| Author | Hean Vuthana |
| Call Number | AIT Thesis no. AE-95-28 |
| Subject(s) | Fish ponds--Cambodia
|
| Note | A thesis submitted in partial fulfillment of the requirement for the degree of
Master of Science, School of Environment, Resources, and Development |
| Publisher | Asian Institute of Technology |
| Abstract | Turbidity has been a major problem in promoting the development of small-scale
aquaculture in Cambodia. It discouraged the farmers from fish pond culture. The study was
divided into field work in Cambodia and laboratory work in AIT. Field work was conducted
to identify factors associated with turbidity in fish ponds and to take water and soil samples.
Field surveys included a preliminary survey of the whole of Svay Rieng province, farmer
interviews, pond observations, and water and soil sampling. Thirty four farmers were
interviewed in depth, 10 under the P ADEK program located on light gray agricultural soils in
Romeas Hek district, and 14 and 10 farmers under the AIT Aquaculture Outreach program
located on light gray and gray agricultural soils, respectively, in Svay Rieng district. High
turbidity was mainly associated with the nature of pond soil. Pond management and specific
pond inputs were identified as important factors to achieve removal of turbidity in fish
ponds.
Soil samples were analyzed in the laboratory to evaluate soil properties associated
with turbidity. Nine experiments with nine different soil samples and with six treatment
materials (quicklime; alum; salt; a combination of quicklime-alum; sub sua, a local
herbaceous plant; and cow manure) were carried out in duplicate indoors in 1.5 L plastic
containers to evaluate required dosages to remove turbidity from experimental turbid waters
prepared by mixing soil samples with distilled water. Each material was run with a series of
five dosages.
All chemicals were able to remove 100% of the turbidity but high loading rates of
cow manure and sub sua discolored the water due to chlorophyll. Dosage of chemical
material depended on the amount of turbidity to be removed. Quicklime, alum, and a
combination of quicklime-alum were good coagulants but salt was less effective. Quicklime
treatment increased alkalinity rapidly, alum increased acidity rapidly, but a combination of
quicklime-alum increased alkalinity only slightly with increasing dosage. Quicklime was the
best material which should be recommended to farmers in Cambodia to remove turbidity in
fish ponds. The required dosage of treatment materials used to remove turbidity in the range
of 628 - 2846 FNU in experimental turbid water could be estimated by linear regression
equation Y = a X + b, for quicklime RD = 0.037 TR + 29.40 where RD is the required
dosage of quicklime (mg/I) and TR is the turbidity to be removed (FNU). This equation may
be used for trial dosages to remove turbidity which may be vary from pond to pond because
of different composition of water. The required dosage obtained from this study should be
tested with pond water prior to recommendation to farmers in Cambodia |
| Year | 1995 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Edwards, Peter;Szyper, James P. |
| Examination Committee(s) | Yakupityage, Amararatne;Sununtar Setboonsarng |
| Scholarship Donor(s) | The Swedish International Development Authority (SIDA) |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1995 |