| The manufacturing of fiberboard is accompanied by a big amount of waste water, which contains rigorous concentration of pollutants. Along with the increasingly strictness of effluent standards, it is in dire need of the advanced treatment and recycling of the fiberboard waste water. This research adopts the Fenton oxidation-biological aerated filter technology to treat the effluent from the secondary clarifier. The action principles and influencing factors of Fenton oxidation are first studied. The next is about the influencing mechanism of those factors on the treatment effects. The experiments on the influence of a single factor enable to determine the optimum operational parameters and provide an investigation of the effects of Fenton on the enhancement of the biodegradability of the waste water. Then combining the Fenton processing with the biological aerated filter processing, the quick start of BAF and the effects of CODcr removal are tested. In the process, the influencing factors of BAF treatment such as the gas-water ratio and hydraulic loading etc. are also examined. The purpose is to find the optimum operation of the combined treatment technology.In view of the low biodegradability of the effluent from the secondary clarifier, this research, ensuring the reducing of organic load, first uses Fenton to enhance the biodegradability of the waste water, which lays the foundation for the later processing. After the orthogonal experiments and single-factor analysis, the conditions of the optimum operation are established as:pH value for 5.0, the amount of FeSO4·7H2O added for 3mmol/L, mole ratio of [H2O2]/[Fe2+] for 4:1, reaction time for 2 hours. Under such conditions, the treatment effect of Fenton system is obvious:CODcr content is reduced to 100mg per liter from 300mg per liter with the removal rate of 67 percent; the color of the processed water changes to pale yellow from red brown of the raw water with the removal rate of 85 percent.The biodegradability of the effluent is greatly enhanced by the Fenton processing:the value of BOD5/COD increases to over 0.35 from about 0.2. Then it is processed in biological aerated filter. Experiments show that the run-up time of BAF is short with one month's biofilm formation. Besides, experiments show the influence of gas-water ratio and hydraulic loading and other factors on the CODcr removal rate: with the gas-water ratio (hydraulic retention period) controlled as 2.5:1, the inflow rate as 8L/h (hydraulic loading 1.02m3/(m2·h)), temperature as 20℃, pH value as 7.5, the rate of CODcr removal by BAF can amount to 60% on average and the CODcr content of the processed water is reduced to 50mg per liter from 100mg per liter.According to research, the Fenton oxidation-biological aerated filter technology receives a significant effect in removing pollutants contained in the fiberboard manufacturing effluent. The removal rate of CODcr is up to 83%, and the removal rate of color amounts to 85%. The results indicate that the various indexes of eventually discharged water are up to the table 2 discharge requirements of Discharge Standard of Water Pollutants for Pulp and Paper Industry (GB3544-2008) and the local discharge standard. It provides a technology reference for the advanced treatment of fiberboard effluent by combined treatment. |
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