NOVELTY - The electrode has a frame (101) that is provided with a non-conductive substance. A first conductive substance is linked or secured to the frame so as to be electrically connected to a planar electrode material as the current collectors (102). The first conductive substance and frame are taken together to form a unitary structure of the frame. The first conductive substance is attached or secured to the structure of the frame. The frame is attached to an exterior or perimeter of the planar electrode material.    USE - Electrode such as anode and cathode for use in bio-electrochemical system (claimed) used for treating water and generating electricity and value-added products such as methane and hydrogen.    ADVANTAGE - The first conductive substance is linked or secured to the frame so as to be electrically connected to a planar electrode material as the current collectors so as to remove biological oxygen demand (BOD) in wastewater while generating modest amounts of electricity such that the bio-electrochemical systems (BES) is provided with the potential to enhance the closure and energetics of water treatment systems. Thus, the efficiency and economic viability of BES systems incorporating the electrodes, materials and designs of the electrodes are improved effectively while increasing the characteristics such as conductivity, surface area and bio-compatibility and reducing the cost of materials and construction. Hence, the individual electrodes in multi-electrode BES are maintained or replaced easily. The current collector facilitates the transfer of electrical current from the electrode to the external electrical circuitry. Thus, the overlapping assembly prevents shifting the inter-locking tongue and groove assembly.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a bio-electrochemical electrode cassette;    (2) a bio-electrochemical system;    (3) a method for operating bio-electrochemical system; and    (4) a method for constructing electrode material for bio-electrochemical system.    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional views of the planer electrode with the electrical contact point protruding from the frame.    Planar electrode (100)    Frame (101)    Current collectors (102)    Contact point (103)    Overlapping assembly (104)