Experiment On Treatment Of Chemical Wastewater By Catalyzed Iron Internal Electrolysis Coupling With Biofilm Treatment

The catalyzed iron inner electrolysis (CIIE) process is a new developed method for wastewater treatment, which is easier for the refractory organic pollutants to turn into biodegradable matters. It will be used widely coupling with biological treatment processes. It is necessary to study the effect of coupling process on the chemical wastewater treatment and the effect of CIIE on biofilm, extracellular polymeric substances (EPS), etc.The continuous lab-scale experiment using the process of catalyzed iron inner electrolysis coupling with a moving bed biofilm reactor(CIIE-MBBR) was conducted to treat the chemical wastewater in Taopu wastewater treatment plant in Shanghai. At the same time the parallel experiment not using the coupling process was carried out. A comparison was done between the coupling reactor and not coupling reactor on the treating effect, biofilm mass and EPS. Also the effects of working conditions on the coupling process were investigated and the causes were discussed.Under the following conditions as: the filling density of Fe/Cu was 27.06 Kg/m3, the packing ratio of support media was 50%, hydraulic retentiong time(HRT) was about 16h and DO was around 4mg/L, etc., the experimental results showed that compared with the not coupling reactor, the removal efficiencies of COD, color, PO₄^3--P, TP and TN were 5.8%,20.8%,23.6%,33.6% and 29.7% higher, respectively. The coupling process could alleviate the shock loading. The filling density of Fe/Cu had more obvious effects on the removal of P and color, than on the removal of COD, NH3-N. When DO is 4mg/L, the coupling process is especially effective on the removal of both NH3-N and TN, achieving synchronization nitrification and denitrification.The Fe content of biofilm in the coupling reactor was more than 14%. The coupling process increased the biofilm mass on the filler. The total amount and protein content of EPS in coupling reactor were higher than those in not couplingreactor, but the polysaccharides content was almost no change.The pilot-scale experiment on pretreatment of the mixed chemical wastewater in Taopu industry zone by CIIE process was carried out. The results show that it is an effective pretreatment process with obvious decolourising performance. Under the condition of micro-aeration, the average removal efficiencies of color> COD> PO43--P and TP are 41.3%, 54.5%, 87.5% and 79.4%, respectively. Furthermore, the process could adjust the influent quality and alleviate the shock loading. The results of long-term operation in pilot-scale experiment indicated that CIIE process had a good coupling with the following biological treatment processes, which made the whole system running more stably and improved the quality of effluent. The passivation and hardening of Fe/Cu in CIIE process could be avoided effectively as long as bounce-back was done rationally.The catalyzed iron inner electrolysis with PAM flocculation (CIIE-PAMF) process had obvious effect on the removal of main pollutants in the mixed chemical wastewater treatment. Especially under aeration, the CIIE-PAMF process was more effectively than CIIE.