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Water treatment

were used to collect

were used to collect samples for DO analysis and plastic cylinders of 250 ml were used for iron and manganese. Sterilised bottles of 250 ml were used for bacteriological analysis. Table 3.3 Sampling points and frequency at the MSF pilot system. 1991-1993 Sampling Point 01 02 05 1.1 1.2 1.3 1.4 Parameter 03 3.1 3.2 2.1 2.2 04 4.1 4.2 3.3 3.4 5.1 5.2 4.3 5.3 4.4 5.4 Turbidity (NTU) 3d 3d 3d 3d 3d 3d 3d Colour (PCU) (1) 2w 2w 2w 2w 2w 2w 2w Faecal coliforms (CFU/100 ml) 2w 2w 2w 2w 2w 2w 2w Temperature ( o C) 4d pH (Units) f f f f Total iron (mgl -1 ) m m m m m m m Total manganese (mgl -1 ) m m m m m m m Total solids (mgl -1 ) m m m m m m m Suspended solids (mgl -1 ) (2) 2w 2w 2w 2w(4) 2w(4) 2w 2w Volatile solids (mgl -1 ) m m m m m m m Filterability (ml.3min -1 ) (3) f f f Dissolved oxygen (mgl -1 ) f f f f Total hardness (mgl -1 Ca CO 3 ) m m m m Total alkalinity (mgl -1 Ca CO 3 ) m m m m Chemical oxygen demand (mgl -1 ) m m m m m m Headloss (cm) 4w 4w 4w 4w 4w Flow (ls -1 ) d d d d(5) d d= daily; w= weekly; f= fortnightly; m= monthly (3) Only in period I (1) It was reduced to 3f in periods III and IV (4) It was reduced to 3f in period III in points 1.2 and 5.2 (2) It was reduced to 3f in period IV (5) Only in point 2.1 3.1.7 Analytical methods. Samples obtained throughout the MSF pilot studies were analysed using methods typical of water treatment systems, as outlined in table 3.4. The analytical techniques used conformed to established procedures as defined by Standard Methods (APHA et al, 1989) unless noted otherwise. Specific considerations about some of the analytical methods follow. Turbidity (NTU) measurements were performed with a HACH ® Model 2100 A (Hach Company., Loveland, Colo.). Calibration was performed according to the manufacture's specification on three turbidity standards made from three formazin primary turbidity standards (100, 10 y 1 NTU) at 3-month interval. Secondary standards were used to check calibration prior to every set of measurements. Direct turbidity measurements were performed on samples with turbidity readings

Table 3.4 Analytical water treatment methods and references Parameter Standard Methods (APHA et al, 1989) Equipment and other references Turbidity (NTU) Part 2,130 B Hach turbidimeter Colour (PCU) Shimadzu. Spectroph. UV-120-01, 455nm (Annex 3) Suspended solids (mgl -1 ) Part 2,540 D (Annex 3) Filterability test (ml.3min -1 ) Wegelin, 1986 Total solids (mgl -1 ) Part 2,540 B Volatile solids (mgl -1 ) Part 2,540 G Temperature ( o C) Part 2,550 A Hediger, Basel (-10ºC - 100ºC) Silt test (%) Lloyd, 1974. pH (Units) Part 4,500 A WTW 522 Total alkalinity (mgl -1 CaCO 3 ) Part 2,320 B Total hardness (mgl -1 CaCO 3 ) Part 2,340 C Dissolved oxygen (mgl -1 ) Part 4,500 C Microprocessor Oximeter OXI 537 WTW Chemical oxygen demand (mgl -1 ) Part 5,220 B Total iron (mgl -1 ) Part 3,500 Fe D Shimadzu spectrophotometer UV-120-01, 510nm Total manganese (mgl -1 ) Part 3,500 Mn D Shimadzu spectrophotometer UV-120-01, 525nm Faecal coliforms (CFU/100 ml) Part 9,222 Colour measurements were performed with a Shimadzu ® model UV-120-01 (Shimadzu Corporation. Tokyo, Japan) operating at 455-nm, providing a light path of 1cm or 10 cm based on adaptation of the procedure specified, section 2120B of the Standard Methods (APHA et al, 1989). Calibration curves were obtained with platinum-cobalt standards in the ranges 0-10 and 0-100 PCU, prepared from a standard solution of 500 PCU. Collected samples were centrifuged at 3000 rpm for 15 min., before taking absorbance readings. These readings were used to estimate colour measurements using calibration curves as shown in Annex 3. Samples with colour readings ≥100 PCU were diluted with distilled water to readings