Performance of synthetic organic polymer (polyacrylamide) and natural organic polymers (pectin) as flocculant in coagulation-flocculation treatment will be assessed. Analysis of functional group of organic polymer was done by Fourier Transform Infrared Spectroscopy - Attenuated Total Reflectance (FTIR-ATR). Response Surface Methodology - Central Composite Design (RSM-CCD) was used to evaluate the interaction effects of pH, coagulant dose and flocculant dose. The experiment was conducted in lab scale of 500mL of sample textile wastewater with six paddle of conventional jar test. Trimmed Spearman-Karber method has been used to estimate median lethal concentration (LC ) values and 50 their confidence intervals. The result shows polyacrylamide added in the treatment was the best at optimum pH 5, coagulant dose at 275 mg/ L and flocculant dose at 35 mg/ L with 88 and 80% removal. In contrast, additions of natural organic flocculant only manage to remove 54.2 and 67 % at the optimum pH 5, coagulant and flocculant dosage at 427.4 and 21.9 mg/ L respectively. However, polyacrylamide treatment claimed to be more toxic based on lethal concentration (LC50) at 17 % compare to natural organic flocculant at 34%.
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