A rapidly mixed tank consists of a treatment unit used to disinfect a solution. The solution enters the 2000 m3 tank at a rate of 0.4 m3/s. The pollutant contains 7.94 CFU per liter and has no 0 mg/l of chlorine. The treatment unit uses a stock solution containing 750 mg/L which is released a rate that will cause the chlorine concentration in the tank to be 2 mg/L. The chlorine reacts with the water in such a way that it is depleted at a rate (in mg/L-h) given by ra = ( -0.45 / h) Cci. When exposed to chlorine, the bacteria die off at a rate (in cells/L-s) given by: 0.03 •Ccl -Cbact + Ccl Ipact 1mg a) Calculate the required flow rate in L/s of the stock solution when the system is operating at steady state, including a schematic of the system. b) Determine the bacterial concentration (in CFU/L) thar should be expected in the effluent from the tank?

A rapidly mixed tank consists of a treatment unit used to disinfect a solution. The solution enters the 2000 m3 tank at a rate of 0.4 m3/s. The pollutant contains 7.94 CFU per liter and has no 0 mg/l of chlorine. The treatment unit uses a stock solution containing 750 mg/L which is released a rate that will cause the chlorine concentration in the tank to be 2 mg/L. The chlorine reacts with the water in such a way that it is depleted at a rate (in mg/L-h) given by ra = ( -0.45 / h) Cci. When exposed to chlorine, the bacteria die off at a rate (in cells/L-s) given by: 0.03 •Ccl -Cbact + Ccl Ipact 1mg a) Calculate the required flow rate in L/s of the stock solution when the system is operating at steady state, including a schematic of the system. b) Determine the bacterial concentration (in CFU/L) thar should be expected in the effluent from the tank?

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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A rapidly mixed tank consists of a treatment unit used to disinfect a solution. The solution enters the 2000 m3 tank at a rate of 0.4 m3/s. The pollutant contains 7.94 CFU per liter and has no 0 mg/l of chlorine. The treatment unit uses a stock solution containing 750 mg/L which is released a rate that will cause the chlorine concentration in the tank to be 2 mg/L. The chlorine reacts with the water in such a way that it is depleted at a rate (in mg/L-h) given by rcl = ( -0.45 / h) CCl. When exposed to chlorine, the bacteria die off at a rate (in cells/L-s) given by:a) Calculate the required flow rate in L/s of the stock solution when the system is operating at steady state, including a schematic of the system.b) Determine the bacterial concentration (in CFU/L) thar should be expected in the effluent from the tank?
As an operator of a wastewater treatment facility, you have learned that your plant runs well at an SRT (based on MLVSS (X) in the aeration basin) of 12 days. If today’s MLVSS (X) concentration is 2,700 mg/L and the RAS (Xr) concentration is 5,500 mg/L, how many L of sludge should you waste from the secondary clarifier today? Other design conditions: Average influent flow = 12,000 m3/d Influent soluble BOD = 150 mg/L Required effluent TSS = 30 mg/L Aeration tank Volume = 1,000 m3
The plant operators at the Acme WWTP maintains the 10,000 gal aeration basin shown below with a constant 1500mg/L mixed liquor suspended solids (MLSS). The suspended solids are separated in a clarifier with recycle of the separated sludge. The recycle flow rate is 5,000 gal per day and 500 gal of recycle are wasted daily. Given that the plant treats 25,000 gals of liquid waste per day and the effluent contains 30 mg/L MLSS, find the solids retention time assuming the system is at steady-state.
The wastewater from a synthetic textile manufacturing plant is discharged to a municipal treatment plant for processing with domestic wastewater. The characteristics of the synthetic textile wastewater are 1500 mg/L BOD, 2000 mg/L SS, 30 mg/L nitrogen, and no phosphorus. The characteristics of the domestic wastewater are 200 mg/L BOD, 240 mg/L SS, 35 mg/L nitrogen, and 7 mg/L phosphorus. Find the BOD, SS of the mixture. The ratio of flow rate is domestic/textile = 4/1
A small town discharges its sewage effluent in a nearby river. The river has an initial background BOD of 23.5 mg/L.The oxygen deficit just upstream from the point of discharge of the sewerage is 4 mg/L. The river is flowing at aspeed of 43 km/day. You have been asked to determine the impact of this town’s sewerage discharge on the rivergiven that the deoxygenation rate coefficient kd is 0.3/day, and the reaeration rate coefficient kr is 0.5/day.a) A sensitive fish species inhabits the river 120 km from the point of discharge. Determine if the impact of theBOD will have led to the minimum DO before or after the location of the fish species.b) Find the minimum DO due to the effluent discharge.c) Discuss the oxygen deficit in relation to the location of the fish species and whether the fish are at risk due tothe discharge upstream.
