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 m³/d; and concentration = 0.6% Qi ci Solids Loading Rate (SLR) = 40 kg ds / m².d, and SLR A ci Qi Tc 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%) Te: Time in compression zone (=2 days) Expression for thickening zone depth=

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 m³/d; and concentration = 0.6% Qi ci Solids Loading Rate (SLR) = 40 kg ds / m².d, and SLR A ci Qi Tc 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%) Te: Time in compression zone (=2 days) Expression for thickening zone depth=

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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A wastewater stream A with 200 m3 /h of flow rate and BOD of 300mg/I mixes with stream B having flow rate of 400m3/h and BOD 225mg/l. A completely mixed activated sludge process is used to treat the mixture. BOD of effluent stream is 10 mg/l. Given Y= 0.5, k=5 day", Kd=0.06 day ; Ks=100 mg/l and MLVSS= 2000 mg/l. Assume all other parameters if necessary Find (a) BOD and flow rate of mixture (b) Mean residence time (c) Oxygen requirement (d) F/M ratio (e) Recycle ratio (f) Sizing of the tank
3. Circular clarifiers are used to remove solid materials from water. They allow continuous treatment of water and can handle fairly large flows. Solids settle to the bottom of the clarifier and are carried away by a small stream of water (the waste stream). Most of the water exits the tank as treated effluent. Assume a clarifier receives a flow of 0.10 m3/s with a solid concentration of 800 mg/L. If the waste stream consists of 3% of the incoming flow and carries 90% of the incoming solids, a) what is the solids concentration in the waste stream, and b) what is the solids concentration in the treated effluent?
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