The Study On The Treatment Of Phenol Resin Wastewater By Combined Electrochemical Oxidation And Moving-bed Biofilm Reactor

The phenol resin wastewater contains high organic pollutants which are difficult to degrade by biology. Phenol and formaldehyde are main pollutants that could restrain and poison bacteria disposing the wastewater.So some pretreatment process must be carried on to deal with phenol resin wastewater. Treatment of phenol resin wastewater by moving-bed biofilm reactor combined with electrochemical oxidation pretreatment were studied in this paper. Using anode materials that were synthesized independently in the electrochemical oxidation, lab research has determined the optimal parameter.A engineering project was based on this research and favourable result was obtained.Meanwhile the studies of Ti/RuO₂ anode preparated by brush coating thermal decomposition, Ti/SnO₂ anode preparated by brush coating thermal decomposition, Ti/SnO₂-Sb₂O₃/PbO₂ anode preparated by brush coating thermal decomposition and anode deposit were represented by testing polarization curves. Ti/SnO₂-Sb₂O₃/PbO₂ anode was one of the present best anode materials for electrochemical wastewater treatment.After the polycondensation of one single phenol resin wastewater, it is effective to use electrochemical oxidation removing phenol and formaldehyde. In polycondensation process, the proportion of phenol and formaldehyde is 1.5:1 while using 6 g·L^-1 HCl. The removal rates of phenol and formaldehyde are 79%and 94%, in electrochemical time of 18h, when current density is 40mA·cm^-1 and pH value is 1.47.According to the real project, six different phenol resin waste waters were mixed and treated by the combined process of electrochemical oxidation and moving-bed biofilm reactor. The optimal parameter is obtained: Electrochemical time is 20h, when current density is 40mA·cm^-1 and electrolyte concentration is 70 mM·L^-1. Bio-carrier volume of moving-bed biofilm reactor is 10%, HRT is 6h.The removal rates of phenol and formaldehyde are both 99.9%. this combined process of electrochemical oxidation and moving-bed biofilm reactor is highly practicable. This technics has been successfully applied in the engineering project which was designed for the treatment of phenol resin wastewater.The quality of effluent has achieved the third national standard(GB8978-1996).