Abstract:

The treatment of municipal wastewater with chemical coagulation and electro-coagulation was an effective technology. The experiment was carried out with CaO, Ca(OH)₂ and FeCl₃  as the flocculants. Mixing time and the amount of reagent being used were investigated. It showed that the treatment effect was the best with 0.1%(m/V）Ca(OH)₂ and 0.1mL/100mL FeCl₃(40%,m/V) as the flocculants and mixing time is 5 minutes. The left SS and turbidity were 6 mg/L and 3.5 NTU, respectively. The SS removal ratio was up to 97%. The residual COD and TP were 166 mg/L and 3.66 mg/L, respectively. During the electro-coagulation,the COD removal ratio and the TP removal ratio were up to 87.1% and 97.5% at a current density of 20 mA/cm2 using 0.3‰ H₂O₂ as a reagent in 20 minutes. It reached the first class discharge standard of China national wastewater(COD＜50 mg/L,TP＜0.5 mg/L).

Key words: municipal wastewater, chemical coagulation, electro-coagulation