Project background: From pit latrines to wetlands - periurban solutions near Colombo, Sri Lanka. Course: Course Content. Knowledge

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1 From pit latrines to wetlands - periurban solutions near Colombo, Sri Lanka Arve Heistad Norwegian University of Life Sciences Departmenet for Mathematical Sciences and Technology Project background: National Water Supply and Drainage Board (NWSDB) in Sri Lanka have arranged a post educational course for engineers as part of the Third Water Supply and Sanitation Project, package C. This project was financed by NORAD and coordinated by Statkraft Grøner AS. The Norwegian University of Life sciences, has been responsible for the educational part of the project. August Knowledge - The key to understand present problems, and Multi-diciplinary cooperation - The key to solve present problems and to avoide future problems. Course: Intensive lectures (two weeks) in Sri Lanka Project work under supervision (seven months) Final lectures/discussion on project works (one week) in Sri Lanka Evaluation: Project Report and written exam. Course Content Groundwater transport and protection Recipient water biology and chemistry. Eutrophication Microbial risks related to wastewater discharge. Problem formulation, goals for water quality, and.. Treatment options Centralized vs. decentralized. Source separation, infiltration (pit latrines), wetland systems, package treatment plants, sludge treatment (composting, soil ammendment, anaerobic biogasreactors, sludge as fertilizer) Management challenges in general and for decentralized systems Sri Lanka: Population: > Population density: >300 /km 2 Figure showing the distribution of different toilet systems Exclusive = WC

2 Eutrofication Bacteria, virus og protozoa Giardia int. Norwalk Campylobacter sp. MS-2 Den globale helsebyrden (DALY=Disability Adjusted Life Years) Disease/Injury Rank %DALYs Rank %DALYs Lower respiratory Diarrhoeal Perinatal period Depression Heart disease Tuberculosis Road accidents HIV Lung cancers Heistad and Jenssen 2005 Murray et al. (1996) Science 274: Example Project work: Designing of wastewater treatment processes for the housing scheme at Galwala, Mahara. The houses has been constructed by the National Housing Development Authority to provide housing facilities for the poor people living in shanties. Houses are already occupied, before proper water supply and sanitation is established. Objective: Analyse the situation and design a sustainable wastewater treatment system.

3 What are the requirements? - identifying the problem National guidelines on water quality? Any local problems? (eutrophication, smell,hygienic) Limitations? Economi Operation and maintainance Knowledge Water quality in recipient: E.coli: /100 ml Tot.P: 0,5 mg/l BOD: 8,25 mgo/l

4 Water quality in the well: E.coli: /100 ml Scale Rubber cap Water container Water supply Air supply (the level controls the the water level in the pad) Plastic pad 10 cm

5 Subsurface flow wetlands. Subsurface flow wetlands (SSF) use a bed of soil or gravel as a substrate for the growth of rooted emergent wetland plants. Pre-treated wastewater flows by gravity, horizontally or vertically, through the bed substrate, where it contacts a mixture of facultative microbes living in association with the substrate and plant roots, (Raimund Haberl, University of Agricultural Sciences. Institute for Water Provision. Viena) The SSF are common design as a secondary treatment and consist of channels, trenches or pits filled up of granular material, gravel generally, although new materials are been used from the last years as the Lightweight Aggregates (LWA), Filtralite made from clay or shale by heating to temperatures above 1000ªC.

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7 Conclusions: The traditional engineering approach to pollution problems is high-tech solutions. Most problems related to wastewater treatment can be solved by inexpensive, and technical simple means. More attention to the recipient requirements will give more precise goals and result in higher yields on the money spent on action, and will make the regulation more easy to understand. All participants on the course have administrative positions. Their knowledge should be used for further training of their own personel. Is this happening? A higher degree of international participation would be beneficial.