In this article we will discuss about:- 1. Introduction to Activated Sludge Process 2. Oxygen Requirements and Transfer 3. Secondary Settling 4. Advantages and Disadvantages of Activated Sludge Process. Introduction to Activated Sludge Process: The activated sludge process was developed in England in 1914 by Ardern and Lockett and was so named because it involved the production of an activated [...]
In this article we will discuss about:- 1. Operations and Units of an Activated Sludge Plant 2. Operational Difficulties in Activated Sludge Plant. Operations and Units of an Activated Sludge Plant: Fig. 13.2 shows a typical flow diagram for an activated sludge plant. The activated sludge process is usually preceded by preliminary and primary treatments of sewage for which screening [...]
Following are the three methods which are employed for the purpose of aeration in activated sludge process: 1. Diffused Air Aeration 2. Mechanical Aeration 3. Combined Diffused Air and Mechanical Aeration. Method # 1. Diffused Air Aeration: In the diffused air aeration method compressed air is introduced into the mixture of sewage and returned activated sludge (or mixed liquor) in [...]
Various systems of mechanical aeration have been developed to achieve the required Agitation, most of which are patented. Some of these systems of mechanical aeration which are commonly used are as indicated below: 1. Hartley System or Birmingham Bio-Flocculation System 2. Haworth System or Sheffield Aeration System 3. Link-Belt System 4. Kessener System 5. Simplex System. 1. Hartley System or [...]
The various types of activated sludge processes are listed below: 1. Conventional Activated Sludge Process 2. Tapered Aeration Process 3. Step Aeration Process 4. Contact Stabilization Process 5. Complete Mix Process 6. Modified Aeration Process 7. Extended Aeration Process. The characteristics and design parameters for these processes are given in Table 13.3. These processes are described in details below: Type [...]
The loading rate of aeration tank is based on the following four parameters: 1. Hydraulic Retention Time (HRT) 2. Volumetric BOD Loading or Volumetric Organic Loading 3. Food to Micro-Organism Ratio (F/M Ratio) 4. Mean Cell Residence Time (MCRT) or Sludge Retention Time (SRT) or Sludge Age. Parameter # 1. Hydraulic Retention Time (HRT): Hydraulic retention time is a loading [...]
In this article we will discuss about:- 1. Rate of Sludge Production 2. Sludge Recycle—Sludge Volume Index (SVI) 3. Wasting of Excess Sludge Qw. 1. Rate of Sludge Production: It is important to know the quantity of sludge produced per day, because it will affect the design of the sludge handling and disposal facilities. The quantity of sludge (or biological [...]