Ejazul Islam

Employing floating treatment wetlands (FTWs) and constructed wetlands (CWs) is one of the most eco-friendly strategies for the bioremediation of water contaminants. Here, the efficiency of FTWs and CWs was compared for the degradation of phenanthrene-contaminated water for the first time. The FTWs and CWs were established by vegetated Phragmites australis in phenanthrene (1000 mg L⁻¹)-contaminated water. Both wetlands were augmented with a bacterial consortium of four bacterial strains: Burkholderia phytofirmans PsJN, Pseudomonas anguiliseptica ITRI53, Arthrobacter oxydans ITRH49, and Achromobacter xylosoxidans ITSI70. Overall, the wetlands removed 91–93% of the phenanthrene whilst the augmentation of the bacterial strains had a synergistic effect. In comparison, the CWs showed a better treatment efficiency, with a 93% reduction in phenanthrene, a 91.7% reduction in the chemical oxygen demand, an 89% reduction in the biochemical oxygen demand, and a 100% reduction in toxicity. The inoculated bacteria were found growing in the shoots, roots, and water of both wetlands, but were comparatively better adapted to the CWs when compared with the FTWs. Similarly, the plants vegetated in the CWs exhibited better growth than that observed in the FTWs. This study revealed that the FTWs and CWs vegetated with P. australis both had promising potential for the cost-effective bioremediation of phenanthrene-contaminated water.

Antibiotic contamination of water is an emerging global issue with severe implications for both public health and the environment. Ciprofloxacin (CIP) is a synthetic fluoroquinolone antibiotic, which is broadly used in human and veterinary medicines around the world to treat various bacterial infections. The presence of CIP in the aquatic environment poses serious health problems to human beings and other living entities. Floating treatment wetland (FTW) is a low-cost and eco-friendly wastewater remediation technology. In the current study, the Canna indica. (Indian shot) was vegetated in a floatable mat to develop FTWs. A consortium of three bacterial strains, Acinetobacter lwoffii ACRH76, Bacillus pumulis C2A1, and Acinetobacter sp. HN3, was immobilized on iron oxide nanoparticles (Fe₃O₄-NPs) and augmented in the FTWs for the remediation of CIP-contaminated (100 mg/L) water. The augmentation of bacteria (immobilized or free) in the FTWs significantly enhanced the removal of CIP from water. The maximum reduction in CIP (98%), chemical oxygen demand (COD; 90%), biochemical oxygen demand (BOD; 93%) and total organic carbon (TOC; 95%) was observed in FTWs that had Fe₃O_4-NP supported bacteria. This study reveals that FTWs have a great potential to remove the CIP from contaminated water, albeit its CIP removal efficiency was substantially enhanced by augmentation with Fe₃O₄-NPs supported bacteria.

The unwanted occurrence of antibiotics in the environment is an emerging concern of non-target toxicity and antimicrobial resistance. Floating treatment wetland (FTW) is a low-cost and ecofriendly wastewater remediation strategy; however, the effect of immobilized bacteria on its efficacy during the remediation of ciprofloxacin (CIP)-contaminated water has not been documented. In this study, Phragmites australis was planted to develop FTW, and it was augmented with a bacterial consortium (Acinetobacter lwoffii ACRH76, Bacillus pumulis C2A1, and Acinetobacter sp. HN3), with and without immobilization for the remediation of CIP-contaminated (100 mg L⁻¹) water. The augmentation of bacteria (immobilized or in suspension) in the FTWs significantly increased the elimination of CIP from the water. Maximum removal of CIP (97%), COD (92%), BOD (93%), and TOC (90%) from the water was observed in the FTWs having immobilized bacteria. This research revealed that the FTWs have tremendous potential to remove the CIP from the water and its removal efficiency can be enhanced via immobilized bacterial augmentation strategies.

