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Abstract:Landfill leachate is a toxic effluent of a decomposing landfill. It is produced when rainwater percolates through the landfill leaching out contaminants and pollutants. Untreated leachate is a potential source for the contamination of soil, surface and ground water. In this study, the treatment processes such as granular activated carbon (GAC) adsorption/bio-sorption (batch) and advanced oxidation were evaluated using synthetic landfill leachate (SLL) as a contaminant. Advanced oxidation of SLL was studied using Fenton's reagent (H 2 O 2 /Fe +2 ). The total organic carbon (TOC) removal efficiency (of landfill leachate) was evaluated for sequential adsorption/bio-sorption (on GAC) and Fenton process and compared with photocatalysis. The percent TOC removed by GAC bio-sorption at the peak bio-growth was 85, 92 and 97 % for the 20, 40 and 60 g/l GAC respectively.The Advanced oxidation process removed 60% of the TOC at an optimum dose of Fenton's reagent (15 and 400 milli moles of Fe +2 and H 2 O 2 ). Photo-catalysis with TiO 2 removed only 30% of the TOC. The TiO 2 coated on powdered activated carbon (PAC) as a photo catalyst led to even lower TOC removal of less than 7%.

This study of the Quantitative Estimation Precipitation (QEP) of rainfall, detected by two Meteorology Radars over Chi Basin, North-east Thailand, used data from the Thai Meteorological Department (TMD). The rainfall data from 129 rain gauge stations in the Chi Basin area, covering a period of two years, was also used. The study methodology consists of: firstly, deriving the QPE between radar and rainfall based on meteorological observations using the Marshall Palmer Stratiform, the Summer Deep Convection, and Regression Model and calibrating with rain gauge station data; secondly, Bias Correction using statistical method; thirdly, determining spatial variation using three methods, namely Kriging, Inverse Distance Weight (IDW), and the Minimum Curvature Method. The results of the study demonstrated the accuracy of estimating precipitation using meteorological radar. Estimated precipitation compared against an equivalent of 2 years of rain station measurement had a probability of detection (POD) of 0.927, where a value of 1 indicated perfect agreement, demonstrating the effectiveness of the method used to calibrate the radar data. The bias correction method gave high accuracy compared with measured rainfall. Furthermore, of the spatial estimation of rainfall methods, the Kriging methodology showed the best fit between estimation of rainfall distribution and measured rainfall distribution. Therefore, the results of this study showed that the rainfall estimation, using data from a meteorology radar, has good accuracy and can be useful, especially in areas where it is not possible to install and operate rainfall measurement stations, such as in heavily forested areas and/or in steep terrain. Additionally, good accuracy rainfall data derived from radar data can be integrated with other data used for water management and natural disasters for applications to reduce economic losses, as well as losses of life and property.

Rainwater has been used as drinking water in Thailand for centuries especially in the rural parts and is accepted as an important water resource. From past to present, the quality of rainwater has changed with the land use of the landscape and its water quality is influenced by a diverse range of conditions such as the management of pollutant sources, the catchment condition, wind and meteorological conditions and the location of rainwater collection points. In this study, the quality of rainwater collected off roofs at several locations was examined. Granular activated carbon (GAC) filtration was used as a pretreatment to microfiltration to remove the dissolved organic matter (DOC). After an initial adsorption period, the biofilm that formed on the GAC (biofilter) was found to remove DOC by up to 40 %, 35 % and 15% for bed filter depths of 15 cm, 10 cm and 5 cm respectively. Biofilters also removed nitrate and phosphate by more than 80% and 35%. The hollow fibre membrane micro filtration with pore size of 0.1 m µ was used to treat the effluent from biofiltration to remove the microorganisms/pathogens in the rainwater. Although there was no significant additional removal of DOC by MF, the biofilter removed all microorganisms. The use of biofilters as pretreatment to MF/UF could remove a higher amount of DOC, remove microorganisms, increase the membrane treatment efficiency, and reduce membrane fouling.

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