Estimate the reduction in bacteria during the passage of wastewater that initially contains 106 organisms per milliliter through three stabilization ponds that are arranged in series. The volumes of the three ponds are 10,000; 20,000; and 6,000 m3, respectively. The flowrate is 1000 m3/d. Assume that steady-state conditions apply, that the ponds are completely mixed due to wind action, that first-order decay kinetics apply, and that the value of the reaction rate constant k is 1.0 d-1. What is the overall conversion for these ponds in series? Instead

Estimate the reduction in bacteria during the passage of wastewater that initially contains 106 organisms per milliliter through three stabilization ponds that are arranged in series. The volumes of the three ponds are 10,000; 20,000; and 6,000 m3, respectively. The flowrate is 1000 m3/d. Assume that steady-state conditions apply, that the ponds are completely mixed due to wind action, that first-order decay kinetics apply, and that the value of the reaction rate constant k is 1.0 d-1. What is the overall conversion for these ponds in series? Instead

Sustainable Energy

2nd Edition

ISBN:9781337551663

Author:DUNLAP, Richard A.

Publisher:DUNLAP, Richard A.

Chapter14: Ocean Thermal Energy Conversion And Ocean Salinity Gradient Energy

Section: Chapter Questions

Problem 20P

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Estimate the reduction in bacteria during the passage of wastewater that initially contains 106 organisms per milliliter through three stabilization ponds that are arranged in series. The volumes of the three ponds are 10,000, 20,000, and 6000 m³, respectively. The flow rate is 1000 m³/d. Assume that steady-state conditions apply, that the ponds are mixed completely because of wind action, that first- order decay kinetics apply, and that the value of the reaction rate coefficient k is 1.0 d ¹. Would the efficiency improve if all of the ponds were equal in volume (12,000 m³/pond)?
A storage tank of a treatment water has a holding capacity of 750 m' up to an overflow point. The treatment water having silica content of 0.003 mg /L is flowing in to a tank at a rate of 30 L/sec. the out flow from the tank to the high pressure boilers is 30 L/sec. With time the quality of treatment water increased to 0.025 mg/L. Assuming that the inflow in to and out flow from the tank remains constant at 30 L/sec, calculate the time required for the silica content in the storage tank to increase to 0.01 mg/L.
1. A wastewater treatment plant serving a city of 200,000 discharges 1.10 m/s of treated effluent having an ultimate BOD of 50.0 mg/L into a stream that has a flow of 8.70 m/s and a BOD of its own equal to 6.0 mg/L. The deoxygenation constant ka, is 0.20/day. a. Assuming complete and instantaneous mixing, estimate the ultimate BOD of the river just downstream from the outfall. b. If the stream has a constant cross section, so that it flows at a fixed speed equal to 0.30 m/s, estimate the BOD remaining in the stream at a distance 30,000 m downstream. 2. The wastewater in the question above has a dissolved oxygen concentration of 2.0 mg/L and a discharge rate of 1.10 m/s. The river that is receiving this waste has BO equal to 8.3 mg/L, a flow rate of 8.70 m/s, and a temperature of 20°C. Assuming complete and instantaneous mixing, estimate the initial dissolved oxygen deficit of the mixture of wastewater and river water just downstream from the discharge point.
In an activated sludge treatment system, the BOD concentration decays according to first order kinetics, with a decay constant k BOD= 1.5 h-1. The flowrate is 1.010 3m3/d, and the volume of the activated sludge system is 100 m3. If the BOD concentration entering the system is 100 mg/L, what is the BOD concentration in the effluent (in mg/L)? Report using the correct number of SIGNIFICANT FIGURES. You can model the treatment system as a plug flow reactor.
A stream containing no biochemical O2 demand (obviously a hypothetical situation) has a DO of 5.00 mg/L and a flow rate of 8.70 m3/s. The temperature of the stream is 15 degrees Celsius. The average velocity in the stream is 0.174 m/s. The average depth is 5 m. Determine the reaeration coefficient and the rate of reaeration.
Question 2 A factory with a wastewater flow of 0.011 m/s and a BOD5 of 590 mg/L discharges into a small stream. The stream has a minimum dry season flow of 1.7 m/s. Upstream of the factory, the BODS of the stream is 0.6 mg/L. The BOD rate constants ka at 20 °C are 0.115 di for the factory wastewater and 3.7 d1 for the stream. The temperature of both the stream and the factory wastewater is 20 °C. After mixing, the DO was 6.3 mg/L, the velocity was 0.1 m/s, the mean depth was 2.5 m and the decay constant, ka , was 0.75 d. a. Calculate the initial ultimate BOD after mixing (HINT: First find Lo in each flow). b. Determine the time when the critical DO occurs c. Where does the critical DO occur? d. Determine whether any fish migration will occur if they require a DO level of at least 3 mg/L in their habitat.
1. A tank initially holds 10 gal of fresh water. At t 0, a brine solution containing 4 pounds of salt per gallon is poured into the tank at a rate of 2 gal/min, while the well- stirred mixture leaves the tank at the same rate. Find (a) the amount and (b) the concentration of salt in the tank after half an hour.
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?
Glycerin (specific gravity 1.26) in a processing plant flows in a pipe at a rate of R L/s. At a point where the pipe diameter is 832mm, the pressure is 300 kPa. Find the pressure at a second point where the pipe diameter is 300 mm if the second point is 1.0 m lower than the first point, neglect the head loss
Design an aeration tank in a sewage treatment plant with following information and report the required values. Influent flow = 10,000 m3/day, BOD, = 150 mg/ Effluent BODS 20 mg/l, MLVSS = 3000 mg/I. %3D Kinetic coefficients can be found in the literature. 1) Kinetic coefficients and their sources. 2) SRT and HRT 3) Volume and size of aeration tank
A wastewater treatment plant processes its mixed sludge by employing the gravity thickening followed by anaerobic digestion. The thickened sludge has a flowrate of 4,000 m³/d at a solids content of 5% and must be conveyed over a 100m-long pipeline (Hazen-William coefficient C = 100) between the gravity thickeners and anaerobic digesters. Size the diameter of the pipe and estimate the friction headloss using both simple multiplication factor method and rheological method, respectively.
3. Consider the design of a wastewater treatment plant (WWTP) for a community with the following design data: TABLE 1: Design Data Design data Flow-0.150m³. s-¹ Influent suspended solids-280mg L-¹ Influent BODs = 500mg L-¹ -1 Sludge concentration= 6.0% Efficiency= 60% Effective length= 40.0 m Width = 10.0 m Liquid depth = 2.0 m Weir length= 75.0 m Table 2: Acceptability Criteria Parameter Detention time (hours) Overflow rate (m- day) Weir loading (m³-day m¹') Acceptable range 1.5-2.5 80-120 <250 (c) Assume that the primary sedimentation process in this treatment facility removes 60% of the suspended solids (SS) and 40% of the BODs of the raw sewage. Determine the SS and BOD5 concentrations in the primary sedimentation effluent flow.