Thermal Hydrolysis Comes to Texas!

Transcription

1 Thermal Hydrolysis Comes to Texas! Samir Mathur PE, BCEE CDM Smith Summer Seminar July 25, 2014

2 Presentation Outline Thermal Hydrolysis fundamentals TRA solids masterplan overview Testing objectives Testing procedure and results Project Status

3 Thermal Hydrolysis Thermal Hydrolysis is a process by which sludge is heated and pressurized with the purpose of reducing organic solids to make them more readily biodegradable.. In other words, it s a pressure cooker. Before After

4 THP Uses Heat and Pressure to Rupture Cells Courtesy: Krueger

5 What is Thermal Hydrolysis? TH is a high pressure steam pre-treatment for anaerobic digestion Disintegrates cell structures/organic materials Dissolves naturally occurring cell polymers (exopolymeric substances-eps), a form of protein, into an easily digestible feed for anaerobic digestion

6 Thermal Hydrolysis Process (Cambi) Process gases (to digester) Raw sludge 14-18% DS REACTOR Recycled Steam 97 o C 1.5 hr PULPER 165 o C 6 bar 20 min homogenized sludge 11 bar hydrolyzed sludge steam bar 102 o C 1.5 hr FLASH TANK to Digester 8-12% DS

7 Thermal Hydrolysis Process (Cambi) Pre-Treatment Before Anaerobic Digestion 7

8 Thermal Hydrolysis 8

9 TRA Solids Master Plan Completed in 2010 Phased implementation Convert lime stabilization to digestion Thermal hydrolysis recommended

10 Current Solids Handling Process Primary Primary Sludge Thickening Dewatering Class A Land Application Lime Thickening Landfill WAS

11 Proposed Solids Handling Process Primary Biogas Thickening Pre-Dewatering Dewatering Class A Land Application Solids Screening Thickening Thermal Hydrolysis Mesophilic Digestion Landfill Compost WAS Soil Amendment

12 Benefits of Thermal Hydrolysis Process Class A product Higher volatile solids destruction Higher biogas production Ability to feed digesters at higher solids concentration Improved sludge dewaterability

13 How Well Will This Process Work For TRA CRWS? Confirm benefits of thermal hydrolysis Process for TRA Testing conducted at Virginia Tech University by Dr. John Novak

14 Testing Objectives Determine: Volatile solids destruction of PS and WAS Maximum and optimum solids concentration that can be fed to the digesters Optimum digester operating temperature based on ammonia toxicity limitation Dewaterability of the sludge after thermal hydrolysis and digestion Specific gas production

15 Testing Procedure Seed sludge provided by Chertsey WWTP, UK (03/11) Control digester Fed thickened sludge (4 to 5 %) No pretreatment Thermal hydrolysis digester Fed diluted dewatered sludge (10 to 12 %) Pretreated using thermal hydrolysis Compare sludge characteristics between the control and thermal hydrolysis digesters

16 Sludge Sample Collection Blended sludge w/o lime Dewatered cake w/o lime

17 Control Digester Parameter Digester Temperature Solids Feed 4% SRT Condition 37 o C and 42 o C Phase I - 20 days Phase II 15 days

18 Thermal Hydrolysis Digester Parameter TH temperature Digester Temperature Condition 170 o C Solids Feed 10% SRT 37 o C and 42 o C Phase I - 20 days Phase II 15 days

19 Laboratory Methods

20 Results

21

22

23 60 Solids Reduction 15 Days/42 o C 50 Solids Reduction (%) Control TS Reduction Cambi TS Reduction Control VS Reduction Cambi VS Reduction

24

25 30.00 Gas Production- 42 o C Volume (lts/day) Control TH 42C

26

27

28

29 Dewatering Data Control Digester Thermal Hydrolysis Digester Total Solids (%)

30 Summary Thermal hydrolysis would be an effective process for TRA 9 to 10% increase in VS destruction Ammonia production is not inhibitory, even at 42 o C, resulting in lower cooling costs Low odor product can be expected Almost 10% increase in solids concentration after dewatering Results are similar to previous testing at VT for Blue Plains WWTP

31 Current Status Project is proceeding to full scale implementation Currently in preliminary design

32 Questions?