| Based on the treatment principle of micro-electrolysis and regarding the dissolution of iron as an index, the best response to micro-electrolysis reaction conditions portfolio with orthogonal experiments and single factor experimental method was determined. The removal effect of the independent SBR process and the micro-electrolysis-SBR process on organic compounds, ammonia-nitrogen, phosphorus and other pollutants in the municipal sewage was compared. The removal mechanism of the iron-carbon activated sludge was studied in this paper. The results were shown as following:(1) The micro-electrolysis-SBR process had high efficiency in the removal of COD and nitrogen. Its reaction time was short, capacity of resisting the impact load was strong and function of active sludge was good. Therefore the application prospect of this method in wastewater treatment was very extensive.(2) The main factor that affects the dissolution rate of iron was HRT, the next were pH, amount of iron-carbon and iron-carbon ratio. The best conditions were that: HRT was 80 min, pH was 7.5, the quality of iron was 50g/L and iron-carbon ratio was 4∶6. Under the selected conditions, the concentration of iron dissolved s 47.11mg/L.(3) The micro-electrolysis-SBR process can improve the removal rate of COD. When the COD concentration of influent was 300 mg/L, the average removal rate of COD was improved to 91.3% from 81.1%, the average removal rate increased from 76.1% to 94.4% when the COD concentration of influent was 500 mg/L, the COD concentration of effluent was decreased from 120.2 mg/L to 28.3 mg/L. In addition, the micro-electrolysis-SBR process only needed 40 minutes to complete degradation, while SBR process needed 80 minutes. Therefore the combined process saved reaction time, reduced energy consumption and the cost of sewage treatment.(4) The micro-electrolysis-SBR process had obvious advantages in the treatment of high concentration of ammonia nitrogen than independent SBR process. When the influent concentration of ammonia was 30 mg/L, the removal rate of two processes can reach to 90%. The advantage of micro-electrolysis-SBR is not obvious, but when the influent concentration of ammonia was increased to 60 mg/L and 100 mg/L, the removal rates of independent SBR process were 75% and 68%, while ammonia nitrogen removal by micro-electrolysis-SBR could be maintained at about 95%.(5) The micro-electrolysis-SBR process had no obvious advantages in the treatment of high concentration of phosphorus than independent SBR process. The micro-electrolysis-SBR process show some advantages only when the influent concentration of phosphorus is 3 mg/L. When the influent concentration of phosphorus was improved, the phosphorus removal rate of two processes were 50% to 75%, the removal rate of MSBR was even lower.(6) After putting the iron and activated carbon padding, the sludge concentration in the bioreactor was different. Under the same volume load the concentration of iron sludge reached to 3.17 g/L, the concentration of conventional activated sludge process was only 2.12 g/L. In addition, the sludge load of iron sludge was reduced from 0.55 kg COD/kg MLSS·d to 0.30 kg COD/kg MLSS·d. When the sedimentation rate of activated sludge was concerned, the iron sludge finished sedimentation 15 minutes less than activated sludge, and sludge SV% respectively were 51 % (ordinary sludge), 31 %(biological iron sludge) . As to the internal structure of sludge, the iron sludge was denser than the ordinary sludge, and the sludge flocs were larger. In addition, there were a lot of protozoa and micro-metazoanin in the iron sludge system.
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