| Due to the high water volume and difficulties in treatment, dye wastewater pollution has become a pressing environmental problem. Biosorption has been shown to be the most promising method for dye wastewater treatment. In this method, to reduce processing costs and improve the biosorption efficiency, the primary task is to prepare the low-cost and high efficiency biosorbent.The Penicillium janthinellum isolated from the marine sediment samples was used as starting strain, using its self-immobilization ability to prepare biosorbent, which could remove dyes from aqueous streams. This paper mainly studied the preparation conditions of P1pellets and its forming mechanism. The best carbon source of Penicillium janthinellum mycelial pellets was glucose and the best nitrogen was ammonium tartrate. The P1pellets will be at the best station in condition of that the initial culture pH value is5.0, the agitation speed of rotary shaker is160rpm and the fermentation temperature is28℃This strain had a strong tolerance on salt, the pellets still can form even if NaCl concentration was70g.L-1. The process of P1pellets formation can be divided into3stages:the spore sprout and mycelium outgrow, mycelium adhesion form pellet core; mycelium grow constantly as time increases, under the shearing force the mycelium intertwined like balls of loose twine; because of the mal-condition of the medium, the mycelial pellets began autolyzing from the inside.The biosorption of nine different dyes(including Congo Red, Naphthol Green B, Methyl Red, Crystal Violet and so on) with P1mycelial pellets were studied. Results indicated that P1pellets had an excellent biosorption of dye removal, decolorization rate of five different dyes (Congo Red, Naphthol Green B, Chrome black T, Amido Black10B and Natural Red) could reach90%. In order to deeply understand the effect of different factors on P1pellets biosorption efficiency and its biosorption mechanism, Congo Red was taken as studied object for the follow-up study.The best condition of biosorption was as following:initial dye pH value is5.0 and rotational speed is120rpm. P1mycelial pellets had a strong tolerance on high salt concentrations, when the salt concentration up to200g.L-1the decolorization rate of Congo Red was still above87%. When P1pellets were reused for five times, the dye removal rate can still be up to91.3%. Kinetic studies indicated that the biosorption behavior followed the pseudo-second-order kinetic model (R2>0.99). The experimental data of P1pellets biosorption Congo Red were fitted by Langmuir model and Freundlich model, Langmuir model (R2>0.99) is superior to Freundlich model in describing the P1pellets biosorption behaviour. The decolorization process studied was mainly due to biosorption, dyes can be adsorbed both on the surface of cell walls and in the inner cell structures.In this paper, nonviable P1mycelium was used as biosorbent for anionic dye Congo Red wastewater treatment. The optimum biosorption conditions were gained as follow:biosorbent size<74μm, initial dye pH is5.0, shaking speed is180rpm and NaCl concentration is10g.L-1. Pseudo-second-order kinetic model and Intraparticle diffusion model yielded good fit to experimental data, intra-particle diffusion probably contributed to the rate-determing step. The modeling of the experimental data at equilibrium was performed with Langmuir model and Freundlich, results indicated that the biosorption of Congo Red dye by nonviable P1mycelium obeys the formation of monolayer molecule sorption, the maximum biosorption capacity was185.2mg·g-1. |
PDF Full Text Request