Treatment Of Texitile Dyeing Wastewater By Constructed Wetland With Bacterial Augmentation

The preliminary preparations of this study included plant selection,selection of microorganisms and construction of vertical flow constructed wetlands.The experiment began to purify and repair the Congo Red wastewater by using different configuration modes of vertical flow constructed wetlands,and obtained their purification effect on Congo Red wastewater.The dynamic changes of plant physiological indexes and water quality during the restoration process,and the factors affecting the purification of textile dyeing wastewater by vertical flow constructed wetland were studied.The purpose of this research is to find a more effective way to treat textile dyeing wastewater,and provide basic data and theoretical support for further exploration wastewater treatment process by constructed wetlands.The results are as follows:1.In screening plants for constructed wetland,the percent decolorization of Orange??in the five wetlands commonly used plants,Acorus calamus,Typha orientalis,Phragmites australis,Canna indica and Pontederia cordata,were not more than 25%,but in the other three dyes,the final percent decolorization is greater than 75%,indicating that the chroma of the Orange??is more difficult to remove.Canna indica had the highest growth rate under the four azo dye treatments among five plant species,furthermore,Canna indica had the highest plant height increase of 26.75 cm in Congo red.The growth rate of Canna indica showed significant difference compared with other plants under different dyes(p<0.05).It shows that Canna indica has the strongest tolerance to azo dyes among the five plant species.2.The change of water quality indicates that artificial wetlands with different plant configurations all have good effects on the purification of dye wastewater and the percent decolorization can reach more than 98%,furthermore,the difference of dye removal of artificial wetlands with different configurations is not significant(p>0.05).The physical indexes of water quality in constructed wetlands with different plant configurations were different,on the 21st day after treatment,the electrical conductivity(EC),oxido-reduction potential(ORP),total dissolved solids(TDS)and dissolved oxygen(DO)in the water of the Canna indica group were27.64%,27.69%,10.23%and 39.53%higher than those in the Acorus calamus group.3.The stress resistance test on plants mainly includes the growth rate of plants,the damage rate and the physiological indexes of plants.The plant relative growth rate of shoot length after dye stress was reduced and the relative growth rate of shoot length of Canna indica plus dye group was 62.64%lower than that of control group,and the relative growth rate of shoot length of Acorus calamus is lower than that of Canna indica.The stress effect of dye on the plant was also analyzed from the physiological indicators of SOD and POD.In the initial stage of stress,the tolerance of Acorus calamus to dye wastewater was better than that of Canna indica,but with the prolonging of stress time,the tolerance of Canna indica was better than that of Acorus calamus.4.After the addition of exogenous dye-degrading bacteria,the dmanage rate of Canna indica is 77.06%,indicating that the addition of bacteria has a better effect on the growth of Canna indica.After the exogenous bacteria were added,the EC,ORP,TDS and DO in the water increased to different extents,indicating that the addition of exogenous bacteria makes the plant growth environment better and enhances the purification effect of the constructed wetland.In the late stage of treatment without added bacteria,the physiological indicators of Acorus calamus such as SOD and POD are higher than that of Canna indica.It indicated that the microbial-plant combined repair system had better effect than the single use of phytoremediation dye wastewater.5.In the process of continuous treatment of wastewater containing dye in 3 or 5 days cycle,the percent decolorization of the constructed wetlands of the two plants were high,reaching99.50%,and the difference in the percent decolorization of different time cycle was small,and the impact of the percent decolorization of artificial wetlands with different plant configurations was also small.The average water consumption of Canna indica and Acorus calamus in the period of 5 days is 14.10 L/m~2·D and 8.48 L/m~2·D respectively.The average water consumption of Canna indica and Acorus calamus.in the period of 3 days is 8.40 L/m~2·D and 3.76 L/m~2·D respectively.