This document discusses pre-liming of sludge before centrifugation using DehydrisTM Lime. It provides details on the DehydrisTM Lime process, including its advantages over traditional dewatering methods. Specifically, it leads to higher sludge dryness of 20-45% compared to 4-6% from traditional thickening. It also describes a case study of a wastewater treatment plant in Calais, France that implemented pre-liming with DehydrisTM Lime prior to centrifugation, achieving a final dry solids content of 28% and allowing agricultural reuse of the biosolids.

1. Dehydris™
Lime
ADVANCED DEWATERING OF SLUDGE BY PRE- BIOSOLIDS
LIMING BEFORE CENTRIFUGATION
PRODUCE QUALITY SLUDGE AND GENERATE
SAVINGS WITH PRE-LIMING
P-PPT-B-005-EN-1107

2. BIOSOLIDS
CONTENTS
Dehydris™
Lime Dehydris™ Lime on the dryness scale
Dehydris™ Lime Workshop
Uses and post treatments
Operation Description
The plus of Dehydris™ Lime
References
Case Study: Calais (62), FRANCE
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3. Dehydris Lime
BIOSOLIDS
DRYNESS SCALE COMPARISON
Dehydris™
Lime 60 – 90 %
20 – 45 %
4–6%
0.4 %
Dryness
Process Thickening Dehydration Drying
Sludge volume
/
Extracted water
volume
Range Name Drainis™ Dehydris™ Evaporis™
Dehydris™ Osmo
Evaporis™ LT
Process Name Drainis™ Turbo Dehydris™ Lime
Evaporis™ LE
Dehydris™ Twist
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4. BIOSOLIDS
Dehydris Lime PROCESS (1/2)
Dehydris™
Lime
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5. BIOSOLIDS
Dehydris Lime PROCESS (2/2)
Dehydris™
Lime
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6. Dehydris Lime – USES AND POST TREATMENTS
Dehydris Lime
Uses Uses
Post treatments
Thermal Drying
Landfill • No recycling (dryers STC, BDS) Agriculture re-use
• Improved drying kinetic
• Reduced volume of cake • Reduced volume of cake
• Dryness: 30% • Calcium intake
• Heap holds its shape
• Biological stability
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7. BIOSOLIDS
OPERATION DESCRIPTION
Dehydris™
Lime Area of application:
• Physical-chemical and biological UWW sludge,
whether or not digested
Used limes: Classic quicklime
• Quicklime thermicity delayed
°
60° C
• Quick lime thermicity delayed or
température
Quicklime thermicity delayed
fine quick lime
Maintaining the rate of reaction
• Liquid lime solution ready for use
Delayed activation as sharp
as for classic quicklime
Polymers: Reactivity time
•
delay
High pH stable polymers
• Standard polymer is used for digested sludge
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8. BIOSOLIDS
Dehydris Lime ADVANTAGES
Dehydris™
Lime • Intimate mixing of lime in sludge
– stability sustainable organic
• Identical dryness to that obtained with
post-liming
– up to 50% gain compared to dewatering with
centrifuge only
• Granular structure
– heap holds its shape
• Reduced phosphate content in the
centrates returned to the plant inlet
• Simple implementation
• Easy-to-run unit
• Enhanced security
– No mechanical blade mixer
– No dust
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9. AMONG Dehydris Lime REFERENCES
Start-up Type
Contract Capacity Date Sludge-end use
of sludge
Calais (62), France 120,000 PE 2007 Activated sludge Agricultural spreading
Île d’Arrault (45), France 100,000 PE 2011 BRM (Ultrafor™) Agricultural spreading
Basse Wavre, Belgique 200,000 PE 2010 Anaerobic digestion Agricultural spreading
Château-Thierry (02),
40,000 PE 2012 Activated sludge Agricultural spreading
France
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10. A CASE STUDY:
CALAIS « JACQUES MONOD » (62), FRANCE
CONTEXT:
• A 120 000 p.e. UWW treatment plant (prolonged
aeration)
• Replaces post-liming (mixer out of use) by pre-
liming prior to centrifugation (a Degrémont
Services achievement)
• Pre-liming commissioned in 2007
DESIGN:
• The sludge treatment line:
– Floatation, pre-liming, centrifugation
• Treatment capacity : 800 Kg DS/hour
• Delayed temperature increase quick lime, lime
treatment rate: 30% CaO/DS
• Centrate dephosphatation efficiency >75%
• Final dry solids content: 28%
• Sludge end use:
agricultural spreading
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