A sewage lagoon that has a surface area of 10 ha and a depth of 1 m is receiving 1.3 MGD of sewage containing 100 mg/L of biodegradable contaminant. At steady state, the effluent fromthe lagoon must not exceed 20 mg/L of biodegradable contaminant. Assuming the lagoon is well mixed and that there are no losses or gains of water in the lagoon other than the sewageinput, what biodegradation reaction rate coefficient (d-1) must be achieved for a first-order reaction?O 0.354O 0.2O 0.1O 0.5A Moving to the next question prevents changes to this answer.Question 29 of 34 >

Lagoons in wastewater treatment are water bodies like ponds which are designed in such a way that it…

Answered: A sewage lagoon that has a surface area…

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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The City of Marietta has been directed by the City Board to upgrade its primary Wastewater Treatment Plant (WWTP) to include a secondary treatment process that can meet an effluent standard of 20 mg/L of BODs and 20 mg/L of suspended solids (SS). They want to select completely mixed activated sludge system. The BOD5 of the SS is estimated to be 50% of the SS concentration. Assume L:W within 4:1 and maximum depth of 4.5 m and maximum length of 50 m for the tank. Assume the reasonable values of missing parameters from FE Exam Handbook. The effluent characteristics from the primary treatment process are: Flow = 0.150 m's, BOD5 =75 mg/L. Assume the values for the growth constants as K, = 100 mg/L BOD5, Mm = 2.5 d-1, kg = 0.05 d'1. Y = 0.50 mg VSS/mg BODs removed, MLVSS = 2,800 mg/L, MISS - 1.20 (MLVSS), wastewater temperature = 25.0°C. Assume 8% 02 transfer rate and BOD5 to BODu ratio as f = 68%. If SRT (qc) = 14.5 days, the volume of the aeration tank is nearly?
A storm sewer is mixed into a small stream. The stream before the mixing point has a NaCi concentration of 25 mg/L. If the storm sewer has a Nacl concentration of 1.8 g/L and the storm sewer flowrate is 2.5 L/min, calculate for the concentration of the salt in the stream after the discharge point (mixing point). The stream has a flowrate of 2.6 cu.m/s. Assume a complete mixing of the storm sewer flow and the stream flow. Assume also that the salt is nonreactive and that the system is at steady state.
A flowing stream has a temperature of 14°C, flow rate of 3.0 m}sec, saturated dissolved oxygen content and BODs of 15 mg/L with reaction rate constant of 0.13/day. Waste is discharged into the stream at a flow rate 0.5 m3/sec, temperature of 30°C, ultimate BOD of 50 mg/L and dissolved oxygen content of 2.5 mg/L. The discharged waste has same characteristics as the initial pollutant in the stream with the same reaction rate constant of 0.13/day.Determine: 4. Oxygen deficit in the resulting combine flow at the mixing point.5. Oxygen deficit and dissolved oxygen content in the stream at exactly one day after the initial mixing of the waste into in the stream if the deoxygenationand reaeration rate constants are 0.2/day and 0.4/day, respectively.6. Length of time in days to reach minimum oxygen content, in the stream at the same rate constants given in part e above. 7. The maximum oxygen deficit in the stream at the same rate constants given in part e above. 8. The minimum dissolved oxygen…
Q- A river has a flow of 1000 million litres per day (MLD). BOD5 of 5 mg/litre and Dissolved Oxygen (DO) level of 8 mg/litre before receiving the wastewater discharge at a location. For the existing environmental conditions, the saturation DO level is 10 mg/litre in the river. Wastewater discharge of 100 MLD with the BOD5 of 200 mg/litre and DO level of 2mg/litre falls at that location. Assuming complete mixing of wastewater and river water, the immediate DO deficit (in mg/litre, round off to two decimal places), is
7
A municipal wastewater flow of 1,000 m³/d contains 400 mg/L BOD5 and is treated to be in a trickling filter. The filter will use a plastic filter medium with a specific surface area of 200 m³/m² and will operate with a recirculation ratio of 100% and a hydraulic loading of 25 m³/m² -d. Taking both surface loading and volumetric loading criteria into consideration, what volume (m³) of plastic media should be installed?
An activated sludge wastewater treatment system was designed and operated in a steadystate under the following conditions:• Reactor volume of 10,000 m3in total;• Sludge concentration (MLSS) of 3200 mg/L in the reactor;• Return sludge concentration at 8000 mg/L (the underflow of the secondary clarifier)• Each day, 400 m3 of underflow sludge (return sludge) was wasted as excesssludge;What is the average Sludge Residence Time (SRT)?
3. A 55.0 ML/d wastewater treatment plant discharges to a river system with a maximum spring flow of 149.5 m3/min and a minimum summer flow of 98.2 m3/min (upstream of the outfall from the plant). What total allowable BOD (mg/L) could be discharged by the plant if the BOD in the river after dilution must not exceed provincial standards, and there is already 1.1 mg/L of pollution in the river upstream?
Problem: 1. Design a facultative pond to treat (10650)gpm of sewage having (10650/20)mg/L of BOD. The average summer and winter temperature is 43°C and 13°C, respectively. Convert the same pond into aerated lagoon, if the concentration of influent BOD reaches to (10650)mg/L. 2. Determine the diameter of a trickling filter for a wastewater flowing at the rate of (10650)m³/day. The influent BOD (S.) concentration for the wastewater is (10650 * 10)mg/L, whereas desirable effluent BOD should be as per NEQS.
A city wishes to discharge wastewater primary effluent to a river which supports a trout. The state requires the city to show that the trout population is protected. Trout require a minimum of 4 mg/l of dissolved oxygen to survive. Determine the minimum downstream dissolved oxygen concentration from the following information about the wastewater discharge and river. Does the minimum dissolved oxygen concentration meet the requirements? Wastewater discharge=0.45m3/s, river flow rate= 8.5 m3/s, river cross-sectional area=19m2, dissolved Oxygen concentration in the wastewater= 0.2mg/l, dissolved oxygen content of the river upstream = 8.1mg/l, saturation dissolved oxygen concentration at 20 C= 9.0 mg/l, BOD concentration in wastewater = 85 mg/l, BOD concentration upstream in the river= 0.2 mg/l, BOD decay constant = 0.2 d-1, and the reaeration constant for the river= 0.4 d-1.
i). A town produces 8 million litre of sewage per day. BOD of sewage is 260 mg/L, it is to be discharged into a river flowing at a rate of 0.2 m³/s and it's BOD is 5 mg/L. Find out the BOD of river after mixing? [Assume mixing is instantaneous]
Design an oxidation pond for treating domestic sewage contributed by 10,000 persons supplied with water at 200 litres per person per day. The BOD and suspended solids are 300 m g/l each. Permissible organic loading for the pond is not less than 500 kg/ha/day. The detention period is not to exceed 6 days. Assume width to length ratio as 1 : 2, and operational depth as 1.2 m. Assume any other data. Sewage volume may be taken equal to water supplied.

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