Simulation And Optimization Of JHB Wastewater Treatment Process Based On Model ASM2D

Johannesburg Process (JHB) is one of the variant processes of traditional A2/O processswhich is used in wastewater treatmen. JHB process not only inherited the advantages oftraditional A2/O process, the Settings of pre-hypoxia pool eases the effects of nitrogen oxides,carried by backflow sludge, on subsequent anaerobic reaction. JHB process has the goodremoval efficiency of nitrogen and phosphorus. On the basis of experimental study onlaboratory test of JHB process and insight into the activated sludge model NO.2d, using theMatlab programming, adjusting the parameters of the model and correcting the model by themethod of sensitivity analysis, then use the JHB process model after checking to simulate theoperating conditions of optimized simulation, thus provide reference to guide its practicalapplication. Through this topic research, got the following conclusions:（1）Experimental study of JHB process: Under the operating condition of the sludge ageof20d, hydraulic retention time of11.5h,the water distribution ratio in the process of the pre-hypoxia pool is0.5, the reflux ratio of the sludge is1, the reflux ratio of nitrifying liquid is2,dissolved oxygen in aerobic pool is3.5mg/L, temperature of25℃, neutral pH, thedenitrification ability is good, the accumulation phenomenon of nitrate nitrogenn is slowedand it aslo has certain denitrifying phosphorus accumulating function in the process of thepre-hypoxia pool; The anaerobic pool has good anaerobic environment and can be very goodfor the release of phosphorus; hypoxia pool not only has obvious denitrifying denitrification,but alos a significant denitrifying phosphorus accumulating function; in the process of aerobicpool, the nitration reaction and aerobic phosphorus absorption function is remarkable. In JHBprocess system, the removal rate of phosphate was97.2%and the effect is obvious; it has astrong nitrification ability and ammonia nitrogen removal rate can be as high as99.1%; thenitrate nitrogen concentration in oxygen pool is0.656mg/L and its removal rate was78.21%,the denitrification is significant; the removal rate of COD is good as94.17%and its effluentconcentration is24mg/L. The experimental results show that the JHB process has a goodremoval efficiency of nitrogen and phosphorus.（2）Through the sensitivity analysis of parameters in JHB process model based on ASM2D model,YH、YP O4、q PP、 PAOandK PSfor the phosphorus concentration has a quitelarge influence, parameters such asYP HA、i PSF、bP AO、bP Phas a very big impact onphosphorus concentration; Parameters AUTandbA UThas much effect on the ammonianitrogen concentration, the influence ofq PPand on ammonia nitrogen concentration isgreat; In addition to the parameters ofi NSFhas bigger influence on the nitrate nitrogenconcentration, the other parameters are not sensitive to it; Most of the parameters on the CODhave no effect, the impact of H、bh、 andK HFon the effluent COD is small. Throughthree times of related parameters to adjust, making the the relative error between measuredvalues and the values of ASM2D model simulation of JHB process is less than5%. The wholeadjusted parameter are:=0.87、i NSF=0.01、 HNO3=1.5、bP AO=0.05、 PAO=1.8、bA UT=0.13、 AUT=1.8、K PNO=0.4.3（3）According to the model ASM2D of JHB process after correction to simulate theoptimum operating conditions. Considering the two aspects of technical feasibility andeconomic costs, the optimum operation scheme of the process are got: system sludge age ofabout20d, the hydraulic retention time of about10h, the water distribution ratio in theprocess of the pre-hypoxia pool is about0.7, sludge reflux ratio is about1.5, nitrifying liquidreflux ratio is about2~2.5. In this condition, the effluent concentration of water qualityindicators is lower than test results, the removal rate of orthophosphate and ammonia nitrogenwere97.31%and99.1%.