Appropriate Technologies for Wastewater Treatment and Effluent Reuse for

Irrigation

By Dr. Menahem Libhaber Lead Specialist, LAC Region Presented in the World Bank

Water Week February 17­19, 2009

Outline

n Issues Related to Wastewater Treatment in Developing Counries

n The Concept of Appropriate Technology for Wastewater Treatment

n Examples of some Appropriate Wastewater Technology Treatment Processes

World Population Growth Forecast Source: WDR 2003

Implications of the Trends of Population Growth and Urbanization

n In most Developing Countries the percentage of wastewater that undedrgoes any type of wastewater treatment is very low, usually less than 10%

n If currently wastewater treatment coverage in Developing Countries is low, in view of population growth forecasts and scarcity of financial resources, perspectives of expansion of coverage are slim, unless simple, low cost technologies will be used

n Not always is the highest effluent quality required. In Developing Countries the autopurification capacity of receiving bodies needs to be taken into account

Trends of Selecting Wastewater Treatment Processes in Developing Countries

n In industrialized countries there is a continuous trend to achieve higher and higher effluent qualities by using more and more sophisticated process

n Devloping counties tend to copy trends in industrialized countries and apply cutting edge technologies, due to drive to copy and pressures of equipment manufucturers, consulting firms and construction firms

Implication of Using Complex Treatment Process in Developing Countries

n Investments in complex process can sometimes be mobilized through grants and soft loans, however O&M costs can not be financed from those sources and there is no budget for O&M after completing construction

n It is not rare to see in Developing Countries that complex plants deteriorate rapidly due to insufficient O&M budget and are abandoned

n That implies that complex processes, especially aerobic processes, which consume a lot of energy, should be avoided in Developing Countries

Tratamiento Convencional: Proceso de Lodos Activados Diagrama de Flujo

Vista Aerea de una Planta de Lodos Activados

The Appropriate Technology Treatment Processes Concept n Developing Countries cannot affoard expensive, difficult to operate wastewater treatment processes and should use appropriate technology processes

n Appropriate technologies mean simple processes of proven technology, of low investment and O&M costs, simple to operate and with capacity to yield any required quality

n Such processes exists and are especially fitted to warm climates (which are the climates in most developing countries)

n Reasons for past neglect of appropriate technology processes

Unit Process

Preliminary Treatment

Preliminary Treatment by Preliminary Treatment by Rotating Fine Screens Rotating Fine Screens

Sea­ and River Outfall

•0.2 – 1.5 mm mesh sieve •Completely made out of stainless steel •Integrated press zone

Rotating Fines Screens Plant La Plata, Argentina

Vortex Grit Chamber Desarenador Tipo Vortex

Preliminary Treatment in Cartagena

Submarine and Large River Outfalls

Submarine Outfall Discharging Preliminary Treated Effluent

Table 1. Relative Risk Potential to Human Health Through Exposure to Sewage Through Outfalls (From WHO, 2003 1 ).

Discharge type Treatment Directly on

beach Short outfall

Effective outfall

None Very high High NA Preliminary Very high High Low Primary (including septic tanks)

Very high High Low

Secondary High High Low Secondary plus disinfection — — — Tertiary Moderate Moderate Very low Tertiary plus disinfection — — — Lagoons High High Low

The sewage discharges, or outfalls, are classified into three principal types: (i) discharge directly onto the beach; (ii) “short” outfalls, where sewage­polluted water is likely to contaminate recreational waters; and (iii) “effective” outfalls, designed so that the sewage is efficiently diluted and dispersed and to ensure that it does not pollute recreational water areas. While the terms “short” and “long” are often used, outfall length is generally less important than proper location and effective diffusion. An

effective outfall is assumed to be properly designed, with sufficient length and diffuser discharge depth to ensure that the sewage does not reach the recreational area.

WHO (2003): Guidelines for Safe Recreational Water Environments. Volume 12, Coastal and Fresh Waters, World Health Organization, Geneva, Switzerland, p. 80 (http://www.who.int/water_sanitation_health/bathing/srwe1/en/).

Potencial Relativo de Riesgo de Salud Publica Resultante de Contacto con Aguas Sevidas Descargads via Emisarios Submarinos

Stabilization Lagoons (Oxidation Ponds)

A Conventional Anaerobic­Facultative Lagoons Wastewater Treatment Plant in the City of Santa

Cruz, Bolivia

Raw Wasteater

Treated Effluent

Rotating Fine Screens

Covered Anaerobic Lagoon

First Facultative Lagoon

Second Facultative Lagoon

Polishing Pond

Recirculation Stream

LAS Mixers

Flow Diagram of the Proposed Wastewater Treatment Process of the Santa Cruz, Bolivia, Four Lagoons Wastewater Treatment Plants

