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Jan 31 2019· Gravity thickeners are essentially circular primary settling tanks with or without mechanical thickening devices The dilute sludge is fed into the settling tank where solids are allowed to settle over a few days The thickened sludge is withdrawn from the bottom of the tank and pumped to the digesters or dewatering equipment
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Continuous discharge of solids from a gravity settling tank can be achieved without mechanical aid if the tank is shaped so that the sludge flows naturally towards the discharge port This requires relatively steepsided conical vessels the angle of the cone is generally between about 40° and 60° and thus the diameter of a settling tank is invariably rather less than a thickener
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Sludge Thickening Sludge thickening is a process in which the solids concentration is increased and the total sludge volume is correspondingly decreased but the sludge still behaves like a liquid instead of a solid Thickening commonly produces sludge solids concentrations in the 3 to 5 range whereas the point at which sludge begins to
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A thickenerclarifier drive unit supplies the torque to rotate the rake arms through the thick sludge The drive is usually made of cast iron because of its durability Usage Examples Thickeners and clarifiers are often used in water and wastewater treatment plants to
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Gravity thickeners are similar to clarifier tanks and settling tanks that allow for suspended solids from slurries to gradually sink to the bottom of the tank As the solids collect at the bottom of the tank it forms into a sludgelike material that needs to be constantly removed by the use of high powered nonclog slurry pumps for disposal
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xvEPA United States Environmental Protection Agency Biosolids Technology Fact Sheet Gravity Thickening DESCRIPTION Thickening is the process by which biosolids are condensed to produce a concentrated solids product and a relatively solidsfree supernatant
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Sludge is usually pumped continuously from the settling tank to the thickener which has a low overflow rate so that the excess water overflows and the sludge solids concentrate in the bottom A blanket of sludge is maintained by controlled removal which may be continuous at a low rate
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Chapter 5 Sludge treatment for gravity thickeners according to the sludge sourceSludge source Influent S Expected under flow S Mass loading kgdm2 h3 settling zone typically taken as 15m h4 Thickening zone it is a sludge storage region and have to be
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Sludge Facilities The sludge handling facilities includes two gravity thickener tanks one vacuum drying bed and a building housing controls sludge pump vacuum pump and a polymer feed system The backwash water and sludge vacuumed from the settling basins flows by gravity to the thickener tanks through a 20inch pipe
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a gravity thickener handles waste activated sludge the influent sludge is analyzed as having 7200 mgL and theeffluent sludge is 15 what is the removal efficiency You are troubleshooting a DAF thickener and the sludge is too thin what are possible causes possible problems with filamentous bacteria and rediced biomass activity
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Sludges are thickened primarily to decrease the capital and operating costs of subsequent sludge processing steps by substantially reducing the volume Thickening from 1 to 2 solids concentration for example halves the sludge volume Further concentration to 5 solids reduces the volume to onefifth of its original volume
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proven settling clarification technology for biological floc allowing capacity sludge systems to free up reactor capacity for multistage treatment processes thereby enabling the removal of nitrogen to ≤ 30 mgL and gravity thickener where it thickens to 3 – 6 solids BIOREACTOR TANK
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Thickening is defined as removal of water from sludge to achieve a reduction in moisture content of slurries The resulting material is still fluid Thickening is used at most wastewater treatment plants as an economic measure to reduce the volume of sludge or for greater efficiency in subsequent processes
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SLUDGE THICKENING FSFNG001 Page 3 of 31 2 GRAVITY THICKENING 21 General description of the unit The gravity thickening design is similar to a clarifier Thickeners are usually circularshaped the feed is carried out through a pipe to a central hood serving as distribution and still area with a height that has no effect on compaction
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bubbles form in the activated sludge and cause sludge blanket flotation in the final clarifier An indication of the occurrence of denitrification can be obtained by holding the sludge in the settling test jar for several hours If the sludge rises pops within 2 hours or less denitrification problems
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Gravity thickeners are essentially settling tanks with or without mechanical thickening devices picket fence type Plain settling tanks can produce solids contents in sludges of up to 80 percent for primary sludges and up to 22 percent
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Thickening is usually the first step in sludge treatment because it is impractical to handle thin sludge a slurry of solids suspended in water Thickening is usually accomplished in a tank called a gravity thickener A thickener can reduce the total volume of sludge to less than half the original volume
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Sludge tends to stratify in the gravity thickener while continuing biological activity which includes the production of gases that can cause accumulated sludge to float Gravity thickener operation responds to changes in process temperatures therefore loading
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E Gravity belt thickener a rotating media continuous belt receives sludge and dewaters it using the force of gravity to separate the water F Gravity thickening solids settle and compact by gravity in a clarifierlike settling tank 116 121 Explain how various types of treatment affects the fuel value of sludge
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sludge rise in the settling test jar within 2 hours or less •In filamentous sludges these problems can be worse due to the trapping of the nitrogen gas in the open or bridged
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settling spontaneously flocs of activated sludge This process is associated with problems such as formation of flocs with poor settling properties and floating
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The Difference Between a Clarifier and a Thickener is subtle as they will visually look the same Fundamentally thickeners and clarifiers are both used to settle solids which results in the separation of liquids and solids Thickeners are used to concentrate solids while clarifiers are used to purify liquids A thickener will give you a high density underflow while a clarifier will not
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eration in thickening secondary sludge 10 Explain why filamentous bacteria in secondaey sludge causes thickening problems 11 Recall that an increase in temperature causes an increase in biological activity 12 Recall that gravity thickener operation varies between summer and winter due to the effect of temperature on gasification 13
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Analysis of Sludge Settling and Rising Behavior in In Kuwait''s wastewater treatment plants solids separation problems may occur in activated sludge system such as bulking sludge which affects the quality of the secondary effluent sludge gravity thickener The thickened sludge is
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