The following points highlight the six main mills for reducing tube thickness and sizing. The mills are:- 1. Pilger Mill 2. Mandrel Mill 3. Plug Mill 4. Reeling Process 5. Assel Mill 6. Stretch Reducing Mill. 1. Pilger Mill: The tubular shells produced in piercing process are further processed. Pilger mill is commonly used after rotary piercing. This process consists [...]
In this article we will discuss about:- 1. Introduction to Transverse Rolling of Discs 2. Components of Transverse Rolling of Discs 3. Study of Deformation. Introduction to Transverse Rolling of Discs: The transverse rolling processes are used to roll shapes on cylindrical components. The commonly known processes are as follows: (i) Transverse rolling of discs. (ii) Roll piercing of solid [...]
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 [...]
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 the process of batching and mixing of concrete. Batching of Concrete: The correct measurement of the various materials used in the concrete mix is called batching. It has been observed that batching errors are partly responsible for the variation in the quality of concrete. This operation can be properly and better controlled than [...]
In this article we will discuss about:- 1. Introduction to Compaction of Concrete 2. Voids in Concrete 3. Methods 4. Types of Vibrators. Introduction to Compaction of Concrete: The process of compaction of concrete consists essentially of the elimination of entrapped air from the concrete. The oldest means of achieving this aim is by punning with a rod, or by [...]
In this article we will discuss about:- 1. Process of Hydration for Concrete 2. Objects of Concrete Curing 3. Necessity 4. Methods 5. Period of Concrete Curing 6. Maturity of Cured Concrete. Process of Hydration for Concrete: Concrete derives its strength by the hydration of cement particles. The process of hydration is not a momentary action, it continues for long. [...]