| Nowadays, we are facing with water resource shortage along with water pollution. It was important to undertake the cost effective technology to treat polluted water whilst encourage water reuse. Soil aquifer treatment(SAT) was an efficient technology, using the infiltration process of mediation, adsorption and biodegradation on the pollutants in the environment to achieve the goal of recycling water. For a better understanding of the transport and attenuation of para-nitrophenol(P-NP) and the change of microbial community at the stress of p-nitrophenol in soil aquifer treatment system, two column experiments were operated to investigate the physical, chemical, and microbial dynamics. At the same time, the bio-augment method was used to enhance the SAT biodegradation system. This study provide valuable result on the attenuation potential of for the bio-enhanced SAT system(BIO-SAT). The following conclusions can be drawn based upon the investigations:(1) The river sand and quartz sand were used as the porous media for producing the iron-oxide coated sand. Characterization of membrane results shows that the surface of oxidized iron film was flocculent or lamellar without fixed shape. From the study of point of zero charge, the result showed that the point of zero charge was increased, and the streaming potential and surface zeta potential also change and increased its adsorption capacity. This material could be more suitable for application in the future work.(2) Study of absorption kinetics indicated that the absorption kinetics could be governed by the Freundlich model. The absorption capacity was raised and the diffusion model study demonstrated that the pore diffusion was higher than sufficient diffusion.(3) A microbial strain was isolated from agricultural soil and identified as Pseudomonad sp., with the NCBI number of KU550766 and named Pseudomonas sp. PRM. Pseudomonas sp. could use p-nitrophenol as the sole carbon, nitrogen and energy source. The RSM modeling method was used to optimize the biodegradation conditions.(4) Study of metabolic pathway indicated that one of metabolite was Hydroxyhydroquinone, and according to metabolic pathway, the real-time PCR method was established. The degradation kinetics of P-NP was elucidated via the discrete mathematical models that yielded coefficient parameters of the Haldane and Gompertz models. The result showed that when the concentration of p-nitrophenol was higher than 247.24 mg/L,the degradation rate was inhibited. And growth kinetics model fitting results showed that at low concentration of p-nitrophenol, the strains showed a short delay time and high productivity.(5) The SAT column experiment was operated about 7 cycles, which demonstrated that two reduction zones were revealed at the middle of the column and the biodiversity of the microbial community could be destroyed under the P-NP stress. Absorption was the main removal mechanism according to the obtained experimental data.(6) By using the displacement method, the BIO-SAT system was operated about 36 days, which showed perfect outcome for the P-NP removal at a higher concentration. From the PCR-DGGE molecular study, enhanced bacteria could form a stable biological community with indigenous communities.(7) Through the Canonical Correspondence Analysis(CCA) microbial degradation and environmental factors, the results showed that the p H was a very important parameter affects the degradation of nitrophenol degradation bacteria. The metal ions under the condition of low concentration can promote the growth of microbial degradation.(8) The health risk assessment and non-cancer-risk assessment for the reclaimed water SAT/BIO-SAT treatment showed a low risk and thechnology developed can be used at good safety. |
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