A method for refinery wastewater treatment, the method comprising: passing a wastewater effluent through a hybrid electrode stack, wherein the hybrid electrode stack comprises: - a first part which comprises a plurality of hybrid electrodes i.e. hybrid working electrodes composed of sacrificial metals, biocompatible coagulants, and conductive electrodes; wherein the conductive electrodes are coated or filled or mixed with the sacrificial metals along with the biocompatible coagulants; wherein the sacrificial metals are selected from aluminum (Al) and/or iron (Fe) or their different forms; and wherein the biocompatible coagulants are selected from the group consisting of tannic acid, galacturonic acid, sorbitol, and chitosan; - a second part which comprises a plurality of hybrid electrodes i.e. hybrid counter electrodes arranged in alternate sequence to form a stack and are connected in a parallel circuit with the first part; and - a non-conductive spacer and an electrode header unit for avoiding short circuit between the electrodes; wherein the non-conductive spacer has the first and second parts mounted on it either vertically or horizontally, applying a direct current potential of 5-10 V across the hybrid electrode stack under ambient conditions to initiate flocculation, coagulation and oxidation reaction, and separate contaminants present in the wastewater effluent, and discharging from the hybrid electrode stack a treated wastewater having a reduced BOD and COD content and a purity of 80 to 85%, wherein the wastewater effluent is passed through the hybrid electrode stack at a flow rate to maintain a hydraulic retention time of 45-60 mins and at an ambient pressure. - a first part which comprises a plurality of hybrid electrodes i.e. hybrid working electrodes composed of sacrificial metals, biocompatible coagulants, and conductive electrodes; wherein the conductive electrodes are coated or filled or mixed with the sacrificial metals along with the biocompatible coagulants; wherein the sacrificial metals are selected from aluminum (Al) and/or iron (Fe) or their different forms; and wherein the biocompatible coagulants are selected from the group consisting of tannic acid, galacturonic acid, sorbitol, and chitosan; wherein the conductive electrodes are coated or filled or mixed with the sacrificial metals along with the biocompatible coagulants; wherein the sacrificial metals are selected from aluminum (Al) and/or iron (Fe) or their different forms; and wherein the biocompatible coagulants are selected from the group consisting of tannic acid, galacturonic acid, sorbitol, and chitosan; - a second part which comprises a plurality of hybrid electrodes i.e. hybrid counter electrodes arranged in alternate sequence to form a stack and are connected in a parallel circuit with the first part; and - a non-conductive spacer and an electrode header unit for avoiding short circuit between the electrodes; wherein the non-conductive spacer has the first and second parts mounted on it either vertically or horizontally, applying a direct current potential of 5-10 V across the hybrid electrode stack under ambient conditions to initiate flocculation, coagulation and oxidation reaction, and separate contaminants present in the wastewater effluent, and discharging from the hybrid electrode stack a treated wastewater having a reduced BOD and COD content and a purity of 80 to 85%, wherein the wastewater effluent is passed through the hybrid electrode stack at a flow rate to maintain a hydraulic retention time of 45-60 mins and at an ambient pressure.