THROUGH BIOGAS UTILIZATION IN PSYTTALIA WWTP, ATHENS, GREECE - - PowerPoint PPT Presentation

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THROUGH BIOGAS UTILIZATION IN PSYTTALIA WWTP, ATHENS, GREECE - - PowerPoint PPT Presentation

May 17, 2023 160 likes •560 views

GREEN ENERGY PRODUCTION THROUGH BIOGAS UTILIZATION IN PSYTTALIA WWTP, ATHENS, GREECE Speaker: Mrs Gina Stefanakou Deputy Director WWTP Division & Head of Psyttalia WWTP Department 1 EYDAP S.A., www.eydap.gr EYDAP S.A. Athens

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Speaker: Mrs Gina Stefanakou Deputy Director WWTP Division & Head of Psyttalia WWTP Department EYDAP S.A., www.eydap.gr

GREEN ENERGY PRODUCTION THROUGH BIOGAS UTILIZATION IN PSYTTALIA WWTP, ATHENS, GREECE

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EYDAP S.A.

Athens Water-Supply and Sewerage Company S.A.

  • Formed in 1980 through merging of the Greek Water

Company (utility) and the Athens Sewerage Organization (state-owned)

  • Athens Stock Exchange entry in 1999
  • Current Shares:

61 % Greek State 10 % Agricultural Bank of Greece (state-owned) 29 % Private shareholders

  • Personnel: 2900

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Athens Water Supply and Sewerage Company

Serves the population of Athens metropolitan area with

Water services 4 Water treatment plants (Galatsi, Menidi, Kiourka, Aspropyrgos) 8.400 km of water distribution network Wastewater collection 6.000 km of sewer network Wastewater treatment 2 plants in operation (Psyttalia, Metamorphosis) 1 plant in test operation (Thriassio WWTP - West Attica) 5 plants in design phase (Peania-Kropia WWTP, N. Makri-Marathon WWTP, North Mesogaea WWTP, Lavreotiki WWTP & Fokea WWTP - East Attica)

EYDAP S.A.

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Akrokeramos installations Psyttalia island Salamina installations Port of Piraeus

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Psyttalia Wastewater Treatment Plant

Psyttalia WWTP installations were constructed by the Greek Ministry for the Environment, Physical Planning and Public Works, with European Union co-funding, in three phases: 1994 Phase A’ works completion, including wastewater pretreatment and primary treatment installations, primary sludge treatment installations, inverted siphon system for pretreated wastewater transport to Psyttalia and submerged outfall system for treated wastewater dispersion to the Saronic Gulf. 2004 Phase B’ works completion, including wastewater biological treatment installations and surplus activated sludge treatment installations. 2007 Phase C’ completion – construction of sludge thermal drying unit.

Construction Phases

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Additionally, the following works have been constructed at Psyttalia WWTP by EYDAP S.A. with European Union co-funding:

 Wastewater pretreatment unit on Salamina Island and submerged

pipes for wastewater transport from Salamina to Psyttalia (2002)

 Two cogeneration plants for heat and power (CHP) utilizing biogas

(2001 & 2009) and

 One CHP plant utilizing natural gas (2009)

Psyttalia Wastewater Treatment Plant

Construction Phases

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Psyttalia Wastewater Treatment Plant

Population equivalent (design, peak): 5 600 000 Design flow-rate (mean): 1 000 000 m3/d Peak flow-rate : 27m3/s (Phase A) 16 m3/s (Phase B)

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Psyttalia WWTP Flow - diagram

ELECTRIC ENERGY BIOGAS THERMAL ENERGY NATURAL GAS ELECTRIC ENERGY THERMAL ENERGY DRIED SLUDGE UTILIZATION EFFLUENT SLUDGE PUMPING GRAVITY THICKENING (TANKS) DIGESTION WASTEWATER INFLOW PUMPING COGENERATION (BIOGAS) DRYING SCREENING GRIT REMOVAL PRIMARY SEDIMENTATION DEWATERING MECHANICAL THICKENING (BELTS) FINAL SETTLING TANKS BIOREACTORS COGENERATION (NATURAL GAS)

