The study was developed at the Municipality of São Gabriel do Oeste, State of Mato Grosso do Sul, Brazil, where were performed analyses of water samples, including physical and chemical aspects, obtained through Hanna multi-parameter probe into four different parts of the study area. Landsat satellite 8 (L8) and unmanned aerial vehicle (UAV) was also used to generate vegetation indices, using the visible spectral range for both types of images and normalized difference vegetation index (NDVI) just for L8. Later, these ratios were correlated to chlorophyll a that has a key role in photosynthesis. Regarding the physical and chemical parameters, the collection point 2 was the most differed to the others; this may have happened to be a dam with little flow in an eutrophication process. Through the water absorbance curve in the visible wavelengths, it is possible to estimate comparatively water body that has larger amounts of dissolved materials in the water. There was a high correlation between vegetation indices generated from aerial photographs and L8 image, with chlorophyll a extracted from water in the laboratory. In this sense, they are likely to use to forecast future scenarios. It is suggested the use of aerial photographs of UAVs for monitoring the environmental quality of small water bodies, considering its high spatial and temporal resolution.

Stream biomonitoring tools are largely lacking for many developing countries, resulting in adoption of tools developed from other countries/regions. In many instances, however, the applicability of adopted tools to the new system has not been explicitly evaluated. The objective of this study was to test the applicability of foreign diatom-based water quality assessment indices to streams in Zimbabwe, with the view to highlight challenges being faced in diatom-based biological monitoring in this developing country. The study evaluated the relationship between measured water quality variables and diatom index scores and observed some degree of concordance between water quality variables and diatom index scores emphasising the importance of diatom indices in characterisation and monitoring of stream ecological conditions in developing countries. However, ecological requirements of some diatom species need to be clarified and incorporated in a diatom-based water quality assessment protocol unique to these regions. Resources should be channelled towards tackling challenges associated with diatom-based biological monitoring, principally taxonomic studies, training of skilled labour and acquiring and maintaining the necessary infrastructure. Meanwhile, simpler coarse taxonomy-based rapid bioassessment protocol, which is less time and resource consuming and requires less specialised manpower, can be developed for the country.

The effect of direct current (DC) on phenol biodegradation under aerobic/anaerobic condition was investigated in this study using a bioelectrochemical reactor. It was found that phenol biodegradation was inhibited with current ranged from 10 to 40 mA. The growth of biomass was reduced to 43.2 ± 6.6 % for aerobic sludge and 38.6 ± 7.3 % for anaerobic sludge, but the loosely bound extracellular polymer substances (LB–EPS) were increased 91.2 ± 1.3 % for aerobic sludge and 62.8 ± 0.8 % for anaerobic sludge as the current increased from 10 to 40 mA. Adenosine triphosphate (ATP) content of aerobic sludge was also reduced 0.481 ± 0.04-fold and 0.512 ± 0.05-fold lower and 1.34 ± 0.13-fold higher than that of the control when the current was increased from 10 to 40 mA. The results of phosphate buffer saline adding treatment indicated that lower pH caused by a DC above 10 mA was responsible for the reduced phenol biodegradation, leading to the reduction of biomass. However, lower intensity of current (5 mA) had no significant impact on phenol degradation rate, pH, LB–EPS, ATP content, and cell growth of aerobic/anaerobic sludge. These results give us a more detailed understanding of the effects of electricity on the treatment of phenol containing wastewater.

