The light scattering method is a valuable tool for accessing particle size and structure mainly due to fast and the nonintrusive nature of the measurement. The method is based on a scattered intensity pattern and depends on particle volume, particle morphology, the light wavelength and the scattering angle. The light scattering model, for particles characterised by a fractal structure, is enabled with the use of the Rayleigh-Gans-Debye theory under constrained assumptions. The range of validity of the Rayleigh-Gans-Debye is limited when primary particles constituting aggregate have a size close to the wavelength. In this work, a range of particle sizes was characterised in order to achieve a better understanding of the relationship between flocs size and its fractal dimension. Hence, the width of the power law regime is discussed. What is more, a specific fractal dimension value of activated sludge flocs was found for each of the analysed wastewater treatment plant, which suggests that the spatial structure of suspensions constituting the activated sludge is an individual characteristic of each treatment facility. It has been shown that activated sludge consists of microflocs from the range of 1–10 μm, which constitute approximately 90% of all the population.

The present study focused on exploring the potential of Ag-ZnO composites for complete mineralization of imidacloprid with the aim to sustain the pollutant free safe water supply. The composites were prepared by hydrothermal method and characterized by Scanning electron microscope (SEM), Energy dispersive X-ray crystallography (EDX), X-ray diffraction (XRD) and band gap measurements. These composites were used to study the UV irradiated degradation of imidacloprid while optimizing the process parameters such as time of UV irradiation, pH of medium, pesticide concentration and composite loading. The results of the study revealed an increase in photodegradation of imidacloprid by Ag-ZnO composites than pure ZnO. Temperature and catalyst loading had a positive effect on degradation efficiency, while an inverse relation was observed between pesticide concentration and degradation. Moreover, no harmful degradation products of imidacloprid were observed in GC-MS analyses that confirmed its complete mineralization.

In many developing countries, a landfill remains one of the most extensively employed solid waste disposal solutions. Although a landfill is a well-designed engineering system, the base lining of a landfill may perform poorly and allow the leachate to reach the underlying soil layers and groundwater. Leachates contain a variety of toxic and hazardous contaminants, which are attenuated in the soil by various processes that slow or transform them. Thus, the objective of this research was to study the water and leachate permeability and retention of the liner soil in a landfill experimental cell by subjecting it to geotechnical, chemical-mineralogical, and physicochemical characterizations, water and leachate permeability tests, and mercury intrusion porosimetry (MIP). In addition, the water and leachate retention curves were determined and analyzed using RETention Curve (RETC) software to obtain the unsaturated permeability curves. The leachate in the soil decreased the suction considering the moisture content of the compacted soil in the field, which consequently increased the leachate permeability of the mineral liner. For the same suction value, in the drying pathways, the soil retained a greater amount of distilled water than leachate. In the wetting pathways, the opposite occurred. Microorganisms were detected in the soil during the filter paper test. The permeability coefficients of the unsaturated soil were directly proportional to the gravimetric moisture content for the water and the leachate, which demonstrated that the soil presents lower unsaturated permeability coefficients for water than for leachate for the same water content.

This paper presents a literature review of the quality of greywater generated in different, especially developing, countries, constituents found in greywater, some treatment systems, natural materials for treatment, some reuse strategies and public perception regarding greywater reuse. The review shows that generation rates are mostly influenced by lifestyle, types of fixtures used and climatic conditions. Contaminants found in greywater are largely associated with the type of detergent used and influenced by other household practices. Many of the treatment systems reviewed were unable to provide total treatment as each system has its unique strength in removing a group of targeted pollutants. The review revealed that some naturally occurring materials such as Moringa oleifera, sawdust, can be used to remove targeted pollutants in greywater. The study further showed that user perceptions towards greywater treatment and reuse were only favourable towards non-potable purposes, mostly due to perceived contamination or lack of trust in the level of treatment offered by the treatment system.

