In the present study, the authors attempted to grasp the entire bacterial communities in treated water and activated sludge derived from a laboratory-scale activated sludge reactor using polymerase chain reaction/terminal-restriction fragment length polymorphism (PCR/T-RFLP) that targeted a partial 16S rRNA gene. The authors introduced the sonication-dilution method, an easy and rapid method to prepare PCR-compatible DNA extracts from target samples, and assessed its reproducibility. Results showed that bacterial communities in treated water and activated sludge were successfully profiled using the template DNA prepared by this method. The bacterial community structures in treated water had significant differences from those in activated sludge. Certain peaks in T-RFLP profiles were more intense with the treated water sample, whereas other peaks were found to be more intense with the activated sludge sample. The species corresponding to the peaks that were more intense in treated water samples had a higher tendency to be discharged with treated water, whereas other species detected in activated sludge were more associated with stable flocs. However, principal component analysis (PCA) of the T-RFLP data demonstrated a similar trend of the bacterial communities present in the treated water and activated sludge samples.
In the present study, GB400 was prepared by calcination of gibbsite (GB) at 400°C. The properties of GB and GB400 were investigated and the adsorption of cisplatin onto GB400 was evaluated. The scanning electron microscopy images were obtained and specific surface area, mean pore diameter, pore volume, number of hydroxyl groups, and the solution pH were measured. The observed values for GB400 were superior to those of GB. The optimal pH condition for adsorption of cisplatin using GB400 was about 8. Equilibrium adsorption of cisplatin onto GB400 was reached within 24 h. These experimental data were fitted to the pseudo-second-order equation. Moreover, the amount of cisplatin adsorbed onto GB400 was increased proportionally with temperature. The experimental data were fitted to the Langmuir equation model. The ΔG values were less than -80 kJ/mol, which indicate that the adsorption mechanism of cisplatin onto GB400 is related to chemisorption. The ΔH values were negative, indicating that the adsorption of cisplatin onto GB400 is exothermic. The positive values of ΔS signify an irregular increase of the randomness at the GB400/solution interface during the adsorption process. Cisplatin adsorbed onto GB400 was desorbed using hydrochloric acid solution.
The mutagenicity of one pesticide and 20 pesticide transformation products in water environments (PTPWs), the mutagen formation potential (MFP) of three pesticides and 28 PTPWs were investigated with the Ames Salmonella mutagenicity assay. The mutagenicity of 2-hydroxybenzyl alcohol (a PTPW of iprobenfos) was positive before chlorination. Out of 28 PTPWs, 18 were positive for the MFP. The difference of the MFP distributions between the parent pesticides and their PTPWs was tested statistically, indicating no increase in the MFP through the transformations. Of the 28 couples of parent pesticides and their PTPWs tested, seven couples increased their MFP through the transformations. The greatest ratio of the increase was 38, which was observed for iprobenfos and its PTPW 3-hydroxybenzyl alcohol.
Methane and N2O emissions were measured simultaneously in three types of decentralized wastewater treatment facilities to develop new emission factors (EFs) in Japan. Considering the ratio of the actual load to designed load and elapsed time from last desludging, 24 sites for Johkasou treating domestic wastewater, 6 sites for Johkasou treating night soil only, and 30 sites for vault toilet were selected. Gas samples were collected in the morning, afternoon, and evening for every Johkasou site. The investigation was conducted in summer and winter to estimate the annual average EFs. The EFs of CH4 and N2O of both Johkasou were higher than that used in the national greenhouse gas inventory in 2012, whereas the CH4 and N2O EFs of vault toilet were lower. Especially, N2O EF was only 1% of the national inventory in 2012, and almost zero. According to the results of these three types of decentralized wastewater treatment facilities, the emissions of CO2eq in FY2010 were 1.77 times higher than the national inventory.
Bisphenol A (BPA) is a well-known toxic and endocrine-disrupting compound frequently detected in aquatic environments. Here, we investigated rhizoremediation of BPA-polluted water using giant duckweed (Spirodela polyrhiza). One BPA-degrading bacterium, Novosphingobium sp. FID3, was isolated from the S. polyrhiza roots. Strain FID3 utilized BPA as a sole carbon and energy source. Organic compounds from S. polyrhiza roots supported cell growth of strain FID3, and the strain colonized the sterile S. polyrhiza roots, where it degraded BPA. Strain FID3 colonizing the S. polyrhiza roots was passed down from mother plant to first- and second-generation daughter plants during vegetative reproduction. S. polyrhiza in association with strain FID3 repeatedly removed BPA from secondary effluent water polluted with BPA, whereas S. polyrhiza alone could not remove BPA. Hydroponic systems using S. polyrhiza in association with the BPA-degrading rhizobacterium Novosphingobium sp. FID3 have the potential to be effective and sustainable treatments for BPA-polluted waters.
Eight industrial effluents from Toyama Prefecture, Japan were subjected to three freshwater short-term chronic assays to analyze the potential of ecotoxic impact on receiving water. Tests comprised algal inhibition (Pseudokirchneriella subcapitata), crustacean reproduction (Ceriodaphnia dubia), fish embryo-larva (Danio rerio). Among the eight effluents, chronic toxic effects on alga, crustacea and fish were observed in six, six and one effluents respectively. No-observed-effect concentrations (NOECs) equal to or less than 5% were found in five samples. Nickel and salts were suspected as the causative factors from comparing water parameters with their effects. The impact of these effluents after discharged into receiving water is discussed. The results of the study show the effectiveness of the whole effluent toxicity approach to compensate the present shortcoming of wastewater regulation in Japan.
To explore the cost reduction of water reclamation and reuse facilities in developing countries, a simple ceramic filter made of local materials, such as clay and rice bran, was used in a membrane bioreactor (MBR) process. The feasibility of applying suction filtration to an MBR with a simple ceramic filter was examined by a laboratory-scale experiment; successful results using gravity filtration were reported in a previous paper. The BOD removal performance was satisfactory and demonstrated the feasibility of reusing effluent water for many purposes. The MBR operation with a flux less than 0.2 m/d showed a lower risk of fouling; increasing the flux caused an increase in fouling risk. The suction filtration and gravity filtration results were compared using the total resistance of the filter (R) and the resistance change rate (dR/dt). The R and dR/dt values were estimated higher in the suction filtration compared to those in the gravity filtration. The high dR/dt seemed to cause the necessity of the filter cleaning. The gravity filtration was suggested to be a more advantageous operation than the suction filtration in MBR using the simple ceramic filter.