CIE4485 Wastewater Treatment

Transcription

1 CIE4485 Wastewater Treatment Prof.dr.ir. Jules van Lier 12. Anaerobic Sewage Treatment 1

2 CT4485 Wastewater Treatment Lecture 5b: Anaerobic sewage treatment Prof.dr.ir. Jules van Lier 13 December 2012 Delft University of Technology Challenge the future Learning objectives Understand potentials of direct sewage treatment by anaerobic reactor systems Understand advantages and constraints of anaerobic sewage treatment IWA: Chapter 16 Metcalf & Eddy: Chapt

3 UASB REACTOR DESIGN V r (m 3 ) Relationship between pollution strength and reactor volume Assumptions: min = 4 h Q = 250 m 3 h r v = 15 kg COD m -3 d -1 hydraulic load = 6 m 3 m -3 d V r = Q V r = (c Q) r v -1 (hydraulic load = 6 m 3 m -3 d -1 V reactor = 1000 m 3 ) c (kg COD m -3 ) 3 Anaerobic treatment of municipal wastewaters using UASB reactors systems Temperature.: > 20 C COD infl.: < 1000 mg/l SS-influent: < 500 mg/l 4 2

4 Assessment of the size of a UASB Reactor Relationship between pollution strength and reactor volume 2000 V r (m 3 ) Normal COD-range for domestic sewage Assumptions: min = 4 h Q = 250 m 3 h -1 r v = 15 kg COD m -3 d -1 hydraulic load = 6 m 3 m -3 d V r = Q V r = (c Q) r v c (kg COD m -3 ) Conventionally designed UASB reactors for domestic sewage (COD < 1000 mg/l) are hydraulically limited!! 5 Anaerobic Sewage Treatment Objectives: Removal of biodegradable organic compounds by converting them into methane. Removal of settle-able non-biodegradable compounds Stabilisation of retained sludge. Improving de-watering characteristics of the sludge UASB mostly applied and comprehends 4 units: 1) primary clarifier, 2) biological reactor, 3) secondary clarifier and 4) sludge digester 6 3

5 Basic setup of conventional aerobic sewage treatment screens grit chamber primary activated secondary sedimentation sludge sedimentation tank tank tank Raw sewage Treated effluent Sludge sludge digestion sludge dewatering 7 Basic setup of anaerobic sewage treatment CAPEX reduction?! screens grit chamber high-rate anaerobic treatment Effluent polishing by e.g. pond Raw sewage Treated effluent Coarse: 20 mm? + Fine: 4-6 mm! To be combined with fat/grease removal! sludge drying beds Sludge 8 4

6 Attainable UASB results for domestic sewage Results from Latin America and India: (COD < 500/600 mg/l) <best performances!> V: up to m 3 Hydraulic load restrictive: HRT 6-8 hrs COD Removal: % BOD Removal: % SS Removal: % Pathogen Removal: - Coliforms: 70-90% - Helminth eggs: up to 100%? m 3 /d, Mirzapur, India m 3 /d, Bucaramanga, Colombia 9 COD concentration: influent effluent, Kanpur, India 10 5

7 BOD concentration: influent effluent, Kanpur, India 11 TSS concentration: influent effluent, Kanpur, India 12 6

8 UASB: options for decentralised sewage treatment - compact systems - reduction land demand - reduction sewerage costs Campina Grande, Brasil Odemira, Portugal Masterplan of Recife metropolitan area: decentralised approach (Florencio et al., 2001) 13 Conditions for decentralised / residential - Odor prevention!! - Full treatment until restrictions applications Vivero, Cali, Colombia: in direct vicinity of residential area!! 14 7

9 General lay-out of an anaerobic WWT plant biogas use influent screening grit chamber U A S B Post treatment - polishing pond - Trickling filter -RBC -etc. effluent water sludge biogas sludge drying bed reuse 15 wastewater effluent gutter gas collector The UASB Reactor Distribution box biogas biogas treated water settling zone aperture baffle sludge blanket sludge bed feed inlet deflector beam sludge withdrawal 16 8

10 wastewater detention time settling zone Design Criteria for the UASB Reactor upflow velocity effluent gutter gas collector angle Distribution box number biogas biogas Treated water aperture baffle loading rate velocity sludge blanket concentration sludge bed concentration feed inlet density minimum SRT deflector beam angle sludge withdrawal 17 Internal view 1200 m 3 UASB, Cali, Colombia 18 9

11 Full-scale anaerobic sewage treatment plant, Bucaramanga, Colombia Río Frío WWTP (0,74 m 3 /s) 19 Polyester Circular Distribution Box Clogged inlet pipe Maintenance (declogging) 20 10

12 BUCARAMANGA, Colombia Pre-Treatment 21 Odour combatement, closed reactor system Scum removal 22 11

13 Stainless steel, rectangular influent distribution 23 Anaerobic treatment of domestic sewage, India m 3 /d UASB, Kanpur, India 24 12

14 Full-Scale Experience in Brazil 48,000 m 3 UASB Curitiba (Atuba Sul) 24 modules of 2000 m 3 each 25 CURITIBA, Brasil - Atuba Sul WTW 26 13

15 Engineering details, UASB Brasil 27 UASB as Pre-Treatment in Sao Paulo, Brasil Piracicaba WWTW Rio Claro WWTW 28 14

16 Conventional Activated Sludge vs Integrated Anaerobic & Aerobic Treatment Biogas Disintegration of Sewage Sludge Waste sludge Influent Preliminary Treatment Primary Sedimentation Anaerobic Process Tank Activated Aerobic Polishing Sludge Effluent Thickener Biogas Digester Dewatering Sludge Disposal 29 Integrated anaerobic treatment post treatment, Brasil UASB Trickling filter Tilted plate settling device 30 15

