The role of brain oscillations in feature integration.

Our sensory system is able to build a unified perception of the world, which although rich, is limited and inaccurate. Sometimes, features from different objects are erroneously combined. At the neural level, the role of the parietal cortex in feature integration is well-known. However, the brain dynamics underlying correct and incorrect feature integration are less clear. To explore the temporal dynamics of feature integration, we studied the modulation of different frequency bands in trials in which feature integration was correct or incorrect. Participants responded to the color of a shape target, surrounded by distractors. A calibration procedure ensured that accuracy was around 70% in each participant. To explore the role of expectancy in feature integration, we introduced an unexpected feature to the target in the last blocks of trials. Results demonstrated the contribution of several frequency bands to feature integration. Alpha and beta power was reduced for hits compared to illusions. Moreover, gamma power was overall larger during the experiment for participants who were aware of the unexpected target presented during the last blocks of trials (as compared to unaware participants). These results demonstrate that feature integration is a complex process that can go wrong at different stages of information processing and is influenced by top-down expectancies.

Kinetics of combined hydrothermal pretreatment and anaerobic digestion of lignocellulosic biomass (pepper plant and eggplant).

A large quantity of lignocellulosic biomass is generated annually across the world which leads to environmental pollution and requires valorization. This study investigated the effect of hydrothermal pretreatment on the anaerobic digestion and co-digestion of the residual pepper plant and eggplant with a focus on kinetics. Two thermal hydrolysis rates were observed, with the optimal conditions for the hydrothermal pretreatment of lignocellulosic biomass being 120°C for 40 min. Subsequently, single and combined biomethanization was successfully carried out in laboratory-scale completely stirred tank reactors at mesophilic temperature (35°C). A high increase in methane production was observed after the pretreatment of the pepper plant and eggplant. The pretreated and co-digested wastes led to an optimal methane yield of 79 ± 23 mL CH4/g VS. The modified Gompertz model was used to fit the cumulative methane production of the pretreated lignocellulosic substrates. The kinetic model adequately reproduced the experimental results and might be considered a useful tool to simulate the biomethanization behaviour of complex organic substrates.

Experimental and CFD evaluation of ozone efficacy against coronavirus and enteric virus contamination on public transport surfaces.

The limited information about the routes of the transmission of SARS-CoV-2 within the ongoing pandemic scenario mobilized the administration, industry and academy to develop sanitation and disinfection systems for public and private spaces. Ozone has been proposed as an effective disinfection method against enveloped and non-enveloped viruses, including viruses with similar morphology to SARS-CoV-2. Due to this efficacy, numerous gaseous and aqueous phase ozone applications have emerged potentially to inhibit virus persistence in aerosols, surfaces, and water. In this work, a numerical model, a RANS CFD model for ozone dispersion inside tram and underground coach has been developed including the chemical self-decomposition and surface reactions of the ozone. The CFD model has been developed for a real tram coach of 28.6 × 2.4 × 2.2 m (L × W × H) using 1.76 million nodes and the Menter's shear stress transport turbulence model. The model predicts the O3 concentration needed to meet disinfection criteria and the fluid dynamics inside the public transport coach. The effectiveness of the system has been validated with laboratory and field tests in real full-scale coach using porcine epidemic diarrhea virus (PEDV) and murine norovirus (MNV-1) as SARS-CoV-2 and human norovirus surrogates, respectively. Lab-scale experiments on plastic surfaces demonstrated O3 disinfection (100 ppm, 95% RH, 25 min) inactivate > 99.8% MNV-1 and PEDV. Additionally, field tests in real full-scale coach demostrate the efficacy of the system as > 98.6% of infectious MNV-1 and > 96.3% PEDV were inactivated.

Anaerobic co-digestion of winery waste: comparative assessment of grape marc waste and lees derived from organic crops.

