Performance of dithiocarbamate-type flocculant in treating simulated polymer flooding produced water

Produced water from polymer flooding is difficult to treat due to its high polymer concentration, high viscosity, and emulsified characteristics. The dithiocarbamate flocculant, DTC (T403), was prepared by the amine-terminated polyoxypropane-ether compound known as Jeffamine-T403. The product was characterized by IR spectra and elemental analysis. The DTC agent chelating with Fe2+ produced a network polymer matrix, which captured and removed oil droplets efficiently. Oil removal by the flocculent on simulated produced water with 0, 200, 500, 900 mg/L of partially hydrolyzed polyacrylamide (HPAM) was investigated for aspects of effectiveness of DTC (T403) dosage and concentrations of HPAM and Fe2+ ions in the wastewater. Results showed that HPAM had a negative influence on oil removal efficiency when DTC (T403) dosage was lower than 20 mg/L. However, residual oil concentrations in tested samples with different concentrations of HPAM all decreased below 10 mg/L when DTC (T403) dosage reached 30 mg/L. The concentration of Fe2+ in the initial wastewater had a slight effect on oil removal at the range of 2-12 mg/L. Results showed that Fe3+ could not be used in place of Fe2+ as Fe3+ could not react with DTC under flocculated conditions. The effects of mineral salts ions were also investigated.