A wastewater treatment plant discharges 2.16x107 L/hr of treated effluent with an ultimate BOD of 22.0 mg/L and dissolved oxygen concentration of 5.0 mg/L to a river. Upstream of the waste discharge, the river has a flow of 9.0 m3/s, an ultimate BOD of 10.0 mg/L, and dissolved oxygen concentration of 7.0 mg/L. Both the river and effluent are at 20°C. After the river and effluent mix, the river flows at a velocity of 0.13 m/s and has a depth of 1.8 m. The deoxygenation rate constant for the waste is 0.45 day-1. A fish hatchery is located 9.6 km downstream of the waste discharge. The hatchery requires 5.0 mg/L DO for healthy fish growth and reproduction. Is the hatchery requirement being met? show all work
The wastewater contains 7.5 x 105 fecal CFU per liter. The permissible fecal coliform concentration is 3500 fecal coliform CFU/L. Calculate the length of pipe required if the linear velocity of the wastewater pipe is 0.73 m/s. Take the reaction rate constant for the destruction of the fecal coliform is 0.21 per min.
A waste-holding lagoon situated near the main plant of a chemicalcompany receives sludge on a daily basis. When the lagoon is full, it is necessary toremove the sludge to a site located 4.95 kilometers from the main plant. Currently,when the lagoon is full, the sludge is removed by pumping it into a tank truck andhauling it away. This process requires the use of a portable pump that has an initialcost of $800 and an 8-year life. The company can operate the pump at a cost of $25per day, but the truck and driver cost $110 per day.Alternatively, the company has a proposal to install a pump and pipeline to theremote site. The pump would have an initial cost of $600, a life of 10 years, and acost of $3 per day to operate. (a) If the MARR is 15% per year and the pipeline willcost $3.52 per meter to construct, how many days per year must the lagoon requirepumping to justify construction of the pipeline? (b) The lagoon was pumped40 times last year. Which alternative would have been cheaper?…
A lake with a volume of 10.0 x 10^6 m^3 that is fed by a stream with a flow rate of 5 m^3/sec and a pollutant concentration equal to 10mg/L. An industry dishcharges treated wastewater at a rate of 0.5 m^3/sec of the same pollutant into the lake at a concentration 100mg/L. The pollutant has a reaction rate constant of 0.20/day. Assuming pollutant is completely mixed in the lake and that ther is no evaporation and no other water losses or gains, determine the steady-state concentration of the pollutant in the lake.
The discharge from a food processing plant is the only source of BOD in a river. The oxygensag curve shows a minimum DO concentration of 3.0 mg/L. The DO concentrationimmediately downstream of the discharge is at saturation (10.0 mg/L). Other characteristics ofthe system are as follows: u = 60 miles/day; kr = 0.80 days-1; kd = 0.20 days-1.a. Currently the food processing plant does not treat the waste. What percent removal ofthe BOD would be required to ensure that the DO of the river at any locationdownstream of the plant is always greater than 5.0 mg/L?b. How far downstream would the lowest DO levels occur?c. What ultimate BOD concentration of the mixture of the river and waste immediatelydownstream of the discharge would result in a minimum DO concentration of 5.0mg/L?
A conventional aeration tank is to treat a flow of 0.8 mgpd of primary effluent with a BOD of 125 ppm. The MLSS concentration is to be maintained at 1800 ppm, and a food -to-microorganism (F/M) ration of 0.4 is specified. Compute the required volume of the aeration tank. If the SWD is to be 15 ft and the tank length to be three times its width, how long should the tank be.
Consider a wastewater treatment reactor where with an influent flow rate of 2,500 m3/day and where the biomass has the following kinetic characteristics: fs0 = 0.7, KS = 10 mg/l, k= 10 mg/mg VSS-day, b = 0.1/day, Y=0.50 g VSS/g substrate, fd=0.8, and Xa=1,500 mg VSS/l. If the reactor was designed with a safety factor of 30, what is its design fs value.