Search

Effect of temperature on antibiotic resistance genes (ARGs) during vermicomposting of domestic excess sludge remains poorly understood. Vermicomposting experiment with excess sludge was conducted at three different temperatures (15 °C, 20 °C, and 25 °C) to investigate the fate of ARGs, bacterial community and their relationship in the process. The vermicomposting at 25 °C did not significantly attenuate the targeted ARGs relative to that at 15 °C and 20 °C. The dynamics of qnrA, qnrS, and tetM genes during vermicomposting at 15 °C and 20 °C followed the first-order kinetic model. Temperature remarkably impacted bacterial diversity of the final products with the lowest Shannon index at 25 °C. The presence of the genus (Aeromonas and Chitinophagaceae) at 25 °C may contribute to the rebound of the genes (qnrA, qnrS and tetM). The study indicates that 20 °C is a suitable vermicomposting temperature to simultaneously reach the highest removal efficiency of the ARGs and the good biostability of the final product.

The fate and behavior of radioactive cesium (Cs) in the water environment are of great concern. The involvement of bacteria regarding their accumulation capability for this element is the most fundamental factor that needs to be clarified even for exploring the interactions between many environmental factors that involve together in governing the transport and distribution of Cs. As the first systematical study that aimed to evaluate the accumulation capability of environmental bacteria for Cs, bacteria in the sediment of a freshwater reservoir and coastal water environment were isolated and multiplied for contact experiment with Cs under different temperature conditions (5, 25, and 35 °C). The accumulation concentration of Cs in bacteria from freshwater sediment varied in 3.95 × 10−6 to 5.68×10−4ng-Cs/cell, and that from coastal sediment in 1.52 × 10−6 to 7.41×10−4ng-Cs/cell, indicating obvious differences among bacterial species. Bacteria of coastal sediment possessed higher accumulation capability for Cs than bacteria from freshwater sediment, and temperature dependency was confirmed for bacteria from coastal sediment. The findings of this study have great reference value for better understanding and controlling the fate and behavior of radioactive Cs associated with bacteria in the water environment.

The fixation capability of cesium on five recycling materials was compared through two sets of sorption experiments using the materials mixed with and without soil. The estimated Freundlich constant K and the distribution of sorbed cesium on the materials revealed a general order of the fixation capability as carbonized sludge > coconut shell biochar > incinerated sewage sludge ash > rice husk biochar > slag. Parametric strong positive correlations were found existent between the fixation capability of cesium and the property-related indexes of the materials such as cation exchange capacity, organic matter content and the potassium concentration.

Antibiotic resistance genes abundant in municipal excess sludge reduce the agricultural value of vermicompost. However, little attention has been paid on the fate and behavior of the problem-causing agents in vermicomposting. In this study, the fate and behavior of quinolone resistance genes in excess activated sludge during vermicomposting were studied with reactors introduced with Eisenia fetida for three different densities. The substrate pile without earthworms was operated as control in parallel. The results showed that earthworms could significantly reduce the absolute abundance of quinolone resistance genes in the excess sludge, with a reduction ratio of 85.6-100% for qnr A and 92.3-95.3% for qnr S, respectively (p 0.05). For microbial profiles, both the dehydrogenase activity and the abundance of microbes (16S rDNA) revealed a distinct decreasing trend after 7 days from the start of the experiment; however, the bacterial diversity in the final products seemed to be enriched with the emergence of the uncultured Flavobacteriales bacterium and uncultured Anaerolineaceae bacterium. Redundancy analysis revealed clearly that the qnr genes had positive correlations with the targeted indexes of microbial profiles, with the correlations with the bacterial abundance and dehydrogenase activity being more statistically significant than the bacterial diversity (p 0.05). The results of this study suggested that earthworms could promote the attenuation of quinolone resistance genes in the excess sludge through lowering the bacterial abundance and activity, and the promotion effect could be enhanced by increasing the density of earthworms.

The untreated water may lead to an excessive disposal of wastes which may reduce the water quality of water bodies and damage water ecosystems. Wastewater treatment systems are widely implemented in industries and municipalities to decrease toxic wastewater release into aquatic ecosystems. Wastewater recycling, reclamation, recovery, and reuse can be used as tools for the control of water resources and can attract researchers and stakeholders. Currently microbial fuel cells and microalgae are intensively studied as a cost-effective technology to complete sustainable wastewater treatment. These technologies have potential benefits for energy, and environmental and economic sustainability. This chapter will review the challenges, barriers, and opportunities associated with improving wastewater treatment systems.

