Physical treatment methods involve using physical forces to separate and recover undissolved pollutants, such as oil films and oil droplets, from wastewater. These techniques include gravity separation, centrifugal separation, and sieve filtration. Additionally, processes based on heat exchange also fall under physical treatment. These methods are often the first step in wastewater treatment, as they help remove large particles and oils before more complex treatments are applied.
Chemical treatment involves using chemical reactions or mass transfer processes to remove dissolved or colloidal contaminants from wastewater or convert them into less harmful substances. Common chemical treatment units include coagulation, neutralization, and redox reactions. Mass transfer-based methods like extraction, stripping, adsorption, ion exchange, electrodialysis, and reverse osmosis are also used. These latter techniques, especially membrane-based ones, are sometimes referred to as physical-chemical methods because they combine both chemical and physical effects, making them distinct from purely chemical or physical approaches.
Biological treatment methods rely on microorganisms to break down organic pollutants present in wastewater. This method is effective for treating solutions, colloids, and fine suspensions. Biological treatment can be categorized into aerobic and anaerobic processes. Aerobic methods, which require oxygen, are widely used and include activated sludge and biofilm processes. The activated sludge process is versatile and can be adapted in various ways, while biofilm systems use devices like biological filters, rotating biological contactors, and fluidized beds. Anaerobic methods, on the other hand, operate without oxygen and are particularly useful for high-strength organic waste and sludge, often using digesters as the main treatment equipment.
The biological contact oxidation method is a hybrid between activated sludge and biofilm systems. It involves filling a reactor with a medium that supports the growth of a biofilm. Oxygenated wastewater flows through this medium, allowing it to come into contact with the biofilm where microorganisms degrade organic matter. This method ensures efficient mixing and contact between the wastewater and the biofilm, improving treatment performance. Aeration is typically provided at the bottom of the tank to ensure even distribution of oxygen. After treatment, the water is often combined with domestic sewage and disinfected with chlorine before being released.
The simple trolley is a special equipment that must be used in the secondary lining of the tunnel construction process, and is used for the concrete lining construction of the inner wall of the tunnel loop. Lining trolleys are non-standard products that are indispensable for secondary lining during tunnel construction. They mainly include simple lining trolleys, fully hydraulic automatic lining trolleys and grid-frame lining trolleys. Full hydraulic lining trolley can be divided into side-top arch type, full circle needle beam type, bottom mold needle beam type, full circle travel type, etc. In the construction of hydraulic tunnels and bridges, lifting slipforms, jacking slipforms and turning forms are also commonly used.
Simple Trolley,Tunnel Simple Trolley,Trolley For Partial Section Construction,Simple Tunnel Trolley
Anshan Lijian Engineering Group Co. LTD , https://www.lijianformwork.com