**Abstract**

Water is a valuable material. Water used to dispose of nature or enter the consumption cycle requires disinfection and purification to conserve water resources as well as to provide drinking water. Different processes are carried out on the water to increase water quality as much as possible. In general, the filtration process can be divided into two general categories. In the first process, harmful substances are removed from the water. In the second group, the processes are specifically designed to improve the quality and control parameters such as the pH value. The stages of water purification can be divided into different steps more in detail, which physical purification is one of these steps and has been discussed in this chapter.

**Keywords:** wastewater treatment, physical treatment, water quality, sewage dumping, active pharmaceutical ingredients, corrugated plate interceptor

## **1. Introduction**

All societies, both solid and liquid, produce waste. Wastewater can be considered as a combination of waste produced by water from residential, administrative, commercial, and industrial facilities and drained into groundwater or surface water. Untreated wastewater contains pathogenic microorganisms and organic matter. Degradation of untreated wastewater organic matter produces stinking gases. Therefore, wastewater treatment is one of the essential measures that must be taken before discharge into the environment. Wastewater treatment is a practical solution to speed up the process of providing safe and transparent reusable water.

The pollutants can be removed from wastewater using a variety of ways that are divided into three main categories: physical, chemical, and biological processes. A purification process generally consists of five successive steps as described in **Figures 1** and **2**: (1) preliminary treatment or pre-treatment (physical and mechanical); (2) primary treatment (physicochemical and chemical); (3) secondary treatment or purification (chemical and biological); (4) tertiary treatment (physical and chemical); and (5) treatment of the sludge formed (supervised tipping, recycling or incineration) [1, 3].

Physical wastewater treatment is the first step in the treatment of industrial and sanitary effluents, which in addition to increasing the efficiency of other steps, prevents damage to the equipment used in chemical and biological treatment. The equipment and processes used in physical wastewater treatment vary according to the type of effluents and the quality desired for wastewater. In other words, since the wastewaters are mostly very colored and contain high biological and chemical oxygen, they have high electrical conductivity and are considered chemically alkaline.

### **Figure 1.**

*Main processes for the decontamination of industrial wastewaters [1].*

### **Figure 2.**

*Primary and secondary treatment of sewage [2].*

In other words, since the wastewaters are mostly very colored and contain high biological and chemical oxygen, they have high electrical conductivity and are considered chemically alkaline. Accordingly, different parameters affect the cost of selecting a wastewater treatment method. Factors such as the type of pollutants to be treated, the chemical composition of wastewater, the cost of chemicals required, the operating cost, the cost of collecting waste generated by the treatment process, affect selecting a wastewater treatment method [4].

Based on the various processes and steps mentioned for the physical treatment of industrial and sanitary effluents mentioned above, equipment such as the following is required:

*Physical Wastewater Treatment DOI: http://dx.doi.org/10.5772/intechopen.104324*


In this chapter, we will explain each of the above.

### **2. What is physical wastewater treatment**

The separation process of particulate matter and solids in industrial and sanitary effluents is called physical purification. Depending on the type of sewage, there may be pieces of fabric, the foliage of trees, sand and plastic parts, etc. in the fluid entering the treatment plants. Entering these particles into wastewater treatment equipment such as pumps, pipes, and fittings may cause damage. In addition, the failure to remove these items causes a lot of pressure on the equipment in chemical and biological wastewater treatment, and their output quality decreases. For this purpose, with practical and simple equipment, physical treatment processes of industrial and sanitary wastewaters are implemented.

### **3. The most important steps of physical wastewater treatment**

### **3.1 Sewage dumping**

Considering the capacity of the treatment plant and the speed of entering fluid, and the size and amount of dissolved and suspended solids in the wastewater, it is necessary to install appropriate littering in the inlet of the sewage canal. The litters used in this step of physical wastewater treatment are varied, and each one has specific features, the most important of which are the following options:

### *3.1.1 Mechanical garbage collector*

Other types of littering used for large refineries include mechanical garbage collectors. The most important feature of this equipment is that the engine is on top of it. So, after accumulating solid particles in the sewage on the blocker screen, the collection process is done. The mechanical garbage collector is divided into the bar, lattice or lace, strapping, round-trip rod, chain, and cylindrical movement groups in terms of appearance structure. In this type of garbage collector, human resources are not used. It can remove suspended solids up to 2–3 mg. It should be noted that the necessary force for motor movement in mechanical garbage is supplied from electricity and therefore has higher energy consumption than the manual type (**Figure 3**) [5].

### *3.1.2 Handheld sewage collector*

A handheld screen consisting of several bars is located at certain distances and prevents particles with a size greater than two centimeters from entering the treatment plant. As the name of this equipment is known, after accumulating particles and solid patches on the plate, human operators perform the collection process. Garbage

**Figure 3.** *Bar rack and traveling screen [5].*

**Figure 4.** *Preliminary Treatment of Sewage [6].*

*Physical Wastewater Treatment DOI: http://dx.doi.org/10.5772/intechopen.104324*

### **Figure 5.**

*Bar screen in a detritus tank [5].*


### **Table 1.**

*Design parameters and criteria for Bar screens [5].*

collectors have different types of fine and coarse grain. Due to the lack of electricity, it is cost-effective for the physical treatment of wastewater. It should also be noted that the material used to make the body and screen is resistant to acidic and corrosive materials and has a long lifespan (**Figures 4** and **5**) [5].

### *3.1.3 Mechanical sewage collector*

The grating pair is composed of two lattice plates and nets that block the passage of sewage. This type of littering is located in the group of mechanical garbage collectors and without the use of a human operator, the collection of accumulated materials on the plate is done. Due to the use of two lace plates in the overall structure of this

screen, its efficiency and efficiency for physical treatment of wastewater and removal of suspended solids are high and with the destruction of one plate, it is possible to continue working with another plate [5].

The garbage collectors are designed based on the diameter of the seeds to be removed, the width and depth of the canal and rods, the distance between the rods, the vertical slope, the speed and the loss of the allowed head.

**Table 1** shows some design parameters and criteria for mechanically and hand-cleaned screens.
