Which type of sludge thickener requires high energy consumption?
Gravity thickening consumes very little energy, but is effective only for primary or stabilized sludge. Thickening centrifuges require polymer and consume much power (0.5 – 1.3 kWh/m³). Thickening filters (such as our Belt, Disc, Drum or Screw Thickeners) need polymer, but only 0.2 – 0.4 kWh/m³ power.
What are the objectives of sludge thickening?
The primary objective of sludge thickening is to concentrate the solids, thus reducing the volume of sludge. Thickeners may increase the solids concentration by a factor of 2 to 5 and produce a clarified liquid effluent. Thickening is accomplished by either gravity or dissolved-air flotation.
What are the methods of sludge thickening?
The most commonly used thickening processes include gravity thickening, dissolved air flotation, and rotary drum thickening. Centrifuge thickening is also becoming more common. The type of thickening selected is usually determined by the size of a wastewater plant, its physical constraints and the downstream process.
What is the most common sludge thickening practice?
Gravity thickening is the most common practice for concentration of sludge and concentrates sludge through simple gravity sedimentation of the suspended solids. Continuous flow tanks are deep circular tanks with central feed and overflow at the periphery.
What is the difference between sludge thickening and sludge dewatering?
Sludge thickening normally refers to the process of reducing the free water content of sludges; whereas, dewatering refers to the reduction of floc-bound and capillary water content of sludges.
Which thickening approach is commonly used for the secondary clarifier sludge?
Gravity thickening is the most common method used to thicken primary sludge and combined primary and secondary sludge.
How do you reduce sludge in ETP?
The new wastewater treatment processes including SANI®, high-rate activated sludge coupled autotrophic nitrogen removal and anaerobic membrane bioreactor coupled autotrophic nitrogen removal also have a great potential to reduce sludge production.
What is minen thickener?
Thickening is a process where a slurry or solid-liquid mixture is separated to a dense slurry containing most of the solids and an overflow of essentially clear water (or liquor in leaching processes).
What is stabilized sludge?
Stabilisation processes as applied to sludge are those which reduce its odour and putrescence (i.e. decay), and level of pathogenic organisms. This is generally achieved either chemically or biologically.
What is equalization tank?
The main function of the equalization tank is to act as a buffer: to collect the raw incoming sewage that comes at widely fluctuating rates and pass it on to the rest of the sewage treatment plant at a steady flow rate. The tank is rectangular in shape to provide placement of air diffusers for full floor coverage.
How can I reduce sludge?
What is sludge dewatering process?
Sludge dewatering is the practice of minimizing waste by volume to prepare for its effective disposal. Sludge originates during the process of treating wastewater before the water can be released back into the environment.
How does the thickened sludge get into the sludge line?
The thickened sludge is collected at the thickener bottom and is pumped to digesters or dehydration equipment, depending on the sludge line configuration. The rotating mechanism is commonly a central drive with double diametrical arm.
What is the concentration of polymer added to thickened sludge?
If the thickened sludge concentration normally obtained is between 3% and 6%, the polymer addition provides concentrations of 8%. The solids recovery increases from 85-90% to 90- 95%. The type of polymer to be used and its concentration will be dependent on the characteristics of the sludge to be
What is the best method for thickening activated sludge?
Flotation thickening is most applicable to activated sludges but higher float concentrations can be achieved by combining primary with activated sludge. Equal or greater concentrations may be achieved by combining sludges in gravity thickening units 3.
What is a sludge thickening tank?
A design developed in UK by the WRc (Warden, 1983), for waterworks sludge thickening applications, consists of a cylindrical tank of water depth 2–3.5 m with a shallow sloping floor (1 in 20). Sludge is introduced at the central feed well and the supernatant overflows a peripheral weir.