Measurement of visible dust emissions during almond nut-picking operations at various harvester settings.

Peak ambient dust levels in the San Joaquin Valley (SJV) are often coincident with peak agricultural harvest seasons, particularly for nut orchards. Federal reference methods (FRMs), consisting of mass-based sampling techniques, are designed to measure and analyze ambient dust concentrations. However, FRMs generally require meticulous attention to sampling details, tedious labor and logistics, and time-consuming dispersion calculations. This study used opacity-based techniques - the U.S. Environmental Protection Agency (EPA) Method 9 and the Digital Compliance Opacity Technique (DCOT) - to quickly measure relative dust intensity at different harvester settings and to evaluate visible dust emission reductions using a new/low-dust nut harvester. Results indicate that old/conventional harvester at standard settings (3 mph ground speed and 900 rpm blower speed) produced visible dusts with opacities ranging from 23.3% to 29.0%. The dust plume generated from new/low-dust harvesters at similar settings registered lower opacity readings, with an average of 13.94%. The lowest average dust opacity (7.8%) was achieved when the separation fan was turned off. The present results validated the previous FRM emission findings that an old/conventional harvester has the highest PM emissions, but with a potential to achieve 50% reduction by adopting new/low-dust harvesters. Compared to an old harvester, the relative intensity of dusts was reduced by 40%-51% for low-dust harvesters operated at lower ground speeds. Further dust reductions could be achieved by lowering the fan speed (58%) and operating at no fan/blower setting (66.4%). Both visible emission evaluation (VEE) techniques were able to provide rapid quantitative feedback on the effects of operational changes on emitted harvest dusts. At this stage, opacity-based techniques can potentially be adapted as a screening tool for identifying best management practices (BMP) in reducing harvest dusts, rather than to solely rely on FRM mass-based techniques.Implications: U.S. EPA VEE techniques are established, robust methods of dust measurement systems that can be adopted to evaluate visible dust mitigation strategies in the SJV, alongside the existing FRM protocols. The use of Method 9 and DCOT, as both non-disruptive and rapid dust measurement tools, can bring immediate impact concerning the goal of the almond industry to significantly reduce its PM emissions in the next coming years.

Particulate Matter Emission Factors for Dairy Facilities and Cattle Feedlots during Summertime in Texas.

Particulate matter (PM) emissions from dairies and feedlot sources require regular emission factor update. Likewise, development of simple measurement technique to accurately measure pollution concentration is warranted to limit the impact of air pollution and take necessary actions. During June of 2020, a dairy facility from central Texas and a feedlot from the Texas Panhandle region, titled as Dairy B and Feedlot C, respectively, were chosen for measurement of PM emissions in the state of Texas to represent dairy facilities and cattle feedlots PM emission rates. Four stations, each assigned with an EPA-approved Federal Reference Method (FRM) sampler, Texas A&M University (TAMU) designed sampler and handheld non-FRM AEROCET (MET One Instruments) sampler for collocation, were selected within each sampling locations. Drones were also utilized mounted with a handheld AEROCET sampler for simultaneously sampling at a certain height. PM2.5 emissions of Dairy B were all below 24-h PM2.5 standard of 35 µg m-3 as specified by National Ambient Air Quality Standards (NAAQS) even at the 98th percentile. The PM ratio between regulated PM10 to PM2.5 was determined to make an estimate of relative percentage of coarser particles to fine particles in both feedlot and the dairy representative animal facilities. The maximum mean emission factor determined using AERMOD for PM2.5 and PM10 was found to be 0.53 and 7.09 kg 1000-hd-1 d-1, respectively, for the dairy facility while 8.93 and 33.42 kg 1000-hd-1 d-1, respectively, for the feedlot. A conversion factor and correlation matrix were developed in this study to relate non-FRM sampler data from the handheld AERCET samplers with FRM samplers. Cheaper handheld samplers (AEROCETs) may play a potential role in quick and relatively instant measurement of PM emissions to initiate necessary preventive actions to control PM emission from dairy facility and feedlot sources.

Autochthonous Arthrospira platensis Gomont Driven Nickel (Ni) Phycoremediation from Cooking Oil Industrial Effluent.

