1. Sludge Thickening and Dewatering Bob Dabkowski Katy Craig
Hach company
Sludge Thickening and Dewatering
Bob Dabkowski
Katy Craig

2. Hach History
Over 75 years of innovation, customer support and expertise
1947: Hach founded in Ames, Iowa by Clifford and Kitty Hach
For more than 60 years, we've been finding solutions that help you best manage your water and wastewater.
Water analysis has to be right. You deserve complete solutions you can be fully confident in. Hach is your resource for expert answers, outstanding support, and reliable, easy-to-use products.

3. Who we are Brand Promise
Manufacturer and distributor of process and laboratory instruments, chemistries, service and software for water analysis
Solution provider for diverse markets in the industrial and municipal sectors
Innovation leader
527 patents covering 130 patent families
Strong investment in R&D and acquired technologies to drive industry firsts
Driver of the highest quality, delivery and customer value
Leader in customer service, technical support and training
Water analysis has to be right. You deserve complete solutions you can be fully confident in. Hach is your resource for expert answers, outstanding support, and reliable, easy to use products.
Brand Promise

4. Sludge thickening (ST) vs. sludge dewatering (sd)
Produce consistent thickened sludge
Prevent clogging of sludge pump
Reduce polymer consumption
Improve biogas production in anaerobic digester
Primary benefits: Operational Improvements
Dewatering
Create cost savings in
Polymer consumption
Sludge disposal
Primary benefit: Cost Savings
Digester
Static thickener
Static thickener
Filtrate
Centrate
e.g. Drum thickener
Centrifuge
Poly
Poly

5. Real time control systems – theory of operation
Specific polymer dose
Set-point: g polymer / kg TSS
RTC will calculate the optimal polymer dose for every combination of sludge consistency and technology:
2 ways to optimize
Adjust TSS load
Adjust polymer dose
SPECIFIC POLYMER DOSE

6. Sludge thickening with RTC-ST
Variant 1: Load based feed
Digester
Static thickener Q
TSS Q
TSS thick +
Filtrate
TSS
= constant
e.g. Drum thickener
Poly
Polymer

7. Sludge thickening with RTC-ST
Variant 2: Load based polymer dosing
Digester
Static thickener
Q Poly.
TSS thick +
constant
Filtrate Q
TSS
e.g. Drum thickener
TSS
Q Poly.
Poly
Polymer

8. Sludge dewatering with rtc-sd
Variant 1: Load based feed
Digester
Static thickener Q
TSS Q
TSS Centrate +
Centrate
TSS
= constant
Centrifuge
Dewatered sludge
Poly
Polymer

9. Sludge dewatering with rtc-sd
Variant 2: Load based polymer dosing
Digester
Static thickener
Q Poly.
TSS Centrate +
constant
Centrate Q
TSS
Centrifuge
TSS
Q Poly.
Dewatered sludge
Poly
Polymer

10. Real time control sludge thickening
Case Study – Thames Water

11. The following data is from an installation of the Hach RTC-ST System designed to control polymer dose into a sludge thickening application
The wastewater treatment plant co-thickens primary and secondary sludge with rotary drum thickeners and polymer

12. Thames water sludge thickening
From a gravity thickener the sludge is mixed with polymer and added to the rotary drum thickener
The thickened sludge is then sent to anaerobic digestion
Digester
Static thickener
Filtrate
e.g. Drum thickener
Poly
Polymer

13. Before the RTC-ST: Static polymer dose
Thickened Sludge Concentration
Influent Sludge Flow
Influent Sludge Concentration

14. Thames water RTC-ST installation
Feed sludge flow and concentration are used by the RTC-ST to set an initial polymer dose (lb/ton)
Thickened sludge concentration is used by the RTC-ST to adjust the dose to maintain a desired thickened sludge setpoint
Digester
Static thickener
Q Poly.
TSS thick +
TSS
Filtrate Q
TSS
e.g. Drum thickener
TSS
Q Poly.
Poly
Polymer

15. After the RTC-st: variable polymer dose
Targeting 4% Thickened Sludge
Thickened Sludge Concentration
Influent Sludge Concentration

16. In conclusion
Experimented with different Thickened Sludge concentrations
6.1% Average TWAS concentration over study period
About 1% increase compared to original operation
35% Reduction in polymer
5.9% Increase in biogas production (and electricity)
From 45,700 m3/d to 48,400 m3/d

17. Next steps for technology development
Sludge Dewatering – RTC-SD
Seeking US installation site for evaluation and case study – currently only 5 sites in EU
Need data demonstrating cost savings and successful deployment
To improve technology, we would like a partner to assist in testing and refining ability to monitor in centrate (currently experiencing application challenges with air in sample)
Sludge Thickening – RTC-ST
Currently have 1 recently completed installation in US
Seeking US evaluation site and case study
Seeking range of partners with diverse sludge thickening technology for evaluation sites, including DAF (not common in EU)
Ideal Partner
Willing to share investment in site evaluation
Willing to participate in technical presentations/papers