Currently, there is a considerable interest on application of bio-based surfactants as an alternative to conventional synthetic ones as well as in bioremediation technologies to decontaminate polluted sites more effectively. The work is focused on the study of the effects of two biosurfactants, non-ionic Saponin and anionic Rhamnolipids R-90 on the biodegradation of Delor 103, the industrial mixture of polychlorinated biphenyls (PCBs) by bioaugmented bacterial strains. The bacterial isolates used in this study were obtained from long-term PCB-contaminated sediments of the industrial waste Strážsky canal. Enhanced biodegradation of PCBs by Gram-negative strains Achromobacter xylosoxidans (93%) and Stenotrophomonas maltophilia (66%) was observed with the addition of (bio)surfactants Saponin, Rhamnolipids R-90, and Triton X-100 in defined liquid mineral media. The addition of biosurfactant Saponin and Rhamnolipids R-90 increased the PCB biodegradation (55 and 60%, respectively) in the bioaugmented PCB-contaminated sediment inoculated with bacterial strain A. xylosoxidans as well. Regarding to the inhibitory effect of used (bio)surfactants, the obtained IC₅₀ values confirmed that the non-ionic phytogenic Saponin and synthetic surfactant Triton X-100 had a significantly lower toxicity toward bioluminescence of the standard bacteria Vibrio fischeri and used PCB-degrading bacterial strains than the anionic bacterial surfactant Rhamnolipids R-90.

Water body contamination by ammonium is of major concern because it poses huge risks and harm to the environment and human health. Biochar derived from waste spruce sawdust was modified by soaking it into HNO₃ and Na₂CO₃ to obtain a low-cost and high-efficiency adsorbent. The factors affecting the removal of ammonium from aqueous solutions, the mechanisms by which ammonium was adsorbed by the modified biochar, and the potential application of the post-adsorption biochar as an effective N-fertilizer were studied. pH and co-existing ions were affirmed to affect the capacity of the modified biochar to adsorb ammonium. The pseudo-second order kinetic model and Freundlich model could best fit the ammonium adsorption data. Cation exchange was the most important mechanism involved in ammonium adsorption by the modified biochar. The high adsorption capacity of the modified biochar makes it a promising alternative adsorbent to remove ammonium from wastewater. Furthermore, the seedling bioassay experiment demonstrated that the post-adsorption biochar can be cycled back directly to the soil as an effective N-fertilizer.

The golden mussel (Limnoperna fortunei) possesses high fouling potential and has caused damage to various productive sectors. These individuals do not present known natural enemies, but they may be part of the feeding of one or more species of fish, which would help in their control. The main species of fish cultivated in cages in the Itaipu reservoir is pacu (mesopotamicus), and other species have also been evaluated in relation to intensive production viability such as jundiá (Rhamdia quelen) and curimbatá (Prochilodus lineatus). One of the problems faced in the net cages system in the Itaipu reservoir is the inlaying of the golden mussel in the cage’s mesh, making it difficult to handle, requiring more maintenance and reducing the service life of the net cages. This paper aims at evaluate the presence of L. fortunei in the digestive tract of three native species of fish cultivated in cages in the Itaipu reservoir. L. fortunei were present in the gastrointestinal tract of pacus and jundiás, and there was no L. fortunei in curimbatás. It is possible to conclude that for the three species studied, only jundiá and pacu have the capacity to consume and to control the L. fortunei embedded in the mesh of the net cages.

