A / O Process Wastewater With High Salinity Research

Now the researches of the biological treatment of high salinity wastewater were focused on the effects of salinity and salinity shock on organics and ammonia nitrogen removal efficiency and activated sludge performance in intermittent type reactor (SBR). But the study of continuous reaction reactor (A/O) is very little. As to this question, this dissertation was mainly studied the rule of domestication of salt-resistant activated-sludge and the microorganism evolution, the effects of operating parameters of A/0 process on organic matter and ammonia nitrogen degradation in high salinity wastewater at normal temperature (18～25℃) . Besides the effects of drop-low temperature on organics and ammonia removal were studied within 5℃～28℃. It studied dominant factors on achieving short-cut nitrification in high salinity wastewater at normal temperature; the cause of sludge bulking and adjustment measures were researched as well. These researches were promotive to the biological treatment of high saline wastewater.Experiment was conducted at 800～1000mg/L of COD,80～100mg/L of NH₃-N and seawater percentage of 50%(17500mg/L salinity)to investigate the activated sludge domestication and the biological law of microorganism succession. Results showed that autotrophic bacteria of nitration was influenced more greatly than heterotrophic bacteria which was under high salinity circumstance. Microorganisms, such as Protozoa and Cladocera, showed status of activated sludge and the water quality, at the same time they replaced each other from low to advance. The symbolic microorganisms of initial stage, forming stage, increasing stage and autumn were Bacteria, Cladocera, Vorticella and Rotifer respectively.The experiment also studied the effects of operation parameters of the system on organics and ammonia removal. The results showed that the influent experimental parameters were: pH: 7.0～8.5, hydraulic retention time (HRT):6h～18h, COD and ammonia nitrogen removal rate increased with pH and HRT. In the system best pH and HRT of the influent respectively was 8.0～8.5 and 15h. This experimental internal recycling reflux ratio (r) control in 3.5～4 had obtained the good denitrification effect. Increases sludge reflux ratio (R) to be advantageous in enhancing the system organic and the ammonia nitrogen removal rate, when R was 0.4 the removal rate was very low, R≥0.5, the rate soared remarkably. Under this situation, when R was1.0, COD removal efficiency could be 88.23% and the ammonia nitrogen could reach at 88.67%.When seawater proportion was 50%, the removal efficiency of organics and ammonia reduced with the temperature dropping within 5℃～15℃. The temperature from 15℃after 10℃to 5℃, COD removal rate corresponding from 77.8% fell to 60.5% until 54.8%. When the temperature was below 15℃, the drop of ammonia removal rate was much quicker than it of COD, which illustrated the temperature influence to the self-supportive nitrifying bacteria was bigger than the impact on the heterotrophic bacteria.Sludge bulking took place from 6.13 to 7.1, the SVI of activated sludge rised to 310.88mg/L. The zoogloea group was small and sparse around which massive filamentous bacteria grew. Through analysis the causes, harms and recovery measures of sludge bulking, it showed the type of sludge bulking was sulfide-type caused by filamentous bacteria. In the experiment, the method of hydrogen peroxide sterilization and continuously high aerated and supplemented the new sludge was used. After 13 day-long restorations, SVI fell to 100mg/L below, the zoogloea group became bigger and denser, and the sludge bulking problem was solved successfully.Experiment was conducted at 800～1000mg/L of COD,80～90mg/L of NH₃-N and seawater percentage of 50% to study short-cut nitrification and denitrification of high salinity wastewater. Emphatically considering the influence of the temperature, pH and HRT on nitrite accumulation. The result indicated that, the rate of nitrite - type nitrification was increased due to the increase of temperature under the normal temperature, which may reach 50% at 25℃; when pH was 7.0～8.5, the rate of nitrifisation was increased with the increase of pH, which may reach 60% at 8.5; the higher nitrite accumulation rate could be obtained by lengthensing HRT suitably, the rate of nitrifisation could be maintained above 90% by controlling HTR at 15h, pH at 8.0～8.5.