Improved remediation of amoxicillin-contaminated water by floating treatment wetlands intensified with biochar, nutrients, aeration, and antibiotic-degrading bacteria.

Residual antibiotics have become emerging contaminants of concern for their adverse impact on the ecosystem. Additionally, their accumulation in the environment is increasing antibiotic resistance among pathogens. This study assessed the impact of intensification of biochar, nutrients, aeration, and bacteria (BNAB) on the remediation potential of floating treatment wetlands (FTWs) to treat amoxicillin (AMX)-contaminated water. The FTWs were developed with saplings of Vetiveria zizanioides and intensified with biochar (1.5%), nutrients (25 mgL-1 N, 25 mgL-1 P, 20 mg L1 K), aeration (7 mg L-1), and AMX-degrading bacteria. The results showed that all the amendments enhanced the AMX degradation, while the maximum reduction in COD (89%), BOD (88%), TOC (87%), and AMX (97%) was shown by the combined application of all the amendments. The combined application also enhanced plant growth and persistence of the inoculated bacteria in the water, roots, and shoots. This approach can be employed for the low-cost, environment-friendly treatment, and recycling of antibiotic-contaminated wastewater, where BNAB intensification can further improve the bioremediation efficiency of FTWs in the case of heavily polluted waters.

Vetiver grass floating treatment wetlands (FTWs) removed 83% amoxicillin.Intensification of floating treatment wetlands enhanced amoxicillin removal to 97%.Intensified-FTW removed COD, BOD, and TOC by 89%, 88%, and 87%, respectively.Potential of Intensified-FTW for bioremediation of highly polluted water is shown.

Operational parameters optimization for remediation of crude oil-polluted water in floating treatment wetlands using response surface methodology.

The application of floating treatment wetlands (FTWs) is an innovative nature-based solution for the remediation of polluted water. The rational improvement of water treatment via FTWs is typically based on multifactorial experiments which are labor-intensive and time-consuming. Here, we used the response surface methodology (RSM) for the optimization of FTW's operational parameters for the remediation of water polluted by crude oil. The central composite design (CCD) of RSM was used to generate the experimental layout for testing the effect of the variables hydrocarbon, nutrient, and surfactant concentrations, aeration, and retention time on the hydrocarbon removal in 50 different FTW test systems planted with the common reed, Phragmites australis. The results from these FTW were used to formulate a mathematical model in which the computational data strongly correlated with the experimental results. The operational parameters were further optimized via modeling prediction plus experimental validation in test FTW systems. In the FTW with optimized parameters, there was a 95% attenuation of the hydrocarbon concentration, which was very close to the 98% attenuation predicted by the model. The cost-effectiveness ratio showed a reduction of the treatment cost up to $0.048/liter of wastewater. The approach showed that RSM is a useful strategy for designing FTW experiments and optimizing operational parameters.

Immobilization of metribuzin degrading bacterial consortium MB3R on biochar enhances bioremediation of potato vegetated soil and restores bacterial community structure.

Metribuzin (MB) is a triazinone herbicide used for the eradication of weeds in agriculture. Presence of its residues in agricultural soil can potentially harm the establishment of subsequent crops and structure of soil microbial populations. In this study, remediation potential of an MB degrading bacterial consortium MB3R immobilized on biochar was evaluated in potato vegetated soil. In potato vegetated soil augmented with MB3R alone and MB3R immobilized on biochar, 82 and 96% MB degradation was recorded respectively as compared to only 29.3% in un-augmented soil. Kinetic parameters revealed that MB3R immobilized biochar is highly proficient as indicated by significant increase in the rate of biodegradation and decrease in half-life of MB. Enhanced plant growth was observed when augmented with bacterial consortium either alone or immobilized on biochar. Presence of herbicide negatively affected the soil bacterial community structure. However, MB3R immobilized on biochar proved to be helpful for restoration of soil bacterial community structure affected by MB. This is the very first report that reveals improved remediation of contaminated soil and restoration of soil bacterial populations by use of the MB degrading bacterial consortium immobilized on biochar.

Enhanced degradation of hydrocarbons by gamma ray induced mutant strain of Pseudomonas putida.

Soil contamination due to petroleum hydrocarbons is a ubiquitous environmental problem for which efficient remediation alternatives are required. Application of hydrocarbons degrading bacteria with enhanced degradation potential is such an alternative. The aim of present investigation was to induce mutagenicity in Pseudomonas putida through gamma-ray irradiation for the enhanced degradation of crude oil. A total of mutant 10 bacterial strains (300A-J) were screened for their degradation abilities in vitro; among which the performance of 300-B was outstanding. Subsequently, spiked soil (30 g/kg crude oil) was augmented with the wild-type parent strain and mutant 300-B strain in individual experiments. Bacterial inoculation in both experiments enhanced hydrocarbons degradation; however, degradation was 46.3% higher when 300-B mutant strain was employed. This improved oil degradation was found to have a strong positive correlation with the gene abundance and expression of the mutant strain, suggesting its successful survival and catabolic potential in situ. Concomitantly, a better nutrients assimilation and water utilization was observed in the experiment containing 300-B mutant. Yet preliminary, these findings highlight the importance of gamma ray irradiation towards improved degradation potential of previously isolated hydrocarbons degrading bacteria.

Role of nutrients and environmental conditions for the production of dextransucrase from L. mesenteroides KIBGE-IB26.

The bacterial strains capable of producing dextransucrase enzyme were isolated from different fruits and vegetables sources. In primary screening, five strains were selected on the basis dextransucrase production and among them L. mesenteroides KIBGE- IB26 isolated from bottle gourd (Lagenaria Vulgaris) was selected for further studies. For the enhancement of enzyme production, different physicochemical parameters were optimized. Maximum production of dextransucrase was achieved after 06 hrs using sucrose (20.0 g/l) as a substrate at 25°C. Maximum dextransucrase production was achieved when medium pH was kept 7.5 before sterilization. In addition, medium was also supplemented with CaCl2 and K2HPO4 and maximum enzyme production was achieved at 0.0025 g/dl calcium chloride and 2.0 g/dl K2HPO4with enzyme activity of 87 DSU/ml/hr. Production of dextransucrase in shorter period of time makes this strain an attractive candidate for commercial production of dextransucrase.