Sustainable sanitation : a case study in Yasmine and Awda informal settlements (Lebanon)

M-VM

英语. Lebanon is a relatively small country but has the largest concentration of refugees per capita in the world. One quarter of the population are refugees. As the Syrian crisis enters the eighth year, Lebanon has been a host to almost 1.5 million Syrian refugees. The crisis has placed a great constrain on public services, with demands far exceeding the capacity of institutions and infrastructure. The water- and wastewater sector in Lebanon is characterized by unclarified roles and responsibilities with overlapping functions. Proper wastewater management is a national issue, and with the rapid influx of refugees and already constrained sanitation options, conditions in the refugee camps are especially challenging. This thesis focuses upon two refugee camps located in Bar Elias, Bekaa Valley, Lebanon, currently hosting approximately 2200 people. The present wastewater- and sanitation solution at the camps consist of family toilets and showers inside each dwelling. Every household is connected to a wastewater network with separation of greywater (shower, sink, dish- and clothes washing) and blackwater (toilet). The greywater is pumped through the pipe network to a two-chamber septic tank, and then furthermore pumped to a soil infiltration trench for treatment, before effluent discharge into the irrigation channel nearby. The blackwater is stored in a holding tank, and frequently pumped out by a vacuum tanker. The trucks collect the content and transport it to an off-site wastewater treatment plant, and this is a costly procedure. The soil type in the area was fine-grained silty clay soil which was assumed to have limited hydraulic capacity. The different wastewater streams generated in the camps were relatively low, thus the greywater sample analyzed in the laboratory was highly concentrated. The on-site greywater treatment performance was not optimal, and the design of the infiltration system should be changed. This could be done by adding a sand layer between the natural underlying soil and the gravel holding the infiltration pipes, and construct a mound system. The result will be a higher effluent quality, and the treated greywater could discharge into the irrigation channel without causing more pollution. To save water, the treated greywater should ideally be reused for flushing, gardening purposes or laundry washing. Both grey- and blackwater should be handled on-site in a complex system to achieve more sustainable management and reuse of more wastewater resources on-site. Implementation of new technologies such as anaerobic baffled reactors followed by anaerobic filters or optionally upflow anaerobic sludge blankets, will make it possible to produce biogas as a source for energy. The biogas potential could increase by adding organic waste (food waste and animal excreta), and if urine diversion toilets are installed to collect the urine separately. The urine could be used as a liquid fertilizer, while the faeces could be used as soil amendment or solid organic fertilizer in the fields after being dewatered in sludge drying beds. If the assumptions to produce biogas with organic waste is too low and the area requirement is too high, mobile small wastewater treatment systems could be installed in the camps. These solutions are suitable in temporary refugee camps because they are easily transported anywhere.The refugees were in general very open-minded and positive to changes. They were all convinced that if a more sustainable solution would benefit them, it should be implemented. The refugees receive training in self-management of the camp facilities, and participate in classes about water, sanitation and hygiene. This thesis recommends further interaction with the refugees to cultivate ideas and determine their ability to move forward and have a self-supportive system. Acceptance from the local people is a key factor for a successful project since they are the ultimate decision-makers.

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