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27 May 2019

Evapo-transpiration Beds

Author/Compiled by
Meiyoshi Acabal Masgon (Xavier University, SUSAN Center, Philippines)
Robert Gensch (Xavier University, SUSAN Center, Philippines)
Executive Summary

Evapotranspiration beds are an alternative secondary treatment solution for greywater, pre-treated effluents from septic tanks, anal cleansing water or urine from urine diversion toilets in areas with high groundwater tables, or where soils prevent wastewater percolation and where the productive reuse of these wastewater flow streams is not a preferred option. The respective wastewater effluents are discharged into sealed up receptacles where the water evaporates from the soil or transpires from the plants growing there. The dissolved organic matter is removed by bacteria and the remaining nutrients are taken up by plants.

Advantages
Low-cost solution
Easy to construct
Easy to use
Easy to repair if damage occurs
Disadvantages
Tends to clog or overflow
May constitute a risk during the presence of small children
Tends to smell slightly
May attract insects
Evaporation process requires time
Only appropriate in hot and dry climates
In Out

Greywater, Urine or Yellowwater, Fertigation Water, Treated Water (Effluents from On-site Pre-settling Units)

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Factsheet Block Title
Introduction
Factsheet Block Body

Evaporation beds are a low-cost technology that allows for a secondary treatment of different wastewater flow streams like partly treated wastewater from septic tanks, greywater from kitchen and showers, anal cleansing water and or in some cases even for urine from urine diversion toilets. The respective wastewater effluent can be discharged by gravity into sealed up planting beds, containers, inverted tyres or the like where it will be absorbed by soil particles and moves both horizontally and vertically through the soil pores. The liquid fraction moves upwards by capillary action and either evaporates at the surface or is taken up by plants and transpires.The remaining nutrients are taken up by the plants and the dissolved organic material in the effluent is removed by bacteria living in the soil. 

A variety of evaporation bed designs are available and the exact design and measurements depend on the amount and the kind of wastewater to be treated. Source: ECOSAN UE (2007)
A variety of evaporation bed designs are available and the exact design and measurements depend on the amount and the kind of wastewater to be treated. Source: ECOSAN UE (2007)

 

Factsheet Block Title
Mulch beds for anal cleansing water and greywater
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Greywater or anal cleansing water is drained in an inverted tyre planted with flowers. Source: ECOSAN UE (2007)  
Greywater or anal cleansing water is drained in an inverted tyre planted with flowers. Source: ECOSAN UE (2007)  

 

Here the anal cleansing water or greywater from the toilet or the household is discharged by gravity into a sealed up receptacle (e.g. inverted tyre, container or concrete bed) filled with soil and mulch where ornamental plants are grown. The mulch allows better ventilation for aerobic degradation of soil impurities and the plant take advantage of the water and nutrients. The water is released below surface into the mulch bed through a small, perforated bin put upside down. This way the wastewater is spread more evenly and it helps avoiding blockages. The infiltration below surface helps reducing remaining disease transmission risks and odours.

It is preferable to introduce the effluent below surface to prevent odours and decrease the disease transmission risk. Source: ECOSAN UE (2007)     
It is preferable to introduce the effluent below surface to prevent odours and decrease the disease transmission risk. Source: ECOSAN UE (2007)     

 

The water can also be discharged into a mulch bed around a tree. Source: ECOSAN UE (2007)      
The water can also be discharged into a mulch bed around a tree. Source: ECOSAN UE (2007)      

 

The evapotranspiration/mulching bed should be placed close to where the wastewater is generated and ideally in an area exposed to maximum sunlight to allow for maximum evapotranspiration.

A simple way for sub-surface introduction of the liquid is to cut a plastic bottle into half, to connected the neck to the hose bringing the wastewater and finally to burry the bottle and the end of the hose together into the evapotranspiration/mulching bed. It then needs to be covered with soil and leaves and desired plants or trees can be planted on top. Once the plants reach a considerable size, they can either be cut or planted out and replaced with new mulch and another plant. The evapotranspiration beds should be inspected regularly to ensure that the water does not stagnate. To avoid clogging, the hose needs to be washed/rinsed from time to time with warm water. Evapotranspiration beds also offer the possibility to grow biomass (e.g. bamboo) that might be useful at the household level for construction purposes, charcoal production or for composting.

