The characteristics of primary and secondary settling units of activated sludge process is given below. Design a gravity thickener for the combined mixture of sludge from both tanks. Assume the solid loading rate is 40 kg / m².d. The specific gravity of combined sludge is 1.02 and provide two circular thickeners. Type of sludge Primary settling unit Secondary settling unit Specific gravity (assumed) 1.03 1.005 Solid % 2.5 0.6 Flow rate (m'id) 140 350

The characteristics of primary and secondary settling units of activated sludge process is given below. Design a gravity thickener for the combined mixture of sludge from both tanks. Assume the solid loading rate is 40 kg / m².d. The specific gravity of combined sludge is 1.02 and provide two circular thickeners. Type of sludge Primary settling unit Secondary settling unit Specific gravity (assumed) 1.03 1.005 Solid % 2.5 0.6 Flow rate (m'id) 140 350

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. (a) Design a gravity thickener to concentrate the mixture of sludge obtained from primary and secondary settling units in an activated sludge wastewater treatment plant. Make appropriate assumptions in your calculations. Sludge waste flow rate in the primary settling unit= 140 m³/d; and concentration = 2.5% Sludge waste flow rate in the secondary settling unit= 350 m/d; and concentration = 0.6% Qi ci Solids Loading Rate (SLR) = 40 kg ds / m².d, and SLR : A ci Qi Tc Expression for thickening zone depth= 0.75Cu A Ci: Incoming mixed sludge concentration Qi: Incoming mixed sludge flow rate A: Cross section area of the thickening tank Cu: Target underflow concentration (=5%) Tc: Time in compression zone (=2 days)
• Q-3. Settling characteristics of a conceritrated suspension C = 3000 mg/t were deterrmined in a laboratory study. The suspension was settled in a colurmn 100-centimeters high, aind thé height of the interface h, was recorded with tirme Time, minutes 100 79 60 10 15 38 20 25 23 15 30 12 35 40 50 7.5 Calculate the area required to achieve clarification and to yield a thickeried sludge concentration of 25,000 mg/f- for an inıfluent flow rate of 5 mgd.
A completely mixed activated sludge process operating at equilibrium is designed to treat 300 MLD of waste water. The influent and effluent BOD are 200 mg/1 and 18 mg/1 respectively If the F M then the hydraulic retention time is A 0.125 day B 4.21 hours C 8.42 hours D 0.225 day = 0.3 and MLSS is 3800 mg/1,
(a) A groundwater borehole at USM engineering campus contains 3000 mg/L of TDS. The flow is 0.32 m3 /s. The design TDS concentration of the product water is below 400 mg/L. The net pressure is 40 atm. The membrane manufacturer provides that the membrane has a water flux rate coefficient of 2.2 x 10-6 s/m and a solute mass transfer rate of 1.5 x 10-6 m/s. Calculate the membrane area required for the RO system. (B) A water treatment at Nibong Tebal receiving a raw water contains a concentration of 0.5 µg/m3 atrazine from Kerian River. In order to comply with the drinking water quality guideline, the treatment plant should reduce the concentration of Atrazine to 0.1 µg/L. If the dosing of powdered activated carbon have been applied before the coagulation, calculate the minimal dose of PAC in mg/m3 .
A mixed liquor sample form an activated sludge plant was settled in a one-litre measuring cylinder for 30 minutes after which time, a volume of 350 m/ of sludge was recorded. When 50 m/ of the mixed liquor were filtered through a GFC paper for the determination of MLSS the gain in weight of the paper was 0.1375 g. Determine the SVI.
The test Carried aut en an follow. detaits sludge Somple are Weight of Dish =9.52gm Baw Sludge Sempla and duch =23 27ga Aşter Drying Clnstent) After Burning Clnstant) = 6.38gm 9.46gm %3D %3D Calculkt th percentage of total Salidl ad lloldi Solid in t cboue of cowego.
An activated sludge plant with recycle is evaluating its secondary clarification system. Settling column tests are conducted and analyzed for settling velocities at different initial solids concentrations. The data are provided below. The plant flow rate is 10,000 m3/d, with a recirculation ratio of 0.5. The MLSS in the reactor is 4000 mg/L. The desired underflow concentration is 17,000 mg/L. Solids concentration mg/L Settling velocity m/h 1500 6.5 3000 5.1 4500 4 6000 2.95 7500 2 9000 1.4 12,000 0.5 15,000 0.27 17,000 0.2 a. Calculate the required surface area if one clarifier is used. b. Calculate underflow rate, underflow velocity, and overflow rate for single clarifier design. Clearly state your assumptions. c. Calculate the required surface area if two clarifiers are used
1. A wastewater is treated in an aerobic CSTR with no cell recycle. The following hold: Ks= 50mg/l; q^=5mg/mg VSSa-d; Kd= .06d-1; Y= 0.6; S°=220mg/l; fd= 1 a. Determine Ɵcmin, Ɵclim, Smin
sluage system. (ii) The treated effluent containing grit particles from the above (i) activated sludge system is discharged into a secondary clarifier for further treatment. Assume that a spherical body undergoes settling through the clarifier with a terminal settling velocity of 2 m/s. Find the drag force on the grit particle due to the fluid. Assume that Stokes law is valid and dynamic of viscosity of effluent = 0.001 radius of spherical particle = 2 mm). In addition, outline two (2) purposes of the phi factor in particle settling? Kgm ¹s
A two litre graduated cylinder was used to determine the Sludge Volume Index (SVI) of an activated sludge sample. The settled volume was 800 ml and the MLSS concentration was 2800 mg/lt. The SVI of sludge is
1.3, tank width -8 m, the moisture content of the sludge is 95% and the concentration of suspended A rectangular sedimentation tank removes 80% of 0.06 mm diameter particles with SG= solids in the effluent flow is 200 mg/L, detention time 2 hrs for discharge 15000 m³/day. Determine the following: a) Dimension of the tank. Surface over flow rate b) Maximum horizontal velocities keep particles in settling d) The depth of sludge in the basin if its cleaning is daily
Water treatment plant : SOR = 0.35 mm/sec; The analysis of this water found that there are 6 different particle sizes: 0.1 mm with settling velocity of 0.2 mm/sec; and percentage of particles = 10 %; 0.2 mm with settling velocity of 0.25 mm/sec; and percentage of particles = 20 %; 0.3 mm with settling velocity of 0.3 mm/sec; and percentage of particles = 15 %; 0.4 mm with settling velocity of 0.35 mm/sec; and percentage of particles = 5 %; 0.5 mm with settling velocity of 0.4 mm/sec; and percentage of particles = 30 %; 0.6 mm with settling velocity of 0.5 mm/sec; and percentage of particles = 20 %; Calculate the efficiency of this tank ?