Sludge Drying Beds Dorothee Spuhler seecon gmbh Sludge

Sludge Drying Beds Dorothee Spuhler, seecon gmbh Sludge Drying Beds

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Find this presentation and more on: www. sswm. info. Contents 1. Concept 2. How can Drying Beds Optimise SSWM 3. Design Principals 4. Treatment Efficiency 5. Operation and Maintenance 6. Applicability 7. Pros’ and Cons’ 8. References Sludge Drying Beds 3

Find this presentation and more on: www. sswm. info. 1. Concept Background All organic degradation process produce sludge. Sludge has a total solid content of 2 to 10 % and can not be transported easily with simple equipment. Apart from this, sludge is contaminated and occupies large volumes for storage. Therefore it is better to dry or sludge (dewatering) before further use or dumping. Anaerobic sanitation systems (e. g. latrines, septic tanks, aqua privies, anaerobic baffled reactors, biogas reactors) produce less sludge than aerobic treatments (e. g. from trickling filters, activated sludge) and anaerobic sludge also dries better and results in less odour as it is more stabilised. (SASSE 1998) Sludge Drying Beds 4

Find this presentation and more on: www. sswm. info. 1. Concept What is a Sludge Drying Bed ? Sludge drying beds are one of the simplest and oldest techniques for sludge dewatering. They are impermeable beds filled with different layers of gravel and sand. Draining pipes are in incorporated in the bottom of the beds. Sludge is applied in layers on the top gravel beds. Drying is achieved by evaporation and gravity percolation. In planted drynge bed, the removal of humidity is enhanced by evapotranspiration. Dried sludge is not stabilised, but additional composting (e. g. cocomposting) will allow to recycle nutrients and organic matter into agriculture. The effluent (percolate) that is collected in the drainage pipes must be treated correctly. (SANIMAS 2005) Sludge Drying Beds 5

Find this presentation and more on: www. sswm. info. 1. Concept What is a Sludge Drying Bed ? Faecal Sludge Conveyance Septic tank Sludge drying beds Biogas plants Latrines Aqua priviy Sludge Drying Beds Trickling filters Anaerobic baffled reactor Source: adapted from EAWAG/SANDC (2008); TILLEY et al. (2008); WAa. F (2002 ); SANIMAS (2005); BALASUBRAMANIYAM (2008); www. Clker. com and http: //whrefresh. com/wpcontent/uploads/2010/01/potato_field. jp g [Accessed: 10. 06. 2010] Co-composting Fertiliser for agriculture 6

Find this presentation and more on: www. sswm. info. 1. Concept The Role of Sludge Drying Bed in Faecal Sludge Management Source: STRAUSS & MONTANGERO (2002) Source: STRAUSS & MONTANEGRO 2004 Sludge Drying Beds 7

Find this presentation and more on: www. sswm. info. 1. Concept What is a Sludge Drying Bed ? Planted Unplanted Sludge drying beds can be • Unplanted • Planted Unplanted sludge drying beds • Design similar to unplanted filters sand/gravel filters • Require desludging after every cycle of drying (manpower required) Planted sludge drying beds • Design similar to reed beds or vertical constructed wetlands • Do not need desludging after every cycle: Source: STRAUSS & MONTANEGRO 2004 (STRAUSS & MONTANGERO 2002; SASSE 1998; TILLEY et al. 2008) ◦ Porosity is maintained by the root systems of the plants. ◦ Sludge is transformed into biomass (plants) and can be harvested. Sludge Drying Beds 8

Find this presentation and more on: www. sswm. info. 1. Concept Examples: Unplanted Drying Bed Source: SASSE (1998) Sludge Drying Beds 9

Find this presentation and more on: www. sswm. info. 1. Concept Examples: Planted Drying Bed Source: TILLEY et al. (2008) Sludge Drying Beds 10

Find this presentation and more on: www. sswm. info. 1. Concept Examples Covered sludge drying bed at the Arcata wastewater treatment plant (USA) http: //www. humboldt. edu/arcatamarsh/compost. html Unplanted drying bed at a waste stabil - isation pond (WSP) site in Colombia. Source: IRC (2004) Source: EAWAG/SANDC (2008) Unplanted drying beds in Ghana (Sandec) Sludge Drying Beds 11