Immobilization using biochar is a cost-effective and environmentally friendly remediation method to inhibit the transfer of soil contaminants to the food chain. This study evaluated the effects of coconut shell–derived biochar (CSB) and sewage sludge–derived biochar (SSB) on reducing the accumulation of cesium (Cs) by plant from contaminated soil. Pot experiment was conducted by cultivating Napier grass on the soil added with different Cs concentrations (0, 25, and 50 mg kg−1) and biochar ratios (0: control, 5% and 10%). It was observed that both biochars significantly restricted the transfer of Cs to the root, leaf sheath, and leaf blade of Napier grass (p

The widespread proliferation of antibiotic resistance genes (ARGs) is a serious environmental and human health issue. Wastewater treatment facilities (WWTFs) are potential sources to spread ARGs to natural environment, for which, the presence state of ARGs in the sludge, as extracellular ones (eARGs) or intracellular ones (iARGs), along with the sludge settleability, are very important factors. The sludge settleability is closely associated with its floc size and density, bacterial activity, and the proportion of intact/damaged bacterial cells that aggregate together to form flocs for separation in the sedimentation process. It is reasonable to hypothesize that the distribution of eARGs and iARGs may differ with the sludge fractions of different settleability, a topic of great academic and practical significance requiring clarification. In this study, sludge samples from the aerobic contact tank of six household WWTFs were fractionated into fractions with different settling velocities: sludge of low settleability (LS), medium settleability (MS) and high settleability (HS); and the distribution of eARGs and iARGs in the obtained fractions for the widely detected tet G, tet M and sul 1 in water environment was evaluated based on the PMA-qPCR method, together with the evaluation for the well reported mobile genomic element intl 1 and total bacterial 16S rDNA. For the LS fractions, which contained more damaged bacterial cells, the distribution percentages of eARGs were generally higher than those of iARGs. For the HS fractions, which contained flocs with larger sizes formed by both intact and damaged bacterial cells, the relative abundances of ARGs and intl 1 were found apparently lower even if the presence percentages of eARGs were comparatively higher. It is thus inferable that sludge fractions of LS may possess higher transfer potential for ARGs and enhancing their settleability through optimization of the operation conditions is important for mitigating the proliferation of ARGs.

Fruit and vegetable waste (FVW) is generated in large quantities during production, processing, and consumption. Several conventional methods are used for treating the FVW, such as incineration, landfill, anaerobic digestion, and composting. Compared to these methods, vermicomposting has the advantages of effective stabilization of the organic wastes like FVW through joint action of earthworms and microorganisms in decomposition of the easily decaying organic constituents and of higher reuse value for its final product as organic fertilizer. However, treating fresh FVW directly by vermicomposting is difficult to be conducted because of higher water content and C/N ratio of FVW. Excess activated sludge (EAS), as the main by-product of sewage treatment process, is also an organic waste consisting of microorganisms that can be treated by vermicomposting. Vermicomposting of fresh FVW with the addition of EAS is not only reported as a feasible option to solve the problem caused by the higher water content and C/N ratio of FVW but also can enhance the treatment process. The rich content of microorganisms, nitrogen, and phosphorus in EAS can promote the growth of earthworms and enhance the microbial activity, thus improving the decomposition efficiency of FVW and improving the utilization value of the final product as fertilizer. The present chapter summarizes the several conventional treatment methods of FVW and proposes a more feasible and sustainable treatment method of FVW by vermicomposting with the addition of EAS.

The present study investigated the odor emission potential of activated sludge through comprehensive assessment for physicochemical properties and bacterial profile of sludge. Three types of sludges from wastewater treatment plants treating slaughterhouse (SWTP), meat processing (MWTP) and domestic wastewater (DWTP) were used based on distinct morphological features which were speculated to impact odor generation. Total element S in the SWTP sludge with relatively more disintegrated cellular debris exhibited higher level than that in the MWTP and DWTP sludge, while the emitted odorants (hydrogen sulfide and methyl mercaptan) showed the opposite patterns (i.e., the lowest level for the SWTP sludge). Nitrifying bacteria was only detected in the SWTP sludge, which was well in line with abundant nitrate in the corresponding aeration tank. Principal component analysis indicated that the potential of the odor emission from the sludge had strong correlations with dehydrogenase activity, and nitrate, which implies that these parameters may serve as referring indices for evaluating the potential of odor emission of sludge or treated product.

