Large particles and grit in wastewater can obstruct treatment operations or create excessive mechanical wear and maintenance on wastewater treatment equipment. These items must be handled separately to avoid any complications. These elements are removed from the influent wastewater during preliminary treatment. Screening, grit removal, septage handling, odour control, and flow equalisation are all part of the preliminary treatment.
What is screening in waste water treatment?
Screening equipment at the headworks is a must-have for any wastewater treatment facility, regardless of size. Large solids such as wood, fabric, paper, and plastics are removed or reduced from the waste stream using screens or pre-treatment machines. This not only improves the efficiency of the downstream treatment process, but it also protects the equipment, such as pumps.
At wastewater treatment plants, screening is the first unit activity (WWTPs). To minimise damage and clogging of downstream equipment, pipelines, and appurtenances, screening eliminates items such as rags, paper, plastics, and metals.
Coarse and fine screens are used in some modern wastewater treatment systems.To achieve these goals, a variety of equipment can be employed, and there is no one-size-fits-all approach that can be applied to every headworks circumstance. Low flows, limited space, and financial constraints are some of the drawbacks of small systems.
Screens, like other plant equipment, exist in a variety of sizes, capacities, automation, and costs. Screens are classed as coarse, fine, or micro in general, depending on the size of the screening holes.
a) Manual bar screens
A manual bar screen may be a wonderful alternative for small systems due to their constraints. To collect entering debris, these screens contain vertical bars spaced 1 to 2 inches apart. They give a good level of protection for the plant, despite their simplicity. However, there are restrictions, as with any basic equipment.The most obvious disadvantage is that this is a manual activity that necessitates committed labour and might be prohibitively expensive for small systems. This is especially true during high-flow events like storms, which may necessitate more frequent raking and pose a greater risk to the operator's safety.
b) Automatic bar screens
There are various automated methods available to reduce the labour needed with manual bar screens. These can be categorised into several types of groups. There are several types of screens, including chain driven screens, catenary screens, reciprocating rakes, continuous belt screens, and many others.
Vertical bars are typically used to gather solids and remove them with an automated rake system in these choices. Because these are automated, the cost as well as other operational expenditures must be taken into account. Furthermore, because these systems are larger than the manual screen, installing one to a facility may necessitate civil engineering modifications to the influent channel or, if located there, the headworks building.
Although course screens can remove considerable amounts of debris at the headworks, disposal is an additional cost that necessitates operation and maintenance. Furthermore, the stinky wet screens gathered can attract rodents and cause odour complaints from the neighbours.
For more information, contact Netsol Water.