Multi-electrode bioelectrochemical treatment system (ME-BET; membrane less) consisting of six electrode assemblies (E1–E6) was designed and fabricated for the treatment of complex chemical based wastewater with high salt concentration. The performance was compared with single electrode assembly BET reactor (SE-BET). Enhanced TDS and COD removal was observed in ME-BET (32%; 56%) compared to SE-BET (15%; 23%) as a result of in situ bio-potential from multi-electrodes through the oxidation of organic substrate in the wastewater. Inorganic pollutants viz., nitrates (28%; 8%), sulphates (25%; 9%) and phosphates (20%; 7%) removal was higher in ME-BET in comparison with SE-BET and this was also supported with bioelectrogenic activity (584; 160 mW/m3). The study infers that designing of compact reactors with multiple electrodes in a single system enhances the anodic reactions and enable effective treatment of complex wastewaters with simultaneous power production. © 2017 Elsevier Ltd