Factsheet Block Title
Evapotranspiration beds for pre-treated septic tank effluents
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(Adapted from LESIKAR 1999)

Evapotranspiration Bed System. Source: LESIKAR (1999)            
Evapotranspiration Bed System. Source: LESIKAR (1999)

 

Evaporation beds can also be installed at a larger scale, for instance for controlled discharge of septic tank effluents. In such evapotranspiration beds, solid materials are first removed from the wastewater by a septic tank. Then the wastewater is distributed throughout the evapotranspiration bed system. There, final treatment and disposal occur when the water evaporates and plants use nutrients in the effluent and release moisture through transpiration. As the water evaporates, salts, minerals and solids from the effluent accumulate in the bed. During very wet periods when evapotranspiration is low, evapotranspiration beds store water until drier periods when it evaporates and transpires.

Such evapotranspiration beds contain storage trenches, loam backfill around the trenches and sandy loam soil over the top of the loam backfill for grass growth. Generally, the required bed surface area is divided between two beds, which allows for switching between the beds to avoid overloading. A liner and sand cushion are placed in the ground, and the storage system is set on the bed bottom. Generally, the storage system consists of a bed of rocks or gravel of a uniform size ranging from 2 to 5 cm in diameter and a depth of 20 cm or less depending on the bed’s overall depth. Distribution pipes are placed about 1 m apart and no more than 60 cm from the bed walls above the storage system. A water-permeable soil barrier is placed over the rock to prevent clogging of the storage. A loam soil is added to fill the rest of the bed. Selecting the proper soil is extremely important. Loam soil draws the water toward the surface faster than coarse sand. Wicks incorporated into the rock media draw water continuously from the rocks into the soil and toward the surface area, where it evaporates or is taken up by plants. A wick is a column of soil that extends through the rock media to the bottom of the bed. The total wick area should be 10 to 15 % of the bed surface and should be uniformly spaced throughout the bed. After the loamy soil is in place, it is covered with sandy loam and mounded in the centre with a slope of 2 to 4 % toward the outside of the bed (to concentrate the water fluxes to the middle). The last step is to plant vegetation specially selected to transpire the most on top of the bed. Placing grass sod over the bed may be the best approach to establishing grass there. Using seed may let the mounded soil wash away during heavy rainfall before the grass is established. Larger plants with shallow root systems, such as evergreen bushes, may also be used to help to take up water.

Applicability

Evaporation beds are an appropriate solution for the treatment of greywater, anal cleansing water, pre-treated wastewater and urine in areas with high groundwater tables that might get contaminated and where the surrounding soil cannot sufficiently treat wastewater before it percolates to groundwater, such as in rocky soils, or where the soil prevents wastewater from percolating from the application field, such as in heavy clay soils. Evapotranspiration beds may be used if climate is hot and dry to allow for the necessary evaporation and transpiration from the soil and the plants respectively.

Library References
Further Readings

This module introduces the importance of market-based RRR solutions. At the end of this module you have identified key challenges in your local sanitation and waste management system and a RRR-related business idea.

Cover image Module  1

This module sheds light on the importance of studying the business environment and its components like waste supply, market demand, competition and the institutional framework. At the end of this module you have gained insights to evaluating the potential of your business idea.

Cover image Module  2

This module shows how a business idea can be turned into a business model while putting a specific focus on understanding the customer and designing products that meet their needs. At the end of this module you will have developed a business model and positioned your offer in the market.

Cover image Module  3

This module focusses on planning the operations of a RRR related business. During this part RRR technologies will be introduced for different waste streams and tools for planning the production process. At the end of this module you will have blueprinted your production process and the required technology and production inputs.

Cover image Module  4

This module covers key aspects of financial planning and analysis. At the end of this module you will have forecasted your profits, cash flows, required investment and evaluated the financial viability of your business model.

Cover image Module  5

This module enables you to set objectives and plan activities for the launch of your RRR business and identify potential financing sources. At the end of this module you will have developed an action plan for launch and identified appropriate financing sources.

Cover image Module  6

Week 1: Identify challenges in your local sanitation & waste management

Download Materials
Further Readings

SDG 6 along the water and nutrient cycles

This AGUASAN publication illustrates how the water and nutrient cycles can be used as a tool for creating a common understanding of a water and sanitation system and aligning it with SDG 6.

BROGAN, J., ERLMANN, T., MUELLER, K. and SOROKOVSKYI, V. (2017): SDG 6 along the water and nutrient cycles. Using the water and nutrient cycles as a tool for creating a common understanding of a water and sanitation system - including workshop material. Bern (Switzerland): AGUASAN and Swiss Agency for Development and Cooperation (SDC) URL [Accessed: 26.03.2019] PDF

Why shit matters [Video File]

TEDX TALKS (2019): https://www.youtube.com/watch?v=d4yD0kz34jg [Accessed: 28.03.2019]

"3 billion people worldwide live in cities without sewers or wastewater treatment plant infrastructure. This forces them to dump their waste into open waters, contaminating the drinking water for others downstream. Imagine if we could harness nutrients in wastewater instead of harming human and environmental health. Christoph Lüthi sees a renewable, locally produced and growing resource where others see only human waste. Watch his talk to learn why shit matters! "