Excessive use of detergents in wide industrial processes results in unwanted surfactant pollution. Among them, sodium dodecyl sulphate (SDS) has well-known history to be used in pharmaceutical and industrial applications. However, if discharged without treatment, it can cause toxic effects on living organisms especially to the aquatic life. Floating treatment wetlands (FTWs) could be a cost-effective and eco-friendly options for the treatment of wastewater containing SDS. In this study, FTWs mesocosms were established in the presence of hydrocarbons-degrading bacteria. Two plant species (Brachiaria mutica and Leptochloa fusca) were vegetated and a consortium of bacteria (Acinetobacter sp. strain BRSI56, Acinetobacter junii strain TYRH47, and Acinetobacter sp. strain CYRH21) was applied to enhance degradation in a short-time. Results illustrated that FTWs vegetated with both plants successfully removed SDS from water, however, bacterial augmentation further enhanced the removal efficiency. Maximum reduction in SDS concentration (97.5%), chemical oxygen demand (92.0%), biological oxygen demand (94.2%), and turbidity (99.4%) was observed in the water having FTWs vegetated with B. mutica and inoculated with the bacteria. The inoculated bacteria showed more survival in the roots and shoots of B. mutica as compared to L. fusca. This study concludes that FTWs have the potential for the removal of SDS from contaminated water and their remediation efficiency can be enhanced by bacterial augmentation.

High soil surface temperature and loosened soil are major limiting factors of plant productivity in arid and semi-arid coal mining areas of China. Moreover, the extensive and illegitimate burning of crop residues is causing environmental pollution; whereas, these residues could be converted to biochar to benefit soil quality. In this study, the effect of wheat straw biochar (WSB) at rates of 0% (control, CK), 1% (low, LB), 2% (medium, MB) and 4% (high, HB) on soil temperature at different depths (5, 10, 15, and 20 cm) and moisture levels (10 and 20%) was investigated under high soil surface temperature of 50 °C and air humidity of 40%. Our data suggested that soil bulk density was inversely, and soil moisture was directly corelated with soil thermal parameters. Moreover, the increasing rate of WSB addition linearly decreased the soil thermal properties. The maximum decrease in soil bulk density at both moisture levels (10% and 20%) was measured in HB treatment compared to respective CKs. The highest decrease in soil thermal conductivity (59.8% and 24.7%) was found under HB treatment in comparison to respective controls (CK10% and CK20% moisture). The soil volumetric heat capacity was also strongly corelated with soil moisture content (r = 0.91). The WSB treatments displayed differential responses to soil temperature. Under 10% soil moisture, temperature of LB, MB and HB treatments was higher as compared to CK at 5–20 cm depth, and MB treated soil had the smallest increase in temperature. At the 15-cm depth, the MB treatment decreased the temperature by 0.93 °C as compared to the CK20%. Therefore, the effect of WSB on soil temperature was influenced by soil moisture content, soil depth and WSB application rates. It suggested that MB treatment could be a useful farming practice for mitigating soil temperature fluctuation.

The biosorption potential of orange waste (OW) was investigated using synthetic solutions of arsenic and contaminated drinking water under different parameters, e.g. biosorbent dose, initial concentrations of solution, contact time, and pH in a batch system. The optimum conditions were identified as a contact time of 30 minutes, pH 6, biosorbent dose of 1 g L⁻¹, and initial arsenic concentration of 250 ppb. A fluidized bed column was used to study the removal of arsenic in the column. The results showed that biosorption of arsenic gave promising results in batch and continuous system, lowering the arsenic concentration down to WHO standards (10 ppb) for drinking water. The Fourier transform infrared spectra indicated that hydroxyl and carboxyl groups were major active sites for biosorption, while the results of scanning electron microscopy showed obvious changes in surface morphology of OW after the biosorption process. With 90% removal efficiency, results indicated that OW is a cost-effective and eco-friendly biosorbent and comparable to current drinking water treatment technologies. Further research is needed to get the optimum conditions for pilot-scale testing of the biosorption process by OW as well as evaluation of treated water for food quality parameters in order to commercialize the process.

Pilot-scale wastewater treatment systems were investigated for real textile effluent. The parameters of interest in this study were color (Reactive Blue-19 dye), chemical oxygen demand, and growth potential in Triticum aestivum (wheat) and Lolium multiflorum (ryegrass). The dissolved air flotation and electrochemical treatment were studied independently as well as in combination termed as “integrated” (INTG) treatment system for comparative analysis. The overall results showed that the best treatment performance was achieved through INTG treatment as reduction of 63% in COD and 72% in color was achieved without addition of any other chemical at the current density of 1 mA/cm² in 1 h of residence time using aluminum electrodes. The INTG-treated effluent was tested for growth potential studies and the results showed that root/shoot lengths were 20/26% and 34/35% more for wheat and ryegrass, respectively, as compared to the untreated wastewater. This pilot-scale study provides evidence that INTG treatment system is a sustainable technology and the treated effluent can be reused for irrigation purposes.