An electrocoagulation reactor (ECR) apparatus for treatment of a fluid stream, comprising: (A) an electrode packing frame , wherein the electrode packing frame comprises: (i) a pair of opposing inserts , wherein each of the inserts comprises a plurality of insert openings ; and (ii)an electrode stack, wherein the electrode stack comprises a plurality of electrode plates, wherein the plurality of electrode plates comprises an upper and a lower terminal electrode plate , and a plurality of intermediate electrode plates sandwiched between the upper and lower terminal electrode plates , wherein each of the terminal electrode plates is configured as an anode or a cathode, wherein each of the terminal electrode plates is configured to be thinner in comparison to the intermediate electrode plates , wherein each of the intermediate electrode plates is bipolar such that a first planar or flat side of each of the intermediate electrode plates is an anode and an opposing planar or flat side of the same intermediate electrode plate is a cathode, and wherein each of the electrode plates is horizontally stacked within a pair of opposing insert openings formed on the pair of opposing inserts ; and (B) a cell comprising cylindrical sidewalls, wherein the electrode packing frame is inserted within the cylindrical cell, wherein a conducting bar extends across a length of each of the horizontally stacked upper and lower terminal electrodes . (A) an electrode packing frame , wherein the electrode packing frame comprises: (i) a pair of opposing inserts , wherein each of the inserts comprises a plurality of insert openings ; and (ii)an electrode stack, wherein the electrode stack comprises a plurality of electrode plates, wherein the plurality of electrode plates comprises an upper and a lower terminal electrode plate , and a plurality of intermediate electrode plates sandwiched between the upper and lower terminal electrode plates , wherein each of the terminal electrode plates is configured as an anode or a cathode, wherein each of the terminal electrode plates is configured to be thinner in comparison to the intermediate electrode plates , wherein each of the intermediate electrode plates is bipolar such that a first planar or flat side of each of the intermediate electrode plates is an anode and an opposing planar or flat side of the same intermediate electrode plate is a cathode, and wherein each of the electrode plates is horizontally stacked within a pair of opposing insert openings formed on the pair of opposing inserts ; and (i) a pair of opposing inserts , wherein each of the inserts comprises a plurality of insert openings ; and (ii)an electrode stack, wherein the electrode stack comprises a plurality of electrode plates, wherein the plurality of electrode plates comprises an upper and a lower terminal electrode plate , and a plurality of intermediate electrode plates sandwiched between the upper and lower terminal electrode plates , wherein each of the terminal electrode plates is configured as an anode or a cathode, wherein each of the terminal electrode plates is configured to be thinner in comparison to the intermediate electrode plates , wherein each of the intermediate electrode plates is bipolar such that a first planar or flat side of each of the intermediate electrode plates is an anode and an opposing planar or flat side of the same intermediate electrode plate is a cathode, and wherein each of the electrode plates is horizontally stacked within a pair of opposing insert openings formed on the pair of opposing inserts ; and (B) a cell comprising cylindrical sidewalls, wherein the electrode packing frame is inserted within the cylindrical cell, <EOS>