Decanter Centrifuges for Sludge Thickening and Dewatering

• Customization: Available
• After-sales Service: 24 Hours on Line
• Warranty: 12monthes
• Model NO.: LWF
• Separation Mode: Sedimentation Type
• Operating Type: Continuous Type
• Installation: Horizontal
• Centrifuge Type: Horizontal Spiral Centrifuge
• Pressure: Low Pressure
• Condition: New
• Material: SS304 or SS316 L
• Motor: ABB
• Touch Screen: Siemens
• PLC: Siemens
• Transport Package: Wooden Cases
• Specification: 2065*1050*800
• Trademark: Shenzhou
• Origin: China
• HS Code: 8421192000
• Production Capacity: 500sets
• Package Size: 1500.00cm * 1000.00cm * 1600.00cm
• Package Gross Weight: 1020.000kg

Product Description

 

 

The cost of biosolids storage, transportation, and end-use or disposal can significantly impact the choice of decanter centrifuges to perform thickening or dewatering functions. Generally speaking, sludge thickening before dewatering will reduce the tankage needed for storage by removing water; dewatering works to remove more water producing a drier cake material (source: SHENZHOU - Centrifuge Thickening and Dewatering of Biosolids).

According to Science, Sludge thickening commonly produces sludge solids concentrations in the 3% to 7% range, which results in an 80% volume reduction. Several factors determine whether a sludge thickening system is sufficient in the treatment of biosolids.
These include:

• Waste Activated Sludge (WAS) / Secondary Sludge - (0.8-1.3% TS)
  • Has natural separation of free water (floc) and is easily settable
  • Little to no polymer is required. (*)(**)

* Traditional decanter centrifuges used for sludge thickening can work using little to no polymer but require higher energy consumption or the capacity of the equipment is limited. Other thickening technologies (rotary drum, gravity belt, DAF) need polymer to produce 4-5% solids concentration

 

**The  Sludge Thickener will achieve 4-5% solids concentration using no polymer, with 50% less energy consumption and increased capacity compared to traditional decanter centrifuges.

• Primary Sludge - (1.5-5% TS)
  • Solids are heavy and settable but laden with colloidal material (hazy)
  • Hard to remove fine particles
  • Polymer is usually required

• Digested Sludge - (1.5-3% TS)
  • Not easily settable;
  • Polymer is usually required

• Transportation costs based on tonnages
   
• Landfill percent of solids concentration requirements
   
• Whether the sludge can be disposed in a sludge lagoon
• 

  
  
   

Sludge thickening using a decanter centrifuge before a digestion treatment process will reduce the size of the digester, and can be used before sludge storage and liquid land applications. Depending on the utilization of the sludge product (landfilled, land applied or dried) the drier the product the more cost effective it will be for storage, transportation and disposal.
 

Mechanical dewatering with a decanter centrifuge can result in a 95% reduction in volume and a concentration of between 15% to 35% dry solids, compared with 80% volume reduction and solids concentration of 3% to 7% with a sludge thickening-only operation. By removing more water and thereby producing a drier cake product, dewatering will offer significant savings in treatment, handling, and disposal costs.

Advantages of dewatering include the following (source: Biosolids Technology Fact Sheet on Centrifuge Thickening and Dewatering):

• Reduces volume, saving money on storage and transportation
   
• Eliminates free liquids before landfill disposal
   
• Reduces fuel requirements if the residuals are to be incinerated or heat dried
   
• Eliminates ponding and runoff
   
• Optimizes air drying and many stabilization processes

 Municipal sludge and performance expectations are difficult to fully classify due to wide-ranging variations of different processes as well as domestic and industrial contributions to the biomass.

There is a need to:

• Define sludge characteristics
   
• Characterize optimum performance levels expected on the equipment

 To better quantify performance, limits need to be set and terms better qualified. All sludge types as defined below assume industrial contributions are less than 20% of the final dewatered solids concentration and that conventional wastewater treatment processes are employed. Chemical additives (such as potassium permanganate used in odor control) are assumed not to significantly affect sludge conditioning.

