centralized vs. decentralized sewerage systems: which is which for you? by markus starkl

7/29/2019 Centralized vs. Decentralized Sewerage Systems: Which is Which For You? by Markus Starkl

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entra ze vs. ecentra ze ystems: Which is Which For You?

Dr.Dr. Markus StarklMarkus StarklUn vers ty o Natura Resources an L e Sc ences, V ennaUn vers ty o Natura Resources an L e Sc ences, V enna

ChairChair – – IWA Task IWA Task GroupGroup on Centralized andon Centralized and Decentralized WastewaterDecentralized WastewaterManagementManagement inin Developing CountriesDeveloping Countries



Content

Advantages Advantages andand disadvantagesdisadvantages

CaseCase studiesstudies

Funding Funding andand PPPPPP

ConclusionsConclusions



CENTRALIZED OR

DECENTRALIZED?



Definitions

largest solution: whole catchment area, smallest solution: singlelargest solution: whole catchment area, smallest solution: single

households, decentralized solutions inbetweenhouseholds, decentralized solutions inbetween

fully centralized solutions hardly existing, large scale vs. smallfully centralized solutions hardly existing, large scale vs. small

scale decentralized systemscale decentralized system

physical versus operational scalephysical versus operational scale



Technical and economic aspects

ADVANTAGES DISADVANTAGES

aspects

conventional treatment systems (C)•small (natural) treatment systems use lessenergy and less energy for pumping (D)

•substantial pumping required (C)•larger solutions less flexible (C)•newly developed technologies may

•adaptation to local conditions possible(D)

•reuse of wastewater and sludge easier to

be less reliable (D)•sludge handling more difficult in

many small systems (D)

•easier to pilot new technologies (D)

Economic

as ects

•economies of scale (C)•low o ulation densit : smaller solutions

•expensive for remote areas (C)•economies of scale D

may be more economical (D) •duplication of infrastructure (e.g.labs, storage) in small systems (D)

C – centralized / D - decentralized



Social, financial and institutional aspects

ADVANTAGES DISADVANTAGES

Social

aspects

• ocate ar away rom uman

settlements (C)

• ocate near or wit in uman

settlements→ odour, overflow, aestheticissues (D)• ublic resistance C D

Financial

aspects

•smaller solutions affordable and

faster to implement (D)

• large investment required (C)• remote areas last to be connected (C)

•possibility of „stageddevelopment“ (C)

Institutional

aspects

•small number of treatment plantseasier to manage (C)•mana ement conducted b

•many small treatment plants difficult tomanage (D)•remote umanned facilities rone to

organizations with high capacity

(C)

theft and vandalism (D)

C – centralized / D - decentralized



Case studies: failure cases of small scale

decentralized solutions ExamplesExamples of of failurefailure casescases::

constructedconstructed wetland wetland Mexico 2004 0.1 MLDMexico 2004 0.1 MLD

waste waste stabilizationstabilization pondsponds,, IndiaIndia, 2001, 0.5 MLD, 2001, 0.5 MLD constructedconstructed wetland wetland,, IndiaIndia, 1992, 0.5 MLD, 1992, 0.5 MLD

anaerobicanaerobic digesterdigester && reedreed bedbed, Sri Lanka, 2006,, Sri Lanka, 2006,0.05 MLD0.05 MLD

ReasonsReasons forfor failurefailure::

frequentfrequent changechange of of operatorsoperators,, poorly poorly trainedtrainedstaff staff

nono arrangementarrangement oror && lack lack of of fundsfunds forfor O&MO&M

( (mosquitoesmosquitoes,, ratsrats) )



Case studies: success cases of small scale

decentralized solutions ExamplesExamples of of successsuccess casescases::

constructedconstructed wetland wetland, Mexico, 2005, 0.3 MLD, Mexico, 2005, 0.3 MLD

solidsolid immobilisedimmobilised biofilterbiofilter,, IndiaIndia, 2004, 0.04, 2004, 0.04MLDMLD

baffledbaffled septicseptic tank,tank, anaerobicanaerobic filterfilter andandplantedplanted reedreed bedbed,, IndiaIndia, 2010, 0.05 MLD, 2010, 0.05 MLD

duckweedduckweed pondpond,, IndiaIndia, 2004, 0.5 MLD, 2004, 0.5 MLD

ReasonsReasons forfor successsuccess

well well trainedtrained,, continously continously working working operatoroperator

contractcontract with with privateprivate company company forfor O&MO&M

communalcommunal useuse of of sideside productsproducts ( (duckweedduckweed,,fishfish,, treatedtreated WW, WW, communally communally usedused orangeorange

revenuesrevenues

nono energy energy requiredrequired ( (gravity gravity sewersewer) )



Case studies: failure cases of large scale

decentralized solutions ExamplesExamples of of failurefailure casescases::

waste waste stabilizationstabilization pondsponds,, IndiaIndia, 2001, 10 MLD, 2001, 10 MLD

activatedactivated sludgesludge processprocess,, IndonesiaIndonesia, 2004, 8, 2004, 8MLDMLD

activatedactivated sludgesludge processprocess, Nepal, 2001, 17.3, Nepal, 2001, 17.3MLDMLD

R R eeasonsasons forfor failurefailure::

nono revenuesrevenues fromfrom customerscustomers // hi hhi h costscosts forforoperationoperation

notnot sufficientsufficient knowledgeknowledge of of operatorsoperators

notnot fullfull useuse of of ca acitca acit asas notnot enou henou h houseshouses connectedconnected toto sewersewer systemsystem

treatedtreated effluenteffluent notnot reusedreused by by farmersfarmers ((e.g e.g highhighsaltsalt contentcontent fromfrom industrindustr

responsibility responsibility ( (eg eg.. sewersewer andand WWTP) WWTP) sharedshared

betweenbetween tootoo many many institutionsinstitutions



Case studies: success cases of large scale

decentralized solutions ExamplesExamples of of successsuccess casescases::

