This paper analyses the influence of activated sludge technologies on the Particle Size Distribution (PSD) of urban wastewater treatment plants operating under real conditions. The activated sludge treatment systems selected for the analysis are the most widely used in wastewater treatment installations: (a) double step activated sludge, (b) medium load activated sludge, (c) prolonged aeration, and (d) membrane bioreactors The main quality parameters (suspended solids, turbidity, and COD) and PSD in the influent and effluent of each different activated sludge treatment were analyzed during 1 year. The PSD was fitted using the power law ([Formula: see text]) obtaining coefficients A and b to define the particle distribution. Mathematical correlations between this coefficients and the rest of parameters studied were found [Formula: see text]. The relation with the average particle size by mass was also found, ([Formula: see text]). Moreover, a relation between PSD and the particle elimination efficiency of the secondary treatment was study, ([Formula: see text]). Finally, the particulate matter nature was assessed by SEM-EDX. It can be concluded that membrane bioreactor is the technology that produces the best water quality effluent due to physic process of particle separation by ultrafiltration membrane technology.

A series of aluminum oxyhydroxide-incorporated titania composites were prepared by a one-pot synthetic procedure using aluminum tri-sec-butoxide as a precursor. The as-synthesized samples were characterized by Fourier transform infrared spectrophotometer, X-ray diffraction, thermogravimetry and differential scanning calorimetry, nitrogen physisorption, and scanning electron microscopy. It was identified that aluminum oxyhydroxide (γ-AlOOH, or boehmite) was produced as aluminum matrix into which titania, commercially available P25, was incorporated. Photocatalytic activity of all nanocomposites was evaluated with respect to the photodecolorization of methyl orange under UV irradiation and almost complete decolorization was eventually achieved under optimum experimental conditions.

Anionic surfactants, the earliest and the most common surfactants in detergent and cosmetic product formulations contribute significantly to the pollution profile of the ecosystem. Linear alkylbenzene sulfonates (LAS), a major chemical constituent of detergents, forms an imperative group of anionic surfactants. Bioremediation of LAS by conventional processes such as activated sludge is ineffective due to the low kinetics of degradation by unsuitable organisms and foam production. Hence this study was focused on isolating and characterizing indigenous LAS-degrading bacteria from soil. Twenty different LAS-degrading bacteria were isolated from detergent-contaminated soil by enrichment culture technique and degradation efficiency was assessed by Methylene Blue Active Substances (MBAS) assay and by reverse-phase high-performance liquid chromatography (HPLC) analysis. The most efficient LAS-degrading isolates, L9 (81.33 ± 0.7) and L12 (81.81 ± 0.8), were selected and identified as Pseudomonas nitroreducens (MTCC 10463) and Pseudomonas aeruginosa (MTCC 10462). The 16S rDNA sequences of the isolates were deposited in NCBI GenBank under the accession numbers HQ 271083 (L9) and HQ 271084 (L12). The isolates were capable of degrading 0.05 g/l LAS at 25 °C and pH 7.0–7.5. Presence of a solid support caused biofilm formation which in turn enhanced LAS degradation. The isolates tend to display diauxic growth with alternate carbon source such as dextrose. These isolates also have the capability to degrade other xenobiotics like hydrocarbons and pesticides. Since xenobiotic pollutants in nature occur as a mixture of compounds rather than single pollutants, the potential of these two indigenous LAS-degrading isolates to degrade multiple xenobiotics gains relevance.

We examined a performance of the multiplicative stomatal conductance model to estimate the stomatal ozone uptake for Fagus crenata. Parameterization of the model was carried out by in-situ measurements in a free-air ozone exposure experiment. The model performed fairly well under ambient conditions, with low ozone concentration. However, the model overestimated stomatal conductance under enhanced ozone condition due to ozone-induced stomatal closure. A revised model that included a parameter representing ozone-induced stomatal closure showed better estimation of ozone uptake. Neglecting ozone-induced stomatal closure induced a 20 % overestimation of the stomatal uptake of ozone. The ozone-induced stomatal closure was closely related to stomatal ozone uptake rather than accumulated concentrations of ozone exceeding 40 nmol mol⁻¹. Our results suggest that ozone-induced stomatal closure should be implemented to stomatal conductance model for estimating ozone uptake for F. crenata. The implementation will contribute to adequate risk assessments of ozone impacts on F. crenata forests in Japan.

After the accident in Fukushima reactors, a daily monitoring programme was initiated in two laboratories in Belgrade, one at the Vinčа Institute for Nuclear Sciences and the other at Institute for Occupational Health Karajovic. Samples of aerosol and fallout, as well as the random samples of food and water, were collected and analysed, using gross alpha/beta and gamma spectrometry, in order to establish the presence of traces of isotopes indicating Fukushima fallout. Gamma spectrometry measurement of these samples showed clear evidence of fission products ¹³¹I, ¹³⁴Cs and ¹³⁷Cs wtihin 2 weeks after the accident. The activity diminished with time due to dispersion in air and, in case of ¹³¹I, short half-life.