Raw Primary	The feed solids are assumed to come off the bottom of a primary clarifier and therefore have a consistency of 2 - 7% ts. For thickening before anaerobic digestion or tanker hauling, cake at 5 - 10% ts is specified at +95% recovery and is easily obtainable.
Waste Activated Sludge	Most feed solids vary from 0.4 - 2.0% tss. Sludge thickening without polymer yields a 4 - 6% cake for recovery specs of 85 - 90%. Polymer is required at higher level of recoveries and/or while thickening at 7 - 10%. Dewatering and high solids dewatering typically occurs at 90 - 95% recovery levels.
Raw Mixed Primary / Secondary Sludge	Various combinations of mixed primary and secondary sludge are usually found at a concentration between 3 - 6% tss. This analysis assumes a 50:50 blend of sludge types. Recovery levels of +95% are typically achieved using polymer for all modes of separation.
Mixed Anaerobically Digested Sludge	Assuming a 50:50 blend of primary and secondary sludge to the digester, feed solids at 2 - 4% tss typically result in specifications at +95% recovery with polymer.
Aerobically Digested Sludge	For aerobically digested sludge, feed solids at 1 - 2.5% tss typically result. Polymer is used to effect separations at 90 - 95% recovery.

 

Biosolids	Organic matter recycled from sewage especially for us in agriculture as fertilizer. Treated sewage sludge.
Cake	The dried substance (sludge solids) from a decanter centrifuge operation.
Centrate	The liquid discharged from a centrifuge after most of the solids have been removed.
Centrifugal Force	The force (non-real force) that is needed to make things work as you would think in a reference frame that is accelerating.
Countercurrent Technology	In countercurrent flow, the two flows move in opposite directions. Under high centrifugal force, the heavier solids migrate radially outwards towards the bowl, displacing the lighter liquid to the pool surface at a smaller radius.
G-force	An outward force acting on a body rotating about an axis.
Millon Gallons per Day (MGD)	The measurement of water a facility processes each day.
Sludge	The semi-solid residual material which is left behind from the treatment of wastewater.
Slurry	A muddy mixture of a liquid and a solid; a watery mixture of insoluble matter.
STP	Sewage Treatment Plant
Total Solids (TS)	The combination of total dissolved solids and total suspended solids in a liquid.
Total Suspended Solids (TSS)	The portion of fine particles, these do not dissolve, that remains suspended in water.
Variable Frequency Drive (VFD)	Motor controller that drives an electric motor by varying the frequency and voltage of its power supply. The VFD also has the capacity to control ramp-up and ramp-down of the motor during start or stop.
Waste Activated Sluge (WAS)	The excess quantity of microorganisms that must be removed from the biological wastewater treatment process to keep the ration of biomass and incoming pollutant load in balance.

Model	Diameter(mm)	Lenght(mm)	Max speed	L/D ratio	G-force	Capacity(m3/h)	Main motor power(Kw)	Weight(kg)	Dimension (mm)
LW250*1000	250	1000	5000	4	2722	0.5-5	7.5	950	2120*1250*680
LW300*900	300	900	4200	3	2964	1-6	11	1160	2150*1300*900
LW300*1200	300	1200	4000	4	2784	2-6	11	1350	2450*1300*900
LW355*1160	355	1160	3600	3.3	2576	2-8	15	1400	2470*1350*830
LW355*1460	355	1460	3600	4	2576	2-10	15	1800	2750*1350*830
LW400*1200	400	1200	3200	3	2294	3-12	18.5	1800	2730*1600*1080
LW400*1600	400	1600	3000	4	2016	3-15	22	2000	3130*1600*1080
LW450*1800	450	1800	2800	4	1976	4-25	37	2500	3320*1700*1130
LW500*2000	500	2000	2800	4	1750	5-35	45	4000	3520*1800*1170
LW530*1855	530	1855	2600	3.5	2006	5-38	55	4680	3885*1350*1600
LW530*2120	530	2120	2400	4	1709	5-40	55	4800	4150*1350*1600
LW550*2000	550	2000	2800	4	2414	6-40	55	5700	4570*1380*1600
LW650*1950	650	1950	2200	3	1761	6-45	75	5000	4840*1510*1720
LW650*2600	650	2600	2000	4	1456	6-65	90	6000	5490*1510*1720
LW720*2160	720	2160	2000	3	1612	7-80	120	6000	5200*1600*1800
LW720*2880	720	2880	2000	4	1306	7-90	120	8000	3100*1600*1800
LW800*2400	800	2400	1800	3	1451	20-100	150	12000	5820*2000*1300
LW800*3200	800	3200	1800	4	1451	20-120	150	1300	7100*2000*1300