Drainage filters using porous granular material constitute new innovative technologies for remediating phosphorus (P) from agricultural tile drainage water. In drainage filters where convective velocities are often high, we hypothesize that intragranular diffusion may affect solute transport depending on filter characteristics and flow rate. This was investigated for six drainage filter materials (Leca, Filtralite-P®, granulated limestone, crushed seashells, calcined diatomite earth (CDE), and a poorly ordered Fe oxide aggregate (CFH)) conducting a tritium (³H₂O) tracer experiment at low (0.26 cm h⁻¹), medium (23 cm h⁻¹), and high (41 cm h⁻¹) flux densities. The filter materials differed widely with respect to grain-size distribution (D ₅₀ from 1.6 to 3.3 mm), uniformity coefficient (1.7 to 2.2), particle density (1.75 to 2.76 g cm⁻³), bulk density (0.34 to 1.46 g cm⁻³), and water-filled porosity (0.39 to 0.73 cm³ cm⁻³). Measurements of specific surface area (SSA) included both SSABET and SSAEGME to ensure inclusion of the intragranular microporosity, not accounted by N₂-BET. SSA varied widely across methods and allowed the differentiation of filters according to the significance of the intragranular porosity. Tritium transport varied from approximately equilibrium transport at all flow rates in Leca, Filtralite-P®, and limestone, to progressive non-equilibrium transport as flow rate increased in Seashells, CDE, and CFH. In general, the filter materials were highly variable in hydro-physical properties. Filters with (approximately) equilibrium transport were, however, all characterized by low specific surface areas. The non-equilibrium transport was explained by an intragranular diffusion in filters with larger specific surface area (Seashells, CDE, and CFH).

Nitrogen removal by anaerobic ammonia oxidation (anammox) of granular sludge is a globally important emerging technology. The ammonium adsorption properties of anammox granular sludge were studied at varying initial ammonium concentration and sludge concentration. Factors affecting the absorption process as temperature, pH, salinity, and metal cations were also examined. The experimental results indicated that ammonium adsorption by anammox granular sludge occurred quickly (in about 20 min). The optimal pH was 7.0 and the ammonium adsorption process was significantly affected by temperature, salinity, and metal cations. The experimental data were modeled using Langmuir, Freundlich, and Temkin adsorption isotherms and the ammonium adsorption process was fit to the Freundlich isotherm. The kinetic results indicated that the experimental data fit well to a pseudo-second-order model. Both intraparticle diffusion and boundary layer diffusion could affect the ammonium adsorption rate. The thermodynamic parameters ΔG₀, ΔH₀, and ΔS₀ were evaluated and suggested that ammonium adsorption was spontaneous and exothermic. These findings indicate that the adsorption of ammonium should be incorporated into models for nitrogen removal, particularly for the use of anammox granular sludge.

The automobile exhausts are one of the major sources of particulate matter in urban areas and these particles are known to influence the atmospheric chemistry in a variety of ways. Because of this, the oxidation of dissolved sulfur dioxide by oxygen was studied in aqueous suspensions of particulates, obtained by scraping the particles deposited inside a diesel truck exhaust pipe (DEP). A variation in pH showed the rate to increase with increase in pH from 5.22 to about ∼6.3 and to decrease thereafter becoming very slow at pH = 8.2. In acetate-buffered medium, the reaction rate was higher than the rate in unbuffered medium at the same pH. Further, the rate was found to be higher in suspension than in the leachate under otherwise identical conditions. And, the reaction rate in the blank reaction was the slowest. This appears to be due to catalysis by leached metal ions in leachate and due to catalysis by leached metal ions and particulate surface both in suspensions. The kinetics of dissolved SO₂ oxidation in acetate-buffered medium as well as in unbuffered medium at pH = 5.22 were defined by rate law: k ₒbₛ = k ₀ + k cₐₜ [DEP], where k ₒbₛ and k ₀ are observed rate constants in the presence and the absence of DEP and k cₐₜ is the rate constant for DEP-catalyzed pathway. At pH = 8.2, the reaction rate was strongly inhibited by DEP in buffered and unbuffered media. Results suggest that the DEP would have an inhibiting effect in those areas where rainwater pH is 7 or more. These results at high pH are of particular significance to the Indian subcontinent, because of high rainwater pH. Conversely, it indicates the DEP to retard the oxidation of dissolved SO₂ and control rainwater acidification.

A Gram-positive bacterium, designated as strain B1(2015b), was isolated from the soil of the chemical factory “Organika-Azot” in Jaworzno, Poland. On the basis of 16S rRNA gene sequence analysis, the isolated strain was classified as a Bacillus thuringiensis species. Strain B1(2015b) is able to degrade ibuprofen and naproxen, however, these compounds are not sufficient carbon sources for this strain. In the presence of glucose, Bacillus thuringiensis B1(2015b) degrades ibuprofen and naproxen with higher efficiency. Twenty milligrams per liter of ibuprofen was degraded within 6 days and 6 mg l⁻¹ of naproxen was removed within 35 days. Simultaneously, the growth of the bacterial culture was observed. The obtained results suggest that Bacillus thuringiensis B1(2015b) appears to be a powerful and useful tool in the bioremediation of non-steroidal anti-inflammatory drugs-contaminated environment.

