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•Absorption of heavy metal ions (Cu2+, Pb2+, Cd2+ and Zn2+) from squid wastes.•Role of subcritical water treatment temperature on efficacy of squid oil hydrolysis.•Potential of ...aqueous, metal-soap, and oil phases to absorption of heavy metal ions.•Application of chelate ion exchanger for removal of heavy metal ions from squid oil.•The impact of temperature on removal performance of CR11 chelate ion exchanger.
Heavy metal ions (HMIs) are serious threats to the environment. Sub-critical water treatment was used to mimic contamination of squid oil in aqueous, metal-soap and oil phases. Isothermal adsorption of HMIs (Cu2+, Pb2+, Cd2+ and Zn2+) was studied from aqueous phase to oil phase (493, 523, 548, and 573K) for solutions with different initial concentration of HMIs was studied. Decomposition of glycerides into fatty acids was favored at high subcritical temperatures, with metal-soap phase showing the highest chelation ability toward Cu2+ (96%, isotherm 573K). The removal-ability of HMIs from contaminated oil was performed by CR11 chelate ion exchanger, showing facilitated removal from metal-soap and oil phases at low temperatures compared to general-purpose PEI-chitosan bead and PEI-chitosan fiber sorbents. The chelation behavior of Pb2+ and Cd2+ was the same in the OIL, with maximum values of 5.7×10−3 (mol/l) and 5.0×10−3 (mol/l) at 573K, respectively. By contrast, concentration of Zn2+ ion showed a slight increase with increasing temperature due to electrostatic forces between Zn2+ and active sites of glycerides in oil phase. For oil solution, the selectivity of adsorption for CR11, especially for Zn2+, was at least five-fold larger compared to PEI-chitosan bead and PEI-chitosan fiber adsorbents.
In a society where the environmental conscience is gaining attention, it is necessary to evaluate the potential valorization options for agricultural biomass to create a change in the perception of ...the waste agricultural biomass from waste to resource. In that sense, the biorefinery approach has been proposed as the roadway to increase profit of the agricultural sector and, at the same time, ensure environmental sustainability. The biorefinery approach integrates biomass conversion processes to produce fuels, power, and chemicals from biomass. The present review is focused on the extraction of value-added compounds, anaerobic digestion, and composting of agricultural waste as the biorefinery approach. This biorefinery approach is, nevertheless, seen as a less innovative configuration compared to other biorefinery configurations, such as bioethanol production or white biotechnology. However, any of these processes has been widely proposed as a single operation unit for agricultural waste valorization, and a thoughtful review on possible single or joint application has not been available in the literature up to now. The aim is to review the previous and current literature about the potential valorization of agricultural waste biomass, focusing on valuable compound extraction, anaerobic digestion, and composting of agricultural waste, whether they are not, partially, or fully integrated.
The objective of this work was to determine the effect of a controlled micro-aeration as a pretreatment or hydrolytic stage of mixed sewage sludge and the incorporation of solid wastes as a source of ...trace metals in the anaerobic digestion of this pretreated sludge. Three experimental runs were carried out under the same conditions in laboratory-scale anaerobic reactors, to which a previously aerated mixed sludge was added as a substrate and anaerobic sludge as the inoculum. Two anaerobic digesters (blank) were also operated without aerobic pretreatment and without the addition of metallic wastes. The aerobic pretreatment was performed during 48 h at 35 °C with an aeration flow of 0.35 vvm. All anaerobic reactors were operated at the mesophilic temperature of 35 ± 2 °C. Fly ash or Copper mining residues were added to the anaerobic reactors as trace metal supplementation. The aggregated concentrations were 250 mg L−1 fly ash, 25 mg L−1 Copper mining residues and 0 mg/L. The blank reactors produced 38% less methane than those generated in the reactors operating with the pre-aerobic treatment without addition of metallic wastes (controls). It was found that the reactors with micro-aerobic pretreated sludge and the addition of fly ash gave the best yields of methane, producing a 201.6% increase in methane with respect to the blank reactors. On the other hand, the pretreatment of micro-aerobic hydrolysis and the addition of mining residues generated an increase of 185.8% in methane production compared to the blank reactors.
