anaerobic reactors - chernicharo

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Anaerobic Reactors

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  • 8th IWA Specialist Group Conference on Waste Stabilization Ponds

    .

    2nd Latin-American Conference on Waste Stabilization Ponds

    Round TableIntegration of ponds with other systems

    Belo Horizonte, April 2009

    Carlos Augusto de Lemos CherncharoDepartment of Sanitary and Environmental Engineering

    Federal University of Minas Gerais Belo Horizonte - Brazil

  • Brazilian and developing countries:

    Large pieces of flat land are not always available

    Enormous sanitation deficit

    Shortage of financial resources

    Lack of qualified operational personal

    Need of low cost, sustainable and simplified wastewater treatment systems

    Soil characteristics many times inappropriate for large natural systems, such as ponds and constructed wetlands

    Reuse still in early stages

  • Based on that scenario:

    Two process combinations have very interesting features:

    Quality of treated effluent is mainly regulated considering discharge and receiving body standards

    Compact anaerobic treatment systems can play a major role:

    UASB + Polishing Ponds (PP) UASB + Trickling Filters (TF)

    UASB reactor is a very good alternative

  • Brief background on UASB reactors

    Drawbacks and possible improvements

    Examples of full-scale applications

    Summary

    Integration with Polishing Ponds

    Integration with Trickling Filters

    Final remarks

  • Brief background on UASB reactors

  • Main characteristics Advantages Applicability

    Large urban areas

    Small decentralized

    systems

    Small communities

    No oxygen consumption

    Low sludge production

    Sludge is more concentrated and easy to dewater

    Biogas production

    Simple to operate

    Lower O&M costs

    Lower construction costs

    Possibility of energy recovery

    Anaerobic systems: general aspects

    Brief background on UASB reactors

  • UASB Reactor

    The system is self-mixed by the upflow movement of biogas bubbles and by the liquid through the reactor, allowing the contact between the organic matter and the biomass. As a result, biogas is formed.

    Brief background on UASB reactors

  • UASB Reactor

    The 3-phase separator is located in the upper part of the reactor, allowing the separation of gas, liquid and solids

    Brief background on UASB reactors

  • UASB Reactor

    The settling zone allows the exit of the clarified effluent and the return of solids (biomass) to the digestion zone, in lower part of the reactor

    Brief background on UASB reactors

  • UASB Reactor

    The UASB reactor functions, simultaneously, as a primary settler, as a biological reactor, as secondary clarifier and as sludge digester

    Brief background on UASB reactors

  • UASB Reactor Typical configurations

    Brief background on UASB reactors

  • Examples of full-scale applications

  • Location: Itabira Brazil Configuration: UASB reactors + TF

    Design population: 60,000 inhabitants Design flowrate: 120 L/s (1st stage)

    Itabira WWTP

    Examples of full-scale applications

  • Itabira WWTP

    Sludge withdrawal and sampling ports

    Examples of full-scale applications

  • Itabira WWTP

    Feed distribution system and 3-phase separator

    Examples of full-scale applications

  • Itabira WWTP

    Biogas flare and thermal sludge treatment device

    Examples of full-scale applications

  • Location: Belo Horizonte Brazil Configuration: UASB reactors + TF

    Design population: 1 million inhabitants Design flowrate: 1.8 m3/s (1st stage)

    Ona WWTP

    Examples of full-scale applications

    Aerial view

  • Ona WWTP

    Examples of full-scale applications

    Aerial view

  • Feed distribution system (top of the reactor)

    Ona WWTP

    Examples of full-scale applications

  • Feed distribution system (bottom of the reactor)

    Ona WWTP

    Examples of full-scale applications

  • 3-phase separator

    Ona WWTP

    Examples of full-scale applications

  • Biogas system

    Ona WWTP

    Examples of full-scale applications

  • Drawbacks and possible improvements

  • Odour generation

    Most of all are possible to control, with proper designs & adequate construction, operation and maintenance

    Corrosion

    Limited efficiency

    Scum

    Foam

    Anaerobic systems: inherent limitations

    Methane emission

    Drawbacks and possible improvements

  • Proper materials

    Proper lining

    Turbulence minimization

    Turbulence maximization

    Corrosion

    Inherent limitations: corrosion

    Drawbacks and possible improvements

  • Liquid phase

    Turbulence minimization

    Aerobic post-treatment

    Gaseous phase

    Reactor cover

    Gas collection

    Gas treatment

    Gas flare

    Turbulence maximization

    Odour

    Inherent limitations: Odour

    Drawbacks and possible improvements

  • Ongoing researches

    Removal device

    Treatment and final disposal

    Minimize formation

    The problem

    Scum

    Inherent limitations: Scum

    Drawbacks and possible improvements

  • Control of household discharges

    Turbulence minimization

    Aerobic post-treatment

    The problem

    Foam

    Inherent limitations: Foam

    Drawbacks and possible improvements

  • Compliance with local guidelines ? (ex.: dilution, agricultural reuse etc.)

