Study On Microorganisms Of Constructed Wetland On Oil Wastewater

Efficiently treating wastewater which was from petrochemical industry wasurgent, because petroleum pollutants disturbed natural environment severely with theincreasing petrochemical wastewater discharge. Constructed wetland which was aneffective ecology process of sewage treatment could be used to the complement forregular physicochemical process of petrochemical wastewater treatment. This articlemonitored water quality so as to verify the stability of constructed wetland onpetrochemical wastewater. Number of microorganism was counted, meanwhile,bacteria16SrDNA clone library was set up. Water from constructed wetland onpetrochemical wastewater was analyzed for bacterial community and diversity.The main research results indicated that petrochemical wastewater was purifiedwell by vertical-flow constructed wetland. Four constructed wetlands’ capability ofpetroleum removal: Acorus calamus> Phragmites australis>Pontederia cordataL>control group, and there was significant positive correlation between the removalrate of petroleum and temperature, pH（6.48-7.72）, DO（P<0.01）. Capability of CODremoval: Acorus calamus> Phragmites australis>Pontederia cordata L>controlgroup, the significant positive correlation was observed between the removal rate ofCOD and pH, DO（P<0.01；P<0.05）, and the petroleum and COD after constructedwetland could reach the second grade of national wastewater effluent standards.Capability of TN removal: Acorus calamus> Phragmites australis> control group>Pontederia cordata L, and TN concentration could achieve the national first-classdischarging standard. There was significant positive correlation between the removalrate of TN and DO in constructed wetlands which cultivated wetland plants（P<0.05）.Capability of TP removal: Phragmites australis> Acorus calamus>Pontederiacordata L>control group, and compared to petroleum, COD and TN, the removalefficiency of TP is lower after constructed wetland on petrochemical wastewater.Number of bacteria, fungi, actinomyces all showed an increasing trend duringthe run-time of constructed wetland on petrochemical wastewater. According to themultiple comparisons, every two subsurface vertical-flow system had on significantdifference about microbial quantity（P>0.05）. There was significant positivecorrelation between microbial quantity and temperature（P<0.01）. In addition, thesignificant positive correlation was observed between microbial quantity and pH pH（6.48-7.72）among constructed wetlands which cultivated wetland plants（P<0.01）. The research results about the correlation analysis between microbial quantity and DO（0.87-2.94mg/L）that there was significant positive correlation between bacteriaquantity and DO（P<0.01；P<0.05）. The significant positive correlation was obtainedbetween microbial quantity and the removal rate of COD, TN（P<0.01；P<0.05）. Theremoval rate of petroleum and microbial quantity in Acorus calamus group hadsignificant positive correlation（P<0.01）.The nucleotide sequences with closely species were phylogenetic analyzed andphylogenetic trees were constructed. The results showed that bacteria mainlycontained Acinetobacter, Rhizobium, Rhodobacte, Pseudomonas. Acinetobacter hadabsolutely dominant status in winter samples. Pseudomona and Rhodobacte belongedto superior bacterium in spring and summer. Rhizobium was identified in summerPontederia cordata L. And bacterial species were the most abundant in summerAcorus calamus. Based on pyrosequencing approach, microbial diversity andcommunity structure of two samples, which were from Acorus calamus subsurfacevertical-flow system in spring and summer would be analysed. Proteobacteria hadabsolutely dominant status at the phylum level and Alphaproteobacteria occupied adominated position. Bacterial abundance and community diversity of summer samplewas higer than the spring sample. In Acorus calamus subsurface vertical-flow system,there was significant positive correlation between DO and Chao1, Ace, Shannonindex（P<0.01；P<0.05）. In addition, the significant positive correlation was beobserved between temperature, the removal rate of petroleum, TN as well as Chao1,Ace index （P<0.05）.