The Study On The Properties Of Biofilm Electrode Material Used In Organic Wastewater Treatment

The exist of pollutant is the leaving questions rooted in production activity ofpeople. The treatment methods should be mild reaction conditions, withoutsecondary pollution, environmentally friendly and easily controlled. Electrochemicalprocess has certain advantages on the harmless treatment on organic pollutants inwater because of high efficiency and environmental protection. Electrode material isthe heart of electrochemical technology. The exploitation and performance ofelectrode is the key problem of wastewater treatment using DSA anode and biofilmcathode. Aiming to treating wastewater with high efficiency, we make a series offundamental researches on electrochemical oxidation technology and biofilmelectrode treating technology.(1) The study on organic pollutant treatment with electrochemicaloxidation technologyWhen degrading phenol with Ti/RuO₂-TiO₂-SnO₂electrode without Cl-insolution, there will be side effects of oxygen precipitation reaction, which makes thereduce of current efficiency. The Cl-transformed into active chlorine before oxygenprecipitation in solution with Cl-on Ru-Ti-Sn anode. Indirect electro-oxidationhappening primarily. Using PbO₂electrode to degrade phenol has higher degrading efficiency than Ru-Ti-Sn electrode. PbO₂-F-electrode has smaller particle size on thesurface and more effective active point than PbO₂electrode, which makes it has highcurrent efficiency on organic pollutant degradation.The requirements of electrochemical oxidation on the electrode materials arehigh, and the current efficiency in the degradation process is largely influenced bythe electrode electrochemical performance. Electrochemical method also hasproblems of low current efficiency, high energy consumption and big operating costs.Therefore, the development and application of biofilm electrode material which haslow-power and high-performance has great significance.(2) The study on influence factors of biofilm electrode performanceBiofilm thickness, electrolyte components, electrode using method, anddissolved oxygen content have effects on the performance of biofilm electrode.Using biofilm electrode to degrade phenol has faster rate than bare titaniumelectrode. Thin biofilm has high degrading efficiency because of the existence ofbiofilm hindered electronic transfer. There are enough carbon source, nitrogensource and inorganic salt in cathode system of biofilm electrode are keys to fullyplay the degrading performance. The bacteria using in the experiment are mixedbacteria with both aerobic and anaerobic properties.(3) The study on influence factors of biofilm electrode preparation rateThe kind of substrate material, adsorption manner, bacteria content, temperature,phenol concentration, and current strength were studied in this part. Electrostaticadsorption has higher biofilm electrode preparation rate than nature adsorption. Thebiofilm is dense and porous, which can reduce the obstruction of electron transferbetween substrate and solution. The adsorption of bacteria is easier on glassy carbonsubstrate than on titanium substrate when powering on. The biofilm is thin whenthere are not many bacteria in the solution, but too many bacteria has strongcompetition and has bad effect on biofilm electrode preparation. The optimumtemperature is the temperature which can insure the metabolism of bacteria, it is thekey to keep the activity of bacteria. The more phenol exist, the faster the biofilmelectrode prepared. This is due to the high concentration of carbon source and faster the breeding of bacteria. When the current is too low, the adsorption of bacteria isslow. If the current is beyond the accept ability of bacteria, the adsorption also cannot be proceed.(4) The study on selectivity of biofilm electrodePhenol-degrading bacteria can not secrete enzyme for H2O₂decomposing. Thebiofilm on substrate hinders the electron transfer, and slows down the response rateof electrode reaction in solution. Using biofilm electrode method to treat water paintwastewater of containing non-phenolic compounds is not effective, mainly due to thehigh concentration of organic pollutants and high toxicity of wastewater. Bypretreating to improve the biodegradability of water paint wastewater anddomesticating biofilm electrode in wastewater system which can increase thepossibility of wastewater treatment using biofilm electrode. The main components ofvanillin wastewater are phenolic compounds. Dealing vanillin wastewater withbiofilm electrode for phenol degradation shows good degradation effect in a periodof time.