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Two sequential batch reactors (R1 and R2) of aerobic granular sludge (AGS) were inoculated with activated sludge of different origins. The objective was to investigate the granulation and the consistency between the structure of the microbial communities (16S rRNA amplicon sequencing) in each reactor and their metabolic performance (removal of C, N, and P). Both reactors were fed with acetate-based synthetic wastewater, targeting an anaerobic–aerobic cycle reputed to favor the phosphorus- and glycogen-accumulating organisms (PAO and GAO). Stable granulation was achieved in both reactors, where, instead of PAO, the dominant genera were ordinary heterotrophic organisms (OHO) such as Thauera, Paracoccus, and Flavobacterium known for their high capacity of aerobic storage of polyhydroxyalkanoates (PHA). Generally, there was good consistency between the metabolic behavior of each reactor and the bacterial genera detected. Both reactors showed high removals of C and complete nitrification (Nitrosomonas and Nitrospira detected) but a low level of simultaneous nitrification–denitrification (SND) during the aerated phase. The latter causes that nitrates were recycled to the initial phase, in detriment of PAO selection. Meanwhile, the study showed that selecting slow-growing OHOs (with aerobic storage capacity) favors stable granulation, revealing an alternative AGS technology for C and N removal. [ABSTRACT FROM AUTHOR]

Municipal Wastewater Treatment Plants (MWWTPs) have proven to be sources of adverse environmental impacts; however, integrated management can help improve their efficiency. Therefore, this study aims to evaluate the gap between the current management and another based on an international standard applied to WWTPMs, in order to understand their environmental commitment, and to identify the challenges and opportunities they present for the adoption or certification of an environmental management system (EMS) based on ISO 14001. For this purpose, a descriptive cross-sectional study was carried out in two MWWTPs in southern Mexico. In a first step, an automated checklist was designed based on the requirements of the ISO 14001:2015 standard and based on a modified FMEA (Failure Mode and Effects Analysis) calculation method. In a second step, a diagnosis was carried out at the MWWTPs, followed by a SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis to determine internal and external factors until a series of challenges and opportunities was identified. The findings indicate that the selected MWWTPs have a wide gap that keeps them away from efficient management. Among the challenges, "limited financial resources" were identified followed by "high turnover of managerial staff", while the opportunities with the greatest potential for improvement are related to the factors "candidate for investment" and "environmental policy". The treatment plants show a weak environmental commitment, therefore rigorous action plans should be considered, not only to protect the environment but also the investment, and they should be the main promoters that challenge the private sector. [ABSTRACT FROM AUTHOR]

Municipal wastewater treatment plants (MWWTPs) are considered essential to protect human health and aquatic systems. However, several studies in the scientific field have identified adverse environmental effects in these treatment units that involve challenges in the water industry. Therefore, this work has the following objectives: (1) to understand the global context in which MWWTPs operate and (2) to determine the thematic and geographic trend in scientific research. Through the "Publish or Perish" software, scientific articles indexed in the Scopus and Google Scholar databases during the period 2000 to 2020 were obtained. Specific terms were used: "Municipal Wastewater Treatment Plants"; "Municipal Wastewater Treatment Plants," so that all terms must be contained in the title of the document. Categorization was defined according to key concepts considered as adverse effects indicated in the literature and that involve common problems in the water industry at the municipal level. As a result, 1844 documents (papers, reviews, books, book chapters, citations, letters, theses, and conference papers) were retrieved and subjected to a process of refinement (discrimination) where only articles, chapters, conference papers, and reviews were considered. Finally, 800 articles were selected for further content analysis, identifying seven categories and 30 subcategories. The category of "Emerging contaminants" was the most relevant within the research topics, and the category with the least available research was "Air quality." The articles were also analyzed by economic region, identifying Asia with the largest number of studies on various topics. In conclusion, future research should be oriented towards management, energy, and air quality issues, because they are subjects of little research involving process efficiency, energy savings, and impacts on the quality of life. [ABSTRACT FROM AUTHOR]

The effect of the interaction polysaccharide-polysaccharide (P-P) and polysaccharide-protein (P-Pr) blends on thermal and mechanical properties in films as biodegradable alternative of materials for food packaging was studied. Essential oils (cloves and cinnamon) emulsified were successfully incorporated into the films and evaluated as antifungal agents. Films were prepared using the film casting method. The morphological analysis showed that P-Pr films display a fractured rough surface without pores or globular formations and P-P films exhibiting continuous phases and absence of cracks. FTIR spectra evidence interactions between polysaccharides and polysaccharides-protein. Initial degradation temperature ( T ) decreases in two kinds of films with the addition of antifungal agents. P-Pr films showed higher maximum decomposition temperature ( T ) regarding P-P films. The incorporation of carrageenan in films enhances the tensile strength and elongation at break. Higher antifungal activity against Botrytis cinerea and Rhizopus stolonifer was revealed in the films containing cinnamon oil. [ABSTRACT FROM AUTHOR]