•Micro-aeration of mixed sludge improves its hydrolysis and its anaerobic digestion.•The addition of fly ash or mining waste enhanced the anaerobic digestion of sludge.•Combined micro aerobic hydrolysis and use of fly ash improve hugely methane yield.•Metal concentrations of sludge digestates allow its use as fertilizer.
This paper reviews the most relevant uses and applications of zeolites in anaerobic digestion processes. The feasibility of using natural zeolites as support media for the immobilization of ...microorganisms in different high-rate reactor configurations (fixed bed, fluidized bed, etc.) is also reviewed. Zeolite, with its favorable characteristics for microorganism adhesion, has also been widely used as an ion exchanger for the removal of ammonium in anaerobic digestion due to the presence of Na+, Ca2+ and Mg2+ cations in its crystalline structure. This property is also useful for improving the anaerobic process performances in the treatment of wastewaters with high concentrations of nitrogen compounds, such as cattle, pig and chicken wastes, as it prevents process inhibition. The influence of zeolite particle size and doses in batch mesophilic and thermophilic processes when referring to synthetic or different wastewaters is also reviewed. Finally, the role of zeolite in granulation processes, in anaerobic oxidation processes (Anammox) for promoting the retention of the biomass involved (given its low growth rate), and in hybrid and sequencing reactors such as the moving bed biofilm reactors (MBBR) are also discussed.
► The physical properties of zeolite are appropriate for its use in anaerobic digestion. ► The feasibility of the use of zeolite for microorganisms' immobilization is reviewed. ► It has been used as an ion exchanger for ammonium removal in anaerobic digestion. ► The influence of particle size and doses in batch processes are reviewed. ► The roles of zeolite in granulation, Anammox processes, etc. are also discussed.
A lo largo del siglo xviii las milicias se consolidaron como una fuerza que complementó a los ejércitos permanentes, tanto cumpliendo misiones de defensa del territorio como constituyendo una fuerza ...militar de reserva a la que recurrir siempre que la situación lo requiriese. En oposición a sus predecesoras de los siglos anteriores, estas estuvieron organizadas por una regulación común y controladas directamente por la Corona, lo que constituyó su principal garantía de supervivencia frente a sus detractores. En este artículo se expone la creación, organización y evolución de las milicias que se establecieron en la Monarquía de España durante el Siglo de las Luces, con especial atención a la provincial, y, además, se trata de rebatir las críticas vertidas contra estos cuerpos durante su existencia, así como en tiempos posteriores.
The current great concern about plastic pollution opens up opportunities for the production of more sustainable polymers. Inverse vulcanization has emerged as a novel procedure to obtain ...inorganic-organic hybrid polymeric materials. Sulfur is attained as a by-product of oil refining production and makes inverse vulcanization a sustainable process due to a large amount of sulfur without a useful life. In previous studies, vegetable oils were used as a comonomer with sulfur to form copolymers based on sustainable raw material. Nevertheless, compounds from agro-wastes, could be a third comonomer that improves new copolymers bio-applications. In this study, a new series of copolymers with castor oil as vegetable oil and sulfur was formulated by adding a third compound bearing double bonds or heteroatoms. A study was conducted to assess the antimicrobial capacity and antioxidant activity of the copolymers obtained to demonstrate the benefits of adding a new comonomer to improve their bioactivity.
•Valorization of waste from the agro-food and petrochemical industry.•New materials based on elemental sulfur, castor oil, and bioactive compounds.•Synthesis of new copolymers with antioxidant activity.•Synthesis of new copolymers with antimicrobial properties.