Grapes are one the world's leading fruit crops, with close to 77 million tonnes harvested per year. Grapes are commonly used to produce wine; a process which generates different wastes such as grape mark waste (skins, seeds and stalks), lees and other residues. This study evaluates the treatment of winery waste derived from ecological cultivation by anaerobic digestion to produce energy in the form of methane. Grape marc waste, Verdejo and Pedro Ximenez (PX) wine lees were digested under stable conditions at mesophilic conditions. The PX lees showed the highest methane yield production (433 LSTP CH4/kg VS) with a maximum OLR of 4.58 kg VS/m3·d. In the evaluated range the process was stable with a range of biodegradability of 51-79%. Due to different types of winery waste are generated at consecutive stages of the main production process, the sequential treatment of PX lees, Verdejo lees and grape marc waste in the same anaerobic digester could be an interesting option. This procedure would facilitate the management of the residual streams generated in wineries during the year and promotes the circular economy in the Montilla-Moriles Protected Designation of Origin.

Evaluation of hydrothermal pretreatment for biological treatment of lignocellulosic feedstock (pepper plant and eggplant).

Plant residues are an important source of organic matter that can be degraded by aerobic or anaerobic biological processes. However, due to the presence of lignocellulosic material, these residues are not easily biodegradable. Greenhouse crops, such as pepper and eggplant, generate large amounts of this type of waste after harvesting. In this study, a hydrothermal pretreatment was applied at 120 °C and different times to evaluate the enhancement of C and N solubilization in these residues. The highest solubilization of C was obtained at 40 min, as no significant increases were observed at higher times (100% and 68% for pepper plant [PP] and eggplant [EP], respectively). The solubilization of N shows a linear behavior (PP r2 = 0.9670 and EP r2 = 0.9395). Aerobic and anaerobic biodegradability were also evaluated, with better results found for the anaerobic digestion of the pretreated substrates. The nutrients balance with anaerobic co-digestion of both pretreated substrates (50:50% wt) improved methane production by 1.4 and 1.8 with respect to the substrates individually.

Sewage sludge composting under semi-permeable film at full-scale: Evaluation of odour emissions and relationships between microbiological activities and physico-chemical variables.

In the present study, physico-chemical characteristics, heavy metals content, odour emissions, microbial enumeration and enzymatic activities were analysed during industrial scale composting of sewage sludge partially pre-treated to evaluate the effect of a combined system of semi-permeable film and aeration on these parameters. The results related to physico-chemical parameters showed a decrease in total organic carbon (TOC), organic matter (OM), total carbon (TC) along the process. Volatile solids (VS) were also reduced, reaching 36% at 120 days, which is above the limit according to the current legislation. Similarly, metal content was found to be an important variable in the evolution of enzymatic activity, while lead (Pb), zinc (Zn), and nickel (Ni) were the most influential. Moreover, heavy metals were found below the limit of type B compost quality or European class 2 at the end of the process, which is suitable for agriculture soil. The odorous impact generated during the hydrolytic stage was reduced to an average value of 4 ouE/s. This suggests that, covered stage with the semi-permeable film, could be a viable solution to mitigate odour emissions. The highest temperature was reached at 10 days and it was favoured by semi-permeable film. Temperature promoted the presence of thermophilic bacteria and fungi and indicated an early biodegradation process mediated by microorganisms. Statistical analyses revealed a high correlation of physico-chemical variables with microbial activity. Thus, samples from the first 14 days were highly correlated with enzymatic activities such as ß-glucosidase (Ac-ßGlu), protease (Ac-Pr), and dehydrogenase (Ac-De), which have usually been involved in the hydrolysis of organic matter.

Co-composting of sewage sludge and eggplant waste at full scale: Feasibility study to valorize eggplant waste and minimize the odoriferous impact of sewage sludge.

