| Activated carbon has good ability of adsorption and separation. In water treatment plants, the addition of activated carbon prior to a solid-liquid separation process, such as sedimentation, deep filtration, or membrane filtration, is a simple and widely applied method for removing dissolved contaminants that cannot be removed by the separation process itself. But in the actual engineering application, because of biochemical treatment of organic pollutants in water are mainly soluble microbial products (SMP), the molecular weight (MW) distribution is bimodal characteristics. The macromolecular substances in the SMP are apt to form gel water film in the surface of activated carbon, blocking diffusion and mass transportation in the channel of mesoporous. It will lead to activated carbon on the apparent expression is saturated adsorption, but the internal microporous of activated carbon area not make full use. Finally emerge the phenomenon of activated carbon frequently regeneration and high processing cost. Therefore, seek the regular patron between the molecular weight of organic pollutants with activated carbon particle size is the core and key to improve the adsorption performance, reduce the processing cost of activated carbon.In this study, made the preparation of different quality of a material (coal and coconut shell) and particle size of activated carbon (150～2000μm).Took organic adsorption experiment include phenol, PEG-6000and humic acid with the different molecular weight (94-20000), searched the particle size of activated carbon and quantitative matching relation between the molecular weight of organic matter. Then collected activated sludge in aeration tank from water treatment station in Kunming university of science and technology. Added activated sludge into the SBR reactor, under the condition of continuous operation of the reactor, in combination with activated carbon characterization results, observed various operation index, the change rule of validation of biochemical treatment effluent SMP bimodal distribution, made a research on the particle size of activated carbon and its biochemical treatment the influence of water adsorption. The results are as follows:(1) The particle size of the four groups of activated carbon in the process of adsorption with active carbon adsorption quantity increases with the decrease of the particle size. Pore properties of the activated carbon are the main factor affecting the adsorption of organic pollutants. Pore specific surface area of activated carbon is the main factors for adsorption affecting the adsorption of small molecules and weak polar organic pollutants. Activated carbon adsorption of phenol is mainly influenced by the pore specific surface area of activated carbon; for the adsorption of PEG-6000which molecular weight in6000-9000, by the influence of pore specific surface area and pore diameter distribution; pore specific surface area of activated carbon determined the adsorption ability for humic acid, which in molecular weight range of10000～20000.The smaller the particle size of activated carbon, the better adsorption effect of PEG-6000and the humic acid. adsorption capacity of Particle size less than150μm of activated carbon is1.5～4times to the particle size of1000～2000μm for the adsorption of PEG-6000, the humic acid. It shows that small particle size of activated carbon adsorption capacity is bigger.(2) Four groups of different particle size of activated carbon,<150μm of activated carbon has the most biggest surface area and pore volume; From1000to2000μm of activated carbon has the most smallest surface area and pore volume. The experimental data is accord with the experiment of different molecular weight organics adsorption capacity. Activated carbon as adsorbent in water treatment, it needs surface area is greater, pore and holes are more developed. Activated carbon’s specific surface area, pore volume and pore size distribution, pore performance indicators, help to analysis the nature of the activated carbon, but also important basis for effective use of activated carbon. In combination with activated carbon adsorption experiments of different molecular weight organics, characterized by, confirmed that besides contain rich microporous activated carbon, also contain a wide aperture in the hole, and the change of pore structure, reflects the different activated carbon adsorption capacity.(3) Experiments in SBR reactor operation was good, the sludge mixture let stand for30min after the mud line, a small granular pale yellow mud. Conductivity in a reaction cycle, reactors down to380μs/cm, the change is very small. Conductivity in the whole operation cycle is on the decline, it drop from390to340μs/cm. Reactor2group were on COD removal efficiency is obvious, the COD of effluent reach around100mg/L. SBR reactor in the raw water molecular weight and molecular weight less than8k, organic matter ratio is very close. Two molecular weight range of organic compounds contributed fairly to COD. In view of the biochemical treatment of SMP bimodal distribution properties in water, using dynamic adsorption of activated carbon. The adsorption capacity of utilization rate of coal-based activated carbon is51%, and coconut shell activated carbon is23%. Activated carbon has good elimination capacity of organic matter which molecular weight less than8k.In25bed volume, coal-based activated carbon adsorption ability of organic matter has begun to decline. |
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