In the present study, multi-walled carbon nanotubes (MWCNTs) have been used for the rapid removal of four trihalomethanes (THMs) from aqueous solutions. The adsorption capacity of THMs onto MWCNTs was reasonably constant in the pH range of 5–7 but decreased as the pH exceeded 7. Four equilibrium isotherm models, namely, Langmuir, Freundlich, Temkin, and Sips, were applied to determine the best-fit equilibrium expressions. The results showed that all four experimental adsorption isotherms were best correlated by using the Sips model. The maximum adsorption capacities for the CHCl₃, CHCl₂Br, CHClBr₂, and CHBr₃ were found to be 10.98, 6.85, 6.57, and 5.95 mg/g, respectively. The rate of adsorption followed the pseudo-second-order kinetic model. Furthermore, four nonlinear regression-based equations were also derived to model THM adsorption from aqueous solutions by MWCNTs. The modeling results clearly indicated that the empirical formulations satisfactorily described the behavior of the present adsorption process for CHCl₃ (R ² = 0.949), CHCl₂Br (R ² = 0.945), CHClBr₂ (R ² = 0.936), and CHBr₃ (R ² = 0.919). The overall results confirmed that MWCNTs could be a promising adsorbent material for THMs removal from aqueous solutions.

Given that drugs and their degradation products are likely to occur as concoctions in wastewater, the degradation of a mixture of two nonsteroidal anti-inflammatory drugs (NSAIDs), diclofenac (DCF) and naproxen (NPX), was investigated by solar photolysis and titanium dioxide (TiO₂)-mediated solar photocatalysis using an immersion-well photoreactor. An equimolar ratio (1:1) of both NSAIDs in distilled water, drinking water, and river water was subjected to solar degradation. Solar photolysis of the DCF and NPX mixture was competitive particularly in drinking water and river water, as both drugs have the ability to undergo photolysis. However, the addition of TiO₂ in the mixture significantly enhanced the degradation rate of both APIs compared to solar photolysis alone. Mineralization, as measured by chemical oxygen demand (COD), was incomplete under all conditions investigated. TiO₂-mediated solar photocatalytic degradation of DCF and NPX mixtures produced 15 identifiable degradants corresponding to degradation of the individual NSAIDs, while two degradation products with much higher molecular weight than the parent NSAIDs were identified by liquid chromatography mass spectrometry (LC-MS) and Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS). This study showed that the solar light intensity and the water matrix appear to be the main factors influencing the overall performance of the solar photolysis and TiO₂-mediated solar photocatalysis for degradation of DCF and NPX mixtures.

Accumulation of divalent manganese (Mn) and its toxicity in the green alga Scenedesmus quadricauda was studied at circumneutral pH (6.5). A comparison of two applied concentrations (10 or 100 μM) of MnCl₂, MnSO₄, and Mn(NO₃)₂ indicated that mainly sulfate evoked higher Mn accumulation. On the other hand, nitrate rather depleted antioxidative enzyme activities (APX, CAT, SOD), leading to an increase in ROS formation as proven by fluorescence microscopy. Subsequent experiments revealed that increase in pH (from 4.5 to 9.5) increased also Mn content but typically depleted amounts of reduced glutathione and phytochelatin 2. We also measured the size of particles formed from the manganese salts at pH 9.5. Competitive experiment between Ca/K salts (CaCl₂, CaSO₄, Ca(NO₃)₂, KCl, K₂SO₄, KNO₃) and Mn (as Mn sulfate) showed a negative relation between Ca and Mn amount but KNO₃ stimulated Mn accumulation. Microscopy revealed that mainly K salts elevated plasma membrane damage (Acridine orange staining). Data indicate that not only pH but also accompanying anion affects Mn accumulation and that Ca salts may affect Mn toxicity.