A wastewater is to be disinfected with 35mg/L ofchlorine to obtain 99% kill of micro-organisms.The number of micro-organisms remaining alive(N₂) at time t, is modelled byN₁ = No e-kt, where No is number of micro-organisms at t = 0, and k is the rate of kill. Thewastewater flow rate is 36m³/h, and k = 0.23 min1. If the depth and width of the chlorination tankare 1.5 m and 1.0m, respectively, the length ofthe tank (in m, round off to 2 decimal places)is

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Answered: A wastewater is to be disinfected with…

A wastewater is to be disinfected with 35mg/L of chlorine to obtain 99% kill of micro-organisms. The number of micro-organisms remaining alive (N₂) at time t, is modelled by

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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2.40. A solution is known to contain 50 g/m³ of CH₂(CH₂),COOH and 42 g/m³ of NH3-N. Determine the theoretical ultimate carbona- ceous CBOD, the NBOD, and the theoretical total oxygen demand.
Poorly treated municipal wastewater is continuously discharged directly into a lake. The discharge from the wastewater plant into the lake occurs at a flow of Qd = 1 m3/hr. The concentration of phosphate (PO43, M = 95 g/mol) in the discharge flow (Cxd) that is decaying with first-order kinetics is 100 mg/L. The lake is a well-mixed water body of 100 m3. (Phosphate is naturally uptaken by algae with a first- order decay rate constant equal to 0.20/day.) The concentration of phosphate in the incoming river (Cx,r) is 10 mg P/L. The incoming river flow rate is Q, = 10 m3/hr. %3D a) Which of the following equations represent the correct mass balance equation? O va = CxQr - CxdQd -QoutCxvout" kCx,outV %3D O 0 = Cx,Qr + CxdQd -QoutCxvout" kCx,outV X,r O 0 = CxQr + CxdQd -QoutCxvout- kV O 0 = Cx,dQr + Cx,,Qd -QoutCxout- kCxoutV
Please upload your full solution to the following problem. A series of experiments was conducted in a batch reactor to assess the disinfection by chlorine of the protozoan Giardia lamblia. In each experimental run, the concentration of free available chlorine was varied and the time required to kill 99 percent of the organisms was determined. The results showed that a Ct value of 100 mg-min/L was sufficient to achieve 2-log removal. Assume that the Chick- Watson model holds with n = 1. A. What value is the psuedo-first order disinfection rate coefficient k (min ¹) when the chlorine concentration is 1 mg/L? B. At a chlorine concentration of 1 mg/L and a contact time of 10 minutes, what fraction of the G. lamblia organisms would be killed? C. At a chlorine concentration of 10 mg/L and a contact time of 5 minutes, estimate the fraction of the G. lamblia organisms that would be killed. 4
Wastewater is treated with an activated sludge plug flow reactor, similar to one seen at the Norman Water Reclamation Facility. The BOD5 after primary treatment is 100mg/L and the effluent limit is 5 mg/L BOD5. Use 1.00 h-1 as the maximum specific growth rate constant and typical values for the other biokinetic constants. The biomass concentration in the reactor is 2,500 mg/L MLSS based on a recycle ratio of 1. Calculate the mean cell residence time, in hours for this system
Find out after how much time only 2% chlorine will remain in the water sample if its half-life is 6 days.
A batch reactor will be utilized to treat raw water in order to attain a pollutant removal rate of 95 percent. Assuming that the pollutant has a second-order reaction rate constant of 0.35 L/(mg.day), what is the minimum amount of water that must be present in the batch reactor in days?
An activated-sludge system is to be used for secondary treatment of 15,000 m3/d of municipal wastewater. After primary clarification, the BOD is 130 mg/L, and it is desired to have not more than 5 mg/L of soluble BOD in the effluent. A completely mixed reactor is to be used, and pilot-plant analysis has established the following kinetic values: Y = 0.6 kg/kg, kd = 0.07 d-1. Assuming an MLSS concentration of 2,750 mg/L and an underflow concentration of 11,000 mg/L from the secondary clarifier, determine the followings. [Use θc (MCRT or SRT) = 10 day.] 5.1. The volume of the reactor. 5.2. The mass and volume of solids that must be wasted each day. 5.3. The recycle ratio. Hint: θc = VX/QwXu : MCRT (mean cell-residence time) [or SRT (solids retention time)]; average time microbes spend in reactor = ratio of total biomass in reactor to biomass wasted per given time; currently most commonly used design parameter F/Mv: inversely proportional to SRT; ≈U (cell's specific substrate…
A rapidly mixed tank consists of a treatment unit used to disinfect a solution. The solution enters the 2000 m tank at a rate of 0.4 m/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) Ca. When exposed to chlorine, the bacteria die off at a rate (in cells/L-s) given by: Cet Cbact Tbact Img + Ca 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?
The treated waste water is being discharged into a river that has a temperature of 15°C. The BOD rate constant determined in the laboratory for this mixed water is 0.12 per day (base e) at 20°C (Temperature coefficient, 1.047). What fraction of maximum oxygen consumption will occur in first four days?
(4) [Text-problem 4.29] A 90-m³ basement in a residence is found to be contaminated with radon coming from the ground through the floor drains. The concentration of radon in the room is 1.5 Bq L- (becquerels per liter) under steady-state conditions. The room behaves as a CMFR, and the decay of radon is a first-order reaction with a decay rate con- stant of 2.09 × 10-6 s-1. If the source of radon is closed off and the room is vented with radon-free air at a rate of 0.14 m³ s-1, how long will it take to lower the radon concentration to an acceptable level of 0.15 Bq L-¹?