Study On Process Of Treatment Of Wastewater With High Concentrations Of Polyacrymide

Polyacrymide (PAM) is a type of colorless, noncorrosive and viscous colloidal polymer, and is multi-functional linear polymers. Acrylamide (AM) is produced when PAM is degraded. AM is a matter of high carcinogenic and teratogenic organic. A mount of wastewater containing PAM and AM is discharged from domestic chemical companies producing PAM. PAM wastewater is a relatively refractory chemical wastewater with complex compositions, because of poor biodegradability.The treatment methods for PAM wastewater contain special activated sludge, pulsed laser discharge method, Fenton oxidation method, and ultrasonic degradation method, etc. According to current technologies of PAM degradation, composite coagulant was made by attapulgite and PAC by a certain percentage. This coagulant was used for pretreatment of PAM wastewater. Treated wastewater was pumped into anaerobic reactor for improving biodegradability and for denitrification process. Anaerobic effluent was pumped into aerobic reactor for organic matter degradation and nitrification of ammonia.COD removal rate was 33.45% when 375mg/L of attapulgite was added as the only adsorption and coagulation of the nuclei. COD removal rate was 43.22% when 500mg/L of PAC was added as the only coagulation. With attapulgite, PAC coagulation-adsorption system, adding 75mg PAC to 200ml wastewater, the mass ratio of PAC to attapulgite was 4:1. Adding 100mg PAC to 200ml wastewater, the mass ratio of PAC to attapulgite was 6:1. Under the optimal ratio, when pH was 6-6.5, the peak of COD removal efficiency appeared.The pH value of anaerobic effluent increased with the residence time and stabilized at 8.5 at last. When the pH value was 7.5, COD removal rate added up to 45% and the highest concentration of NH4-N was 850mg/L. According to the results of NH4-N, the optimal temperature for anaerobic was 35℃. COD removal rate added up to 52% and the concentration of NH4-N was 860mg/L. The results of 25℃was better than that of 30℃.In aerobic reactor, the optimal pH for PAM degradation was 7.5, and the optimal pH for NH4-N degradation was 8.0. When the concentration of DO was 3.2mg/L, COD removal rate was 85%. By adding activated carbon to the aerobic reactor, the concentration of DO increased 0.6-0.8mg/L and COD removal rate increased by about 4 percentage points, from 84% to 88%. The dosage of activated carbon was 50mg, 250g/t PAM wastewater.