Study Of Microbial Community Structure In The Process Of Dye-Wastewater Disposal By Combined White Rot Fungi Bioreactor

Dye-wastewater has five basic characteristics with high COD, high chroma, high toxicity, high salinity and low B/C, which is the"4 high & 1 low". The dye can exist in environment steadily for a long time. Along with the rapid development of textile industry, dyeing industry becomes one of the biggest pollution sources and consumers of nature waters in our country, so effective disposal of dye-wastewater is an urgent problem for China.Using white rot fungi is a new way to dispose dye-wastewater which receives considerable publicity in recent years. The special catabolic enzymes secreted by white rot fungi are used with some other methods to degrade the synthetic dye into CO2 and H2O.This thesis is based on the National High Technology Research and Development Program (863) project—"Efficient Microbial Technology of Wastewater Treatment "(2006AA06Z331). Design and construct combined white rot fungi bioreactor(white rot fungi-filler reactor, white rot fungi-bagasse reactor and activated sludge reactor) to dispose dye-wastewater from Shanghai No.8 dyeing factory. Using PCR-DGGE and SEM technology to analyze the dynamic changes of the microbial community structure and the relativity between the changes and the treatment effects of the bioreactor.The results show that:(1) When the flow ratio of the Nitrogen-limited medium and the dye-wastewater is 1:2, the decolorizing rate is steadily around 99.6% and the COD removal rate is between 71% to 88%. When the flow ratio goes to 1:4, the decolorizing rate is also steadily around 99.6% and the COD removal rate is above 85%. When the flow ratio goes to 1:6, the decolorizing rate is 98% which is lower than that in the other two conditions. The COD removal rate has a obvious going up process in the prior period, and remains steadily above 70% in the posterior period.When the flow ratio of the Nitrogen-limited medium and the dye-wastewater is 1:2, the diversity index of microbial community structure in white rot fungi-filler reactor chang from 5.58 to 5.5 and go back to5.6 in the end of this operating condition. When the flow ratio of the Nitrogen-limited medium and the dye-wastewater goes to 1:4, the diversity index in white rot fungi-filler reactor remains steadily around 5.6. When the flow ratio of the Nitrogen-limited medium and the dye-wastewater goes to 1:6, the fluctuation of diversity index in white rot fungi-filler reactor is larger than in the other two operating conditions.When the flow ratio of the Nitrogen-limited medium and the dye-wastewater are 1:2 and 1:4, the diversity index in activated sludge reactor both remain steadily at 5.89. When the flow ratio of the Nitrogen-limited medium and the dye-wastewater goes to 1:6, the diversity index in activated sludge reactor is 5.85.(2)Using undiluted or doubling diluted dye-wastewater has no significant impact to the decolorizing rate which remains above 99.5% in both conditions. The COD removal rate basically remains at 88% in the middle and later periods when using undiluted dye-wastewater. When using doubling diluted dye-wastewater the COD removal rate has a greater fluctuation, the maximal value is 85% and the minimum value is 68%.When using undiluted dye-wastewater, the diversity index of microbial community structure in white rot fungi-filler reactor remains steadily at 5.6, when using doubling diluted dye-wastewater, the fluctuation of diversity in white rot fungi-filler reactor is larger, and the diversity index is lower.When using undiluted dye-wastewater, the diversity index of microbial community structure in activated sludge reactor remains steadily at 5.9, when using doubling diluted dye-wastewater, the diversity index in activated sludge reactor is 5.80.(3)According to SEM photos we arrive at following conclusions.When the flow ratio of the Nitrogen-limited medium and the dye-wastewater are 1:2 and 1:4, the growth situation of biomembrane in both white rot fungi-filler and activated sludge reactor is better and the area of biomembrane on filler fibre in each period is larger than that when the flow ratio is 1:6.The biomembrane in both white rot fungi-filler and activated sludge reactor is firmer, and the area of biomembrane on filler fibre in each period is larger when using undiluted dye-wastewater.