s4 meeting sanitation goals in large urban settings in developing nations: proven and innovative...

8/6/2019 S4 Meeting Sanitation Goals in Large Urban Settings In Developing Nations: Proven and Innovative Technologies and Emerging Trends by JSandino

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Meeting Sanitation Goals in LargeUrban Settings In Developing

Nations - Innovative Technologies

and Emerging Trends

Julian Sandino, PhD, IWA Fellow



The World’s Water Infrastructure Gap

• 2.4 billion without access

to adequate sanitation.

•

By 2030: 60% of worldpopulation will be

urban….and mainly poor

•

Large “appropriate”WWT schemes will still

play a role

Source: WHO 2000



Defining Appropriate WW Treatment

Technologies for Larger Urban Applications

• Desirable attributes:

– Low implementation and O&M costs

– Operational simplicity

– Upgrade flexibility – Prioritize public health protection

• Lagoon systems not always suitable given

scale• Conventional “mechanical intensive” (e.g.

activated sludge) solutions not applicable



Chemically Enhanced Primary

Treatment (CEPT)

• “Traditional” physical-chemical treatment: Paris,

1740; England, 1890: > 200 plants

• Renewed interest: Hong Kong, San Diego,

Río de Janeiro, México, Buenos Aires, Bogotá• Chemicals: Coagulants (Fe, Al salts ) + Flocculation

aid (organic polymers)

•

Iron salts preferred: H2S control; compatibility withsludge processing and disposal.

• Increases TSS removal from 40-60% to 70%-85%



CEPT Process Schematic

RawWastewater

PRELIMINARY

TREATMENT

Screenings and Gritto Disposal

PRIMARY

CLARIFICATION

SLUDGE

STABILIZATION

SLUDGE

DEWATERING

Sludge to FinalDisposal / Reuse

Polymer

SECONDARY

TREATMENT/

DISINFECTION

TreatedEffluent

Chemical(Fe Salts, Alum)



When to Consider CEPT

• Primary < Treatment Level <Secondary

• Prior to disinfection (publichealth priority, reuse, oceandischarge)

• Limited space availability

• Phosphorus removal

•

Limited funds• First implementation stage

of treatment program

Stonecutters Island WWTPHong Kong

Point Loma WWTP San Diego

Pavuna and Sarapui WWTPsRio de Janeiro



CEPT Unit Cost Analysis (US$)

Unit CostActivatedSludge +

Disinfection

CEPT +Disinfection

M $ /(m3/s) 30 - 40 15 - 20

$/PE 80 - 100 40 - 50

$/Kg BOD5rem 1.300 - 1.500 1.700 - 1.900

$/m3 0.08 - 0.12 0.04 - 0.06

$/PE/year 6 - 10 3 - 5



Upflow

AnaerobicSludge

Blanket

Reactors

• Developed in the 1970’s for high strength industrial wastes

• 1980’s – 1990’s first medium to large scale municipal applications• Most applications in tropical countries: Brazil, India, Colombia

• Simple design: HRT; upflow velocity; depth; BOD5 removal; sludge

yield; Biogas yield



Municipal UASB Applications

Advantages

• Prim.<UASB<Secondary

• Compact system

• Low energy• Low sludge production

• Low construction and O&M

costs

• Simple to operate

• Biogas as energy

Disadvantages• Requires polishing for

secondary treatment andnutrient removal

• Little control• Slow start-up

• High odor potential

• T>18°C best

• Difficult to separate biogasfrom effluent

• Some bad experiences…butalso some good ones!



Urban UASB Applications:

38.000 – 606.000 PERío Frío WWTP (740 l/s)Bucaramanga, Colombia

Atuba Sul WWTP (1,1 m3/s)

Curitiba, Brazil

Mirzapur WWTP (160 l/s) India Piraciramirim WWTP (350 l/s)Piracicaba, Brazil



UASB Only Unit Costs

TreatmentTechnology

PopulationServedUS$/PE

Avg. FlowTreated

US$x106/m3/s

BOD5 RemovedUS$/kg/d

UASB 30 - 40 12 - 15 900 – 1.100Polishing options (additional)

Unaerated

Polishing Lagoons 9 - 14 6 - 7 850 - 1750Dissolved AirFlotation

10 - 12 6 - 7 1300 - 1400

Trickling Filters 21 - 30 12 - 16 2300 - 2900

Biological Aerated

Filters

33 - 40 19 - 23 2800 - 3200



Sanitation solutions must include

viable plans for residuals management

• Management of residual sludge often

neglected = Increased risk + lost opportunities

• Regulatory frameworks are essential

• Beneficial reuse must be

encouraged/promoted

• Resource recovery (e.g. phosphorus) will be

inevitable



Page

CEPT & UASB: Appropriate Technologies to

Meet MDGs in Urban Settings

• Relative simple technologies

• Significantly smaller area requirements than

lagoons

• Several recent successful applications

• Lower construction and O&M costs than

conventional mechanical options

Simple, compact, upgradable, proven, low-cost = applicable and affordable

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