17 th European Biosolids Organic Resources Conference Seminar
17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition DISINTEGRATING SLUDGE AS CARBON SOURCE FOR DENITRIFICATION 19 th – 21 st November 2012, Leeds
Disintegrating sludge as carbon source for denitrification INDEX 1. Ultrasound engineering 2. A multi-use technology 3. Supporting denitrification 4. Collateral benefits & full balance 5. References 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 1. ULTRASOUND ENGINEERING What is ultrasound? • A wave is a disturbance travelling through a medium • Sound is a wave where excited magnitude is pressure • Ultrasound (US) is a sound wave where the frequency is beyond 20 k. Hz • With adequate frequencies and intensities strong ultrasonic cavitation is produced 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 1. ULTRASOUND ENGINEERING Ultrasonic cavitation • Cavitation bubbles cannot survive in the medium (water) • Forceful implosion takes place and high energy is delivered 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 1. ULTRASOUND ENGINEERING Effect on the sludge 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 1. ULTRASOUND ENGINEERING The reactor • 5 oscillators (1 k. W each) • Reactor volume 30 l • Frequency 20 k. Hz • Intensity 25 to 50 W/cm 2 • Sonication dose 1 to 9 k. Wh/m 3 • Sizes 1. 5 x 1. 1 x 0. 35 m 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 1. ULTRASOUND ENGINEERING Transferring energy to the sludge Sonotrode after 1. 5 to 2 years New sonotrode 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 1. ULTRASOUND ENGINEERING Engineering package & consulting service • Preconditioning sludge • Easily adapted to existing facilities • Fixed, skid or mobile availability • Local & remote control • Gi. MACS • Predictive analysis (Mass balance) • Start up & commissioning • Consulting service & support 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 2. A MULTI-USE TECHNOLOGY Applications in WWTPs 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 2. A MULTI-USE TECHNOLOGY Interested in anaerobic digestion? • An average around 20 to 25% of volatile solids degradation improvement is reached, which means + 20 to 30% biogas production + 10 to 20% dewaterability - 15 to 25% digested sludge - 100% foaming inside the digester - 10 to 15% sludge viscosity 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 2. A MULTI-USE TECHNOLOGY How is that possible? • Treating only 30 - 50% of the Thickened Waste Activated Sludge (TWAS) • US dose ≈ 4 k. Wh/m 3 to reach cell breakdown • CODs and enzymes are released • Hydrolysis step is highly intensified • The organic fraction is further degraded It is only necessary a 5 k. W US unit for each 200 m 3/d of mixed sludge 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 2. A MULTI-USE TECHNOLOGY Just a reference… 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 3. SUPPORTING DENITRIFICATION Denitrification drivers & inconvenient • Facultative bacteria transform NO 3 into N 2 in oxygen absence • A carbon source is required as electron donor • Carbon source presents in wastewater is frequently not enough • Primary treatment removes 40% of the COD and 10 to 15% of the TKN meaning a COD/TKN deterioration 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 3. SUPPORTING DENITRIFICATION What to do when TKN/COD is insufficient? • An external carbon source has to be added, meaning + Chemical costs (methanol, acetic acid…) + Disposal costs (up to 50% of more sludge can be produced) + Electricity costs (to aerate the produced sludge) • An internal carbon source is presented in TWAS • However TWAS readily biodegradable COD fraction is low 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 3. SUPPORTING DENITRIFICATION Extracting the full potential of the sludge • To increase TWAS bio-availability sonication is the key • Sonicated TWAS is an autochthonous carbon source which can support denitrification perfectly • A waste (TWAS) has been transformed into a resource (CODbio) 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 3. SUPPORTING DENITRIFICATION Measuring sludge sonication effect • Ww. TW is self-sufficient in carbon source to denitrify • US dose ≈ 4 k. Wh/m 3 TWAS • COD(soluble + colloidal) is delivered • Sludge hydrolysis rate increases ≈ 200% • 5 to 15 mg NO 3/l removed • 0. 