17 Treatment of concentrated sewage: Middle East / Amman Scum. Flow: m 3.day BOD: mg/l COD: mg/l TSS: mg/l NH 4+ -N: mg/l N-Kj: mg/l P-tot: mg/l Temp.: 16 (W.) 28 (S.) ºC Results two-stage pilot trials Middle East (Jordan): (COD 1500 mg/l) (with post clarification) COD Removal: up to 80% BOD Removal: up to 85% SS Removal: up to 80% Pathogen Removal: insufficient Potential CH 4 production in Amman (at m 3 sewage/day): 30,000 m 3 /day! 5 6 MWe 0.15 Nm 3 CH4/ kg CODrem. 31 Concentrated sewage: SRT prime design criterion! SRT is directly linked to the amount of viable, active biomass in the system: SRT (d) = X reactor V / (Q effl X effl. + Q excess-sludge X excess-sludge ), with X = concentration of viable biomass in kg/m 3 (e.g.methanogens). V = reactor volume (m 3 ) Q = flow m 3 /d SRT is determined by: - incoming suspended solids - solids digestion in the reactor - filtering capacity sludge bed (upflow velocities + sludge characteristics) - growth and decay of new sludge - sludge retention in the settler (upflow velocities) - withdrawal of excess sludge SRT min. 3 * Td (doubling time) of critical biomass (e.g. methanogens) 32 16

18 Required SRT for Hydrolysis in Reactor 180 SRT for stabilized sludge [days] Temperature [ C] 33 Role of anaerobic technology in the water chain Jordan Yemen Egypt Scavenger of solids Mineralisation of organic matter Removal of heavy metals Filtration of Helminth eggs?? Provider of essential nutrients (NH 4+,PO 4 3- ) Production of stabilised soil conditioner Energy producer (for local use) 34 17

19 Cost-effective adjustment effluent N for re-use PhD research Ghada Kassab (2009) - Necessity depends on growth stage and cropping season - UASB used for N solubilisation and denitrification - N is oxidised in post treatment and recycled to UASB UASB Post treatment - System stability - Long-term reliability - On-off switch possible 35 OPEX / CAPEX reduction as driver Full scale UASB application: Sanhour, Fayoum, Egypt (June 2006) Existing plant: Overloaded trickling filters 36 18

20 Proposed Treatment Processes Options Option (1): UASB + Trickling Filters Option (2): UASB + Trickling Filters + Activated Sludge Option (3): Activated Sludge Process Option (4): Lagoons (no land available) 37 Comparison of options Description UASB+TF UASB+TF+AS AS COD effl (80 mg/l) BOD effl. (60 mg/l) TSS effl. (50 mg/l) Investments (MEuro) O&M (euro/year) 14,795 27, ,964 Remarks Complicated Operation High Energy + Complex Sludge treatment UASB = upflow anaerobic sludge bed TF = trickling filter AS = activated sludge 38 19

21 Full scale UASB, Sanhour, Egypt First feasibility studies: mid eighties.. 39 Post-commissioning: GLSS gas leakages Gas Pipe Cap 40 20

22 GLSS Sanhour 41 GLSS gas leakages 42 21

23 GLSS gas leakages 43 Sanhour WWTP COD Removal Aug Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov-2008 COD (mg/l) Date of Sample UASB Effluent Law 48 (80 mg/l) Final Effluent UASB Influent 44 22

24 Sanhour WWTP BOD Removal 1000 BOD (mg/l) Date of Sample 1-Aug Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov-08 UASB Effluent Law 48 (60 mg/l) Final Effluent UASB Influent 45 Sanhour WWTP TSS Removal 1000 TSS (mg/l) Date of Sample 13/08/ /08/ /09/ /09/ /10/ /10/ /11/ /11/ /12/ /12/ /12/ /01/ /01/ /02/ /02/ /03/ /03/ /04/ /04/ /05/ /05/ /06/ /06/ /06/ /07/ /07/ /08/ /08/ /09/ /09/ /10/ /10/2008 UASB Effluent Law 48 (50 mg/l) Final Effluent Influent TSS 46 23

25 Accra, Ghana: 6500 m 3 UASB for Municipal Sewage under construction Korle Lagoon 47 Accra, Ghana: 6500 m 3 UASB for Municipal Sewage RESULTS START-UP phase (in mg/l): Influent Influent Effluent peakvalues UASB Trickling filter Clarifier COD 1, , BOD 1, , TSS , VSS , n.a. ph: 5 12!! COD efficiency (entire plant): 92% BOD / TSS efficiency: 98% HRT: h OLR: 1.6 ( ) kg/m 3 /d 48 24

26 Treatment results UASB + TF, Accra, Ghana. COD (mg/l) COD concentrations through the plant BOD 1000 COD TSS Influent UASB effluent TF effluent Final effluent 49 Trickling filters (in operation), Accra, Ghana UASB Trickling filters 50 25

27 Final clarifiers in operation, Accra, Ghana Final effluent 51 UASB - Post treatment Options, 1-2 (after Chernicharo, 2005) 52 26

28 UASB - Post treatment Options, 3-4 (after Chernicharo, 2005) 53 UASB - Post treatment Options, 5-6 (after Chernicharo, 2005) 54 27

29 UASB - Post treatment Options, 7-8 (after Chernicharo, 2005) 55 Innovative, compact & cost-effective approach: (Harada et al., Japan) 56 28

30 57 Prof. Harada, Nagaoka University, Japan 58 29

31 BIOPAQ UBOX Integrated anaerobic aerobic treatment system GAS OUT EFFLUENT AEROBIC AIR IN ANAEROBIC INFLUENT 59 BIOPAQ UBOX Sewage Treatment Plant Poços de Caldas, Brazil inhabitants 60 30