Pretreatment of Coal Gasification Wastewater by Acidification Demulsion

Abstract

Abstract: General pretreatment processes of ammonia stripping and phenols solvent extraction can reduce the concentration of toxic compounds of the coal gasification wastewater for the following biological treatment. However, some emulsified coal tar still exists in the influent and many substances in coal tar are refractory and toxic to microorganisms. This study is mainly on the removal of emulsified coal tar by acidification demulsion. The ex-perimental results show that the acidification process of the wastewater by pure hydrochloric acid can reduce the chemical oxygen demand (COD), total organic carbon (TOC), total phenolics and oil about 3.1%—11.3%, 6%—10.8%, 5.3%—8.6% and 25.2%—57.4% respectively with pH value in the range of 4 to 7. The analysis of molecu-lar weight distribution indicates that compounds removed from the wastewater by this process are large molecular substances. The experiment also shows that the efficiency of COD removal in the demulsion process by different acids is different and the phosphoric acid is prominent. The preserved time of the wastewater also affects the effi-ciency of demulsion. Small amount low-cost solid additives including kaolin and diatomite can improve the rate of coal tar sedimentation and enhance the removal efficiency of organics in the phosphoric acidification process.

Key words: coal gasification wastewater, acidification, demulsion, pretreatment, coal tar

摘要： General pretreatment processes of ammonia stripping and phenols solvent extraction can reduce the concentration of toxic compounds of the coal gasification wastewater for the following biological treatment. However, some emulsified coal tar still exists in the influent and many substances in coal tar are refractory and toxic to microorganisms. This study is mainly on the removal of emulsified coal tar by acidification demulsion. The ex-perimental results show that the acidification process of the wastewater by pure hydrochloric acid can reduce the chemical oxygen demand (COD), total organic carbon (TOC), total phenolics and oil about 3.1%—11.3%, 6%—10.8%, 5.3%—8.6% and 25.2%—57.4% respectively with pH value in the range of 4 to 7. The analysis of molecu-lar weight distribution indicates that compounds removed from the wastewater by this process are large molecular substances. The experiment also shows that the efficiency of COD removal in the demulsion process by different acids is different and the phosphoric acid is prominent. The preserved time of the wastewater also affects the effi-ciency of demulsion. Small amount low-cost solid additives including kaolin and diatomite can improve the rate of coal tar sedimentation and enhance the removal efficiency of organics in the phosphoric acidification process.

关键词: coal gasification wastewater;acidification;demulsion;pretreatment;coal tar

ZHANGWenqi, MAJun, YANGShidong, ZHANGTao, LIYongfeng. Pretreatment of Coal Gasification Wastewater by Acidification Demulsion
[J]. .

张文启, 马军, 杨世东, 张涛, 李永峰 . 煤气废水酸化破乳预处理功效探讨[J]. CIESC Journal.

References

1    Zhang, M., Joo, H. T., Qian, Y., Gu, X.S., “Coke plant wastewater treatment by fixed bio-film system for COD and NH3-N removal”, Wat. Res., 32, 519—527(1998).
2    Nakhla, G.F., Suidan, M.T., Pfeffer, J.T., “Control of an-aerobic GAC reactors treating inhibitory wastewaters”, J. WPCF, 62, 65—72(1990).
3    Ghoshal, S., Anuradha, R., Luthy, R.G., “Biodegradation of naphthalene from coal tar and heptamethylnonane in mixed batch systems”, Envion. Sci. Technol., 30, 1282—1291(1996).
4    Ramaswami, A., Luthy, R.G., “Mass transfer and bio-availability of PAH compounds in coal tar NAPL-slurry systems. 1. Model development”, Envion. Sci. Technol., 31, 2260—2267(1997).
5    Mueller, J.G., Chapman, P.J., Pritchard, P.H., “Creo-sote-contaminated sites”, Envion. Sci. Technol., 23,   1197—1201(1989).
6    Moerman, W. H., Bamelis, D.R., Vergote, H.L., “Ozona-tion of activated sludge treated carbonization wastewa-ter”, Wat. Res., 28, 1791—1798(1994).
7    Ashmore, A.G., Catchpole, J.R., Cooper, R.L., “The bio-logical treatment of carbonization effluents (1) Investiga-tion  into treatment by the activated sludge process”, Wat. Res., 1, 605—624(1967).
8    Nelson, E. C., Ghoshal, S., Edwards, J.C., Marsh, G.X.,  Luthy, R.G., “Chemical characterization of coal tarwater interfacial films”, Envion. Sci. Technol., 30, 1014—1022(1992).
9    Suzuki, S., Green, P.G., Bumgarner, R.E., Dasgupta, S., Goddard, W.A., Blake, G.A., “Benzene forms hydrogen bonds with water”, Science, 257, 942—945(1992).
10    Luthy, R.G., Ramaswaml, A., Ghoshal, S., Merkel, W., “Interfacial films in coal tar non-aqueous phase liq-uid-water systems”, Envion. Sci. Technol., 27, 2914—2918(1993).
11    Sun, D.Z., Duan, X.D., Jiang, Z.H., Zhou, D., “Demulsi-fication of emulsion liquid membrane by wetting coa-lescence materials”, Chin. J. Chem. Eng., 7(1), 38—46(1999).
12    Desjardins, C., Koudjonou, B., Desjardins, R., “Labora-tory study of ballasted flocculation”, Wat. Res., 36,     744—754(2002).
13    Ching, H.W., Tanaka, T.S., Elimelech, M., “Dynamics of coagulation of kaolin particles with ferric chloride”, Wat. Res., 28, 559—569(1994).
14    Shawabkeh, R.A., Tutunji, M.F., “Experimental study and modeling of basic dye sorption by diatomaceous clay”, App. Clay Sci., 24, 111—120(2003).

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Pretreatment of Coal Gasification Wastewater by Acidification Demulsion

煤气废水酸化破乳预处理功效探讨

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