Modeling Decentralized Source-Separation Systems for Urban Waste Management
Decentralized eco-sanitation system is a promising and sustainable mode comparing to the century-old centralized conventional sanitation system. The decentralized concept relies on an environmentally and economically sound management of water, nutrient and energy fluxes. Source-separation systems for urban waste management collect different solid waste and wastewater streams separately to facilitate the recovery of valuable resources from wastewater (energy, nutrients). A resource recovery centre constituted for 20,000 people will act as the functional unit for the treatment of urban waste of a high-density population community, like Singapore. The decentralized system includes urine treatment, faeces and food waste co-digestion, and horticultural waste and organic fraction of municipal solid waste treatment in composting plants. A design model is developed to estimate the input and output in terms of materials and energy. The inputs of urine (yellow water, YW) and faeces (brown water, BW) are calculated by considering the daily mean production of urine and faeces by humans and the water consumption of no-mix vacuum toilet (0.2 and 1 L flushing water for urine and faeces, respectively). The food waste (FW) production is estimated to be 150 g wet weight/person/day. The YW is collected and discharged by gravity into tank. It was found that two days are required for urine hydrolysis and struvite precipitation. The maximum nitrogen (N) and phosphorus (P) recovery are 150-266 kg/day and 20-70 kg/day, respectively. In contrast, BW and FW are mixed for co-digestion in a thermophilic acidification tank and later a decentralized/centralized methanogenic reactor is used for biogas production. It is determined that 6.16-15.67 m3/h methane is produced which is equivalent to 0.07-0.19 kWh/ca/day. The digestion residues are treated with horticultural waste and organic fraction of municipal waste in co-composting plants.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1328206Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 2555
 H. Orth, "Centralised versus decentralised wastewater systems?," Water Sci. Technol., vol. 55, pp. 259-266, 2007.
 T. A. Larsen and J. Lienert, "Spotlight on NoMix," in Eawag aquatic research, Swiss Federal Institute of Aquatic Science and Technology (Eawag), March 2007, pp4-7.
 S. A. Esrey, I. Andersson, A. Hillers and R.Sawyer, "Closing-the-loop - ecological sanitation for food security," Water Resour., no. 18, 2001.
 J. Lienert and T. A. Larsen, "High Acceptance of Urine Source Separation in Seven European Countries: A Review," Environ. Sci. Technol., vol. 44, pp. 556-566, November 2009.
 C. Remy, Life Cycle Assessment of conventional and source-separation systems for urban wastewater management, Technical University of Berlin, 2010.
 J.F. Smith, "Does Decentralization Matter in Environmental Management?," Environ. Manage., vol. 22, pp. 263-276, 1998.
 H. Yoshida, Japan-s Challenge for the Environmental Sanitation, Waste Management & Recycling Department, Ministry of the Environment, Japan, 2007.
 J. Parkinson and K. Tayler, "Decentralized wastewater management in peri-urban areas in low-income countries," Environ. Urban., Vol 15, No 1, pp.75-90, 2003.
 U.S. Environmental Protection Agency (EPA), Response to congress on use of decentralized wastewater treatment systems, EPA, Office of water, Office of wastewater management, Washington, D.C., pp.ii-iii, April 1997.
 G. Langergraber and E. Muellegger, "Ecological SanitationÔÇöa way to solve global sanitation problem?," Environ. Int., vol. 31, pp. 433-444, 2004.
 Werner C, "EcosanÔÇöclosing the loop", in 2nd International Symposium on ecological sanitation, Deutsche Gesellschaft f├╝r Technische Zusammenarbeit (GTZ), Eschborn, Germany, pp. 245-359.
 R. Otterpohl, Innovative reuse oriented water concepts: high-, mediumand low-tech options, Institute of Municipal and Industrial Wastewater Management, Technical University Hamburg-Harburg, pp. 5.
