Design Principles for

Decentralized Wastewater Treatment Systems

(DEWATS)

Presentation at:

„EcoSan Workshop”

Bangalore, Karnataka –June 15th-18th , 2003

Dipl. Ing-Agr. Pedro Kraemer

(DEWATS Project Coordinator)

FEDINA - BORDA

Foundation for Educational Innovation in Asia

Bremen Overseas Research and Development Association

Background

1,100

6,000

2,500

1,200

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000

World Population Millions

1

Lack of Water and Sanitation

No access to suitable sanitation

No access to adequate Water

India population

World

population

0%10%20%30%40%50%60%70%80%90%

100%

illness deaths

80%

0%10%20%30%40%50%60%70%80%90%

100%

illness deaths

Water borne80%

25%

0%10%20%30%40%50%60%70%80%90%

100%

illness deaths

Water borne

Illnesses and deaths in developing countries due to

contaminated water.

IndiaWater and Sanitation

1,100

170

760

0

200

400

600

800

1,000

In

dia

n

Po

pu

lati

on

Millions

Population No access towater

No adequateSanitation -

69%

15.5%

IndiaSewage Treatment at

medium and large cities

2,902

93%

217

7%

Without STP

With STP

Cities

Cities

• Wastewater treatment is one of the last priorities of public and private investment.-> nobody is interested, “arrangements” are easier

• Conventional treatment units are too expensive.-> difficult to demand their installation

• Conventional treatment units require skilled operators.-> often not performing, most of the time out of order

• Conventional treatment units operational costs are high.-> switched off to safe energy

• Conventional treatment units require regular maintenance.-> often not performing, most of the time out of order

• Nobody likes handling wastewater

A few basic findings:

Reconsideration of the WW treatment approach.

There is a technological gap between pit latrines

and centralized highly sophisticated WW

treatment plants.

Our conclusion:

DEWATS

Our Response:

DEWATS =

D E c e n t r a l i s e d

W A s t e w a t e r

T r e a t m e n t

S y s t e m s

Our Response:

Discrepancies we do need to overcome

• The technology offered does not match with the technical skills available.

• The investment costs do not match with the possibility/willingness to pay.

• The required input for operation (financing, time, labor, skills) do not match with the readiness to provide it.

• The discharging standards do not match with the possibility to enforce them.

• The urgency of pollution control do not match with the awareness and information levels.

• The assigned responsibility for WW do not match with the with the capacity to deliver accordingly.

…..DEWATS is an approach,

rather than a hardware package

That is why….

This means, DEWATS is led by some principles, which represent

the guide frame for designing

• Decentralization: Responsibility, Capacity, Treatment, etc.

• Simplification: Process, Technology, O&M,

• Conservation: Water, Nutrients, Energy

Recycling

Decentralization

Centralized WW Collection and Treatment

WTP

Decentralized WW Collection and Treatment

Decentralize responsibility

• Application of the principle “The polluter pays”

– In industrial sector accepted

–For domestic sector not accepted

–A treatment unit near to the producer allows specific control

• Assign responsibilities

– Individuals (demand)

–Builders (technical offer)

–NGO (Awareness, Training, DEMO)

–Research institutions (develop option)

–Municipalities (enforcement, control)

– Legal entities (legal provisions)

Decentralize responsibility (cont.)

• Treatment close to where it is generated

–Reduction of trunks and collector sewer

–Reduction of intermediate pumping stations

Decentralize technology

• Re-use close to where it is generated

– Irrigation

–Gardening

–Recharge underground water

–Use sewage for agriculture (sewage farm)

Decentralize technology (cont.)

Decentralize Capacity

• Centralized design capacity

–Capacity centers (CDD)

–Training centers

• Decentralized implementation

–Certified builders, architects, engineering offices

–Service units

Simplification

Simplification

Means LOW-TECH,but not necessarily easy.

Natural processes maybe simple from a technical point of view, but complex from an ecological point of view.

Means CLEVERIntegrated, interdisciplinary work

• Diminish the treatments volume by reducing the catchments area through decentralization

– Less volume = easier management– Small surfaces become available for treatment

(sidewalks, private yards, parking lots, alleys, parks, etc.)

– Wastewater composition becomes more accountable

– the risk of failure is reduced (all systems fail)

Simplification (cont.)

• Separation of WW-Streams

Composition of domestic wastewater

Domestic WW Streams

Brown Water

(Faeces)

Anaerobic digestion,

drying, compost,

Mixing with org. residues

Biogas,

Soil conditioner

Sand/gravel filter,

ponds,

biol. Treatment, EM

membrane technology

Gray Water

(Shower, Kitchen,

Laundry etc.)

Irrigation,

Recharge ground water

Yellow Water

(Urine)

Liquid or solid

fertilizer

Hygienization by

storage and drying

Filtration,

biol. treatment

Rain Water

Water supply,

Recharge ground water

Stream

Treatment

Use

Flow chart Concept 1 Date 4/22/2003

1. Stream 2 Stream 4. Stream 3. Stream 5. Stream 6. StreamSoaking gherkins Washing gherkin Brushing floor maceration room Base Juice Toilets General factory cleaning

8.00 m3/d 12.00 m3/d 2.00 m3/d 0.03 m3/d 3.50 m3/d 3.00 m3/d

7 h peak flow 6 h peak flow 3 h peak flow 3 h peak flow 6 h peak flow 3 h peak flow

100% Re-use

2 h HRT 2 h HRT 2 h HRT 15 d HRT 1.5 h HRT 1.5 h HRT

2.29 m3 - Vol 4.00 m3 - Vol 1.33 m3 - Vol 0.45 m3 - Vol 0.88 m3 - Vol 1.50 m3 - Vol

6.50 m3 / d

40% evaporation

0.7 h HRT

1.40 m3 14 m3/d

` 0.85 m2

2 m2 3.90 m3/d

Storage & disposal

17.90 m3/d

5 d HRT

0.8 m depth

145 m2

Irrigation

SettlerSettler Settler

BR

PGF

Settler &

Neutraliza

tion sump

Settler

HRBC

Evaporation

platform

Fish

Pond

Pump

sumpStorage

Storage

Simplification (cont.)

