3.1 Estimation of optimum alum doses
Hmong
The mountain water was sampling raw water for six liters from a weir on-mountain in summer, rainy, and cold seasons in 2019. Then we measured the turbidity, TDS, and pH of mountain water. In summer, the quality of mountain water, that found 1.47 NTU for turbidity, 90 mg/l for TDS, and 7.88 for pH. In rainy seasons, the quality of mountain water was found that 4.10 NTU for turbidity, 60 mg/l for TDS, and 8.57 for pH. Finally, in the cold season found 1.30 NTU, 70 mg/l for TDS, and 8.07 for pH. Comparison of the turbidity of mountain water among three seasons found that the turbidity of rainy season > summer season > cold season as shown in Fig. 1.
Jar test experiment, we added various alum concentrations from 10 mg/l to 60 mg/l in mountain water. Alum concentrations at 10 mg/l, 20 mg/l, 30 mg/l, 40 mg/l, 50 mg/l, and 60 mg/l reduced the turbidity to 0.88 NTU, 1.11 NTU, 0.94 NTU, 0.91 NTU, 0.90 NTU, and 0.62 NTU, respectively, from 1.47 NTU of mountain water in summer season as shown in Fig. 1. In addition, Alum concentrations from 10 mg/l to 60 mg/l reduced the turbidity to 1.33 NTU, 1.50 NTU, 0.97 NTU, 0.74 NTU, 0.98 NTU, and 0.92 NTU, respectively, from 4.10 NTU of mountain water in the rainy season. Finally, Alum concentrations from 10 mg/l to 60 mg/l, all samples reduced the turbidity to 0.01 NTU from 1.30 NTU of mountain water in the cold season.
Figure 5 was the result of optimum alum dose for mountain water in Hmong village. The appropriately dose used in the rainy season was 30 mg/l. Both summer and cold seasons were using for 10 mg/l. In the rainy season of alum concentration use in water treatment was higher than in summer and cold seasons.
Karen
The mountain water was sampling raw water for six liters from a weir on-mountain in summer, rainy, and cold seasons in 2019. Then we measured the turbidity, TDS, and pH of mountain water. In summer, the quality of mountain water, that found 4.30 NTU for turbidity, 90 mg/l for TDS, and 8.67 for pH. In rainy seasons, the quality of mountain water was found that 5.41 NTU for turbidity, 100 mg/l for TDS, and 7.19 for pH. Finally, in the cold season found 0.47 NTU, 80 mg/l for TDS, and 8.01 for pH. Comparison of the turbidity of mountain water among three seasons found that the turbidity of rainy season > summer season > cold season as shown in Fig. 2.
Jar test experiment, we added various alum concentrations from 10 mg/l to 60 mg/l in mountain water. Alum concentrations at 10 mg/l, 20 mg/l, 30 mg/l, 40 mg/l, 50 mg/l, and 60 mg/l reduced the turbidity to 1.20 NTU, 1.57 NTU, 0.96 NTU, 0.64 NTU, 0.68 NTU, and 0.80 NTU, respectively, from 4.30 NTU of mountain water in summer season as shown in Fig. 2. In addition, Alum concentrations from 10 mg/l to 60 mg/l reduced the turbidity to 4.15 NTU, 4.30 NTU, 1.20 NTU, 0.90 NTU, 0.86 NTU, and 0.88 NTU, respectively, from 5.41 NTU of mountain water in the rainy season. Finally, Alum concentrations from 10 mg/l to 60 mg/l, all samples reduced the turbidity to 0.21 NTU for alum 10 mg/l, 0.01 NTU for alum 20–60 mg/l which all reduced from 1.30 NTU of mountain water in the cold season.
Figure 5 was the result of optinum alum dose for mountain water in Karen village. The appropriately alum dose used in the rainy season was 40 mg/l. In summer, the The appropriately alum dose was 30 mg/l, and in cold season was 10 mg/l of alum dose. Comparison of appropriately alum doses among three seasons found that the alum doses of rainy season > summer season > cold season.
Lahu
The mountain water was sampling raw water for six liters from a weir on-mountain in summer, rainy, and cold seasons in 2019. Then we measured the turbidity, TDS, and pH of mountain water. In summer, the quality of mountain water, that found 5.44 NTU for turbidity, 70 mg/l for TDS, and 6.96 for pH. In rainy seasons, the quality of mountain water was found that 7.22 NTU for turbidity, 60 mg/l for TDS, and 7.55 for pH. Finally, in the cold season found 2.35 NTU, 70 mg/l for TDS, and 7.96 for pH. Comparison of the turbidity of mountain water among three seasons found that the turbidity of rainy season > summer season > cold season as shown in Fig. 3.
