What are the various types of Screens in WWTP?
Large solids such as wood, fabric, paper, and plastics are removed or reduced from the wastewater stream using screens or pre-treatment machines. It improves the efficiency of the downstream treatment process. It also protects the wastewater equipment’s. These exist in a variety of sizes, capacities, automation, and costs. These are classified as coarse, fine, or micro in general, depending on the size of the screening holes.
Types of screens used in Wastewater Treatment
Wastewater screens can be classified into three categories: Coarse screens, fine screens, and micro-screens. The size of the screening holes, as well as other mechanical characteristics, are used to classify the screens.
What are Coarse Screens?
Clear holes on coarse screens range from 6 to 150 mm (0.25 t0 6 inch). Parallel bars, rods, or wires, wire mesh, or perforated plates with circular or rectangular apertures make up coarse screens. It's also known as a "bar rack," and it's used to remove coarse materials like rags and big particles that could clog or damage other accessories.
Coarse screens are classified into two, based on the wastewater screening process:
1: Manual coarse screens-Hand-raked coarse screens are used in the screening phase of wastewater treatment at small plants. They're suitable for use as a backup during high-flow seasons.
2: Mechanical coarse screens-Coarse screens that have been mechanically cleaned, improve efficiency and reduce issues in the wastewater treatment process.
It can be further divided into four types or categories:
a-Chain or cable driven screens: These upstream and downstream chain driven screens can rake from either direction. The wastewater stream is cleaned by an automatic chain, which improves the functionality of the wastewater treatment system. These are Fat, oil, and grease insensitive and minimum headroom is required for these screens. The major disadvantage is that the components submerged in water are prone to wear and tear.
b-Catenary screens: These front return, front cleaned chain driven screens feature amazing, yet simple internal mechanics to prevent further jams when large or heavy objects are present.These chains are very heavy and difficult to handle and have a larger footprint.
c-Reciprocating rakes:These are also known as a climber screen. These wastewater treatment screening solutions use a single rake rather than numerous rakes, which makes them less efficient when dealing with heavy loads during the water treatment screening process.They have a high clearance above the water, especially in deep channels.
d-Continuous belt screen: This form of screening, which has several rakes and is continuous and self-cleaning, is ultra-high tech, functional, and efficient, and can handle fine or coarse solid loads.In these screens, headroom is necessary in the range of medium to low. It allows for a pivot design so that the unit can be serviced above the channel.There are several moving parts in these screens and thus the components are prone to wear and damage.
What are Fine Screens?
Fine screens with clear apertures less than 6mm are used in the screening process in water treatment plants. Wire cloth, wedge wire, or perforated plates are used to make them. The following three types of fine screensare used in wastewater treatment which include drum screens, static wedge wire screens and step screens.
What are Microscreens?
Micro screening is the tiniest sort of wastewater treatment screening. Typically, these screens are low-speed drum screens. Filtering fabrics with apertures of 10 to 35 metres line the drums. The retained solid trash is collected and disposed of once the wastewater enters the drum.
Conclusion
Wastewater screening is an important feature of all municipal and industrial wastewater treatment plants because it keeps particles out of the wastewater. These solids must be eliminated at the start of the wastewater treatment process, since they can reduce the efficiency of the entire system, damage expensive and vital water treatment equipment, or taint water, creating modest to large-scale natural upsets for a region's entire ecosystem.
Give us a callon+919650608473 or contact via email at enquiry@netsolwater.com for further consultation or product purchase related query.Our wastewater treatment professionals at Netsol Water can provide you with further screening information.