Design an aerated grit chamber system to treat a 1 day sustained peak hourly flow of 3.40m3/s with an average flow of 2.50m3/s. Determine: (a) the grit chamber volume (assuming two chambers will be used); (b) the dimensions of the two grit chambers; (c)the average hydraulic retention time in each grit chamber; (d) air requirements, assuming 0.4 m3/m-min of air; and (e) the quantity of grit removed at peak flow, assuming a typical value of 0.02 m3/103m3 of grit in the untreated wastewater. The details of the design information used to size the aerated grit chambers are shown in Table Q2. Table Q2. Design information used to size aerated grit chambers Parameter Value / Range Peak flow detention time (min) 4 Depth (m)

Chlorination contact tanks with completely mixed hydraulic patterns give betterdisinfection efficiencies than tanks with plug flow behavior. True or False? Explain your reasoning

SITUATION 2: The ground floor of a residential house has an area of 200 square meters. The plan specifies 4 inches thick concrete floor on fill using Class C concrete mix. Determine the following: Use AREA METHOD. MIXTURE CLASS SAND GRAVEL Thick 50 kg. Cement Per Bag B 40 kg. Cement Per Bag in ness cm. cu. m. 5.0 450 375 30 350 300 .250 .0250 .050 7.5 .675 .563 45 525 450 375 .0375 .075 10.0 .900 .750 60 .700 600 .500 .0500 .100 12.5 1.125 .938 .75 875 750 .625 .0630 .125 15.0 1.350 1.125 90 1.050 .900 .750 .0750 .150 17.5 1.575 1.313 1.05 1.225 1.050 .875 .0880 .175 20.0 1.800 1.500 1.20 1.400 1.200 1.000. 1000 200 22.5 2.030 1.688 1.35 1.575 1.350 1.125 1125 .225 25.0 2.250 1.875 1.50 1250. 250 1.750 1.500 1.250 27.5 2.475 2.063 1.65 1.925 1.650 1.375 .1380 275 36.0 2.700 2.250 1.80 2.100 1.800 1.500 .1500 300 Quantity of cement in bags (50kg). Your answer Sand in cubic meters Your answer Gravel in cubic meters Your answer

Problem 1 A mechanically cleaned bar screen is used in preliminary treatment for the following conditions: Wastewater flow rate = 100,000 m/d Approach velocity 0.6 m/s Open area for flow through the screen = Head loss coefficient for clean screen Head loss coefficient for clogged screen = 0.60 Incline from vertical = 0° %3D 1.6 m2 0.75 I %3D a. Calculate the clean water head loss through the bar screen. b. Calculate the head loss after 40% of the flow area is clogged with solids.

Design a grit chamber to remove sand particles (p, = 2650 kg/m³) with a mean diameter of 0.21 mm. Assume the sand is spherical and the temperature of the wastewater is 20 °C. The wastewater flow is 10,000 m/d. A velocity of 0.3 m/s will be automatically maintained, and the depth must be 1.5 times the width at maximum flow.

don't use Ai.

3.3 Three grit chambers are currently used to treat grits in a WWTP. Each channel is 2.5 ft wide and has a water depth of 2 ft. What is the velocity when the influent flow rate is 12 ft³/sec? a) 1.75 ft/sec b) 0.74 ft/sec c) 1.05 ft/sec d) 0.80 ft/sec 3.4 You performed settling test and found 600 mL settled after 30 min. If the MLSS in the aeration basin was 3000 mg/L, do you have problem? a) yes b) no c) no enough info. d) need to redo test

A constant velocity grit chamber is used in a small coastal community as a form of pre- treatment to incoming wastewater flows. The town regularly experiences a number of visitors during school holiday periods. If the usual wastewater flow is 10 ML per day, and the usual holiday period flow is 18 ML per day, design an appropriately sized grit chamber arrangement if the target grit has a diameter of 0.16 mm with a specific gravity of 2.75. Show your solutions for the following (but not necessarily in this order): 1. Determine the settling velocity for the target particle 2. Assuming a horizontal flow velocity of 0.32 m/s determine an appropriate overflow rate for the grit chamber 3. Determine an appropriate chamber length and cross sectional area and draw figures 4. Comment on how you could accommodate for the seasonal fluctuations in flows.

Which of the following apparatus is used for testing the setting time of hydraulic cement? 1. Vicat needle with 1 mm diamter 2. Hydraulic Jack 3. Vicat needle with 10 mm needle 4. Cnnsolidometer

A municipal water treatment plant employs two circular primary clarifiers arranged in parallel, following the bar screen and grit removal chamber. The plant receives 5.0 MGD. Each clarifier is center-fed (water enters at the center and exits at the perimeter). The clarifier radius is 43.0 ft and depth is 10.0 ft. a) What is the hydraulic detention time in each clarifier? b) What is the hydraulic loading rate (critical velocity) in units of ft3/(ft2-hr)?