Find this presentation and more on: www. sswm. info. 1. Concept Examples Source: EAWAG/SANDC (2008) Source: MUENCH, E. , von 2009) Primary sludge drying bed and reed bed (in the background). Sludge Drying Beds New installation of a constructed wetland with ventilation pipes at the Asian Institute of Technology (AIT) in Bangkok, Thailand 12

Find this presentation and more on: www. sswm. info. 2. How it can optimize SSWM Faecal sludge collected from on-site sanitation installations are commonly dumped untreated, because it is difficult to transport and treatment facilities lye often far away or are not available at all. This causes heavy environmental pollution and major risk for the transmittance of diseases. Sludge drying beds are a simple mean to reduce the volume of the sludge and prepare them for co-composing, which transform them to a safe and valuable fertiliser. Sludge Drying Beds Source: EAWAG/SANDEC (2008) Indiscriminate disposal of faecal sludge, Ouagadougou. (Photo: Eawag/Sandec) Source: ERIKSEN-HAMEL & DANSO (2002) Lettuce farm fertilised with compost at Gyenyasi farmers association in Kumasi. 13

Find this presentation and more on: www. sswm. info. 3. Design Principals Basics Treatment objective: Separation of solid from the liquid fraction of faecal sludge. Similar treatment options: sedimentation/thickening ponds Pre-treatments: Latrines, septic tanks, aqua privies, anaerobic baffled reactors, biogas reactors, trickling filters, activated sludge, etc. Post-treatment: Co-composting in order to transform it into fertiliser Main-components: • Impermeable shallow pond • Drainage pipes in the bottom (perforated PVC pipes or hollow blocks) • Different layers of coarse gravel, sand • Slightly sloped surface for drainage (1: 20) (STRAUSS & MONTANEGRO 2004) Sludge Drying Beds 14

Find this presentation and more on: www. sswm. info. 3. Design Principals Unplanted Sludge Drying Bed Sludge application depth: about 20 cm Loadings: 100 to 200 Kg. TS/m 2/year (STRAUSS & MONTANGERO 2002; WSP 2007) (STRAUSS & MONTANGERO 2002) Percolation: 50 to 80 % of initial Volume Time required for drying: 10 to 20 days (STRAUSS & MONTANGERO 2002) Land requirements: 0. 05 m 2 per capita for a 10 days cycle Sludge Percolate Sludge Drying Beds Drainage (STRAUSS & MONTANGERO 2002) Source: STRAUSS & MONTANEGRO (2004) Achieved drying: 40 to 70 % TS (STRAUSS & MONTANGERO 2002) 15

Find this presentation and more on: www. sswm. info. 3. Design Principals Filter bed Large gravel (d=20 mm): 25 cm Fine gravel (d=5 mm): 25 cm Sand: 10 cm (EAWAG/SANDEC 2008) Source: STRAUSS & MONTANEGRO (2004) Planted Sludge Drying Bed Sludge Drainage Sludge application depth: about 20 cm Loadings: 250 Kg. TS/m 2/year (STRAUSS & MONTANGERO 2002 WSP 2007) (STRAUSS & MONTANGERO 2002) Percolation: 50 to 80 % of initial Volume (STRAUSS & MONTANGERO 2002) Application: Once a week; Desludging: every 5 to 6 years Achieved drying: 40 to 70 % TS Sludge Drying Beds (STRAUSS & MONTANGERO 2002) 16

Find this presentation and more on: www. sswm. info. 3. Design Principals Treatment Efficiency (STRAUSS & MONTAGERO 2002) Suspended solids: >= 95 % COD 70 to 90 % Helminth eggs 100 % NH 4 40 to 60 % Health aspects Dewatered sludge is still infectious; Additional composting of dried sludge in heaps or wind-rows will further stabilise recycled organic materials. (SANIMAS 2005) Operation and Maintenance A splash spate should be used for application of the sludge. In the case of unplanted beds, sludge must be removed frequently. Checking of drainage capacities. Sludge Drying Beds 17

Find this presentation and more on: www. sswm. info. 6. Applicability Any kind of sludge can be treated in drying beds. It is best combined with co-composting in order to produce fertiliser. The method is simple but requires professional design and trained manpower for the operation. However, large land areas are required for the construction. Drying beds are centralised treatment options and thus adapted for larger areas. The operation and maintenance requires an efficient community organization. As odour could be an issue, they should be constructed far away from households. The bottom needs to be sealed to prevent groundwater pollution and the percolate must be treated. Therefore, drying beds are not adapted for areas prone to flooding. At places with frequent rain must be roofed. Sludge Drying Beds 18

