| Author | Uy Kamal |
| Call Number | AIT Thesis no.EV-06-38 |
| Subject(s) | Water--Purification--Arsenic removal--Cambodia
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| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-06-38 |
| Abstract | A local arsenic biosand filter was tested at full scale in the Cambodian district with an extremely high concentration of arsenic in groundwater (up to over 1000g/L). Though the filters were based on the principle of the KanchanTM Arsenic Filter (Nepalese-MIT collaborative effort), a local modification was supposed to make it user-friendly in Cambodia. The trial has yielded the following results for the newly biosand filter with local available media (crushed rock). Based on the five parameters studied, the performance of the crushed rock-filled filter (47.5 days in average for reliable arsenic treatment from 1000 to below 50Ag/L) was substantially better than that of the river sand-filled filter (24 days). However, overall these two filter types did not allow for a reliable and stable performance for the treatment of the highly As-contaminated raw groundwater for an extended period of time. It was found that the both types of biosand filters required a start-up period of two weeks to develop fully rust in order to reduce arsenic to the national permissible drinking level of 50g/L with the outflow rates in the range of 7-10L/h. Fluctuation of arsenic concentration in the treated waters were found to be related to adsorption capacity of iron rust of iron nails and perhaps natural dissolved iron as well. The new iron nails at the initial stage were found to require certain time (up to 2 weeks) to generate full rust, thus making rust development on iron nails is necessary for highly arsenic adsorption capacity. Since the surface/mass ratio of smaller iron nails was much greater than that of the bigger nails, an attention should be paid to this parameter determining the limits of an arsenic adsorption capacity. It was observed that black colored rust was encountered in some iron nails in the media, and it affected arsenic removal efficiency. Therefore, the nail size, iron form, including purity of iron nails should be properly selected before the use. During the filter operation, the outflow rate was found to gradually decline with an accumulation of fine rusted iron particles settled on the top of fine sand layer therefore regular clean-ups were deemed necessary to prevent resulting turbidity of the treated water causing malfunction of the filter. pH of the final treated water was found to be normally slightly higher than in the raw water, potentially as a result of calcium carbonate dissolution from the concrete and the sand media. This condition was found to be beneficial for the overall treatment effciency. Despite the reasonably good performance by the crushed rock-filled filter (2 times higher than for the river sand-filled filter), this performance should be considered inferior and unstable for the current household use in Cambodia. Hence additional modifications are thought to be necessary to adapt Nepalese-developed KanchanTM Arsenic Filter to local socio-economic conditions of Cambodia. |
| Year | 2006 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. EV-06-38 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Shipin, Oleg |
| Examination Committee(s) | Thammarat Koottatep;
Aramaki, Toshiya |
| Scholarship Donor(s) | Government of Sweden (Sida) |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2006 |