Width%=10 ft,Depth=12 ft. The water production rate is 2 MGD. If one cell is taken off line for backwash, the hydraulic loading rate (gpm/ft?) for the filter is?

1) For the water quality analyses shown below, make a bar chart of the ions in the water (using units of mg/L as CaCO3) and label total hardness (TH), carbonate hardness (CH) and non-carbonate hardness(NCH), if applicable. Determine if all the ions in the water have been measured (i.e., is there a charge balance (within 5%)?). Assume the iron (Fe) is all present as Fe2+.