This study aimed to clarify the effect of excess activated sludge (EAS) on vermicomposting of fruit and vegetable wastes (FVW). For this, a novel vermireactor consists of substrate and bed compartments was used for treating five types of FVW (banana peels, cabbage, lettuce, carrot, and potato) with and without the addition of EAS by earthworms. The EAS promoted the growth and cocoon production of earthworms, and the decomposition efficiency of FVW. The changes of dehydrogenase activity revealed that the EAS enhanced the microbial activity in all treatments except for the carrot. The organic matter content, total carbon and the C/N ratio showed a significant decrease after addition of EAS into FVW. The content of nitrogen and phosphorus was also improved in the final products after vermicomposting. This study suggested that the addition of EAS could be a feasible option to enhance the vermicomposting of FVW.

To investigate the sorption capacity of cesium on different forest and agricultural soils, batch sorption experiment was conducted. The Freundlich constant K reflecting the sorption capacity differed greatly with soil types (6 forest soils and 12 agricultural soils) (0.36–5.50 [(µg g−1) (µg L−1)−1/n]). The sorption capacity on agricultural soils was generally higher than that on forest soils. The distribution of the adsorbed cesium on soils was found not uniform and seemed to be different from Na, K, Ca and Mg. A strong positive correlation was revealed between the sorption capacity of cesium and the cation exchange capacity of soils.

The adsorption characteristics of natural organic matter (NOM) were investigated on the basis of fluorescence excitation emission matrix (EEM) by using four different coal-based activated carbons (ACs). For each AC, batch adsorption isotherms were analyzed using a modified Freundlich isotherm model on the basis of the fluorescence intensity of three major fluorescence peaks appeared in the fluorescence EEM reported to be reflective of the humic acid-like (P1), fulvic acid-like (P2) and aromatic protein-like (P3) substances, respectively, together with the well-used overall quality indices of dissolved organic carbon (DOC) and ultraviolet absorbance at the wavelength of 260 nm (UV260). It was found that, for all five quality indices, the adsorption capacity differed with the ACs used, and the modified Freundlich isotherm constant K estimated for P1, P2 and P3 was in close correlation with that of the total organic matter evaluated by DOC. Moreover, no matter which AC was concerned, the magnitude of the estimated K and the removal rate over a broader range of AC dose for P3 were apparently smaller than those for P1 and P2, suggesting the adsorbability of aromatic protein-like substances was lower than that of the humic acid-like and fulvic acid-like substances. The dependency of the adsorption capacity of NOM on the volume of pores in some specific size ranges of the ACs was also revealed.

The characteristics of natural organic matter (NOM) released to water from a soil environment were investigated based on the release potential and the quality indexes of SUVA, fluorescence EEM and molecular weight distribution using eight forest and agricultural soils collected from a representative river catchment (Kani River catchment in Gifu, Japan). The content of organic matter (OM) and its release potential to water differed obviously with type of soil origin, in the following order: vegetable field (VF) < paddy field (PF) < broadleaf forest (BF) < coniferous forest (CF) and VF < PF < CF < BF, respectively. For the released NOM, SUVA under different pH conditions decreased in the following order: neutral condition [3.6-24.0 m-1/(mg/L)] > basic condition [3.5-8.0 m-1/(mg/L)] > acidic condition [2.5-3.0 m-1/(mg/L)]. Humic acids (P1), fulvic acids (P2) and protein-like substances (P3) were the main components of the NOM released under neutral condition. The proportion of P1 and P2 released from the forest soils was lower than that from the agricultural soils. Marked differences in UV-absorbing constituents of NOM between forest and agricultural soils were found in the peak with a molecular weight of about 9800 g/mol identified as PSS (polystyrene sulfonate).

