title: Optimizing the coagulation process in a drinking water treatment plant -- comparison between traditional and statistical experimental design jar tests.
abstract: In this study of coagulation operation, a comparison was made between the optimum jar test values for pH, coagulant and coagulant aid obtained from traditional methods (an adjusted one-factor-at-a-time (OFAT) method) and with central composite design (the standard design of response surface methodology (RSM)). Alum (coagulant) and polymer (coagulant aid) were used to treat a water source with very low pH and high aluminium concentration at Sri-Gading water treatment plant (WTP) Malaysia. The optimum conditions for these factors were chosen when the final turbidity, pH after coagulation and residual aluminium were within 0-5 NTU, 6.5-7.5 and 0-0.20 mg/l respectively. Traditional and RSM jar tests were conducted to find their respective optimum coagulation conditions. It was observed that the optimum dose for alum obtained through the traditional method was 12 mg/l, while the value for polymer was set constant at 0.020 mg/l. Through RSM optimization, the optimum dose for alum was 7 mg/l and for polymer was 0.004 mg/l. Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. The final turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits. The RSM method was demonstrated to be an appropriate approach for the optimization and was validated by a further test.
authors.affiliation: Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 Johor-Bahru, Malaysia. muzaffar@utm.my
authors.forename: M
authors.initials: M
authors.lastname: Zainal-Abideen
authors.forename: A
authors.initials: A
authors.lastname: Aris
authors.forename: F
authors.initials: F
authors.lastname: Yusof
authors.forename: Z
authors.initials: Z
authors.lastname: Abdul-Majid
authors.forename: A
authors.initials: A
authors.lastname: Selamat
authors.forename: S I
authors.initials: SI
authors.lastname: Omar
mesh_terms: D000534:Alum Compounds; D011232:Chemical Precipitation; D009391:Nephelometry and Turbidimetry; D014867:Water / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis* / Q000592:standards*
chemical_list: D000534:Alum Compounds; D014867:Water; C041524:aluminum sulfate