Produced Water Treatment By Electrocoagulation Process: Experimental and Modelling Study

Produced water (PW) is the largest by-product that comes out from wells during oil & gas (O&G) fields exploration. These waters contain high saline content along with other organic and inorganic composition. A mathematical model specifically for treatment of PW with electrocoagulation (EC) techniques has been developed. The mechanistic model considers the dominant Al species contribution to COD removal, multi-scale modelling of the EC reactor, the role of Al chloro complex species in impacting the COD removal and the development of mechanistic approach for the removal of COD by the Al complexes dominantly present in the system. The influence of experimental and model working parameters such as current density (10-20 mA/cm2), initial pH (3.1-8.6), interelectrode distance (1.35-4 cm), mixing speed (130-300 rpm) and scale up of EC reactor (0.3-1.5 L) on Al concentration and COD removal was investigated and modelled. The results showed that EC at the current density of 20 mA/cm2 enabled higher COD removal (78.3%) than at the current density of 10 mA/cm2 (68.3%) and 15 mA/cm2 (75%) and mathematical model prediction of COD removal fits well with the experimental data at 10 mA/cm2, and 15 mA/cm2 with R2 value of 0.96 and 0.97, respectively. The initial pH of 7.3 resulted in higher COD removal (95.85%) than the initial pH of 3.1 (64.5%), 6.1 (79.1%) and 8.6 (81.2%) and model reproduces a good fit at initial pH of 6.1, 7.3 and 8.6 with R2 value of 0.92, 0.96 and 0.98, respectively. The variation of constants involved in the model formulation was optimized according to the effect of model working parameters.