Heavy metals are toxic to microorganisms at specific concentrations and can have a serious effect on the efficiency of biological wastewater treatment plants. The wastewater treatment performance and bacterial communities of activated sludge were investigated at different heavy metal concentrations (0.1–10 mg L−1 for Cd(II), Pb(II) and 1–100 mg L−1 for Cu(II)) in a well-controlled semi-continuous reactor in 30 d period. Glucose was added once every 8 h as the carbon source throughout the experiment. The heavy metal toxicity was related to chemical oxygen demand (COD), total organic carbon (TOC), three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy, bacterial activity and community composition. The first-order consumption rate for glucose showed that the activity was decreasing in comparison to the control. The COD removal efficiency was also decreased from 87% to 26% in all the reactors under different heavy metal concentrations treatment. The PCR-DGGE and sequencing results revealed that the bacterial diversity showed evident variations under heavy metal stress owing to the potential toxicity of heavy metals. At the genus level, Pedobacter steynii and Flavobacterium, were only tolerant to Cu(II) at 100 mg L−1, while Rhodanobacter thiooxydans resisted to all heavy metal concentrations except Cu(II) 100 mg L−1. Cluster analysis and Principal component analysis (PCA) revealed that the microbial community in Cu(II) was different from the sludge samples treated with Cd(II) and Pb(II) concentrations. The study indicated that it is necessary to identify the metal tolerant species of bacteria for maintaining good performance of biological wastewater treatment plants.

Vermicomposting can significantly attenuate antibiotic resistance genes (ARGs) in the excess activated sludge (EAS). However, the effect of earthworms, especially the effect of gut digestion as a critical step in the vermicomposting process, remains unclarified. The purpose of this study was to investigate the response of ARGs (cell-free and -associated) in EAS to gut digestion of earthworms and to clarify the possible mechanism from the viewpoint of bacterial community through quantitative polymer chain reaction (q-PCR) and high throughput sequencing. Compared to the initial sludge, the earthworm casts were observed to have significantly lower absolute abundances of ARGs, especially qnrS, tetM, and tetX with the removal exceeding 90%. Cell-free and -associated ARGs (except sul1 and tetG) had equivalent contributions to the attenuation of each ARG. Remarkable reductions of bacterial number and alpha diversity (chao1 and Shannon) were detected in the casts. Spearman correlation analysis between the targeted genes and bacterial community indicates that twelve different phyla mainly including Acidobacteria, Euryarchaeota, Deinococcus-Thermus, Chlorobi, Firmicutes, Fibrobacteres, and Proteobacteria are the potential ARGs hosts, suggesting that the fate and behaviour of these hosts during gut digestion of EAS by earthworms substantially determined the dynamics of the ARGs. These findings increase our understanding of earthworm gut digestion as an important process for the attenuation of ARGs in EAS, and contribute towards preventing their release into the total environment.

Elimination of antibiotic resistance genes (ARGs) from excess activated sludge (EAS) mixed for effective treatment of different fruit and vegetable waste (FVW) by using a novel vermireactor consisted of substrate and bed compartments was investigated. ARGs (tet G, tet M and sul 1) and mobile genetic element gene (intl 1) were targeted and, through quantitative analysis of their abundances in both the compartments and the fresh cast of earthworms, significant reductions in substrate compartments were confirmed for the treatments for FVW added with EAS and EAS alone even if the reduction extents differed among the types of FVW. Apparent reductions were not found in the bed compartment where the final products accumulated. For the fresh cast, the relative abundances of ARGs and intl 1 against to the total bacterial 16S rDNA decreased markedly. The present study provided an insight for proper controlling of ARGs during vermicomposting of FVW and EAS.

This study aimed to promote vermicomposting performance for recycling fresh fruit and vegetable wastes (FVWs) and to assess microbial population and community of final products. Five fresh FVWs including banana peels, cabbage, lettuce, potato, and watermelon peels were chosen as earthworms' food. The fate test of earthworms showed that 30 g fresh FVWs/day was the optimal loading and the banana peels was harmful for the survival of Eisenia fetida. The followed vermicomposting test revealed lower contents of total carbon and weaker microbial activity in final vermicomposts, relative to those in compared systems without earthworms worked. The leachate from FVWs carried away great amounts of nutrients from reactors. Additionally, different fresh FVWs displayed dissimilar stabilization process. Molecular biological approaches revealed that earthworms could broaden bacterial diversity in their products, with significant greater populations of actinobacteria and ammonia oxidizing bacteria than in control. This study evidences that vermicomposting efficiency differs with the types and loadings of fresh FVWs and vermicomposts are rich in agricultural probiotics.

