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Study On The Poly Bio-Carries Characteristics And The Treatment Of Coke Plant Wastewater In Biological Fluidized-Bed Reactor

Posted on:2003-11-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:P YangFull Text:PDF
GTID:1101360065960787Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
The fluidized-bed reactor with immobilized microbe, a new type biological reactor, is the most efficient one in the field of the organic wastewater treatment. The reasons of its efficiency lie in two aspects: First, it's due to the high biomass concentration brought by the immobilization of microbe on the particle carriers (called bio-particles). Thus the bio-reaction rate and process stability can be improved. Second, it's due to the high diffusion coefficient between the substrate and the microbe by fluidization of the bio-particles. For the difficulty of the immobilization of the microbes and the complexity of the bio-particle fluidizing behavior, the operation condition of the biological fluidized-bed reactor are recognized to be not easy controlled, especially to treatment inhibitors organic wastewater. For this reason, full scale installations on industrial wastewater are very difficulty throughout the world.In this paper, to solve above questions, a low-density spherical porous polymer particles (HP) is first selected as the carriers of the immobilized microbes. Bio-particles were formed on the laboratory/pilot scale. The operation characteristics of the reactor were systemically studied, when the anaerobic fluidized-bed reactor with HP is used to treat the wastewater, which is hard to be degraded. In the process of sulfur-bearing wastewater treatment, the ability of resisting sulfide and sulfate toxicity inhibition in an anaerobic fluidized bed (AFB) with HP carriers has been studied. The settling velocity and bed-expansion characteristics of the HP bio-particles were studied based on the Richardson-Zaki equation. The treatment of coke plant wastewater was first conducted in pilot plant using the anaerobic-anoxia-aerobic (ArA2/O process, taking the biological fluidized beds as the anaerobic-anoxia reactors and the porous polymer carries as immobilized microbial carries throughout the world. The kinetics of the mass transfer and reaction of the HP bio-particles in the fluidized-bed reactor were studied. Based on the Monod model, the Pick law and a two-phase theory of the anaerobic digestion, a model of the mass transfer and reaction was established and was reasonable by central difference method. It is revealed that the HP carrier fluidized-bed reactors are very efficient in the high concentration wastewater, sulfur-bearing wastewater and coke plant wastewater treatment.Experiments and numerical calculation show following results: (1) To select the low-density spherical porous polymer particle carriers from laboratory isIIIfeasible. The HP carriers have small density, suitable pore structure, good microbes familiarity, and resistance to bio-degradation.(2)An AFB reactor has a strong resistance to sulfate in the treatment of the wastewater of sulfate. When a COD:SO42- ratio is higher than 1.45, the reaction cannot be inhibited. (3)By SEM technique analysis it can be concluded that there are rich microbes on the surface of HP carriers in the AFB reactor, and the main bacterial is Methanosarcina. In the interior of carriers there are lots of efficient microbes. It is" the short rod-like microbes resembling Methanotrix sp .pH changed within the film effect the microbial population.(4)Because of the roughness, the drag coefficient (Co)of the bio-particles of HP is higher than that of other carriers, such as smootru rigid and spherical particles and so on, and it is also higher than that obtained by other researchers. The bed-expansion characteristics of the bio-particle carriers can be expressed by Richardson-Zaki equation. It's expansion index is less than that of other carriers in a fluidized-bed bio-reactor.(5)It has been shown by the test results that the application of biological fluidized bed process to treatment of coke plant wastewater is feasible. When the influent NH3-N concentration was 600mg/L, the effluent concentration of NHs-N was less than 15mg/L,(6)In the treatment of high concentration wastewater in an AFB reactor, the biofilm thickness affects removal rate of substrate beca...
Keywords/Search Tags:Fluidized-bed biological reactor, Carriers selection, Bio-particles, Bed-expansion characteristics, Coke plant wastewater, Biological nitrogen removal, Mass transfer and kinetics, Anaerobic dieestion, Biofilm, Microbes immobilization
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