Pumping Station

The Improvement Concept of the Santa Cruz Wastewater Treatment Plants

A F M M

Militamices

Cubiertas

Mixers

Covered Anaerobic Lagoons in the Northern Wastewater Treatment Plant of Santa Cruz, Bolivia

The Mechanism of Improvement in Facultative Lagoons Performance by the use of LAS Mixers

Courtesy LAS International

The Principle of the LAS Mixer Function Courtesy LAS International

The Mechanism of Improvement in Facultative Lagoons Performance by the use of LAS Mixers

Courtesy LAS International

Photo of a LAS Mixer

UASB (Upflow Anaerobic Sludge

Blanket Reactor)

The Onca UASB Treatment Plant, Belo Horizonte, Brazil, Designed to Serve a Population of 1 million

Onca UASB Plant

USAB Effluent, Ronda, Parana, Brazil

Anaerobic Filter

Anaerobic Filter Configuration, Natal Brazil Source: Onofre (1997)

Photos of an Anaerobic Filter During Construction

Anaerobic Filter Effluent aside the Raw Sewage, Natal, Brazil

CEPT (Cemically Enhanced Primary Treatment)

Grit Chamber Bar Screens

Schematic Diagram of the CEPT Process

Primary Sedimentation Tank

Sludge Treatment and Disposal

Coagulant

Flocculant

Effluent

Raw Sewage

Bench­Scale CEPT and Conventional Primary Treatment Effluents

Source: Prof. Harleman, MIT (2004)

Constructed Wetlands

Section of a Horizontal Flow Constructed Wetland

Constructed Wetlands Plant in Copacabana, Bolivia

Combined Processes

UASB Followed by

Lagoons

Process Flow Diagram of the Rio Frio Treatment Plant at Bucaramanga, Colombia

Photo of The Rio Frio Treatment Plant at Bucaramanga, Colombia

Ronda Plant: UASB Followed by Lagoons, Parana, Brazil

Ronda Plant: UASB Followed by Lagoons, Parana, Brazil

UASB Reactor Polishing Lagoon

Raw Sewage UASB Effluent

Lagoon Effluent

UASB Followed by

Anaerobic Filter

Flow Diagram of a UASB Reactor Followed by an Anaerobic Filter in Parana, Brazil

Preliminary Treatment

UASB Reactor

Anaerobic Filter

Sludge Drying Beds

UASB Reactor Followed by an Anaerobic Filter in Tibagi, Parana, Brazil

Preliminary Treatment

UASB

Anaerobic Filter

Drying Beds

The Effluent of the Tibagi Plant, Parana, Brazil BOD 5­25 mg/l, COD 40­100 mg/l, TSS 4­10 mg/l

Anaerobic Filter Effluent

Wastewater Reuse for Irrigation

The Need for Effluent Storage: Typical Annual Cycle of a Stabilization

Reservoir

in Reservoir

to Reservoir

of Reservoir

SEWAGE COLLECTION SYSTEM

SEWAGE TREATMENT

EFFLUENT DISCHARGE

Common Practice ­ No Relation Between Irrigation and Wastewater Disposal

Water Collection System

RESERVOIR

IRRIGATED FIELDS

SEWAGE COLLECTION SYSTEM

Wastewater Reuse Using a Stabilization Reservoir which Combines Storage and

Treatment

RESERVOIR

IRRIGATED FIELDS

SEWAGE TREATMENT

Combined Storage and Treatment

Pretreatment

May consist of a Variety of Processes as: Anaerobic Lagoons, Oxidation Ponds, UASB, Anaerobic Filters, CEPT, Aerated Lagoons, Activated Sludge and others, and combinantions of these proceses

Stabilization Reservoir (for Effluemt Storage and

Treatment)

Municipal

Wastewater

Effluent

For Reuse

(Usually by Drip Irrigation)

Max. Level (Beginning of Irrigation Season)

Min. (End of Irrigation Season)

The Stabilization Reservoir Reuse Concept

Water Depth 8­12 m

A Two Cells in Series Reservoir (Maale Hakishon Reservoir)

Effluent Sample of Maale Hakishon Reservoir

Additional Potential Combined Processes

(only ideas and proposals)

n RFS followed by UASB followed by Sand Filtration and Disinfection

n RFS followed by UASB followed by Dissolved Air Flotation (DAF) and Disinfection

n RFS followed by CEPT Followed by DAF and Disinfection n RFS followed by UASB followed by Constructed Wetlands n RFS followed by Anaerobic Filter followed by Facultative Lagoons

n RFS followed by Anaerobic Filter followed by Constructed Wetlands

n RFS followed by UASB followed by Anaerobic Filter followed by DAF followed by Microfiltration followed by Nanofiltration

Appropriate Treatment Technologies

Versus Size of City

Other Combinations Need a Specific Review to determine if they are adequate for small cities

Other Combinations Need a Specific Review to determine if they are adequate for medium size cities

Other Combinations Need a Specific Review to determine if they are adequate for large cities