Sewage sludge and bulking agent with small proportions of eggplant waste (EP) (4.7 and 8.6%) were co-composted at full scale to evaluate the feasibility of their joint valorization and to reduce the odorous impact during composting. In this sense, physico-chemical, respirometric and olfactometric variables were monitored throughout the co-composting process. The physico-chemical variables studied were related to each other to evaluate their effect on the quality of the final product and the odoriferous impact. It was observed that the reduction in nitrogen concentration was not parallel to the removal of organic matter, which influenced the odor concentration emitted. Furthermore, during the hydrolytic stage of the co-composting process, the odor concentration was lower when the agricultural waste content was highest (8.6% EP: 6317 and 8192 ouE/m3) in comparison with the lowest concentration of EP (4.7% EP: 9214 and 14720 ouE/m3) or without the addition of EP (reference composting pile: 10200 and 22500 ouE/m3). Although sewage sludge is more biodegradable than eggplant waste, the co-composting process was carried out under suitable conditions. Approximately 90 days were required to obtain a stabilized compost. Consequently, co-composting might be a suitable alternative to valorize EP and reduce the odoriferous impact of sewage sludge, with the consequent economic, social and environmental benefits.

Application of ATAD technology for digesting sewage sludge in small towns: Operation and costs.

In an economic context marked by increasing energy costs and stricter legislation regarding the landfill disposal of wastewater treatment plant (WWTP) sewage sludge, and where biomethanization is difficult to implement in small WWTPs, an efficient alternative is required to manage this polluting waste. This study shows that autothermal thermophilic aerobic digestion (ATAD) is a feasible technique for treating sewage sludge in small- and medium-sized towns. The experiments were carried out at pilot scale on a cyclical basis and in continuous mode for nine months. The main results showed an optimal hydraulic retention time of 7 days, which led to an organic matter removal of 34%. The sanitized sludge meets the microbial quality standards for agronomic application set out in the proposed European sewage sludge directive. An economic assessment for the operation of ATAD technology was carried out, showing a treatment cost of €6.5/ton for dewatered sludge.

Centralized management of sewage sludge and agro-industrial waste through co-composting.

In this research study, the co-composting process of a waste mixture containing strawberry extrudate, fish waste, sewage sludge and bulking agent (SEFW, 190:1:22:90 ratio) was carried out in a dynamic-solid respirometer at pilot scale. The aerobic biodegradability of the mixture was previously ensured in a static-liquid respirometer. The advantages and drawbacks of the SEFW co-composting process were subsequently identified through the determination of respirometric activity and the physical-chemical characterization of the waste, as well as the monitoring of odor emissions. The evolution of the physical-chemical variables showed that pH increased slightly and that the organic matter concentration, expressed as volatile solids (VS, %) or oxidable organic carbon (COXC, %), decreased by around 15% in both cases and by approximately 56% in its biodegradable form (total organic carbon, TOC, %). The low odor emission rate (OER) in the least favorable scenario (the maximum odor generation) during SEFW composting was 1.59 ouE/s, whereas this figure reached 3.52 ouE/s when only the organic fraction of municipal solid waste (OFMSW) was composted. Consequently, the co-composting of SEFW is more favorable in terms of odor emission and permits the simultaneous treatment of different types of waste.

Modelling of composting process of different organic waste at pilot scale: Biodegradability and odor emissions.

The composting process of six different compostable substrates and one of these with the addition of bacterial inoculums carried out in a dynamic respirometer was evaluated. Despite the heterogeneity of the compostable substrates, cumulative oxygen demand (OD, mgO2kgVS) was fitted adequately to an exponential regression growing until reaching a maximum in all cases. According to the kinetic constant of the reaction (K) values obtained, the wastes that degraded more slowly were those containing lignocellulosic material (green wastes) or less biodegradable wastes (sewage sludge). The odor emissions generated during the composting processes were also fitted in all cases to a Gaussian regression with R2 values within the range 0.8-0.9. The model was validated representing real odor concentration near the maximum value against predicted odor concentration of each substrate, (R2=0.9314; 95% prediction interval). The variables of maximum odor concentration (ouE/m3) and the time (h) at which the maximum was reached were also evaluated statistically using ANOVA and a post-hoc Tukey test taking the substrate as a factor, which allowed homogeneous groups to be obtained according to one or both of these variables. The maximum oxygen consumption rate or organic matter degradation during composting was directly related to the maximum odor emission generation rate (R2=0.9024, 95% confidence interval) when only the organic wastes with a low content in lignocellulosic materials and no inoculated waste (HRIO) were considered. Finally, the composting of OFMSW would produce a higher odor impact than the other substrates if this process was carried out without odor control or open systems.

