Ying Lu

Bio‐clogging is critical to the efficiency of soil aquifer treatment. In this study, we utilized a percolation column device to investigate the dynamic evolution of biofilm and the corresponding responses changes of three typical hydraulic properties with the column within the percolation column. The results showed that the biofilm development exhibited five‐stage growth morphology: bacterial stage, colony stage, biofilm with filamentous EPS stage, biofilm with mesh EPS stage, and dense biofilm stage. The hydraulic conductivity exhibited nonuniform decay across five stages: initial fluctuation period, swiftly declining period, accelerated declining period, gently decreasing period, and equilibrium stabilizing period. Both bacteria and EPS contribute to the attenuation of the infiltration properties. Due to its hydrophilic nature, EPS played a more prominent role in storing and dispersing water. As such, significant changes in water holding capacity and material transport mechanism occurred at EPS secretion onset. From 0–18 h, bacterial colonization slightly enhanced water retention, accompanied by a gradual rise in the hydraulic dispersion coefficient. After approximately 18 h, substantial EPS production markedly increased water‐holding capacity and transformed the dominant transport mechanism from convection to dispersion.

A quantitative and qualitative assessment using molecular markers derived from compound-specific indices for indicating groundwater impacted by petroleum spills in an oil field was recently undertaken and demonstrated serious contamination, with both high total petroleum hydrocarbons (TPH) (3.68–7.32 mg/L) and hazardous compounds in the groundwater. A petroleum source was identified, and the analysis revealed a decreasing trend of fresh petroleum input, along with groundwater advection and an increasing trend of biodegradation potential at locations farther from the source. This was confirmed via microbial analysis with both biodegrading microorganisms and diversity indices (Shannon, Simpson, and Pielou) and the principal component analysis (PCA) modeling approach, which classified the field samples into three types according to the distribution correlations between different organic compounds. Biodegradation was believed to be the dominant sink of hydrocarbons due to the increasing Pr/C17 and Ph/C18 values with seasonal changes. Raised temperatures activated the microbial degradation process; specifically, low-weight hydrocarbons degraded more rapidly than high-weight hydrocarbons, resulting in the accumulation of an unresolved complex mixture of bioproducts at locations that were farther away. Spatially, the Pr/C17 and Ph/C18 values increased from the upstream to the downstream areas, showing substantial biodegradation. The relationships between the molecular markers and chemical indices were quantified via canonical correlation analysis (CCA) to visually explain the interactive reaction processes. It was also demonstrated that the biodegradation of petroleum organics can be characterized by the consumption of dissolved oxygen and a decreasing Pr/Ph ratio, due to system reduction. These results demonstrate that compound-specific molecular markers, coupled with biochemical parameters, can effectively support a better understanding and effective fingerprinting of the fate and transport of petroleum organic contaminants, thus offering valuable technical support for a cost-effective remediation strategy.

Bio-clogging is critical to the efficiency of soil aquifer treatment. Herein, utilized a percolation recharge device to investigate dynamic changes in biofilm and the corresponding response changes of three typical hydraulic properties of media within the percolation column. The results revealed that the biofilm exhibited a five-stage growth morphology: bacterial stage, colony stage, biofilm with filamentous EPS stage, biofilm with mesh EPS stage, and dense biofilm stage. The hydraulic conductivity exhibited nonuniform decay across five stages: initial fluctuation period, swiftly declining period, accelerated declining period, gently decreasing period, and equilibrium stabilizing period. Both bacteria and EPS contribute to the attenuation of the infiltration properties. Due to its hydrophilic nature, EPS played a more prominent role in storing and dispersing water. As such, significant changes in water holding capacity and material transport mechanism occurred at EPS secretion onset. From 0-18h, bacterial colonisation enhanced water-holding capacity somewhat, whereas the hydraulic dispersion coefficient gradually rose. After 18 hours, a substantial amount of extracellular polymers were produced, considerably enhanced water-holding capacity and altered medium migration from convection to dispersion.

Secondary effluent reclamation and reuse is an effective solution to the water shortage problem, and the safety of reused water is a matter of increasing concern. p ‐Nitrophenol (PNP), a common secondary effluent pollutant, can be efficiently removed using the eco‐friendly bioaugmented soil aquifer treatment (SAT) system at the laboratory scale. In this study, a sewage treatment plant in Changchun was selected as a case study to apply the bioaugmented SAT system for field scenarios efficiently. The bioaugmented SAT system was simulated using HYDRUS‐1D code. Biodegradation and adsorption coefficient were conducted from the batch experiment. Based on the degradation experiments, the concentration of bacteria injected into SAT system was designed to be 6 × 10 ¹⁸ colony‐forming units (CFU) m ⁻³ . To enhance the efficiency of the bioaugmented SAT system, the key parameters were optimized based on the sensitivity analysis and the response surface methodology, which showed that the optimal operating conditions were an initial concentration of 86.11 mg L ⁻¹ , a medium of 4.27‐m thickness, and a wet/dry ratio of 0.28. Specifically, alternated wetting–drying conditions and increasing the medium thickness reduced PNP within a specific range. This work demonstrates the performance and applicability of the bioaugmented SAT system for removal PNP in secondary sewage effluent.

Groundwater is subjected to contamination threats from human activities, such as agriculture, especially long-term farming in the Sanjiang Plain, China. Identifying the sources and distribution of pollution is essential for its reasonable prevention and control. In this study, we analysed the chemical characteristics of 389 samples at 60 shallow groundwater monitoring points from 2011 to 2015 in the Sanjiang Plain using traditional hydrochemical methods, water quality assessment, Pearson’s correlation, and principal component analysis (PCA). Although groundwater type in this area was predominantly HCO₃-Ca·Mg, three forms of nitrogen pollution (ammonia, nitrate, and nitrite) were all detected in this area. The interaction of natural geochemical and anthropogenic factors during hydrochemical formation is confirmed by the high coefficients of variation and Gibbs plots of the main ions in the water. The overall shallow groundwater situation was described as good, with more than 40% and 90% of groundwater samples suitable for drinking and irrigation according to the quality assessment, respectively. The proportion of poor water quality in the wet season was higher than that in the dry season. NO₃-N and NH₃-N were identified as the major anthropogenic pollutants in the study area. Results from Pearson’s correlation and principal component analysis shows two main pollutants fall into two chemical controlling factors together with natural chemical parameters, which implies that the migration and transformation of pollutants may have affected the overall hydrochemical characteristics of the regional groundwater. Therefore, findings from this paper can provide insight into the chemical evolution of groundwater in response to long-term agricultural activities and can help contribute to better management of groundwater resources and agricultural sustainable development.