In this paper, we review the latest developments in biological methods used in the removal of hydrogen sulphide, present in the liquid phase in anaerobic reactors. The toxicity of H2S to ...methane-forming microorganisms and the problems caused by the presence of this compound in the biogas generated during this process, as well as the main causes of hydrogen sulphide generation in anaerobic processes of wastes are also reviewed. We especially discuss the fundamentals in applying micro-aerobic conditions to remove dissolved hydrogen sulphide from the aqueous phase of an anaerobic reactor. The alternative technology of simultaneous removal of sulphide, nitrate, and organic matter is under recent investigation. Therefore, this review paper includes a study and analysis of the microbiological basis of this technology, the physical and chemical factors that influence the process and the potential application of this technology on different types of wastewaters and situations. Also considered are the fundamentals of both biofilm reactors and microbial fuel cells desulphurization. Because relatively few studies on modeling desulphurisation processes are available, we discuss the advances made in that area.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The high production of raw olive oil mill wastewater (OMW) is a current environmental problem due to its high organic load and phenol compounds. In this work, photo-Fenton reaction as an advanced ...oxidation process has been chosen for OMW treatment. In this sense, different iron salts (FeCl3, Fe2(SO4)3, FeSO4·7H2O, and Fe(ClO4)3) as catalysts were used in order to compare their effects on treatment. For each catalyst, different H2O2 concentrations (2.5, 5.0, 7.5, 10.0, 15.0, 20.0, and 30.0%, w/v) as oxidizing agents were tested. The common experimental conditions were temperature 20 °C, the catalyst/H2O2 ratio = 0.03, pH = 3, and ultraviolet light. The Lagergren kinetic model, in cases of total organic carbon removal, for the best H2O2 concentration per catalyst was used. During the experiments, the water quality was determined by measuring the removal percentages on chemical oxygen demand, total carbon, total organic carbon, total nitrogen, total phenolic compounds, total iron, turbidity and electric conductivity. The best catalyst was FeCl3 and the optimum H2O2 concentration was 7.5% (w/v). At these optimal conditions, the removal percentages for chemical oxygen demand, total phenolic compounds, total carbon, total organic carbon and total nitrogen were 60.3%, 88.4%, 70.1%, 63.2% and 51.5%, respectively.
To reduce the impact on the environment and enhance the sustainability of resources, it is necessary to promote and strengthen the use of landrace cultivars that advocate regenerative agriculture. In ...this study, the growth and development as well as the anaerobic digestion (AD) of six different landrace cultivars, two commercial hybrids cultivars and a public genotype of Sorghum bicolor have been evaluated. The landrace cultivars, in general, presented greater heights, biomass yields and compactness shoots as well as similar or an improvement in grain production compare to the commercial varieties. The AD of the different sorghum straws was performed in batch mode at mesophilic temperature (35°C). The landrace cultivar Zahina (ZH) obtained the highest final methane yield (413 ± 79 NL CH4 kg−1 VS, volatile solids) but the landrace cultivars Zahina gigante (ZHG) and Trigomillo (TG) were the ones that obtained the highest methane per biomass production (13.7 and 12.7 NL CH4 shoot unit−1, respectively). By contrast, the commercial varieties were the ones that obtained the lowest methane yields. Two mathematical models, first‐order kinetics and the Transference Function model, were used to fit the experimental data with the aim of describing and simulating the anaerobic biodegradation of these S. bicolor straw varieties and obtaining the kinetic constants. Both models allowed for adequately fitting the experimental results of methane production with time. In particular, the fastest biomethanization occurred using the commercial variety PR88Y20 (PR88) (specific rate constant k = 0.148 ± 0.008 days−1), while the slowest one was obtained from Panizo (PAN) variety (k = 0.064 ± 0.005 days−1). In addition, the highest values of the maximum methane production rate, Rm, were attained for the varieties ZH and PR88, which were 87.1% and 71.3% higher than that achieved for the PAN variety, which exhibited the lowest value.
Landrace cultivars presented greater biomass, compactness and grain production. Zahina (landrace cultivar) obtained the highest final methane yield: 413 NL CH4 kg−1 VS. Zahina gigante and Trigomillo (landrace cultivars) achieved the highest methane per biomass production.
The use of photocatalysis for wastewater treatment is an important area of research, which is not yet fully exploited at an industrial level and has significant potential in the disposal of many ...industrial effluents, particularly the effluents that are difficult to treat by conventional treatment processes. This reprint tries to know the latest advances in the field of wastewater treatment by photocatalysis. In this sense, it is worth mentioning the treatments based on photolysis, TiO2/solar light, oxidants/ultraviolet irradiation, oxidants/catalyst/ultraviolet irradiation, etc. In addition, the reprint describes catalyst manufacturing methods and reaction mechanisms.
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