Week 2: Identify RRR products and business opportunities

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Further Readings

A public-private partnership linking wastewater treatment and aquaculture (Ghana) - Case Study

AMOAH, P., MUSPRATT, A., DRECHSEL, P. and OTOO, M. (2018): A public-private partnership linking wastewater treatment and aquaculture (Ghana) - Case Study. In: Otoo, M. and Drechsel, P. (Eds.). Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries. Oxon (UK): Routledge - Earthscan. Section IV, Chapter 15, pp.617-630. URL [Accessed: 26.03.2019]

Briquettes from agro-waste (Kampala Jellitone Suppliers, Uganda) - Case Study

GEBREZGABHER, S. and MUSISI, A. (2018): Briquettes from agro-waste (Kampala Jellitone Suppliers, Uganda) - Case Study. In: Otoo, M. and Drechsel, P. (Eds.). Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries. Oxon (UK): Routledge - Earthscan. Section II, Chapter 3, pp.41-51. URL [Accessed: 26.03.2019]

Cooperative model for financially sustainable municipal solid waste composting (NAWACOM, Kenya) - Case Study

OTOO, M., KARANJA, N., ODERO, J. and HOPE, L. (2018): Cooperative model for financially sustainable municipal solid waste composting (NAWACOM, Kenya) - Case Study. In: Otoo, M. and Drechsel, P. (Eds.). Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries. Oxon (UK): Routledge - Earthscan. Section III, Chapter 3, pp.362-370. URL [Accessed: 26.03.2019]

Week 1: Analyse waste supply

Download Materials
Further Readings

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Week 2: Analyse market demand

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Further Readings

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Week 3: Analyse your competition

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Further Readings

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Week 4: Analyse the institutional environment

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Further Readings

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Week 1: Meet the Business Model Canvas

Download Materials
Further Readings

A public-private partnership linking wastewater treatment and aquaculture (Ghana) - Case Study

AMOAH, P., MUSPRATT, A., DRECHSEL, P. and OTOO, M. (2018): A public-private partnership linking wastewater treatment and aquaculture (Ghana) - Case Study. In: Otoo, M. and Drechsel, P. (Eds.). Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries. Oxon (UK): Routledge - Earthscan. Section IV, Chapter 15, pp.617-630. URL [Accessed: 26.03.2019]

Briquettes from agro-waste (Kampala Jellitone Suppliers, Uganda) - Case Study

GEBREZGABHER, S. and MUSISI, A. (2018): Briquettes from agro-waste (Kampala Jellitone Suppliers, Uganda) - Case Study. In: Otoo, M. and Drechsel, P. (Eds.). Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries. Oxon (UK): Routledge - Earthscan. Section II, Chapter 3, pp.41-51. URL [Accessed: 26.03.2019]

Cooperative model for financially sustainable municipal solid waste composting (NAWACOM, Kenya) - Case Study

OTOO, M., KARANJA, N., ODERO, J. and HOPE, L. (2018): Cooperative model for financially sustainable municipal solid waste composting (NAWACOM, Kenya) - Case Study. In: Otoo, M. and Drechsel, P. (Eds.). Resource recovery from waste: business models for energy, nutrient and water reuse in low- and middle-income countries. Oxon (UK): Routledge - Earthscan. Section III, Chapter 3, pp.362-370. URL [Accessed: 26.03.2019]

Week 1: Plan your production process

Download Materials
Further Readings

Compendium of Sanitation Systems and Technologies. 2nd Revised Edition

This compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.

TILLEY, E. ULRICH, L. LUETHI, C. REYMOND, P. ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag) URL [Accessed: 28.07.2014] PDF

Week 2: Understand the treatment process

Further Readings

Treatment technologies for urban solid biowaste to create value products: a review with focus on low- and middle-income settings

LOHRI, C. R., DIENER, S., ZABALETA, I. MERTENAT, A. and ZURBRÜGG, C. (2017): Treatment technologies for urban solid biowaste to create value products: a review with focus on low- and middle-income settings. In: Reviews in Environmental Science and Bio/Technology, Volume 16, Issue 1, pp 81–130. URL [Accessed: 26.03.2019] PDF

Week 3A: Design technology systems for nutrient recovery

Further Readings

Co-composting of Solid Waste and Fecal Sludge for Nutrient and Organic Matter Recovery

COFIE, O., NIKIEMA, J., IMPRAIM, R., ADAMTEY, N., PAUL, J. and KONÉ, D. (2016): Co-composting of Solid Waste and Fecal Sludge for Nutrient and Organic Matter Recovery. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 3. URL [Accessed: 27.03.2019]