    Post-treatment for the removal of carbonand pathogens (well established)

    Improvement of anaerobic effluent quality(Ongoing research)

    Post-treatment for the removal of N and P(research still needed)

    Limited efficiency

    Inherent limitations: Limited efficiency

    Drawbacks and possible improvements

  • Micro-aeration inside the reactor?

    Stripping outside the reactor?

    Methane emission

    Inherent limitations: Methane emission

    Biological oxidation?

    Drawbacks and possible improvements

    The problem

  • UASB technology: summary

    Consolidated technology in many warm-climate regions

    Great advantages and broad application, but operational limitations still exist

    Further expansion and wider application can be significantly hindered if design and operationaldrawbacks are not solved

    Drawbacks and possible improvements

  • Integration with Polishing Ponds

  • UASB reactor + Polishing Ponds: typical flowsheet

    Integration with Polishing Ponds

  • Location: Centre for Research and Training on Sanitation UFMG/COPASA Design population: 250 inhabitants Design flowrate: 1.6 m3/h

    UASB reactor + Polishing Ponds: Experimental Units

    Integration with Polishing Ponds

  • 180 mg/L

    60 mg/L

    COD

    TSS

    Integration with Polishing Ponds

    Performance regarding organic matter and solids

    Operational conditions:

    - HRT: 10 to 13 days

    - H: 0.60 to 0.80 m

  • 20 mg/L

    Operational conditions:

    - HRT: 10 to 13 days

    - H: 0.60 to 0.80 m

    103 MPN/100 mL

    NH3

    E. coli

    Performance regarding ammonia and E. coli

    Integration with Polishing Ponds

  • UASB + PP system: summary

    Area required is large: 2 3 m2/inhabitant

    Total HRT is lower than in most natural treatment systems

    UASB reactor: main unit responsible for organic matter removal

    Ponds: responsible for excellent coliform and good ammonia removals

    Coarse filter: decreases algal concentration, thus leading to complementary BOD and SS removal

    Integration with Polishing Ponds

  • Integration with Trickling Filters

  • UASB reactor + Trickling Filter: typical flowsheet

    Integration with Trickling Filters

  • Location: Centre for Research and Training on Sanitation UFMG/COPASA Design population: 500 inhabitants Design flowrate: 3.2 m3/h

    Compact UASB + Trickling Filter System: Experimental Units

    Integration with Trickling Filters

  • Integration with Trickling Filters

    Compact UASB + Trickling Filter System: Experimental Units

  • Individualized compartments

    Location: Centre for Research and Training on Sanitation UFMG/COPASA Design population: 400 inhabitants Design flowrate: 2.6 m3/h

    Trickling Filter with different types of packing media

    Integration with Trickling Filters

  • Full-scale UASB + TF system: Itabira Minas Gerais

    Integration with Trickling Filters

  • Concentraes de DBO total (mg/L) - efluente UASB e decantadores FBP

    UASB Escria anel DHS Condute0

    10

    20

    30

    40

    50

    60

    70

    80

    90

    Concentraes de SST (mg/L) - efluentes UASB e decantadores FBPs

    UASB Escria anel DHS Condute0

    20406080

    100120140160180200220240260

    Concentraes de DQO total (mg/L) - efluente UASB e decantadores

    UASB Escria Anel DHS Condute0

    50

    100

    150

    200

    250

    300

    350

    400

    450

    60 mg/L

    180 mg/L

    60 mg/L

    BOD COD

    TSS

    Integration with Trickling Filters

    Performance regarding organic matter and solids

    Operational conditions: Average temperature: 250C HLR: 20 m.m-2.d OLR 0.43 kgBOD.m-3.d-1

  • 20 mg/L

    Operational conditions: Average temperature: 230C HLR: 10 m.m-2.d-1 OLR 0.38 kgBOD.m-3.d-1

    NH3

    Integration with Trickling Filters

    Performance regarding ammonia removal

    20 mg/L

    O

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