Improvement of anaerobic digestion of sewage sludge through microwave pre-treatment.

Sewage sludge generated in the activated sludge process is a polluting waste that must be treated adequately to avoid important environmental impacts. Traditional management methods, such as landfill disposal or incineration, are being ruled out due to the high content in heavy metal, pathogens, micropolluting compounds of the sewage sludge and the lack of use of resources. Anaerobic digestion could be an interesting treatment, but must be improved since the biomethanisation of sewage sludge entails low biodegradability and low methane production. A microwave pre-treatment at pilot scale is proposed to increase the organic matter solubilisation of sewage sludge and enhance the biomethanisation yield. The operational variables of microwave pre-treatment (power and specific energy applied) were optimised by analysing the physicochemical characteristics of sewage sludge (both total and soluble fraction) under different pre-treatment conditions. According to the variation in the sCOD and TN concentration, the optimal operation variables of the pre-treatment were fixed at 20,000 J/g TS and 700 W. A subsequent anaerobic digestion test was carried out with raw and pre-treated sewage sludge under different conditions (20,000 J/g TS and 700 W; 20,000 J/g TS and 400 W; and 30,000 J/g TS and 400 W). Although stability was maintained throughout the process, the enhancement in the total methane yield was not high (up to 17%). Nevertheless, very promising improvements were determined for the kinetics of the process, where the rG and the OLR increased by 43% and 39%, respectively, after carrying out a pre-treatment at 20,000 J/g TS and 700 W.

Integral valorisation of waste orange peel using combustion, biomethanisation and co-composting technologies.

Although recent research has demonstrated that waste orange peel (WOP) is a potentially valuable resource that can be transformed into high value products, heat generation, biomethanisation and composting might be considered the most feasible alternatives in terms of yield. This study revealed that WOP can be successfully valorised through combustion. However, a previous drying step, which generates hazardous wastewater, is required and harmful NOx are emitted with the flue gases. In contrast, a high yield of renewable methane (280LSTPCH4/kg added COD, chemical oxygen demand) and an organic amendment can be obtained through the thermophilic biomethanisation of WOP following the removal of valuable essential oils from the peel. Co-composting of WOP combined at different proportions (17-83%) with the organic fraction of municipal solid waste (OFMSW) was also demonstrated to be suitable. Moreover, a 37% reduction in odour generation was observed in co-composting of WOP compared to single composting of OFMSW.

Dynamic olfactometry and GC-TOFMS to monitor the efficiency of an industrial biofilter.

Biofiltration is the most widely used technique for eliminating odours in waste treatment plants. Volatile organic compounds (VOCs) are among the odorous compounds emitted by waste management plants, and serve as variables to measure odour emissions depending on the type of aeration process used. In this work, we assess the performance of an industrial-scale biofilter where composting is the main source of VOCs and odour emissions. Dynamic olfactometry is the sensorial technique used to determine odour concentration, while gas chromatography-time of flight-mass spectrometry (GC-TOFMS) is used to perform the chemical characterization. This work examines a total of 82 compounds belonging to 15 odorous families of VOCs, particularly mercaptans, sulphur-containing compounds, alcohols and terpenes, among others. Principal component analysis (PCA) is used to assess the influence of each of these families of VOCs on the total variance of the measure with regard to both the input and output flow of the biofilter. Finally, partial least-squares (PLS) regression is used to estimate the odour concentration in each of the samples taken at the inlet and outlet of the biofilter in each of the samples based on the chemical information provided by chromatographic analysis. The study shows that there is an adequate correlation (r=0.9751) between real and estimated odour concentrations, both of which are expressed in European odour units per cubic metre (ou(E)·m(-3)).

