Study On Treatment Of Paper-mill Mid-stage Wastewater By Combined Hydrolysis Acidification And Activated Sludge Technology

This paper deals with hydrolysis acidification and activated sludge combined technology to study paper-plant mid-stage wastewater from Wuhan Chen-ming paper- plant, which is characterized as high concentration of undegradable organic compounds and low concentration of nitrogen and phosphorus.Principles of hydrolysis acidification and activated sludge for treatment of mid-stage wastewater were systemically expatiated. Firstly, hydrolysis acidification was used to change some hard to degradable organic compounds into small molecular and easily decomposed organics. Then aeration was utlized to improve removal rate of contamination in wastewater. Anaerobic-activated sludge combined process could unite anaerobic and anaerobic reaction, taking the advantages of different microbes, which has a good applying prospect to remove high concentration organic compounds.Optimum process parameters were determinated through experiments. This paper aimed at developing a reasonable technology to dispose paper-plant mid-stage wastewater, offering some theoretical and practical reference data for the process of wastewater like mid-stage wastewater. Experimental results are shown as follows:Anaerobic pretreatment can increase biochemical quality of mid-stage wastewater, when the temperature is under 40℃and hydraulic retention time(HRT) was 10h, the effect of anaerobic was very distinct. After that, the removal rate of COD is about 34%. The technologic parameters for the latter activated sludge are: hydraulic retention time was 12h, the DO of the intermixed liquid was 3mg/L, volume load was below 1.5kgCOD/m3·d, the removal rate of COD is about 80%. As a result, COD in discharged water is certified. But when the temperature is more than 40℃, the unitary technology's removal rate of COD is about 55%. The discharged water cannot reach the emission control regulations.