Improvement of Onsite Wastewater Treatment By Use of Electrically Conductive Carbon Cloth

The purpose of this research is primarily focused on carbon oxidation in domestic septic systems. Small-scale septic waste reactors utilizing electrically conductive carbon cloth were assessed for improving carbon oxidation and therefore the overall efficiency of on-site wastewater treatment systems. A bioelectrochemical system was developed to enhance carbon oxidation in septic systems using electrically conductive carbon cloth as an anode/cathode bridge to transfer electrons from strictly anoxic septic wastewater to an oxic system outside of the septic reactor. This 'septic snorkel' (so named since the system 'breathes' via the carbon cloth extends into an aerobic zone) was designed to lower the carbon loading on the leach field, while being simple to deploy at the field level, which would be necessary for regulatory and stakeholder approval. The concept is predicated on previously published work that demonstrated Fe(III) amendment to septic wastewater increased carbon mineralization. Data with Fe(III) amendment (an analogous system) demonstrated that mineralization of 14C-labeled acetate, lactate, propionate, starch, glucose, and oleic acid increased by as much as 100%, while completely suppressing methane production. Bench scale results using different carbon cloth setups suggested that complete and open circuit configurations improved soluble COD removal by 25% and 23% respectively. Select 14C-labeled compounds were also tested using the carbon cloth system. Interestingly, reactors with carbon cloth alone (no circuitry) showed the highest mineralization for all 14C-labeled compounds. Increases in mineralization ranged from 16% to 82%.