Optimal clarification of emulsified oily wastewater using a surfactant/chitosan biopolymer

PEREZ CALDERON J.; SANTOS M.V.; ZARITZKY NOEMI.

Journal of Environmental Chemical Engineering

ELSEVIER SCI LTD

Lugar: Amsterdam ; Año: 2018 vol. 6 p. 3808 - 3818

2213-3437

The presence of emulsified oils in wastewater from the petroleum and petrochemical industry causes a significantenvironmental concern. The effect of chitosan (CH) and sodium dodecyl sulfate (SDS) doses on the destabilization of emulsified wastewater was analyzed based on key parameters such as: residual turbidity (%RT), relative length of the clarified zone (CL), chemical oxygen demand (% COD) and zeta potential (ZP).A response surface methodology and central composite design were applied for optimizating the influence ofCH and SDS doses, on the performance of the demulsification process. A desirability test allowed to calculate the optimal doses of CH and SDS to produce: i) minimum values of%RT and ZP and ii) maximum values of CL and % COD removal.A novel kinetic model based on first order equations for both stages: coagulation/flocculation and settling of the flocs was proposed to describe clarification using measurements of static dispersion of light and back scattering profiles (BS). The proposed model is a useful tool for predicting clarification times and to analyze the governing mechanisms of the process.Coagulation/flocculation occurs in less than 3 h reaching very low turbidity values in the clarified zone (< 11% RT). Additionally, the BS profiles after 3 h showed that at the optimal dosage of CH and SDS 70% of the total volume was clarified with a total hydrocarbon removal of 98.61%. This study demonstrates that CH constitutes a potent flocculating/coagulating agent in waste-water emulsified systems from petroleum industry