Determine the minimum possible surface area of a secondary clarifier treatingactivated sludge with a design influent flow rate (Q) of 1,000 m³/d, a returnactivated sludge (RAS) recycling ratio of 25%, and a mixed liquor totalsuspended solids (MLSS) concentration of 4,000 mg/L, if the overflow rate mustbe less than 33 m/d and the solids loading rate must be less than 250 kg/m²/d.Express your answer in m² and round up to the next integer.

Step 1: Given:The influent flow rate is 1,000 m³/day.The return activated sludge (RAS) flow is 25%…

Answered: Determine the minimum possible surface…

Solid Waste Engineering

3rd Edition

ISBN:9781305635203

Author:Worrell, William A.

Publisher:Worrell, William A.

Chapter6: Biological Processes

Section: Chapter Questions

Problem 6.1P

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Determine the required solids retention time (SRT) of a completely mixed activated sludge aeration tank for a conventional activated sludge system treating a design flow rate of 34,560 m³/d, where the effluent standards are 30.0 mg/L for BODs and 30.0 mg/L for total suspended solids (TSS). Assume that the BOD5 of the effluent TSS is 70% of the TSS concentration. Assume the BODs concentration leaving the primary clarifier is 128 mg/L that the MLVSS concentration (X₂) is 2,500 mg/L. Assume the following values for the growth constants: Ks 100 mg/L BODS ⚫ Hm - 2.5 d 1 kd = 0.050 d 1 Y = 0.50 mg VSS/mg BODs removed Express your answer in days and round to the nearest 0.1.
Given a settling tank operating at 80% TSS removal efficiency, an inflow of 0.5 m3/s, and an influent concentration of 100 mg/L. Assuming steady state operations, at what flow would operators have to remove sludge in order to achieve a TSS concentration of 1500 mg/L in the sludge? Answer: 0.027 m3/s
Determine the required volume of a completely mixed activated sludge aeration tank for a conventional activated sludge system treating a design flow rate of 34,560 m³/d, where the effluent standards are 30.0 mg/L for BOD5 and 30.0 mg/L for total suspended solids (TSS). Assume that the BOD5 of the effluent TSS is 70% of the TSS concentration. Assume the BOD5 concentration leaving the primary clarifier is 128 mg/L that the MLVSS concentration (Xa) is 2,500 mg/L. Assume the following values for the growth constants: • K = 100 mg/L BOD5 • μm = 2.5 d−1 • kd = 0.050 d 1 Y = 0.50 mg VSS/mg BOD5 removed Express your answer in m³ and round to the nearest integer.
An existing rural 4-lane highway is to be replaced by a 6-lane divided expressway (3 lanes in each direction). Traffic volume data on the highway indicate that the AADT (both directions) during the first year of operation is 24,000 with the following vehicle mix and axle loads. Passengercars=50percent 2-axle single-unit trucks (12,000lb/axle)=40percent 3-axle single-unit trucks (16,000lb/axle)=10percent The vehicle mix is expected to remain the same throughout the design life of 20 years, although traffic is expected to grow at a rate of 3.5 percent annually. Using the AASHTO design procedure, determine the minimum depth of concrete pavement required for the design period of 20 years. Pi=4.5J=3.2Pt=2.5Cd=1.0Sc=650lb/in.2So=0.3Ec=5106lb/in.2R=95k=130lb/in.3
Refer to Problem 2.C.1. Results of the sieve analysis for Soils A, B, and C are given below. To obtain a more representative sample for further geotechnical testing, a ternary blend is created by uniformly mixing 8000 kg of each soil. Answer the following questions. a. If a sieve analysis is conducted on the mixture using the same set of sieves as shown above, compute the mass retained (as a percentage) and cumulative percent passing in each sieve. b. What would be the uniformity coefficient (Cu) and the coefficient of gradation (Cc) of the mixture?
Two materials, A and B, are to be separated using two unit operations, 1 and 2. The feed has 10 tons/h A and 4 tons/h B. The split (fraction of material rejected by each operation) is given in Table P5-14. a. Which sequence of operations, (l?2) or (2?1), will yield the greatest recovery of material A? b. What will be the purity of material A using that sequence? c. What will be the efficiency of separation for the entire process train with regard to material A using the Worrell-Stesed equation?
A sand has Gs = 2.66. Calculate the hydraulic gradient that will cause boiling for e = 0.35, 0.45, 0.55, 0.7, and 0.8.
Refer to Figure 7.24. The following data were collected during the field permeability measurement of a confined aquifer using a pumping test. Determine the hydraulic conductivity of the permeable layer. Use Eq. (7.49). Thickness of the aquifer, H = 4.5 m Piezometric level and radial distance of the first observation well: h1 = 2.9 m; r1 = 17.8 m Piezometric level and radial distance of the second observation well: h2 = 1.8 m; r2 = 8.1 m Rate of discharge from pumping, q = 0.5 m3/min

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