Psyttalia Wastewater Treatment Plant

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Akrokeramos Installations

Wastewater Pretreatment

Debris Removal Screening Grit Removal Odor Control Twin inverted siphon

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Psyttalia Wastewater Treatment Plant

Wastewater treatment processes Akrokeramos (mainland)

Inlet Pumping Station 9 Archimedes Screw Pumps capacity 3m3/sec each, total capacity 27 m3/sec Pretreatment Screening 6 pairs of screens (30 / 10 mm) Grit removal 6 aerated spiral-flow channels Odor control (sodium hydroxide and sodium hypochlorite solutions, air treatment capacity 140 000 m3/h) Wastewater transport to Psyttalia through twin inverted siphon system

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Psyttalia Wastewater Treatment Plant

Wastewater pretreatment (Salamina island) Population served 7 000 (start of operation), 32 000 (full service) Flow-rate Peak 700 l/s Average (full service) 7000 m3/day Pretreatment Screening: Screen (20 mm) Grit removal: Aerated spiral-flow channel (retention time 3 min) Wastewater transport to Psyttalia through twin pipe system Current status of operation: Limited flow, pending further service connections

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Wastewater Inlet Channel Primary Treatment Biological Treatment Final Settling Filtration C.H.P. Gas-holders Sludge Thermal Drying Sludge Digesters

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Psyttalia Wastewater Treatment Plant

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Wastewater treatment processes Psyttalia island

Primary sedimentation 6 tanks (combined area 12 000 m2) Biological treatment 12 bioreactors (combined volume 300 000 m3) Organic load removal and nitrogen reduction Final settling 64 rectangular tanks (combined area 52 000 m2) Filtration - Disinfection 3 sand-filters (one spare; com. capacity 1500 m3/h) and mechanical filters 2 UV disinfection units Production of process water, for use in facilities on Psyttalia Outfall system Two main pipes (1870 m long each, depth 65m) Receiving waters: Inner Saronikos Gulf

Psyttalia Wastewater Treatment Plant

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Effluent Disposal Requirements

Based on Approved Environmental Terms according to Directive 91/271/EEC : Treated Effluent Concentration (mg/l) BOD5 25 COD 125 Suspended Solids 35 Total Nitrogen Removal (%) >70

Psyttalia Wastewater Treatment Plant

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Typical wastewater inflow characteristics (mg/l) COD: 720, BOD5: 320, TSS: 350 Operation efficiency Load reduction (%) exceeding COD 93 BOD5 93 TSS 93 Total Nitrogen 75

Psyttalia Wastewater Treatment Plant

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Psyttalia Wastewater Treatment Plant

Sludge Treatment Processes - Biosolids

Thickening Primary sludge gravity thickening Surplus activated sludge thickening Sludge mixing Digestion Dewatering Thermal drying Biosolids : Organic products of municipal wastewater treatment that can be beneficially used.

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Sludge Τhickening

Primary sludge: Fine screening Six screens (5 mm gaps) Gravity thickening facilitated / aided by use of polyelectrolyte solution 3 tanks (combined area 1500 m2) Odor control unit (2 lines) Waste activated sludge: Mechanical thickening aided by polyelectrolyte 14 belt thickeners (comb. capacity: 1750 m3/h) Sludge in-pipe mixing prior to digestion

Psyttalia Wastewater Treatment Plant

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Sludge Digestion

Method: anaerobic, mesophilic, high-rate Installations: 8 digesters (combined volume 80 000 m3) Type: Cylindrical, conical bottom, fixed-cover (dome-like) Mode of operation: parallel Biogas production from partly destruction of sludge organic content Mixing medium: Compressed biogas Heating medium: Water Heating source: Cooling water from CHP plant using Biogas