Monitoring of pile composting process of OFMSW at full scale and evaluation of odour emission impact.

In this study, the evolution of odour concentration (ouE/m(3)STP) emitted during the pile composting of the organic fraction of municipal solid waste (OFMSW) was monitored by dynamic olfactometry. Physical-chemical variables as well as the respirometric variables were also analysed. The aim of this work was twofold. The first was to determine the relationship between odour and traditional variables to determine if dynamic olfactometry is a feasible and adequate technique for monitoring an aerobic stabilisation process (composting). Second, the composting process odour impact on surrounding areas was simulated by a dispersion model. The results showed that the decrease of odour concentration, total organic carbon and respirometric variables was similar (around 96, 96 y 98% respectively). The highest odour emission (5224 ouE/m(3)) was reached in parallel with the highest microbiological activity (SOUR and OD20 values of 25 mgO2/gVS · h and 70 mgO2/gVS, respectively). The validity of monitoring odour emissions during composting in combination with traditional and respirometric variables was demonstrated by the adequate correlation obtained between the variables. Moreover, the quantification of odour emissions by dynamic olfactometry and the subsequent application of the dispersion model permitted making an initial prediction of the impact of odorous emissions on the population. Finally, the determination of CO2 and CH4 emissions allowed the influence of composting process on carbon reservoirs and global warming to be evaluated.

Odour in composting processes at pilot scale: monitoring and biofiltration.

Although odour emissions associated with the composting process, especially during the hydrolytic stage, are widely known, their impact on surrounding areas is not easily quantifiable, For this reason, odour emissions during the first stage ofcomposting were evaluated by dynamic olfactometry at pilot scale in order to obtain results which can be extrapolated to industrial facilities. The composting was carried out in a commercial dynamic respirometer equipped with two biofilters at pilot scale filled with prunings (Populus) and mature compost obtained from the organic fraction of municipal solid waste. Given that the highest odour emissions occur in the first stage of the composting process, this stage was carried out in a closed system to better control the odour emissions, whose maximum value was estimated to be 2.78 ouF S-1 during the experiments. Odour concentration, the dynamic respiration index and temperature showed the same evolution during composting, thus indicating that odour could be a key variable in the monitoring process. Other variables such as total organic carbon (CTOC) and pH were also found to be significant in this study due to their influence over odour emissions. The efficiency of the biofilters (empty bed residence time of 86 s) was determined by quantifying the odour emissions at the inlet and outlet of both biofilters. The moisture content in the biofilters was found to be an important variable for improving odour removal efficiency, while the minimum moisture percentage to obtain successful results was found to be 55% (odour removal efficiency of 95%).

Usual variables and odour concentration to evaluate composting process and odour impact.

Organic waste management by means of composting produces unpleasant odours. The odour emissions of composting piles composed of the organic fraction of municipal solid waste and sewage sludge were monitored and controlled by means of dynamic olfactometry. This technique is used to determine the odour concentration expressed in European odour units per cubic metres (ou(E)/m3). To validate the technique, we analysed both respirometric variables and traditional variables such as total organic carbon and pH during composting. Finally, a dispersion model was used to evaluate the impact of the odour emissions of the wastes on neighbouring areas, not finding any differences in the cases evaluated.

Use of organic acids in the composting of municipal solid waste: a pilot-scale study.