Decentralized composting in India

DRESCHER, S. and ZURBRÜGG, C. (2004): Decentralized composting in India. In: Harper et al. Sustainable Composting: Case Studies in Guidelines for Developing Countries. Loughborough (UK): Water Engineering and Development Centre (WEDC), Loughborough University, Part2: Case Studies, Chapter 3, pp.15-27. URL [Accessed: 27.03.2019] PDF

Low Cost Composting Training Manual: techniques based on the UN-Habitat/Urban Harvest-CIP community based waste management initiatives

KARANJA, N., KWACH, H. and NJENGA, M. (2005): Low Cost Composting Training Manual: techniques based on the UN-Habitat/Urban Harvest-CIP community based waste management initiatives. Nairobi (Kenya): UN-Habitat. URL [Accessed: 27.03.2019]

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Week 3B: Design technology systems for energy recovery

Further Readings

Briquette Businesses in Uganda. The potential for briquette enterprises to address the sustainability of the Ugandan biomass fuel market

FERGUSON, H. (2012): Briquette Businesses in Uganda. The potential for briquette enterprises to address the sustainability of the Ugandan biomass fuel market. London (UK): Global Village Energy Partnership (GVEP) International. URL [Accessed: 27.03.2019] PDF

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Week 3C: Design technology systems for water recovery

Further Readings

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Chapter 3 - Technology Selection

VEENSTRA, S., ALAERTS, G. and BIJLSMA, M. (1997): Chapter 3 - Technology Selection. In: Helmer, R. and Hespanhol, I. (Eds). Water Pollution Control - A Guide to the Use of Water Quality Management Principles. London (UK): World Health Organization (WHO)/United Nations Environment Programme (UNEP). URL [Accessed: 27.03.2019]

Guidelines for the safe use of wastewater excreta and greywater. Volume I. Policy and Regulatory Aspects

Volume I of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater focuses on policy, regulation and institutional arrangements. Accordingly, its intended readership is made up of policy-makers and those with regulatory responsibilities. It provides guidance on policy formulation, harmonisation and mainstreaming, on regulatory mechanisms and on establishing institutional links between the various interested sectors and parties. It also presents a synthesis of the key issues from Volumes II, III, and IV and the index for all four volumes as well as a glossary of terms used in all four volumes is presented in Annex 1.

WHO (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume I. Policy and Regulatory Aspects. Geneva: World Health Organisation URL [Accessed: 10.04.2019]

Guidelines for the safe use of wastewater excreta and greywater. Volume II. Wastewater Use in Agriculture

Volume II of the Guidelines for the safe use of wastewater, excreta and greywater provides information on the assessment and management of risks associated with microbial hazards and toxic chemicals. It explains requirements to promote the safe use of wastewater in agriculture, including minimum procedures and specific health-based targets, and how those requirements are intended to be used. It also describes the approaches used in deriving the guidelines, including health-based targets, and includes a substantive revision of approaches to ensuring microbial safety.

WHO (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume II. Wastewater Use in Agriculture. Geneva: World Health Organisation URL [Accessed: 05.06.2019] PDF

Guidelines for the safe use of wastewater excreta and greywater. Volume III. Wastewater and Excreta Use in Aquaculture

Volume III of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater deals with wastewater and excreta use in aquaculture and describes the present state of knowledge regarding the impact of wastewater-fed aquaculture on the health of producers, product consumers and local communities. It assesses the associated health risks and provides an integrated preventive management framework.

WHO (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume III. Wastewater and Excreta Use in Aquaculture. Geneva: World Health Organisation URL [Accessed: 08.05.2019]

Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture

Volume IV of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater recognizes the reuse potential of wastewater and excreta (including urine) in agriculture and describes the present state of knowledge as regards potential health risks associated with the reuse as well as measures to manage these health risks following a multi-barrier approach.

WHO (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture. Geneva: World Health Organisation (WHO) URL [Accessed: 09.05.2019] PDF

Week 3: Analyse financial viability

Further Readings

Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans

OTOO, M., DRECHSEL, P., DANSO, G., GEBREZGABHER, S., RAO, K. and MADURANGI G. (2016): Testing the implementation potential of resource recovery and reuse business models: from baseline surveys to feasibility studies and business plans. Colombo (Sri Lanka): International Water Management Institute (IWMI), CGIAR Research Program on Water, Land and Ecosystems (WLE). Resource Recovery and Reuse Series 10. URL [Accessed: 27.03.2019]

Week 1: Set objectives and plan activities for launch

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Further Readings

Week 2: Finance the launch

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Further Readings

Alternative Versions to

No Structure Described.