Find this presentation and more on: www. sswm. info. 7. Pros’ and Cons’ Advantages: Disadvantages: • Easy to operate • Requires large land area • Dried sludge can be composted and used as fertiliser • Re-use or treatment of seepage water required • Simple operation, no skilled personnel required • Only applicable during dry seasons or needs a roof • Results in much reduced volume of sludge • Manual labour or specialised equipment is required to remove dried sludge from beds • Can achieve pathogen removal • Can cause odour problems • Can be built with local materials Sources: adapted form SANIMAS (2005); http: //www. training. gpa. unep. org/content. html? id=215&ln=6 [Accessed: 10. 07. 2010] Sludge Drying Beds 19

Find this presentation and more on: www. sswm. info. 8. References BALASUBRAMANIYAM, U. , ZISENGWE, L. S. , MERIGGI, N. , BUYSMAN, E. (2008): Biogas Production in Climates with long cold Winters. Wageningen: Wageningen University Available at: http: //www. wecf. eu/english/publications/2008/biogas-coldclimates. php [Accessed: 20. 04. 2010] EAWAG/SANDEC (2008): Fecal Sludge Management. Lecture notes. (=Sandec Training Tool 1. 0, Module 5). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC) EAWAG/SANDEC (2008): Fecal Sludge Management. Presentation. (=Sandec Training Tool 1. 0, Module 5). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC) ERIKSEN-HAMEL, N. S. , DANSO, G. (2008): Urban Compost: A Socio-economic and Agronomic Evaluation in Kumasi, Ghana in REDWOOD, M. (ed) (2008): Agriculture in Urban Planning: Generating Livelihoods and Food Security. Earthscan/IDRC. Available at: http: //www. idrc. ca/en/ev-135127 -201 -1 -DO_TOPIC. html SANIMAS (2005): Informed Choice Catalogue. PPT-Presentation. remen Overseas Research and Development Agency (BORDA) and United States Agency for International Development (USAID) SASSE, L. (1998): DEWATS Decentralised Wastewater Treatment in Developing Countries. Bremen: Bremen Overseas Research and Development Association (BORDA) Available at: http: //www. borda-net. org/modules/wfdownloads/uploads/062%20 BORDA_Dewats -Handbook. pdf [Accessed: 27. 05. 2010] STRAUSS, M. , MONTANEGRO, A. (2002): FS Management – Review of Practices, Problems and Initiatives. London and Duebendorf: DFID Project R 8056, Capacity Building for Effective Decentralised Wastewater Management, Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). Available at: http: //www. eawag. ch/organisation/abteilungen/sandec/schwerpunkte/ewm/fsm/index_EN [Accessed: 10. 06. 2010] STRAUSS, M. , MONTANEGRO, A. (2004): Fecal Sludge Treatment, Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). Available at: http: //www. eawag. ch/organisation/abteilungen/sandec/schwerpunkte/ewm/fsm/index_EN [Accessed: 10. 06. 2010] TILLEY, E. , LUETHI, C. , MOREL, A. , ZURBRUEGG, C. , SCHERTENLEIB, R. (2008): Compendium of Sanitation Systems and Technologies. Duebendorf and Geneva: Swiss Federal Institute of Aquatic Science (EAWAG) & Water Supply and Sanitation Collaborative Council (WSSCC) Available at: http: //www. eawag. ch/organisation/abteilungen/sandec/publikationen/compendium_e/index_EN Accessed: 09. 04. 2010] WAa. F (2002) Sanitation Technology Options. Pretoria: Department of Water Affairs and Forestry (WAa. F) Available at: http: //www. bvsde. paho. org/bvsacd/cd 66/Technical. pdf [Accessed: 27. 05. 2010] Sludge Drying Beds 20

Find this presentation and more on: www. sswm. info. “Linking up Sustainable Sanitation and Water Management” Main Funding Partners: Further Funding, Content & Dissemination Partners Compiled by: Sludge Drying Beds 21

“Linking up Sustainable Sanitation, Water Management & Agriculture” SSWM is an initiative supported by: Compiled by: Sludge Drying Beds 22