| The starch wastewater has the characteristics of high COD, which belongs to the industrial wastewater. According to the characteristics of the starch wastewater, the multi stage hydrolytic acidification-biologic contact oxidation process has proposed for this kind of wastewater. By a large number of experiments and theoretical analysis, we can draw the following conclusions:(1) The multi stage hydrolytic acidification-biologic contact oxidation process for the starch wastewater is feasible.(2) As the starch wastewater has higher COD concentration , the micro-organisms require a longer acclimation time (about 36 days) to enter the normal operation of the systems, and the micro-organisms can adapt to the basic nature of starch wastewater and to achieve a good effect.(3) The H1 has the thin ,black and loose biofilm, such as the micelles bacteria. The O1 has the thick, brown black and close biofilm compared to bacteria, filamentous bacteria, bacteria-based micelles. The H2 has the thin, black and strong biofilm compared to bacteria, a small amount of filamentous bacteria and bacteria-based micelles. The O2 has the thick, light brown and close biofilm compared to bacteria, filamentous fungi, bacteria micelles, a small number of paramecium, stentor ande vorticella. The H3 has the thin, black and loose biofilm compared to bacteria, filamentous bacteria.The O3 has the thick, light brown and loose biofilm compared to bacteria, a small amount of filamentous bacteria, a large number of vorticella, arcella, epistylis and rotifer.(4) When the pilot HRT are at 72,66,60,54 and 48 h, the COD removal efficiency of each unit are gradually reduced, O1 and O3 are more pronounced. When the HRT are longer than 54h, each unit of COD removal efficiency is stable, when the HRT is less than 54h, each unit of COD removal efficiency is decreased significantly. When the HRT is longer than 54h, the system can achieve the standard effluent COD concentration level of (GB8798-1996). The economic HRT model is applicable for 60h, the water flow is 5.53 L/d, the volume load is 1.60KgCOD/m3.d, the average COD removal efficiency of the system is 97.90%, the average effluent COD concentration is 84mg/L.(5) When the water volume load is 1.60KgCOD/m3.d (the HRT is 60h), in the O1 the p(DO) is 0-1 mg/L, in the O3 the p(DO) is 3-7 mg/L, as the dissolved oxygen of the O2 unit is higher, the O2 unit effect on the COD removal gradually increased, when the p(DO) is increased 34mg/L, the average p(COD) in the O2 is 423mg/L, the average COD removal efficiency of the O2 unit is 53.4%, the system as a whole COD removal average rate is 98.0%, the best concentration of dissolved oxygen in the O2 is 3-4mg / L; when the p(DO) is 0-1 mg / L in the O1 , the p(DO) is 3-4mg/L in the O2, in the O3 the increasing dissolved oxygen make the COD removal efficiency gradually increased, the system effluent COD concentration gradually is decreased, the removal rate gradually is increased, in the O3 the p(DO) is 5-6mg/L, the average COD of the effluent is 71mg/L, the unit average COD removal efficiency is 83.2%, the total average COD removal efficiency in the system is 98.2% (?); when the p(DO) is 6-7mg/L in the O3, the removal efficiency of the O3 significantly decreased, the effluent COD concentration gradually become larger, the removal rate decreases.In the O3 the dissolved oxygen in the best concentration is 5-6mg/L.(6)When the water volume load is1.60KgCOD/m3. d (the HRT is 60h), the O1 p(DO) is 0-1 mg/L,the O2 p(DO) is 3-4mg/L, the O3 p(DO) is 5-6mg/L, the temperature on the various units of the COD removal efficiency will be affected. In less than 15-30℃, each unit of hydrolytic acidification of the COD removal efficiency is increased as the temperature increased, but the change is not particularly evident. in less than 15-25℃, the first bio-contact oxidation unit with increasing temperature increase in the 25℃-30℃or less with increasing temperature in reducing the effect of removing, at 25℃the effect of removing is the best, when the overall system average COD effluent is 53mg/L, the total average COD removal efficiency is 98.7%.(7)When the system is affected by water volume load, the HRT is 60h, the system maintains at the COD load of 1.602kgCOD/m3·d-1.919kgCOD/m3·d, the effluent COD concentration is 84mg/L-98mg/L; when system maintains at the COD load of 1.999kgCOD/m3·d-2.839kgCOD/m3·d, the effluent COD concentration is 100mg/L-200mg /L; when the system is relatively largely impacted, the COD load reaches 2.839 kgCOD/m3·d-3.198kgCOD/m3·d, the effluent COD concentration is 200mg/L-220mg/L However, when the load is cut down to the original level, the system gradually restored to the original condition. Multi-hydrolytic acidification-bio-contact oxidation treatment for starch wastewater has some impact load resistance.(8) Based on the Monod equation, the dynamics model of the multi stage hydrolytic acidification-biologic contact oxidation process for starch wastewater is proposed as: (?),the R is 0.9695.
|
PDF Full Text Request