• Reducing water for transport of residues– Reduced volumes to be treated

– Increased concentration of pollutants

Simplification (cont.)

• Treatment until re-use is possible

– 1st Identification of re-use options then, planning the treatment unit

• Most pollutants are substances needed for agriculture

Organic

Phosphorus

Nitrogen

Potassium

Simplification (cont.)

• Selecting the right technology

– Priority given to anaerobic technology in warm climates

– Priority given to aerobic technology in cold climates

– Using gravity instead of pumps– Avoiding valves– Oxygen incorporation by helophytes (swamp

plants) – Aeration by vorticity– Opting for condominial sewer lines– Integrating treatment modules in unused

spaces (alleys, roads, parking areas, gardens, private yards, parks, etc.)

Simplification (cont.)

• Standardization

– Assign treatment systems to specific decentralized pollution sectors

• Identify sectors and their clusters

– Prefabrication of modules (mass production)• Single House units

• Baffle modules

• Distribution boxes

• Applied research

–Distribution systems

–Filter material

–Odour reduction (EM, biofilter)

DEWATS – Field Laboratory

Simplification (cont.)

• Including wastewater treatment unit in the planning and designing task of architects and builders

– Design buildings taking into account the requirements of treatment units

– Ensure correct slop to operate per gravity

– separation of streams,

– reduction of wastewater

– integration in the landscape

– Trained local craftsmen offer technology assed by certified planning units

Conservation / Recycling

• Conservation of Fossil Energies–Reducing electrical equipment

–Applying anaerobic technology; using biogas

–Selecting and reducing construction material

• Conservation of fresh water resources

–Reducing water for transport (water-saving devices, water- saving attitude)

–Substituting fresh water by treated wastewater (agriculture, cleaning)

• Conservation of nutrients–Returning nutrients contained in the

wastewater to the fields (peri-urban agriculture)

Conservation and Recycling

• Use of the treatment products

– Treated wastewater (Irrigation, water recharge, technical water, landscaping, micro- climate)

– Nutrients (agriculture, horticulture, forestry, aquaculture)

– Biogas (heating, electricity generation)Methane = greenhouse gas

Conservation and Recycling

• Locate the treatment where the products are needed– Public recreation areas– Farm land– Industry (co-fermentation)

• Centralized utilization of WW treatment products

– Sludge digestion centers at focal points• Cogeneration• Compost

– Treated wastewater pipeline

– Urine collection centers

DEWATS technical approach

DEWATS concept incorporates the following attributes:

• Treatment for organic wastewater from domestic and industrial sources

• Affordable prices

• Fulfillment of discharge standards

• Treatment of wastewater flows from 1-1000 m3/d

• Tolerance to inflow fluctuation

• No dependence on energy

• Minimal maintenance

• Reliability and longevity

• Reuse of wastewater and its contents

DEWATS Modules

Baffled-ReactorAnaerobic- Filter

Facultative-LagoonSeptic-Tank

Planted Gravel-FilterSludge Drying Bed

1. Sedimentation and floatation

2. Fermentation of bottom sludge

gas

manhole

inflow outflow

scum

settling particles

sludge

separation chamber polishing chamber

Principle of the Septic Tank

Septic Tank

gas

manholes

inflow

scum

sludge

sedimentation inoculation of fresh wastewater with active sludge final settler

4. Sedimentation of mineralised (stabilised) suspended particles

1. Sedimentation / floatation of solids

Principle of Anaerobic Baffled Reactor

2. Anaerobic digestion of suspended and dissolved solids through sludge contact

3. Anaerobic digestion (fermentation) of bottom sludge

Baffled Reactor

1. Sedimenta tion / floa ta tion

2. Anaerobic digestion of suspended and dissolved matter inside the filte r

3. Anaerobic digestion (fe rmenta tion) of bottom sludge

gas manhole

inflow

scum outflow

filter mass

grill

sludge

sedimentation tank filter tanks

Principle of Anaerobic Filter

Anaerobic filter

1. Continuous oxygen supply to the upper layers

2. Helophytes provide oxigen to the lower layers

3. Roots of plants provide favourable environment for bacteria diversity

4. Anaerob - facultative conditions in the lower layers

internal water level

inflow manhole

central outlet shaft

final outlet

cross

distribution

trench

filled with

rocks

main filter body filled with coars gravel

cross

collection

trench

filled with

rocks

perforated

pipe

connected to

swivel pipe for

adjustable

upper sand

layer

Principle of the Horizontal Filter

O2O2OO

large and shallow filter

Horizontal Filter

large and shallow filter

DEWATS system

The right combination and dimension of the

modules make DEWATS successful.

DEWATS Examples

Examples

Anaerobic baffled reactor

Off-plot system

gas

manholes

inflow

scum outflow

sludge

sedimentation inoculation of fresh wastewater with active sludge final settler Anaerobic Baffled Reactor

Planted Horizontal Sand/Gravel Filter

Off-plot SystemHorizontal Planted filter

BORDA

Community Based Sanitation

BORDA

Tel.: ++91-80-5492712

Tel/Fax: ++91-80-5492713

eMail: borda.india@vsnl.net

Homepage: www.borda.de

For more information,

please do not hesitate to contact us:

Thanks for your attention !