appropriate technologies for wastewater treatment and effluent
TRANSCRIPT
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