The potential of cattail (Typha latifolia) and water hyacinth (Eichhornia crassipes) biomass to remove Pb and Cd ions from metal solutions was determined. The removal efficiency of Pb and Cd decreased with the increase in the initial concentration of metal aqueous solution but increased with the increased biomass doses. The biosorption was unaffected by the increase in pH from 5.0 to 6.5. Metal removal efficiency increased with increased contact time and then reached equilibrium in about 45 min. Higher q_max (the Langmuir model) and K_F (the Freundlich constant) suggest that both cattail and water hyacinth biomass have a greater affinity for Pb(II) than Cd(II). The better fitness of the adsorption kinetics in the pseudo-second-order model than in the pseudo-first-order model indicates that biomass has an inclination toward chemisorption. The present study showed that cattail and water hyacinth biomass are promising biosorbents that provide a green, practical, and cheap solution to household water filtering systems in rural communities.

Urban rivers flowing through cities are places of recreation and relaxation for citizens. However, these rivers are sometimes contaminated by Escherichia coli (E. coli). Therefore, the purpose of this study was to develop a simple method to investigate E. coli contamination in river water. From May to October 2019, water samples were collected from five locations in the Toga River in Kobe City, Japan, and the fecal coliform density (FCD) was measured, along with the electrical conductivity and the chloride ion concentration of the river water. Comparison of these water quality parameters with actual fecal coliform densities revealed a high correlation between electrical conductivity and FCD. Whereas, little correlation was found between FCD and chloride concentration. Receiver operating characteristic (ROC) analysis was used to evaluate the method that uses the electrical conductivity as an estimating parameter. The area under the curve (AUC) was used as a measure of the performance of the ROC curve algorithm. The calculated AUC value stayed high, above 0.95, over a wide range of FCD values, suggesting that this rapid monitoring method is appropriate for assessing the quantity of contaminating fecal coliforms in the range higher than 300/100 mL.

Stenotrophomonas maltophilia has been increasingly recognized as an opportunistic pathogen that causes pneumonia and bloodstream infections. In spite of its clinical importance, literatures on the quantitative monitoring of Stenotrophomonas in the water environment are not available. In this study, Stenotrophomonas spp. contained in treated wastewater, pond water and river water were quantified by a selective agar medium. The numbers of blue colonies on VIA agar plates were in ranges of 1.9 to 24.7 CFU/mL for treated wastewater and 0.6 to 15.8 CFU/mL for other environmental samples. The species of 88 isolates with blue colonies on the VIA agar plates consisted of Stenotrophomonas spp. (85%) and others (15%) based on 16S rRNA sequencing and genus-specific PCR targeting 23S rRNA. The number of Stenotrophomonas spp. in the samples was roughly 1/50 level of the number of coliform group bacteria. Most Stenotrophomonas isolates (> 97%) were susceptible to both sulfamethoxazole/trimethoprim and levofloxacin.

We determined the concentrations of 2-methylisoborneol (2-MIB) and geosmin in final effluent from wastewater treatment plants in Kyoto City, Japan, investigating variations during treatment. The concentrations of 2-MIB and geosmin in final effluent were 5.1–29.8 and 3.9–13.9 ng/L, respectively. Geosmin concentrations in primary effluent were higher than those in influent. The concentration of 2-MIB increased in the reactors, while that of geosmin decreased. The anaerobic-anoxic-oxic and step-feed biological nitrogen removal processes lowered 2-MIB and geosmin concentrations more than did the anaerobic-oxic activated sludge process. Other factors regulating the concentrations of earthy and musty odor compounds may include activated sludge flowing from the secondary settling tank, changes in total nitrogen removal efficiency, anaerobic conditions in reactors or secondary settling tanks, and deterioration of activated sludge, including by formation of a scum layer.