Study On The Effect Of Combined Remediation Of Phenol Wastewater By Plants And Microorganisms

Phenol is an important organic chemical raw material for the preparation of chemical products such as phenolic resin,salicylic acid and caprolactam.It is also one of the main pollutants in the wastewater discharged from chemical plants.The annual production capacity can reach more than one million tons.Phenol waste water is characterized by wide source,difficult degradation and great harm.Therefore,how to effectively remove phenol from waste water has become one of the key problems in the field of contemporary environment.The purpose of this study is to screen and isolate bacterial strains with good degradation of phenol under aerobic conditions from activated sludge of waste water treatment ponds in Jinan and Laiwu coking plants,to further explore the effects of different physical and chemical factors on the degradation of phenol by bacteria and screen plants that can better repair phenol waste water.Finally,a plant-microorganism combined remediation system was constructed to study the effects of strains on plant physiological response and the removal efficiency of phenol waste water by the combined system.The specific research results of this paper are as follows:(1)A strain A1 with good degradation effect on 100 mg/L phenol under aerobic conditions was screened from activated sludge obtained from waste water treatment tank of coking plant,and its removal rate of phenol within 48 hours was 75.02%.The strain was identified as Bacillus thuringiensis.The results showed that strain A1 had strong degradation ability in the temperature range of 30-40?,pH range of 6.0-9.0 and initial phenol concentration range of 50-200 mg/L.Among them,the optimum conditions for degradation of phenol by strain A1 were rotating speed 200 r/min,temperature 35?,initial pH value 7.0,and the removal rate of phenol solution with initial concentration of 50 mg/L was more than 90% within 48 hours.(2)According to the removal rate of phenol from plants and the manifestation of toxic symptoms of plants,Acorus calamus and Typha orientalis with strong phenol tolerance and efficient phenol removal properties were selected from five aquatic plants(Typha orientalis,Phragmites australis,Canna indica,Pontederia cordata,Acorus calamus).Among them,the removal rate of phenol by Acorus calamus was 84.72%,and that of Typha orientalis was 79.46%.(3)In the study of plant-microorganism remediation of phenol waste water,the removal rate of phenol by plants decreases with the increase of phenol concentration.With the increase of phenol concentration from 50 mg/L to 200 mg/L,the final removal rate of Acorus calamus decreased from 91.28% to 71.06%,and that of Typha orientalis decreased from 87.51% to 58.71%.Phenol removal efficiency of plant-microorganism combined remediation system is better than that of plant alone.Among them,the combined system of strain A1 and Acorus calamus has the best effect on phenol removal,and the removal rate of phenol solution of each concentration is more than 80%.(4)The SOD,POD activity and chlorophyll content of Acorus calamus and Typha orientalis showed a trend of first increase and then decrease under the stress of phenol in a short time.However,with the extension of stress time,the activity of SOD and POD and chlorophyll content of Acorus calamus and Typha orientalis showed a trend of decrease compared with that under the treatment without phenol.Moreover,MDA content and relative conductivity of plants increased with the increase of stress degree under long-term stress.After strain A1 was applied,the stress resistance of plants increased under phenol treatment conditions.The plant growth rate,SOD,POD activity and chlorophyll content of Typha angustifolia and Acorus calamus increased compared with the same concentration control group,while MDA content and relative conductivity decreased.