Experimental Study On Dye Wastewater Treatment By White Rot Fungi And Control

Dye waste is a unmanageable organic pollution in environmental area. Traditional wastewater-treating bio-technologies have a very limited ability in treating dye waste. From the 1980, it have been found that white rot fungi have a high-ability in degrading the wastewater, such as pesticide-wastewater, oiliness-wastewater, ammunition-wastewater, paper making-wastewater. In this paper, dye waste was the treating object. This paper has focused on the researches of dye wastewater treating by white rot fungi, including selection of white rot fungi, treating effect of dye wastewater, nutrition control and degrading mechanism. The following were the results:1. Twelve fungi have been gotten from open country in China. And ten fungi have been secreted by in this study.2. The ten fungi have different cultivating-characters in shaking-flask experiments: well-regulated pellets, bad-regulated fungi-cake and fungal floc. The ten fungi have obvious different abilities in degradation of dye waste-water. The well-regulated pellets (1#, 9#, 12#) have the highest ability and their nutrition liquid was very clear. This proved that the ability of degradation was related to fungal pellets and nutrition liquid.3. Another two fungi (9#ml, 12#ml) have been gotten by UV-treating ways. They had the higher degrading-ability than the ten fungi. 12#ml had the highest degrading-ability in all fungi, so it was chosen in other experiments. Another result was that there was a high degrading-ability too if soluble starch was substituted to saccharose in nutrition liquid.4. In the slab-experiments, the effect of nutrition control to fungi growing was very obvious: fungi can grow faster in saccharose or soluble starch substrates than in carboxymethylcellulose or lignin substrates. The growth quantity was very small in slab when the concentration of dye waste was 20%. Perhaps the reason was the toxicity of dye waste.5. In white rot fungi bio-reactor experiments, a high degrading ability can begotten when the concentration of carbon fountain was 30g/L or 10g/L. When the concentration of nitrogen fountain was 560mg/L or 56mg/L, there was a very high degrading ability too. These results were valuable to engineering practice. The procession was very complicated, but some results can be reached as follows.(1) White rot fungi utilized most carbon and dye in the first 24 hours. The COD was depressed very fast and some VFA was created. Then pH was depressed.(2) There was some relationship in VFA, NH3-N and pH. The change of VFA and NH3-N would bring the change of pH. In most conditions, the concentration of NH3-N arose. Perhaps the reason was the rupture of double-N bonds in dyes. The autolyze of fungi can add fuel to the fire of NH3-N arisement.(3) Total N and COD were depressed in the same time. So white rot fungi utilized carbon ,nitrogen and dye-outgrowth in the same time.6. In the frosted slice experiment, two results have been found. 漏The microstructure of white rot fungi pellets have been changed under the condition of long HRT and high dye concentration. Very tight pellets have been changed to incompact pellets and long mycelium have been changed to short ones. Perhaps these were produced by bio-toxicity of dye or autolyze of pellets. (2)In shaking-flask experiments, bio-absorption was the most important decolorizing action in the first 24 hours. Bio-degradation was the most important decolorizing action in the followed time. So there was a result that lignin enzymes can be secreted in some time to degrade the dye absorbed by fungi pellets.