Psyttalia Wastewater Treatment Plant

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Psyttalia Wastewater Treatment Plant

CH4 CO2

Carbohydrates Proteins Lipids Phosphorylated Organics Glucose Amino-acids Fatty Acids Phosphates (PO4

  • 3)

Acetic Acid Propionic Acid Lactic Acid Cells (Biomass) Cells (Biomass) Stabilized Organic Compounds

Extracellular enzymes Acid-producing microorganisms Methane-producing microorganisms

Complex Organic Compounds

Hydrolysis

Soluble Organic Compounds

Acids Formation

Organic Acids

Methane Formation

Anaerobic Digestion

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Psyttalia Wastewater Treatment Plant

Sludge Digestion

Phase A digesters: 4 Heating and mixing: 6 heat-a-mix units in each tank Phase B digesters: 4 Heating: external heat exchangers Mixing: top-mounted hanging lances

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Psyttalia Wastewater Treatment Plant

Biogas temporary storage

Biogas produced at the anaerobic digestion plant is temporarily stored in the gas-holders (two tanks with 5600 m3 capacity each) and it is utilized as a fuel at the sludge thermal drying unit and at the gas- engines of the CHP plant.

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Dewatering plant

Decanter characteristics

  • Number: 6
  • Type: Centrifugal
  • Capacity: 70 m3/h each
  • Bowl diameter / length (mm): 725 / 2911

Psyttalia Wastewater Treatment Plant

Dewatering Plant (foreground)

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Cogeneration plant for Heat and Power production (CHP) utilizing natural gas (gas-turbine)

Psyttalia Wastewater Treatment Plant

Sludge Thermal Drying

Sludge Thermal Drying Unit

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Hot gases Granular sludge Dried granules and water-vapor carrying gases

Thermal drying plant evaporating capacity: 40 t water / h (4 parallel units) Hot gases temperature: 400 o C

Sludge Thermal Drying Rotating Drum Method

Psyttalia Wastewater Treatment Plant

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Utilization of Biogas produced at Psyttalia WWTP Psyttalia Wastewater Treatment Plant

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Psyttalia Wastewater Treatment Plant

The need for sustainable development combines environmental protection with meeting energy needs and in this framework the full utilization of available renewable energy sources including biogas, is a continuous necessity and one of the major goals for Psyttalia WWTP.

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Sludge Digestion Biogas

Composition of biogas produced from the sludge anaerobic digestion process

  • Methane CH4

61 - 65 %

  • Carbon Dioxide CO2

34 - 38 %

  • Nitrogen Ν2

0.05 %

  • Oxygen Ο2

0.0001 %

  • Hydrogen Sulfide H2S

1000 - 2000 ppm

Psyttalia Wastewater Treatment Plant

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PSYTTALIA WWTP

NATIONAL GRID MANAGER

SLUDGE THERMAL DRYING

CHP PLANTS

BIOGAS

GAS-HOLDER GAS-HOLDER BURNERS BOILER DIGESTER HEATING HEAT EXCHANGER

ELECTRIC ENERGY

ON-SITE CONSUMPTION ENERGY SALE

DIGESTER HEATING CLOSED CIRCUIT HEAT

SLUDGE D I G E S T E R BIOGAS PRODUCTION IN DIGESTERS BIOGAS STORAGE IN GAS HOLDERS U T I L I S Α T I O N

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Dried sludge silos

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Psyttalia Wastewater Treatment Plant

Biogas Utilisation as Fuel in Sludge Thermal Drying

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THERMAL DRYING Psyttalia WWTP - Rotating Drum Method

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Thermal Drying - Dried product characteristics

  • Satisfying US EPA 503 Class A specifications for hygienized sludge
  • Particle size 1 – 5 mm
  • Maximum temperature 45oC
  • Dried solids content (%) 90 – 95, mean 92
  • Maximum dust (<75 μm) content < 1% w/w