Jar test experiment was added various alum concentrations from 10 mg/l to 60 mg/l in mountain water. Alum concentrations at 10 mg/l, 20 mg/l, 30 mg/l, 40 mg/l, 50 mg/l, and 60 mg/l reduced the turbidity to 1.11 NTU, 1.45 NTU, 2.11 NTU, 0.67 NTU, 0.96 NTU, and 0.73 NTU, respectively, from 5.44 NTU of mountain water in summer season as shown in Fig. 3. In addition, Alum concentrations from 10 mg/l to 60 mg/l reduced the turbidity to 2.75 NTU, 2.63 NTU, 2.34 NTU, 0.83 NTU, 0.71 NTU, and 1.02 NTU, respectively, from 7.22 NTU of mountain water in the rainy season. Finally, added alum concentrations from 10 mg/l to 60 mg/l, the turbidity reduced to 0.63 NTU for alum 10 mg/l, 0.39 NTU for alum 20 mg/l, 0.01 NTU for alum 30–60 mg/l, which all reduced from 0.47 NTU of mountain water in the cold season.
Figure 5 was the result of optinum alum dose for mountain water in Lahu village. The appropriately alum dose used in the rainy and summer seasons were 40 mg/l. In cold season, the the appropriately alum dose was 10 mg/l. Comparison of appropriately alum doses among three seasons found that the alum doses of rainy season = summer season > cold season.
Lisu
The mountain water was sampling raw water for six liters from a weir on-mountain in summer, rainy, and cold seasons in 2019. Then we measured the turbidity, TDS, and pH of mountain water. In summer, the quality of mountain water, that found 5.61 NTU for turbidity, 30 mg/l for TDS, and 8.39 for pH. In rainy seasons, the quality of mountain water was found that 4.01 NTU for turbidity, 30 mg/l for TDS, and 8.37 for pH. Finally, in the cold season found 2.80 NTU, 30mg/l for TDS, and 7.65 for pH. Comparison of the turbidity of mountain water among three seasons found that the turbidity of summer season > rainy season > cold season as shown in Fig. 4.
Jar test experiment, we added various alum concentrations from 10 mg/l to 60 mg/l in mountain water. Alum concentrations at 10 mg/l, 20 mg/l, 30 mg/l, 40 mg/l, 50 mg/l, and 60 mg/l reduced the turbidity to 1.15 NTU, 0.79 NTU, 0.70 NTU, 1.42 NTU, 2.28 NTU, and 2.05 NTU, respectively, from 5.61 NTU of mountain water in summer season as shown in Fig. 4. In addition, Alum concentrations from 10 mg/l to 60 mg/l reduced the turbidity to 1.26 NTU, 0.84 NTU, 0.68 NTU, 1.95 NTU, 2.09 NTU, and 1.91 NTU, respectively, from 4.01 NTU of mountain water in the rainy season. Finally, Alum concentrations from 10 mg/l to 60 mg/l, all samples reduced the turbidity to 0.01 for alum 10–60 mg/l which all reduced from 2.80 NTU of mountain water in the cold season.
Figure 5 was the result of optinum alum dose for mountain water in Lisu village. The appropriately alum dose used in the rainy season and summer were 20 mg/l. In cold season, the the appropriately alum dose was 10 mg/l. Comparison of appropriately alum doses among three seasons found that the alum doses of rainy season = summer season > cold season.
Our studies applied alum in form of potassium alum (KAl(SO₄) ₂·12H₂O) which is the difference from previous studies (Baghvand et al., 2010, Lanciné et al., 2008 Zainal-Abideen et al., 2012, León-Luque et al., 2016,, Saritha et al., 2017). Table 1 shows optimum coagulant doses 10–14 mg/l for turbidity 1.30–7.22 NTU. The mountain water was raw water samples which low turbidity than other surface waters for Jar test experiments (Lanciné et al., 2008, Baghvand et al., 2010, León-Luque et al., 2016, Saritha et al., 2017). The optimum coagulant doses of raw water used between 12–300 mg/l which depended on raw water types, coagulant types, quality of raw water such as pH, temperature, natural organic matters (NOM) (Hand et al, 2012).