Changes of bacterial and fungal community during vermicomposting of vegetable wastes by hatchling, juvenile and adult Eisenia foetida were investigated through analysis of the extracted bacterial 16S rDNA and fungal 18S rDNA with quantitative polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE) and sequencing. After 60 days of composting, significantly lower values of microbial activity and bacterial and fungal densities were revealed in the products of composting with earthworms than in the control (without earthworms). PCR–DGGE images showed vermicomposting significantly enhanced the diversities of bacterial and fungal communities. However, for their structures, sequencing results revealed that, compared to the control where the bacterial Firmicutes were predominant, in the composts with earthworms, the bacterial Bacteroidetes and Actinomycetes, and the fungal Sordariomycetes were found dominant. In addition, some beneficial species of bacteria and fungi against pathogens were also isolated from the vermicomposting products.

To generate information for better understanding of the behavior of cesium in relatively closed water bodies, experiments using four columns consisted of the sediment phase and the overlying water phase, together with batch sorption experiments were conducted, and the kinetics and the binding potential of cesium by sediment were investigated. Through model analysis with both the first order and the pseudo-second order reaction models, the kinetic parameters of cesium within the four columns were determined. In addition, by analyzing batch equilibrium data with both Freundlich and Langmuir isotherm models, associated sorption parameters were also generated. Comparisons of the models’ suitability for description of both kinetics and binding capacity of cesium were thus made, and the effects of pH and EC on the binding capacity were also studied.

The merged image of the high spatial and the high spectral resolution images could provide more information than each individual image. In this study, the feasibility of using the merged image to extract bambootree mixed forests was examined. To achieve this, the merged image was generated from SPOT PAN and Landsat ETM+ satellite images by applying IBS (Intensity- Hue-Saturation) transform, PCA (Principal Component Analysis), Multiplicative transform, and Brovey transform, respectively. The spectral and spatial information was thus evaluated. Among the four merged methods, IHS transform was proved the most effective to present useful information from original images. Besides, using the created merged images with all four merging methods, the land cover type was further classified by the maximum likelihood classifier method, overall extraction accuracy for the bamboo forest was shown to be 80.9%, 75.3%, 74.2% and 78.7%, respectively. Since the classified result displayed the presence of the bamboo forest in mixtures with different tree crown, the results were further interpreted with the aid of the aerial photographs. As a result, bamboo in the mixtures were determined and the occupation percentages of bamboo crown were grouped into four categories : above 90%, 70-90%, 50-70% and 30-50%. For all four categories, reclassification was performed and the extraction accuracy for bamboo forest were obtained as 80.0%, 71.1%, 62.2%, and 53.3%. The corresponding bamboo area ratio in each category against the whole bamboo area occupied by this type, mixed vegetation were 32.4%, 31.3%, 20.5% and 15.7%, respectively. Therefore, it is clear that using the merged image, a great part of the bamboo-tree mixed forest could be extracted in addition to pure bamboo forest; and it is also possible for better assessment of the current bamboo distribution situations and future expansion tendencies in local or larger basin areas.

An approach to use satellite data to estimate quantitatively the fixation of nitrogen by different forest types over river basin ecosystems was proposed and applied to a mountainous area located in the upper reach of Nagara river basin (Gifu Prefecture, Japan) covered predominantly with multiple vegetation types. In addition to satellite data, this approach also involved the use of census data, statistical data and previous results available in the literature as supporting material. With this approach, the annual amounts of nitrogen absorbed by different categories of forest vegetation classified in terms of species and ages using the satellite data were estimated. Validation tests were performed by comparing the satellite data-based estimations (N satellite) with estimations from a budget model (N model) and statistics data (N record), respectively. The estimated N satellite values coincided well with the values of N model and were somewhat larger than those of N record, although the values of N satellit...