Psyttalia Wastewater Treatment Plant

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Psyttalia Wastewater Treatment Plant

CHP Plants utilizing Biogas

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GAS - HOLDERS

ELECTRIC ENERGY THERMAL ENERGY THERMAL ENERGY

DIGESTERS

CONSUMPTION ON-SITE SALE TO NATIONAL GRID ELECTRIC ENERGY SALE TO NATIONAL GRID

BIOGAS UTILIZATION AS FUEL IN CHP PLANTS FOR ELECTRIC POWER AND HEAT PRODUCTION

CHP PLANT 7,14 ΜWe

Phase A’

Power grid

Phase B’

Power grid Power supply to Phase B’ installations at Psyttalia WWTP Commisioning 2001 Commisioning 2009 Power supply to Phase A’ installations at Psyttalia WWTP

Electric energy surplus Electric energy surplus

CHP PLANT 4,25 ΜWe 33

CONSUMPTION ON-SITE

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TECHNICAL CHARACTERISTICS OF 7.14 MWe CHP PLANT

 Number of Gas-Engines

3

 Mechanical Power

2 521 kW

 Electrical Power Capacity

7.14 MWe

 Heat Capacity

10.35 MWth

 Number of Pistons

12V

 Frequency 1 000 rpm  Peak Biogas Consumption

3 x 1 000 m3/h

 Biogas Inflow Pressure

14 mbar

 Fuel Pressure (Biogas after compression) 3.2 bar  Generators Capacity

2 900 KVA

 Generators Output Voltage 3 300 V  Electric Current Frequency 50 Hz  Voltage to Grid

20 KV

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7.14 MWe CHP PLANT FLOW DIAGRAM

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Biogas Psyttalia WWTP Psyttalia WWTP Power Mechanical Electrical Grid Energy Energy Heat Flue Gases Gas Engine Generator Combustion Power Production Compression Digestion Dehumidi- fication Psyttalia Substation Akrokeramos Substation Storage Cleaning

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TECHNICAL CHARACTERISTICS OF 4.25 MWe CHP PLANT

 Number of Gas-Engines

2

 Mechanical Power

2 495 kW

 Electrical Power Capacity

4.25 MWe

 Heat Capacity

6.8 MWth

 Number of Pistons

20V

 Frequency 1 500 rpm  Peak Biogas Consumption

2 x 925 m3/h

 Biogas Inflow Pressure

14 mbar

 Fuel Pressure (Biogas after compression) 40 mbar  Generators Capacity

3 400 KVA

 Generators Output Voltage 3 300 V  Electric Current Frequency 50 Hz  Voltage to Grid

20 KV

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Internal Combustion Engine G

Biological stage for Hydrogen Sulfide removal Chemical Stage

Biogas Ο2

Nutrients

Ο2 NaOH

Replenishment

Η2S

Activated Carbon Filter

Gas-engine Feed Gas-holders

Biogas

Measurement Biological Stage Control Measurement Chemical Stage Control

Biological Desulphurization Unit

Process Water

Generator

Biological Desulphurization Unit 4,25 MWe CHP Plant

Nitrates Nitrogenous substances

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Production and Utilisation of Biogas

Biogas Thermal Energy: 6.4 kWhth / m3 Biogas Production (mean) : 65 000 m3 / day 24 x 106 m3 / year 70% - 90% to CHP & Thermal Drying Plants Biogas Utilization 10% - 30% for Digester heating Electricity Production from CHP Plants (mean): 35 000 MWhe/year

Psyttalia Wastewater Treatment Plant

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Environmental , Economic and other Benefits from Biogas Utilization  Fuel savings  Considerable reduction of power purchasing cost Income from sale of surplus power Reduced emissions of pollutants to the atmosphere Gain of know-how New jobs creation

Psyttalia Wastewater Treatment Plant