UASB­Dissolved Air Flotation Combination UASB­Dissolved Air Flotation Combination UASB­Dissolved Air Flotation Combination

UASB­Sand Filtration Combination UASB­Sand Filtration Combination UASB­Sand Filtration Combination

CEPT­Sand Filtration Combination CEPT­Sand Filtration Combination

UASB­Lagoons Combination UASB­Lagoons Combination

UASB­Anaerobic Filter Combination UASB­Anaerobic Filter Combination UASB­Anaerobic Filter Combination

Submarine Outfalls Submarine Outfalls

Reuse for Irrigation Systems Reuse for Irrigation Systems Reuse for Irrigation Systems

Constructed Wetlands

CEPT CEPT

Anaerobic Filters Anaerobic Filters Anaerobic Filters

UASB Reactors UASB Reactors UASB Reactors

Lagoon Systems of various types including LAS Mixers aided systems and Covered Anaerobic Lagoons

Lagoon Systems of various types including LAS Mixers aided systems and Covered Anaerobic Lagoons

Rotating Fine Screens Rotating Fine Screens Rotating Fine Screens

Small Cities* Medium Size Cities** Large Cities***

Proposed Appropriate Technology Treatment Process Classified according to their Adequacy for use in Various Categories of Size of Cities

Treatment Capacity and Costs of the Presented Appropriate Technology Processes

25­30% 1­1.5 6­30% 5­30 80­95% 90­95% UASB­Anaerobic Filter Combination

2.5­3% 0.1­0.15 4­30% 3­30 99.9% 99.9% Submarine Ourfalls

5­8% 0.2­0.4 40­50% 30­50 75­90% 75­95% Reuse for Irrigation Systems

50­80% 2­4 40­60% 30­60 80­90% 80­90% Constructed Wetlands

50­80% 2­4 35­50% 30­50 80­90% 70­75% CEPT

15­20% 0.8­1 15­25% 10­25 70­80% 70­80% Anaerobic Filters

25­30% 1­1.5 25­40% 20­40 60­70% 60­75% UASB Reactors

5­8% 0.2­0.4 25­50% 20­50 80­95% 90­95% Covered Lagoons Followed by LAS Mixers Aided Facultative Lagoons

5­8% 0.2­0.4 25­40% 20­40 80­95% 90­95% LAS Mixers Aided Lagoons

5­8% 0.2­0.4 25­40% 20­40 70­90% 70­90% Conventional Lagoons Systems

2.5­3% 0.1­0.15 4­10% 3­10 0­30% 0­30% Rotating Fine Screens

100% 4­5 100% 80­100 80­90% 80­90% Conventional Activated Sludge (Just for reference, this is not an appropriate process)

Percentage of Activated Sludge Cost

US$/Year/Habitant Percentage of Activated Sludge Cost

US$/Habitant

O&M Cost Investment Cost TSS Removal Capacity,

%

Total BOD Removal Capacity,

%

Process

Treatment Capacity and Costs of the Presented Appropriate Technology Processes

25­30% 1­1.5 38­50% 30­50 80­90% 80­90% UASB­Dissolved Air Flotation Combination

25­30% 1­1.5 38­50% 30­50 80­90% 80­90% UASB­Sand Filtration Combination

50­80% 2­4 40­50% 40­50 80­90% 80­90% CEPT­Sand Filtration Combination

2.5­3% 1­1.5 38­50% 30­50 70­80% 85­90% UASB­Lagoons Combination

25­30% 1­1.5 6­30% 5­30 80­95% 90­95% UASB­Anaerobic Filter Combination

2.5­3% 0.1­0.15 4­30% 3­30 99.9% 99.9% Submarine Ourfalls

5­8% 0.2­0.4 40­50% 30­50 75­90% 75­95% Reuse for Irrigation Systems

50­80% 2­4 40­60% 30­60 80­90% 80­90% Constructed Wetlands

50­80% 2­4 35­50% 30­50 80­90% 70­75% CEPT

15­20% 0.8­1 15­25% 10­25 70­80% 70­80% Anaerobic Filters

25­30% 1­1.5 25­40% 20­40 60­70% 60­75% UASB Reactors

5­8% 0.2­0.4 25­50% 20­50 80­95% 90­95% Covered Lagoons Followed by LAS Mixers Aided Facultative Lagoons

5­8% 0.2­0.4 25­40% 20­40 80­95% 90­95% LAS Mixers Aided Lagoons

5­8% 0.2­0.4 25­40% 20­40 70­90% 70­90% Conventional Lagoons Systems

2.5­3% 0.1­0.15 4­10% 3­10 0­30% 0­30% Rotating Fine Screens

100% 4­5 100% 80­100 80­90% 80­90% Conventional Activated Sludge (Just for reference, this is not an appropriate process)

Cost Cost

Many Thanks for Your Attention