Experimental Study On Densadeg Technique In Enhanced Wastewater Treatment

The research of this paper is partial contents of the Shandong 2009 Special Environmental Protection fund project of "application study on Densadeg technique in upgrading the sewage treatment plant". According to the needs of upgrading for municipal sewage treatment plant, the applicability of Densadeg in advanced treatment process was studied in sewage plant. Through the static experiments and the continuous small-scale tests, my experiment made some primary lab researches about the running of Densadeg, in which used the secondary effluent of biological contact oxidation tank and settled water as raw water. At the same time, it also analyzed and compared the treated effects of the two kinds of raw water, and it also established the mass balance equation. The main research results of the thesis are as follows:(1). The optimum dosage of FeCl3 and PAM is selected at 45mg/L and 0.4mg/L respectively, by static experiments which took FeCl3 as the coagulants and PAM as the flocculants. In this situation, the removal rate of SS reached 91.89% with the SS values of supernatant 15mg/L.(2).The data acquired from the static experiments was taken to be used in the dynamic tests. After the continuous running of small-scale Densadeg, the optimum sludge recirculation and dosage of FeCl3 can be acquired at 60L/h and 60mg/L respectively. Under this optimal conditions, the removal rates of SS,TP and COD reached 75.64%,77.89% and 62.74%,with SS,TP and COD values of the effluent 28mg/L,1.09mg/L and 134.33mg/L respectively (temperature:9.3-10.8℃).(3).During the test of selecting the optimum sludge recirculation (temperature:16.5-18.3℃), the SS,TP and COD values of the effluent are 61.37mg/L,1.78mg/L and 194.77mg/L with the sludge recirculation of OL/h, under which condition the removal rates of SS,TP and COD only reach 65.13%,59.08% and 50.12%, whereas at the sludge recirculation of 60L/h, the removal rates of SS,TP and COD could reach 93.52%,89.72% and 72.78%, with the SS,TP and COD values 14mg/L,0.534mg/L and 106.28mg/L respectively. The result implied the sludge recycling can greatly affect the Densadeg's running. (4).Temperature plays an important role in treatment effect through analysis and comparison of the data. At the water temperature of above 15℃, the removal rates of SS and TP could reach more than 90%, and of COD is more than 70%. While at the water temperature of below 10℃, the removal rates of SS and TP could only reach between 70%-80%, and the removal rates of COD is only about 50%.(5).Taken the entire Densadeg as the research object, it has established the mass balance equation for SS. The balance ratios of SS achieved 99.18%.