 S. Narain, "The flush toilet is ecologically mindless," Down to Earth, vol. 10, No. 19, 2002.
 D. Duncan, "Is it time to kill off the flush toilet?," TIME, Nov. 06, 2008.
 R. Otterpohl, "Design of highly efficient Source Control Sanitation and practical Experiences", Hamburg, Germany, 2000.
 U. Jeppsson and D. Hellström, "Systems analysis for environmental assessment of urban water and wastewater systems", Water Sci. Technol., vol. 46, no 6-7, pp. 121-129, 2002.
 P. Daniel, "Material Flow Analysis (MFA) and Embodied Resource Analysis for Sustainable Water ManagementÔÇöA Regional Application in Australia", in International Society for Ecological Economics (ISEE), Griffith University, Brisbane, Australia.
 A. Tillman and M. S. H. Lundström, "Life Cycle Assessment of municipal waste water systems," Int. J. Life Cycle Ass., vol 3, pp. 145- 157, 1998.
 R. M├╝hleck, A. Grangler and M. Jekel, "Ecological assessment of ecosan concepts and conventional wastewater systems", in 2nd international symposium on ecological sanitation, pp. 733-740, April 2003.
 Housing Development Board (HDB), "HDB Key Statistics 2010", HDB Annual Report 2009/2010, pp. 8.
 B. Yuen, "Public Housing-led Recreation Development in Singapore," Habitat Int., vol. 19, no 3, pp. 239-252, 1995.
 Hofstetterm, A.G. and Eisenberger, Urologie f├╝r die Praxis, Springer, 2nd ed., Berlin, Germany, February 1996.
 Jocham, D. and Miller, K., Praxis der Urologie, Thieme, 3rd ed., Stuttgart, Germany, October 2007.
 R. G. Feachem, D. J. Bradley, H. Garelick and D.D. Mara, "Sanitation and disease-health aspects of excreta and wastewater management," World Bank studies in Water Supply and Sanitation, 1983.
 K.M. Enferadi et al, "Field investigation of biological toilet systems and grey water treatment," Water Engineering Research Laboratory, United States Environmental Protection Agency, 1986.
 L. Rossi, J. Lienert and T. A. Larsen, "Real-life efficiency of urine source separation," J. Environ. Manage., vol. 90, pp. 1909-1917, 2009.
 H. Jönsson, T. Stenström, J. Svensson and A. Sundin, "Source separated urine-nutrient and heavy metal content: water saving and faecal contamination," Water Sci. Technol., vol. 35, no 9, pp. 145-152, 1997.
 M. Maurer, W. Pronk and T.A. Larsen, "Treatment processes for sourceseparated urine," Water Res., vol. 40, 2006, pp. 3151-3166.
 Economie Ecologie Technologie, DESAR: Decentralised Sanitation and Reuse phase 1, July 2008, pp. 23, 39.
 K. D. V. S. Yadav, Vermiculture and vermicomposting using human faeces as feed and Eisenia foetida as earthworm species, Department of civil engineering, Indian Institute of Technology, Kampur, India, 2008.
 D. D. Porto and C. Steinfeld, The composting system Book: A practical guide to choosing, planning and maintaining composting toilet systems, Center for Ecological Pollution Prevention, 2000.
 Environment Protection Authority, Victoria, Australia, "Waste Material - Density Data," EPA, 2011.
 H. Chia, Optimization of the two-phase anaerobic digestion system for the co-production of bio-hydrogen and bio-methane from food waste, School of Civil and Environmental Engineering, Nanyang Technological University, 2010.
 Bioste Oy, "Bioenergian ammattilainen - Biogas", Finland.
 American Council for an Energy-efficient Economy (ACEEE), Combined Heat and Power and Clean Distributed Energy Policies, Washington, 2009.
 E. Low, M. Aw and W. L. Chen, Food waste republic: Dirty Secrets of a food paradise, Wee Kim Wee School of Communication and Information, Nanyang Technological University, Singapore, 2010.
 Waste & Resources Action Programme (WRAP), The food we waste, United Kingdom, 2008, pp. 170.