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Experimental Study On The Anaerobic-Aerobic Integrated Reactors Treating High Strength Organic Wastewater

Posted on:2006-12-18Degree:MasterType:Thesis
Country:ChinaCandidate:H XiaoFull Text:PDF
GTID:2121360155965434Subject:Environmental Engineering
Abstract/Summary:PDF Full Text Request
The environmental pollution in our country is very serious at present, it's imperative for wastewater, especially the organic industrial wastewater to be efficiently treated and to be let up to par. However, the problems such as high investment and operating cost, large energy exhaustion, large ground area demand, complicated operation and management procedure, little probability to meet the standard when treating concentrated organic wastewater with bad biological degradability or wastewater with high NH3-N concentration are ubiquitous in the present wastewater treatment engineering projects. It is very necessary to develop new technologies featured with higher efficiency, lower energy exhaustion, less ground area demand and broader applying fields for wastewater treatment.Funded by the national 863 project named develop and application of high efficient anaerobic and aerobic biological reactors, based on the experimental and engineering experiences of one-staged anaerobic, one-staged aerobic and anaerobic-aerobic combined wastewater treatment, this study applied the integrative concept, optimized the configurations of high efficient AFBR and aerobic fluidized bed reactors and assembled them in one reactor to develop a new-type anaerobic-aerobic integrated reactor. A new-type porous polymer carriers used to immobilize the microorganism were added to treat the concentrated organic wastewater. In experiment, the start-up and operating characteristics of the AFBR-aerobic fluidized bed with outer loop integrated reactor were studied, the microorganism immobilization ability of porous polymer carriers was investigated and substrate degradation dynamics and microorganismgrowth dynamics were studied. In another experiment, the nitrogen removal ability of anoxic fluidized bed-aerobic fluidized bed with inner loop integrated reactor was simply tested. In the last experiment, the microorganism immobilization ability of new-type capsule carriers with porous membranes was investigated under both static and dynamic conditions.The start-up and operating experiment of the AFBR-aerobic fluidized bed with outer loop integrated indicated that the system's start-up could obtain fairly good effect within 38 days under the ambient temperature (16~24°C) by means of adding the new-type polymer carriers, gradually increasing the volumetric organic load rate(VOL) and starting the anaerobic and aerobic in turn and during the system's steady operating period, when the average COD concentration in the influent was 3601.8 mg/L, the average COD concentration in the effluent was 384.0 mg/L, the average volumetric organic load(VOL) was 2.54kgCOD/(m3· d) and the average hydraulic retention time(HRT) was 35.lh, the average COD removal rate reached 90.6%, meanwhile, the influent pH was controlled at about 7.0, the anaerobic recycle ratio was controlled between 3~5, the aerobic gas flux was controlled between 0.36~0.50 m3/h.After analyzed the bioparticles' SEM, it can be found that biofilm formed on the carriers in both the anaerobic and aerobic zones, the bioparticles' sphericity was good and some microorganism attached on the anaerobic bioparticles' surface and inner holes, mainly methanogenic cocci and bacilli, in the aerobic bioparticles' inner holes, mainly short bacilli and on the aerobic bioparticles' surface, mainly cocci and few filar bacteria.When water bath temperature was 30, the parameters of anaerobic microorganism growth kinetics and substrate degradation kinetics can be calculated out according to the experimental data. The results were vmM=4.8054 (d"1) ,1^=1806.3 (mgCOD/L), Y=0.0389,Nitrogen removal experiment was carried out in the anoxic fluidized bed -aerobic fluidized bed with internal loop integrated reactor. The results indicated that when the NH3-N concentration in the influent was 280.3- 350.7mg/L, the NH3-N removal rate of the system was 68.5~91.7%, the average value was 81.0%. Meanwhile, for the system, the COD concentration in the influent was 4150.7~4380.1 mg/L, the COD concentration in the effluent was 375.9~650.8mg/L, the average COD removal rate was 88.4%. Therefore, the results showed that the system had good COD removal ability and NH3-N removal effect and it could be applied totreat the organic wastewater with high COD concentration as well as moderate NH3-N concentration.Microorganism immobilization ability of the new-type capsule carriers with porous membranes was studied under both static and dynamic conditions during the last phase experiment. The results indicated that the carries had better microorganism immobilization ability under the static condition, while under the dynamic condition, influenced by the factors such as relatively big carriers' size, poor fluidized performance, limitations of operating conditions and operating time and so on, the AFBR's COD removal rate was relatively low, when the average COD volumetric load rate was 25.9kgCOD/(m3-d), the average COD removal rate was only 27.7%, although microorganisms could be immobilized on the carriers' surface and in the fingerlike channels, microorganisms could hardly be immobilized in the membranous capsules. So it was obvious that adjustments must be done in the carriers' preparation to eliminate the jam of microorganisms in the fingerlike channels and increase the immobilized organisms in the membranous capsules.Results from this paper can provide basic data and applicable parameters for the optimization design of process and configuration of the new-type anaerobic-aerobic integrated reactor, the conditions of reactor's start-up and steady operation and the concentrated organic wastewater treatment performance. Results from this paper can also provide basis to evaluate the microorganism immobilization ability of the new-type porous polymer carriers and capsule carriers with porous membranes and provide scientific basis for the scale-up of the anaerobic-aerobic integrated reactors and the industrial application of the carriers.
Keywords/Search Tags:anaerobic-aerobic integrated reactor, biological fluidized bed, microorganism immobilization, nitrogen removal, kinetics
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