An approach to use satellite data for quantitative estimation of the fixation of nitrogen by different vegetation types over river basin ecosystems was proposed and applied to a mountainous area located in the upper reach of Nagara river basin (Gifu Prefecture, Japan) covered predominantly with multiple vegetation types. In addition to satellite data, this approach also involved the use of census data, statistics data and previous results available in literature as supporting materials. With this approach, the annual amounts of nitrogen absorbed by different categories of forest vegetation classified in terms of species and ages using the satellite data were estimated. Validation tests were performed by comparing the satellite data-based estimations (Ndsatellite) with estimations from a budget model (Ndmodel) and statistics data (Ndrecord), respectively. It was found that the estimated NdsatelliteN (100.8-111.7kg ha-1y-1 for broadleaved forest, 35.4-71.4kg ha-1y-1 for evergreen coniferous forest, 91.4kg ha-1y-1 for mixed forest) coincided well with the values of Ndmodel (96.0-100.4kg ha-1y-1 for broadleaved forest, 48.0-74.0kg ha-1y-1 for evergreen coniferous forest, 82.3kg ha-1y-1 for mixed forest) and were somewhat larger than those of Ndrecord although the values of Ndsatellite and Ndrecord were all in the same order of magnitude for respective vegetation types classified.

This study aimed to investigate the effect of earthworms on physicochemical and microbial properties during vermicomposting of fresh fruit and vegetable wastes (FVW) by contrasting two decomposing systems of FVW with and without earthworms for 5weeks. Compared to control treatment (without earthworms), vermicomposting treatment resulted in a rapid decrease of electrical conductivity and losses of total carbon and nitrogen from the 2nd week. Quantitative PCR displayed that earthworms markedly enhanced bacterial and fungal densities, showing the higher values than control, during the whole decomposition process. In addition, denaturing gradient gel electrophoresis combined with sequencing analysis revealed that earthworms pronouncedly modified bacterial and fungal community structures, through broadening the community diversities of Actinobacteria, Bacteroidetes, Proteobacteria, and Ascomycotina. These results suggest that the presence of earthworms promoted the activity and population of bacteria and fungi, and modified their communities, thus altering the decomposition pathway of fresh FVW.

Multi-temporal Landsat TM data were utilized to classify the cultivated land located in the middle area of the Nagara River basin, Gifu prefecture. Color images of the vegetation indices including DVI, NDVI, SAVI and GVI were composed from respective multi-temporal VI images obtained from original Landsat TM data. The newly composed images clearly demonstrated the cultivated land such as paddy field, upland field and orchard. The distribution of the cultivated land related to the total river basin was also easily discriminated. However, by comparing the change profiles of the vegetation indices, SAVI was confirmed to be the most suitable index to reflect the vegetative conditions of major land-cover categories at different times, and the composed color image based on this index was thus applied for further classification analysis. As compared to the original TM images, classification results based on the composed SAVI image agreed much well with the related census data, with the classification accuracy for the paddy field and the upland field being especially high. The corresponding classification errors for these two land-cover categories were generally below 10%.

The possibility and the reliability of using Landsat TM 7 bands' data only to estimate monthly evapotranspiration (ET) over catchment areas were investigated through the regression analysis between the values of ET calculated from Morton or Penman equation and the data from satellites. The results for the Tokoro and the Abashiri River basin clearly indicated that such an approach was possible and reliable for grassland, forest and water area, and of the total 7 bands examined, four bands which belong to the visible light, near infrared, intermediate infrared and thermal infrared zone were most contributive and important, in the estimation of ET by using Landsat TM data only.

An approach to incorporate the paddy field compartment into the newly developing multimedia fate model "the National Institute for Agro-Environmental Sciences' multimedia environmental fate model (NIAES-MMM-Global)" used to estimate the long-term fate in global environment of current-use pesticides (CUPs) and persistent organic pollutants (POPs) emitted from Japan and all of Asia is presented here. Effects of the rice plant upon the overall environmental fate of targeted chemicals such as CUPs and POPs are assessed by comparing the maximum reservoir capacity (MRC) values calculated with and without the inclusion of rice plants. Rice plants exert a marked effect on the environmental fate of these chemicals and should be considered when paddy field is incorporated into multimedia models to execute predictions that are more reliable. Moreover, the results suggest that the seasonal changes of the rice plant should also be reflected in the models. Accordingly, the scenario description for inclusion of the paddy field compartment in the multimedia models is discussed.