Sedimentation Technology
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The main principle of treatment by sedimentation is to remove readily settleable solids and floating material and thus reduce the suspended solids content. The scraper mechanism which is installed inside the tank collects the settled solids. Almost all treatment plants use mechanically cleaned sedimentation tanks of standardized circular or rectangular design. The selection of the type of sedimentation unit for a given application is governed by the size of the installation, by the characteristics of solid suspension of process liquid and by the experiences etc. Clarification is the process of separating solids from the liquid. The principle is to create floes from the suspended material in the liquid and let these floes settle by gravity in a calculated retention time. The selection of a tank configuration and collector mechanism as scraper type and/or suction type depends upon the characteristics of solids suspension of process liquid. Ast i m designs and manufactures complete range sedimentation tank scrapers. Mainly these equipment are; • Peripheral Driven Scrapers for circular tanks • Travelling Scrapers for longitudinal tanks • Central Driven Scrapers for circular tanks

DRIVEN SCRAPERS In circular tanks; the flow pattern is radial. To obtain a radial flow; the wastewater can be fed to the tank from the center or around the periphery of the tank. During radial flow the suspended solids in wastewater is settled by gravity and the peripheral driven rotating scrapers are used to remove the settled sludge. The scraper blades can either be echelon or logarithmic spiral shaped. By the help of these blades the sludge is pushed towards the center and collected in the central located sludge collection pit. The scraper arms of rotating bridges are mostly designed as...

Travelling Scraper Bridge is designed according to span as Full Wall, Half Wall, Steel Profile orto avoid high wind loads as Truss Beam. Carriages, which are located at both ends of the bridge, can travel on rails with or without pinion rack or on polyurethane lined wheels with guide wheels. The drive unit can be mounted either at the end carriages or at the middle of the bridge. Bridge movement is controlled by limit switches. For removal of settled sludge, both scraping and suction methods can be used. The solids settling in the tank are scraped or pumped to solids hopper. Also for...

Aluminium Truss Bridge with GRP gratings • Anti-frost heating lamp • Scum baffles • Scum removal channels with approaching ramps Over flow weirs • Effluent launders • Inlet diffuser cylinders, Stengel inlets • Channel cleaning brushes • Scraper lifting mechanism for overload protection • Lamella settlers to obtain higher separation efficiency Astim Scrapers and Thickeners are manufactured in epoxy coated or hot dip galvanized carbon steel, stainless steel or aluminium according to requirements or process conditions. Local control panels using PLC or conventional systems which can be...