Compost made from municipal solid waste (MSW) contains heavy metals that can interfere with the use of organic amendment in soil. In order to find effective ways to reduce the potential risk of heavy metals, we have investigated a novel approach by use of organic acid during MSW composting. Citric and oxalic acid dissolutions (0.25 mol x (-1)) were used at determined ratios (kg dried MSW: cm(3) acid). Cr and Ni concentrations were similar in compost, independent of acid contribution. By contrast, Cu concentrations decreased by 63% (at citric acid ratio 1:15), 65% (at citric acid ratios 1:20 and 1:40) and 83% (at oxalic acid ratio 1:40); furthermore, Pb concentrations reduced by 71% (at citric acid ratios 1:20 and 1:40 and at oxalic acid ratio 1:40) and Zn concentrations reduced by 67% (at citric acid ratios 1:10 and 1:20) and 70% (at oxalic acid ratio 1:40). The total metal mass decreased by an average of 12% in the compost fraction, whereas the total percentage of the residual fraction increased by an average of 20%. The acid addition in the studied ratios improved compost quality without negatively influencing biostabilization.

Impact of ammonia and sulphate concentration on thermophilic anaerobic digestion.

The effect of increasing concentrations of ammonia and sulphate on thermophilic anaerobic digestion (52 degrees C) was studied at laboratory-scale. The substrate consisted of a synthetic solution supplemented with ammonia and sodium sulphate. In terms of biogas production, the results showed that the C/N and C/SO(4)(2-) thresholds were 4.40 and 1.60, respectively, corresponding to 620 mg FA (free ammonia)/L and 1400 mg SO(4)(2-)/L. No reduction in biogas production was observed until reaching the above concentration of sulphate in the sulphate toxicity test. However, when the concentration of ammonia was increased to 620 mg FA/L in the ammonia toxicity test, a gradual decrease of 21% was observed for the biogas. In order to characterise each set of experiments kinetically, a biogas production first-order kinetic model was used to fit the experimental data. The proposed model accurately predicted the behaviour of the microorganisms affecting the thermophilic anaerobic digestion, allowing its evolution to be predicted.

Biomethanization of orange peel waste.

Recent research has demonstrated that orange peel waste is a potentially valuable resource that can be developed into high value products such as methane. Following a pre-treatment to extract D-limonene, the anaerobic digestion of orange peel waste was evaluated at laboratory and pilot scale under mesophilic and thermophilic conditions. D-limonene removals of 70% were reached with pre-treatment. The results showed the convenience of thermophilic conditions for treating this waste as the methane production rate and biodegradability were higher than at mesophilic temperature. At pilot scale, a thermophilic continuously stirred-tank reactor working in semi-continuous mode was employed. The OLR was found to be in the range of 1.20-3.67 kg COD/m(3) d; the most appropriate range for working under stable conditions at SRT of 25 d. The methane yield coefficient was found to be 0.27-0.29 L(STP)CH(4)/g added COD and the biodegradability 84-90% under these conditions. However, acidification occurred at the highest OLR.

Anaerobic co-digestion of glycerol and wastewater derived from biodiesel manufacturing.

The anaerobic co-digestion of glycerol and wastewater derived from biodiesel manufacturing, in which COD was found to be 1054 and 428 g/L, respectively, was studied in batch laboratory-scale reactors at mesophilic temperature (35 degrees C). Glycerol was acidified with H(3)PO(4) in order to recover the alkaline catalyst employed in the transesterification reaction (KOH) as agricultural fertiliser (potassium phosphates). Wastewater was subjected to an electrocoagulation process in order to reduce its oil content. After mixing, the anaerobic revalorisation of the wastewater was studied employing inoculum-substrate ratios ranging from 5.02 to 1.48 g VSS/g COD and organic loading rates of 0.27-0.36 g COD/g VSS d. Biodegradability was found to be around 100%, while the methane yield coefficient was 310 mL CH(4)/g COD removed (1 atm, 25 degrees C). At the equilibrium time, the proportionality between r' and the load was constant, showing 1.55 mL CH(4)/(g VSS g COD h). The results showed that anaerobic co-digestion reduces the clean water and nutrient requirement, with the consequent economical and environmental benefit.