A new approach of progressive freeze concentration in removing of 2, 4, 6 trichlorophenol from wastewater: effect of coolant temperature & optimization studies by using response surface methodology (RSM)

2,4,6-Trichlorophenol (TCP) is a poisonous, carcinogenic and mutagenic pollutant that is characterize as a clear and colourless liquid, have strong odour like trichloroethylene or chloroform. 2,4,6-TCP has been classified as one of the primary pollutants as enacted by the Department of Environment (DOE). According to Malaysia in Environmental Quality Act 1979 (Sewage and Industrial Effluent), it should be treated to be less than 1 ppm for inland water discharge. PFC is a separation process by using freezing to progressively produces ice crystal layer by layer on a cooled surface until it forms a large and single crystal block. The aim of this paper is to study the effect of coolant temperature on the performance of progressive freeze concentration (PFC) in removing 2,4,6 TCP from wastewater. The performance determinant used to measure the efficiency of the process were effective partition constant, K and TCP reduction, TR. To achieve the objective of the experiment, 100 ppm of TCP simulated wastewater samples were used throughout the experiments to ensure the data obtained can be applied to the industries in the future. The experiments were operated at different coolant temperature started at -3⁰C, -4⁰C, -5⁰C, -6⁰C, and -7⁰C. Operation time was kept constant at 30 minutes and circulation flowrate rate 700 rpm. By conducting experiment to study the effect of coolant temperature towards PFC performance, it was found that low K value and high TR was obtained at -6oC. Moreover, this paper also aims to obtain the optimum coolant temperature and circulation flowrate for better performance of PFC using Response Surface Methodology provided by STATISTICA 12.5 software. The values of R2 of the model obtained for K and TR were 0.957 and 0.927 respectively indicates that the ANOVA model were fit as it was more than 0.9. According to the ANOVA analysis, PFC system was predicted to be able to produce low K value of 0.15 at -4.55⁰C of coolant temperature and 1255rpm of circulation flowrate. The analysis also predicted that the PFC able to produce TR as high as 84.81% at -5.04oC of coolant temperature and 862.08 rpm of circulation flowrate. Validation experiments also was done to verify the prediction of ANOVA analysis, and the K and TR value were obtained at 0.415 and 73% with percentage error of 176.67% and 13.93% respectively.