Waste Waste stabilizationstabilization pondsponds,, IndiaIndia, 2001, 14.5, 2001, 14.5MLDMLD

Waste Waste stabilizationstabilization pondsponds,, IndonesiaIndonesia, 2004, 10, 2004, 10MLDMLD

BiofiltrationBiofiltration andand ASP, China, 2006, 300 MLD ASP, China, 2006, 300 MLD

Tertiary Tertiary treatmenttreatment plant,plant, IndiaIndia, 2012, 40 MLD, 2012, 40 MLD easonseasons oror successsuccess ::

PPP facilitates outcomePPP facilitates outcome--based monitoring based monitoring

wastewater wastewater billbill combinedcombined with with water water bill 30%bill 30%of of tariff tariff) )

lablab within within WWTP WWTP premisespremises andand competentcompetent

economiceconomic benefitbenefit:: reusereuse of of treatedtreated by by nearby nearby industry industry,, farmersfarmers oror hotelshotels



Enabling conditions: policies and incentives I

small scale solutions:small scale solutions:

llaws and regulations need to be reviewed withaws and regulations need to be reviewed with

respect to their compliance to the needs of respect to their compliance to the needs of

decentralised technologiesdecentralised technologies

O en software for decision su ort?O en software for decision su ort?

UNESCO Hydro Open Software Initiative (www.hopeUNESCO Hydro Open Software Initiative (www.hope--initiative.net)initiative.net)

the local knowledge required for O&M→ supportthe local knowledge required for O&M→ supportof community based organizationsof community based organizations

arge sca e so u ons:arge sca e so u ons: cost sharing incentive for centralised systemscost sharing incentive for centralised systems

land availabilit in densel o ulated urban areasland availabilit in densel o ulated urban areaslimitation for large scale WWTPlimitation for large scale WWTP→ consideration in→ consideration in

urban development and land use plansurban development and land use plans



Enabling conditions: policies and incentives II

all types of decentralised solutionsall types of decentralised solutions

policies should make follow up andpolicies should make follow up andmon tor ng man atory a so years a termon tor ng man atory a so years a ter

implementationimplementation definition of roles and responsibilities of definition of roles and responsibilities of

ns u ons w respec o nanc ng,ns u ons w respec o nanc ng,implementing and monitoring/control of implementing and monitoring/control of

infrastructure as well as for cost recovery isinfrastructure as well as for cost recovery is

BAT conceptBAT concept incentives to implement treatment systemsincentives to implement treatment systems

. . ,. . ,space requirements, potential for reuse of sidespace requirements, potential for reuse of sideproducts:products: . .. .

funding funding

indirect benefits: e.g. lower proporty taxindirect benefits: e.g. lower proporty tax



Funding and PPP

USE BENEFITS

BENEFITS OF SANITATION AND WASTEWATER TREATMENT

DIRECT IMPACTSNON-USE

BENEFITS

local authorities bank funds (EU)

additional guarantee

Improvedhygiene

Decreased number of

incidences of waterrelated diseases

Increased productivity

Costs avoided forhealth treatment

Enhanced tourism

activities

dbfo - contractmunicipality Private Partner

financing agreement

employmentcontracts

Reduced waterpollution

Provision of infrastructure Employment, profit for

Increased productivity

Reducedeutrophication Increased fish stock

ncreasebiodiversity

Cooperation-turnkey-

Self-

management

, ,

25 years

Inhabitants,

local staff subcontracts for

construction, and

delivery

soc o-econom c

interactions?

Provision of resources

oca economicy anincreased capacity

Reduced cropping costs

through saving of fertilizer

Reduced pre-treatment

Reducedpressure onavailable

resources

Management-

modell

model

DBO - model

model-

modelcustomers

sub partners water delivery,or waste water disposal

TENDER Example: Moscow, Lasko (SI), Vodice (HR)costs for downstream

users

Value of by-products

Concession

Innovative recovery of O&M costs: Case study India (baffled septic tank,anaerobic filter and planted reed bed, India), peri-urban slum community, 0.05Innovative recovery of O&M costs: Case study India (baffled septic tank,anaerobic filter and planted reed bed, India), peri-urban slum community, 0.05

Risk with community Risk with private

Rural

area

,•implemented in cooperation with tourism project („Mughal Heritage Trail“)

•revenues from tourism project used to pay tour guides and operators of WWTP

,•implemented in cooperation with tourism project („Mughal Heritage Trail“)

•revenues from tourism project used to pay tour guides and operators of WWTP



Conclusions

Which scale is optimal needs to be identified in a detailed Which scale is optimal needs to be identified in a detailed--

technical aspects such as environmental, financial, social andtechnical aspects such as environmental, financial, social andinstitutional ones)institutional ones)

recyling, reuse and energy recovery should be integral to all scalesrecyling, reuse and energy recovery should be integral to all scales

in general, a lack of data on actual performance of decentralisedin general, a lack of data on actual performance of decentralised

of existing decentralized plantsof existing decentralized plants

EC FP7 and GOI/DST funded project “Supporting consolidationEC FP7 and GOI/DST funded project “Supporting consolidation,,

replication and upreplication and up--scaling of scaling of sustainable wastewatersustainable wastewater treatment and reusetreatment and reusetechnologies fortechnologies for India” will document and evaluate existing technologiesIndia” will document and evaluate existing technologiesin Indiain India

centralized vs. decentralized sewerage systems: which is which for you? by markus starkl

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