Carbonaceous material obtained from industrial sewage sludge and Na-zeolitic tuff were used to adsorb cadmium from aqueous solutions in column systems. The Bohart, Thomas, Yoon-Nelson, and mass transfer models were successfully used to fit the adsorption data at different depths, and the constant rates were evaluated. The parameters such as breakthrough and saturation times, bed volumes, kinetic constants, adsorption capacities, and adsorbent usage rates (AUR) were determined. The results show that the breakthrough time increases proportionally with increasing bed height. The adsorption capacity for cadmium for Na-zeolitic tuff was higher than carbonaceous material. The results indicated that the Na-zeolitic tuff is a good adsorbent for cadmium removal. [ABSTRACT FROM AUTHOR]

The adsorption behavior of denim blue from aqueous solutions in column systems, using both carbonaceous material and Fe-zeolitic tuff (Fe-Z), was determined. The breakthrough data obtained for denim blue adsorption were fitted to the empty-bed contact time, Bohart-Adams, Thomas, and Yoon-Nelson models. The parameters such as breakthrough and saturation times, bed volumes, kinetic constants, adsorption capacities, and adsorbent usage rates (AUR) were determined. The results show that the breakthrough time increases proportionally with increasing bed height, but it decreases as the kinetic constant increases. The adsorption capacity for denim blue for carbonaceous material was higher than Fe-Z. AUR was lower for carbonaceous material than Fe-Z. The results indicated that the carbonaceous material from pyrolysis of sewage sludge is a good adsorbent for denim blue removal. [ABSTRACT FROM AUTHOR]

Novel adsorption materials-Fe-Ni nanostructures and C/Fe-Ni composites-with the carbonaceous material coming from sewage sludge, have been developed and evaluated to remove indigo carmine from aqueous solution. The adsorbents were characterized by transmission and scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and Brunauer-Emmett-Teller analysis. Sorption kinetics and isotherms were determined and the adsorption behaviours analysed. All adsorbents here studied have exhibited good efficiency to remove indigo carmine from aqueous solution. Pseudo-second-order kinetic and Langmuir-Freundlich isotherm models were successfully applied to the experimental data. Fe-Ni nanostructures adsorption capacity was 977.18 mg/g, followed by C/Fe-Ni 75/25% composite with 654.33 mg/g, and a lowest value, 486.41 mg/g, was obtained for C/Fe-Ni 95/5% composite. It can be suggested that the sorption mechanism of the dye is chemisorption on these heterogeneous novel, cheap and efficient functional materials. All materials provide the highest adsorption capacities in pH between 4 and 10. In addition, three sorption-desorption cycles using 30% HO solution and distilled water were performed; sorption efficiencies of both composites (C/FeNi 75/25% and C/FeNi 95/5%) decreases in each cycle, but this behaviour is not observed for FeNi nanoscale oxides. [ABSTRACT FROM AUTHOR]

Objective: The present work was carried out to investigate the effects of temperature, initial pH, initial concentration, and contact time on the biosorption of lead (Pb) and cadmium (Cd) by modified stalk sponge of Zea mays using a batch technique. Methods: The biomass was chemically modified with a 0.1 M NaCl solution. The lead and cadmium sorption process was evaluated at 20°C, 30°C, 40°C, and 50°C. Results: The results showed that the modified stalk sponge of Z. mays had a good capacity for biosorption of Pb(II) and Cd(II). The kinetic behavior was described by the pseudo-second-order model for both metallic species. The experimental isotherms obtained at different temperatures were fit with Langmuir and Freundlich models. Thermodynamic parameters Δ H and Δ S were calculated using the van't Hoff equation, and the results show that Pb(II) and Cd(II) sorption by modified stalk sponge of Z. mays is an exothermic and spontaneous process. [ABSTRACT FROM AUTHOR]

Actually, there is a growing interest in finding efficient low-cost materials that allow the removal of chemical substances from water in order to decrease the environmental impact. The use of nanoscale systems is a new area of investigation for the elimination of polluting agents from water among other useful applications in science and technology. In this work, removal of indigo blue in water solutions has been evaluated using Fe/Cu nanoparticles and composites of C/Fe –Cu nanoalloy. The first composite was using carbon obtained by pyrolysis of sewage sludge with Fe/Cu nanoparticles (MCL-NP); the second one was made with commercial activated carbon and Fe –Cu nanoparticles (CAC-NP). Synthesis of materials were carried out by the sodium borohydride reduction of FeSO4⋅7H2O and CuSO4⋅5H2O aqueous mixture. Batch adsorption and isotherm experiments were carried out in order to know the behavior of each adsorbent material employed. The experimental data were adjusted to Langmuir, Freundlich, and BET models. [ABSTRACT FROM AUTHOR]

The sorption behavior of dye remazol yellow using surfactant modified zeolitic rock and a carbonaceous material obtained by pyrolysis of sewage sludge and treated with HCl (1.0%) solution was determined. The kinetic and sorption isotherms experimental results were best adjusted to the pseudo-second order model and to the Langmuir–Freundlich isotherm model which indicate that the sorption process is chemisorption on heterogeneous materials. Remazol yellow could be removed from the saturated modified zeolitic material by different processes, unfortunately, the surfactant was removed together with the dye, the best results were found using Fenton’s reagent. Thermal treatment was the best method found to remove the dye from the carbonaceous material. [ABSTRACT FROM AUTHOR]