What Material is used for the construction of screens in STPs?
Sewage screening, a crucial component of all municipal and commercial sewage treatment plants, captures sewage solids. These solids must be eliminated right at the start of the water treatment procedure, since they may impair system performance, harm expensive and crucial water treatment equipment, or taint water, resulting in modest to significant natural disruptions for an area's entire ecosystem.
Let’s understand the material used in the construction of screens in STPs!
1: Coarse Screen
Clear holes on coarse screens range from 6 to 150 mm (0.25 to 6 in). Parallel bars, rods, or wires, wire mesh, or perforated plates with apertures, which are often round or rectangular make up coarse screens. It is also known as a "bar rack" and is used to get rid of coarse particles, like rags and big debris that could clog or harm other accessories.
Coarse screens are divided into two categories based on the sewage screening process, used to clean them:
1. Hand cleaned coarse screens
2. Mechanical coarse screens
2: Micro Screens
Micro screening is the smallest type of screening used in the treatment of sewage. These are mostly low-speed drum screens. Filtering textiles with holes between 10 and 35 mm line the drums.
Water enters the drum, and the solid waste that was retained, is gathered and disposed of.
3: Fine Screen
Fine screens which have clear apertures smaller than 6mm are used in the screening process in sewage treatment plants. They are constructed from perforated plates, wedge wire, or wire cloth.
These are screening instruments used in sewage treatment to remove fine particulates, much as micro screens. There are three typical kinds of fine screens used in sewage treatment:
1. Drum Screens (rotating cylinders in the flow channel)
Hollow drums are used to create these screens. The interior/hollow section of the drum is used to pass the wastewater through. The solid is kept inside the drum, and gravity force is used to remove the screens. Moreover, drums can be sprayed clean using external water jets.
2. Step Screens
These have fixed and movable plates across the width of the channel.
3. Static Wedge Wire Screens (used by large treatment plants with ample floor space)
They are constructed of screens with flexible woven wire mesh that are typically erected for river supplies. The adaptable woven wire mesh is additionally connected to an adjacent bar screen, composed of mild steel.
These screens move in either a vertical or horizontal motion. To clear the debris that has gathered or clogged on the outside of the screens, water jets are fired from the inside.
What is the sewage treatment plant's screen size?
It ranges between 20 and 40 mm for surface waters (upstream the strainer).
Raw water requirements for municipal wastewater are as follows:
· 15 to 30 mm for raw water (although fine screening is required upstream from a straining or lamellae settling process)
· 10 mm or less for sludge (if necessary)
Conclusion
We understand the filter's capacity and cycle rate must be created, to output the necessary water flow rate for a screen to function properly. The size and concentration of the debris, the input flow rate of the current, and the cross-sectional area of the channel, are all factors that affect this.
Mesh size or wire diameter and recycle system speed are two screen design considerations, which have an impact on the overall result.
How can we assist?
Netsol Water is a top manufacturer of wastewater treatment plants, and industrial and commercial water treatment facilities in India.
We have created and implemented new technologies various manufacturing and commercial sectors, for the treatment of wastewater. Our products are suitable for a wide range of applications.
Contact us at +91 9650608473 or enquiry@netsolwater.com for expert advice.