این پایان نامه به زبان انگلیسی، مربوط به دپارتمان مهندسی محیط زیست دانشگاه ایالتی لندن (University College London) انگلستان میباشد که در سال 2014 انجام و با رتبه عالی مورد تایید قرار گرفته است است.
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این پایان نامه به زبان انگلیسی، مربوط به دپارتمان مهندسی محیط زیست دانشگاه ایالتی لندن (University College London) انگلستان میباشد که در سال 2014 انجام و با رتبه عالی مورد تایید قرار گرفته است است.
این پایان نامه به زبان انگلیسی، مربوط به دپارتمان مهندسی محیط زیست دانشگاه ایالتی لندن (University College London) انگلستان میباشد که در سال 2014 انجام و با رتبه عالی مورد تایید قرار گرفته است است.
Abstract
With growing pressures on water supplies
worldwide, rainwater harvesting (RWH) is increasingly seen as a
viable option to provide drinking water to an expanding population.
However, rooftop runoff is not without quality issues.
Microbiological and chemical contamination have been detected in
several studies, posing a health risk for consumers. This research
explores the use of silver ions, combined with conventional
filtration and settling mechanisms, as a safe and affordable
treatment method that can be applied at a small scale. The systems
were installed and tested in rural communities of San Miguel de
Allende, a Mexican semi-arid region, throughout two different
periods of fieldwork analyses. Lab-scale models were also
implemented at UCL, in order to further refine the technology.
Silver has been known for centuries to be a powerful disinfectant,
with no known harmful effects to humans if applied in appropriate
doses. However, implementation in small-scale rainwater harvesting
systems has received little attention, possibly due to a general
perception that it is complicated and/or expensive. The devices
studied in this thesis are able to dose silver ions at a relatively
low cost, avoiding the use of complex nano-materials. System
performance is seen to be highly linked to source water
conductivity and ionic strength, highlighting the importance of
adapting the technology for the specific case of RWH. Total
coliform elimination efficiencies of up to 99.9% are achieved in
the field, with a marked exception where cross-contamination from
external seepage occurs. Sites with relatively clean rooftops show
an absence of total coliforms in the untreated runoff, compared
with others where values as high as 1650 CFU/100 ml are recorded.
Disinfection using an emerging technique for bacteriophage
detection is investigated in the laboratory, indicating a capacity
to inactivate viral particles. Technology adoption issues are also
explored, particularly where increased contamination occurs due to
insufficient stakeholder participation. Observations show that the
silver ion dispensers themselves require little maintenance, while
the other components of the system tend to pose more of a
challenge.