With the rapid development of ultra-high-voltage direct-current (UHVDC) transmission, the strength of environmental static electric field (SEF) around UHVDC transmission lines increased substantially, which has aroused widely public attention on the potential health effects of SEF. In this study, the effect of SEF exposure on learning and memory ability was investigated. Institute of Cancer Research mice were exposed to 56.3 kV/m SEF for a short term (7 days) or long term (49 days). Behaviors in the Morris water maze (MWM) test, hippocampal neurotransmitter contents, and oxidative stress indicators were examined. Results showed that short-term SEF exposure significantly prolonged escape latency and decreased the number of platform-site crossovers, as well as decreased the time spent in the target quadrant in the MWM test. Meanwhile, serotonin level and the ratio of glutamate level to γ-aminobutyric acid level changed significantly. Besides, malondialdehyde content and glutathione peroxidase activity increased significantly, while superoxide dismutase activity decreased significantly. After long-term SEF exposure, all indices above showed no significant differences between the SEF and sham exposure groups. These data indicated that short-term exposure to 56.3 kV/m SEF could cause abnormal neurotransmitter levels and oxidative stress in the hippocampus, which led to the decline in learning and memory ability. Under the condition of long-term exposure, the SEF-induced disturbances in neurotransmitter contents and redox balance were offset by the compensatory responses of mice, and thus, the learning and memory ability returned to normal level. The temporary and reversible decline in learning and memory ability was only a common biological effect of SEF rather than a health hazard.

The generation of ozone microbubbles (O₃MB) is an effective means of sterilizing plant culture media against bacteria and pathogens; however, the use of O₃MB can induce precipitation of metal ions from the medium, such as iron (Fe) and manganese (Mn), that are important to plant growth. Here, we evaluated whether addition of a chelator, either ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA), could prevent this side effect of O₃MB sterilization. We compared nutrient composition, medium sterility, and plant growth after various treatments (0, 0.1, 0.01, 0.001, or 0.0001% (w/v) of EDTA and DTPA addition after O3MB generation). Metal chelators (EDTA and DTPA) are widely used in algal and plant growth solutions to maintain iron (Fe) solubility in hydroponic solutions, EDTA is used in agriculture to remove heavy metals from heavily contaminated soils and also as a plant fertilizer, and DTPA has a wide range of applications including removal of heavy metals from agricultural soils. Thus, the available evidence indicates that addition of a chelator after O₃MB generation may prevent precipitation of oxidized Fe or Mn in a culture medium. The addition of a chelator resulted in a concentration-dependent reduction in precipitates and the maintenance of Fe and Mn concentrations in the medium. Although O₃MB sterilization did not affect plant growth, the addition of a chelator at concentrations of 0.1, 0.01, or 0.001% (w/v) had a significant deleterious effect. However, at a concentration of 0.0001%, the chelator had no significant effect on plant growth but did result in the maintenance of a higher Fe and Mn concentration compared to the O₃MB treated control. The addition of a chelator did not alter the sterilizing effects of O₃MB. These results indicate that the addition of a chelator at a concentration of 0.0001% to an O₃MB-sterilized culture medium enabled the retention of dissolved Fe and Mn without affecting plant growth. The use of O₃MB, plus a chelator, is an effective disinfection method in hydroponic culture.

Lake eutrophication has become a worldwide challenge, and the empirical chlorophyll a-total phosphorus (Chla-TP) relationship provides a management target for TP concentrations. Neglecting the dynamics of the relationship at the lake-specific scale would mislead the eutrophication control strategy. The Bayesian hierarchical model (BHM) is a flexible tool to explore dynamics of the Chla-TP relationship and improves the overall estimation accuracy by partial pooling of data. In this study, we used the BHM to show the spatial and seasonal dynamics of the Chla-TP relationship in one of the most eutrophic lakes in China (Lake Dianchi). We defined an indicator (the Chla/TP ratio, CPR), to represent the susceptibility of Chla to TP. We conducted a model selection process and used the CPR-TP curves to show the spatial and seasonal dynamics of the Chla-TP relationships. We determined that the wind caused the spatial dynamics due to the horizontal transport of phytoplankton, while the water temperature and the percentage of soluble reactive phosphorus led to the seasonal dynamics via increasing the growth rate of phytoplankton. These findings helped the eutrophication control in Lake Dianchi. We found that compared with the strategy to decrease the TP concentration, decreasing the susceptibility is expected to be more effective. Finally, we concluded that exploring the dynamics of the Chla-TP relationship provided an important basis for eutrophication control at the lake-specific scale.