| The zeolite has more pore size, rough surface and strong adsorption performance,therefore, the unburned spherical zeolite composite filler (ZCF) between5to9mmwas prepared by0.15~0.18mm natural zeolite powder as main raw material, pulp andcement as binder, it’s porosity was46.8%, the apparent density was1.65g/cm3,intensity was76.8N and the bulk density was0.965g/cm3. The composition analysisof ZCF was used X-Ray Diffraction (XRD), observed the inner and outer surface wasused Scanning Electron Microscope (SEM) and investigated the adsorbing capacity ofammonia and phosphorus of ZCF, the results shown that the rough outer surface andhighly internal porosity could make a good place for microorganism growth, andenhanced the biomass on the biofilm, however, the adsorbing capacity of the ammoniaand phosphorus were both lower, was1.20mg N/g and0.39mg P/g respectively.The ZCF was loaded into experiment column, the wastewater was prepared by thelower concentration of ammonia nitrogen and phosphorus as simulate wastewater, andthen built the lab-scale biological aerated filter (BAF) device. Used the up-flow inletfor nitrogen and phosphorus removal by adsorption, and studied the performance ofthe system start and biofilm culturing for the nitrifer cultured complete. During thisstage, the dynamic simulated wastewater treatment was used the lower filter speedand moderate aeration rate. The results shown that kept the influent ammonia nitrogenand phosphorus concentration in10-15mg N/L and1.5-2mg P/L, respectively. Thehydraulic retention time (HRT) was5.4h, filtering rate was0.16m/h, temperaturewas room temperature, the water temperature was16.2±2.0℃, pH was7.3±0.2, DOwas about6mg/L, the gas water ratio (GWR) was2-3:1, under this operationcondition, the ammonia nitrogen removal efficiency and the phosphorus removalefficiency was from71.43%to99.46%and from28.9%to83.0%, respectively.During the stable stage, mainly studied the removal effeciency of the nitrogen andphosphous under different of the GWR and HRT. The results indicated that: during theGWR=0.25:1, HRT=5.4h, the average water temperature was26.7℃, pH was7.3,the NH4+-N removal efficiency almost reached99.5%, and also ensured theconcentration of the NO2--N not exceeded to0.01mg N/L, yet the average removalefficiency of the TN was about38.5%, the average removal efficiency of the TP wasabout35.9%, was not good. And then with the HRT decreased, the effluent NH4+-N,TP concentration had a certain floating, the total tendency was with the decreased of HRT, the effluent NH4+-N, TP, NOx--N and TN concentration all increased, the TN, TPgrowth obviously, the performance of the reactor on the lower organic loading systemduring the three setting HRTs, the BAF operation stability was moderate, the NH4+-Nremoval was well, the TP removal inefficiency.To futher reduced energy consumption, achieved the treatment low nitrogen andphosphous removal in BAF, used the newer intermittent aeration recycling process,during this kind of operation, prelimiary studied the effects of different air exposuretime for the stable operation time in BAF, as well as the different exposure time onbiological regeneration and BAF performance. The BAF stable operation standardwas the effluent of the NH4+-N≤2mg N/L, when exceeded the standardconcentration, continue to run a day for monitoring, stop running after, according tothe set time to aerate, after stopped aerate, go on run the BAF. Results shown that: the24h aeration time got the optimum running effect, kept the influent pH, T, TOC/TCinvariable, the BAF could operated stable for about6days, the average effect ofnitrogen and phosphorus was63.3%and26.4%, respectively, the average removalefficiency of NH4+-N was84.1%.. |
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