Extraction and analysis methods have been developed for the detection of the following four antibacterial agents and two natural estrogens in treated municipal wastewater sludge and commercial compost: sulfamethoxazole (SMX), sulfadimethoxine (SDM), tetracycline (TET), oxytetracycline (OXY), estrone (E1), and 17β-estradiol (E2). The antibiotics and estrogens were extracted from secondary sludge and mixed compost using ultrasonic solvent extraction. Citric acid (pH 4.7) and methanol were used as extraction buffer, followed by tandem-solid-phase extraction cleanup, strong anion exchange + hydrophilic–lipophilic balance for antibiotics and CarboPrep/NAX for estrogens. For quantification, two different methods were employed, using HPLC–MS/MS, with an electrospray ionization source for antibiotics and an atmospheric-pressure chemical ionization source for estrogens. Recoveries were 11–31% for the sulfonamides (SMX and SDM) and tetracyclines (TET and OXY) and 30–59% for the estrogens (E1 and E2) over the entire method. Limits of detection for the extraction method were in the nanogram per gram range for dry weight sludge and compost samples. Neither of the two sulfonamide antibiotics was detected in secondary sludge or mixed compost samples. Estrogens were found in compost in amounts of 160 ± 65 ng/g (E1) and 21 ± 3 ng/g (E2), but not in sludge. The tetracyclines, as well as what is believed to be the 4-epimer of OXY, were found in both sludge and compost in amounts of 1.57 ± 0.67 and 2.95 ± 0.42 μg/g (TET), 0.56 ± 0.12 and 6.51 ± 0.52 μg/g (OXY), and 7.60 ± 1.68 and 1.35 ± 0.24 μg/g (4-epi-OXY), respectively. These results indicate that sorption-prone compounds are not removed during the wastewater treatment process and can persist through sludge digestion and that the composting process does not sufficiently eliminate these particular contaminants. Thus, biosolids (even composted) are an additional source of drug residues leaching into the environment, and it must be considered while using biosolids as fertilizer.

2-Methylisoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin) are two commonly observed taste and odor compounds present in drinking water sources. The effects of pH on the analysis of the two chemicals are investigated using a gas chromatograph and mass spectrometric detector (GC/MSD) coupled with three pre-concentration methods, namely solid-phase micro-extraction (SPME), purge-and-trap concentration (PTC), and liquid–liquid extraction (LLE). At neutral and alkaline pH conditions, the concentrations detected for both compounds remain constant. However, a substantial reduction of concentration for both chemicals is observed when the water solution pH is less than 5. Under acidic conditions (pH ≅ 2.5), the 2-MIB concentrations detected by GC/MSD coupled with SPME, PTC, and LLE are 87%, 16%, and 37% lower than those measured at pH 6–7, respectively. For geosmin, a decrease in concentration is only observed when using GC/MSD-SPME, presumably due to the higher extraction temperature compared to the other two techniques. The pH-dependent behavior was attributed to dehydration of the tertiary alcohols of 2-MIB and geosmin under acidic conditions. The dehydration for 2-MIB and geosmin is reversible, and the analysis can be mitigated by adjusting the water solution pH back to a neutral condition.

Synthetic and persistent endocrine disrupting chemicals (EDCs) such as 17α-ethinylestradiol (EE2) have been frequently detected in the effluent of wastewater treatment plants and induce hazards to humans and wildlife. In this study, biogenic Mn oxides were tested for the removal of EE2, and factors affecting the reaction were also investigated. The biogenic Mn oxides produced by Pseudomonas putida strain MnB1 were nano-sized and poorly crystallized particles. A concentration of 7.9 mg l−1 biogenic Mn oxides showed 87% EE2 (1 mg l−1) removal efficiency in 2 h, which confirms the excellent potential of biogenic Mn oxides for removal of estrogens. EE2 removal was enhanced at high Mn oxide doses and at low pH. Co-existing heavy metals significantly inhibit EE2 removal, due to their competition for the reactive sites of biogenic Mn oxides. Humic acid (HA) also obstructed EE2 removal, but the adverse effect was alleviated as HA concentration increased, possibly due to the formation of soluble complexes with the released Mn2+, of which adsorption onto Mn oxides reduces surface reactive sites.

Lead forms stable compounds with phosphate and the immobilized Pb becomes less available to soil biota. In this study, we tested the bioavailabilty of Pb using earthworms (Eisenia fetida) and plants after immobilization of Pb by a soluble P compound and an insoluble rock phosphate compound in the presence of phosphate-solubilizing bacteria (Enterobacter sp.). Rock phosphate in the presence of phosphate-solubilizing bacteria and a soluble P compound enhanced Pb immobilization as measured by NH4NO3-extractable Pb concentration, thereby reduced its bioavailability as evaluated by earthworm Pb loading and sunflower (Helianthus annuus) Pb uptake under greenhouse conditions. However, soluble P treatment increased the concentration of Pb in soil solution thereby inhibited the root elongation of mustard (Brassica hirta) seedlings. Sunflower plants in the Pb-spiked soil without P amendments showed symptoms of necrosis and stunting because of Pb toxicity. Both soluble and insoluble P treatments significantly increased shoot and root weight and decreased Pb concentration in shoot by more than 50% compared to the control. However, high Pb concentration in soil solution was found in soluble P treatment, which can be attributed to dissolved organic carbon–Pb complex formation, thereby increasing Pb mobility. The inoculation of phosphate-solubilizing bacteria can facilitate phytostabilization of Pb-contaminated site.

Surfactants have been used for environmental remediation to remove hydrophobic organic compounds (HOCs) in water and soil. However, there are limited studies on the use of surfactants in confined micelle arrays to remove pesticides and polycyclic aromatic hydrocarbons from water. We studied the recovery of HOCs using two confined surfactants: nonionic Triton X-100 and cationic 3-(trimethoxysily)propyl-octadecyldimethyl-ammonium chloride (TPODAC). The micelle arrays were confined on a mesoporous silica matrix deposited onto a magnetic iron core. These magnetic, dispersible sorbents can be used to recover HOCs, minimizing the application of surfactants when compared to soil-washing techniques. The TPODAC-based sorbent had better average recovery of the HOCs studied compared to the Triton-X sorbent, and was, in general, comparable to activated carbon. It performed well with the chlorinated pesticides, in part due to additional interactions between the cationic sites and the polar compounds.