7 to 0. 12 kg NO 3/kg TWAS 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 3. SUPPORTING DENITRIFICATION Process control: COD/TN delivered 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 3. SUPPORTING DENITRIFICATION Process control II: enzymatic activity 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 4. COLLATERAL BENEFITS & FULL BALANCE Not only nitrogen removal is reached!! • When sonicated TWAS is recycled back to the biological reactor cell lysis and cryptic growth process takes place meaning a significant excess sludge reduction • New flocs are formed (less interstitial water) when cell content is released into the medium meaning a dewatering improvement • Associated problems with bulking and foaming are completely removed 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 4. COLLATERAL BENEFITS & FULL BALANCE Carbon sources comparison per kg COD/d Chemical (£/d) Ultrawaves vs methanol - 0. 250 Ultrawaves vs acetic acid - 0. 820 Disposal (£/d) - 0. 066 - 0. 054 Electrical (£/d) - 0. 076 Dewatering (£/d) - 0. 003 - 0. 002 Consumables Ultrawaves (£/d) Total saving (£/d) + 0. 044 - 0. 351 - 0. 908 Parameter 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 4. COLLATERAL BENEFITS & FULL BALANCE An example: 600 kg COD/d are needed Chemical (£/d) Ultrawaves vs methanol - 150. 00 Ultrawaves vs acetic acid - 492. 00 Disposal (£/d) - 39. 60 - 32. 40 Electrical (£/d) - 45. 60 Dewatering (£/d) - 1. 80 - 1. 20 + 26. 40 - 210. 60 - 544. 80 - 76, 869. 00 - 198, 852. 00 Parameter Consumables Ultrawaves (£/d) Total saving (£/y) 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 5. REFERENCES Bünde WWTP: some figures • Plant size: 40, 000 PE (actually 54, 000 PE) • COD at the inlet: 380 mg/l (70 mg/l at the outlet) • TN at the inlet: 50 mg/l (15 mg/l at the outlet allowed) • Biological process: alternating nitrification-denitrification at sludge age of 22 days • Stabilisation problems: High VS content in sewage sludge, poor dewaterability and floating sludge 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 5. REFERENCES Bünde WWTP: ultrasonic installation • 5 k. W US unit installed • 30% of TWAS (4% in TS) is disintegrated • Sonicated flow rate is 1 m 3/h • US dose 5 k. Wh/m 3 • The purchase of 500 kg/d of methanol was avoided 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 5. REFERENCES Bünde WWTP: results in nitrogen removal Parameter Conventional Ultrawaves Difference Variation (%) Q (m 3/d) 12, 834 16, 101 3, 267 25. 46 CODinfluent (kg/d) 3. 838 4. 682 844 21. 99 Ninfluent (kg/d) 494 669 175 35. 43 Ninorg effluent (kg/d) 93. 6 65. 4 - 28. 2 - 30. 13 N removed (kg/d) 400. 4 606. 6 203. 2 50. 75 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 5. REFERENCES Bünde WWTP: results in sludge reduction Parameter Conventional Ultrawaves Difference Variation (%) Q (m 3/d) 12, 834 16, 101 3, 267 25. 46 CODinfluent (kg/d) 3. 838 4. 682 844 21. 99 CODperiod (ton) 480 585 105 21. 88 WASperiod (ton) 267 232 - 35 13. 11 (WAS/COD)period 0. 56 0. 40 - 0. 16 - 28. 70 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 5. REFERENCES Datansha WWTP • 150, 000 m 3/d • A 2 O process • Sludge production 61 ton/d • 25% improvement in N removal (> 3 mg/l reduced) • 20% sludge reduction 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification 5. REFERENCES Other references • Wujiang WWTP 85, 000 m 3/d (A 2 O process) 0. 75 yuan/m 3 methanol 20 to 40% TWAS sonicated 20% TN reduction increased (> 3 mg/l) and TP decreased from 10 up to 0. 3 ppm • Gaobeidian WWTP 25% TN reduction increased (20% TP) • Ellmendingen STP • Wuxi WWTP 25% sludge reduction 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification … more details can be found in our paper submitted for this event Any questions? 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
Disintegrating sludge as carbon source for denitrification Contact: Luis Vergara Technical Director luis@ultrawaves. co. uk 17 th European Biosolids & Organic Resources Conference, Seminar & Exhibition
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