Nickel (Ni) leftovers arise from both catalyst application interventions and Ni alloy piping of the cooking oil industry (COI) being wasted as pollutants of freshwater bodies via discharged effluent. The current study assessed one of the indigenously feasible Ni removal systems comprising autochthonous Arthrospira platensis Gomont (AP)-driven Ni phycoremediation cells (NPCs). After screening AP for hyperaccumulation in the Ni spiked solution, AP was transferred to the NPCs. Propagation of the AP inoculum was proportionate to the pollution load drop of COI with 22.97 and 55.07% drops in the biochemical (BOD) and chemical oxygen demand (COD), respectively. With the 0.11 bioconcentration factor, there was an uptake of 14.24 g mineral with 16.22% Ni removal and a 36.35 desorption ratio. The experimental data closely fitted with the Langmuir and Freundlich isotherms, respectively. The study concluded that A. platensis could be taken for treatment of Ni-loaded industrial effluents at the microcosmic level.

Use of ultrasound for aiding lipid extraction and biodiesel production of microalgae harvested by chitosan.

In this work, chitosan, a biodegradable flocculant, was investigated to determine its utility in flocculating microalgae, its effect on cell integrity, and its impact on lipid extraction and the conversion to fatty acid methyl ester (FAME). Results showed that chitosan adequately performed flocculation on Chlorella vulgaris microalgae and achieved a high harvesting efficiency of 96.35 ± 1.96% when implemented under the following conditions: chitosan dose = 120 mg/L-1, pH = 5, mixing speed = 150 rpm for 20 min, followed by 10 min of settling time. Moreover, scanning electron microscope (SEM) combined with transmission electron microscope (TEM) demonstrated that chitosan protected the cells' structure from morphological damage. Finally, the highest lipid extraction yield and biodiesel production was obtained from the chitosan-harvested biomass when the microalgae were pretreated with ultrasound.

Social network and extension service in farmers' agricultural technology adoption efficiency.

The purpose of the article is to analyze the interaction effect between social network and extension service in farmers' agricultural technology adoption efficiency (TAE). The empirical analysis refers to samples of farmers' water-saving irrigation technology (WSIT) adoption from Minqin, China. The result indicates that social network and extension service can improve farmers' TAE, but they are found to be competitive from the perspective of overall social network. While from the perspective of four dimensions of social network, interaction and trust have positive effects on farmers' TAE, and learning and trust are found to be competitive with extension service. The policy implication describes as follows. First, government should pay attention to farmers' social learning and demonstration effect. And series of measures should be taken to cultivate farmers' social network. Second, extension service should be improved to satisfy farmers' multiple demand on agricultural technology. Third, government should combine the effects of social network and extension service, and make different promotion strategies for different regions. In addition, other influential factors cannot be ignored.

Particulate matter emission factors using low-dust harvesters for almond nut-picking operations.

The lack of an available particulate matter (PM) PM2.5 emission factor for almond harvesting operations has become a challenge for particulate matter regulations and emissions inventory in California. Low-dust harvesters are viewed as one of the strategies to reduce PM emissions and help achieve the state's PM2.5 attainment targets. This paper evaluates the potential emission reduction from using low-dust harvesters compared to the conventional. Orchard boundary measurements of PM concentrations were collected to back-calculate emission rates using inverse dispersion modeling. Emissions from four low-dust harvesters (Flory 850, Exact E3800, Weiss-McNair 9800 and Jack Rabbit) were compared to those from a conventional harvester (Flory 480) in two orchards, located in the Fresno County. Emissions of PM2.5, PM10 and total suspended particles were observed to be lower for all new harvesters compared to the conventional harvester. The range of reductions varies from about 40% to 77% in PM2.5 emissions based on emission factors generated. The average ratio of PM10 to PM2.5 emissions is about 12.5%. The results of these tests imply that these new low-dust harvesters are capable of reducing PM emissions without affecting product quality. Therefore, the San Joaquin Valley Air Pollution Control District should consider including the use of these new harvesters in the conservation management practices (CMP) for the reduction of PM emissions in the valley. Implications: The results of this research indicate that almond low-dust harvesters could potentially reduce PM emissions over traditional harvesters without any negative effect on product quality. Therefore, the use of these new harvesters should be considered as part of almond best management practices and updating of emissions inventory in the San Joaquin Valley.

Effects of hydrochloric acid washing on the microstructure and pyrolysis bio-oil components of sweet sorghum bagasse.

Acid washing is an alternative and promising approach for biomass to produce high-quality bio-oil. The hydrochloric acid washing pretreatment of sweet sorghum bagasse was performed in this study. The effects of acid washing on the ultrastructure of sweet sorghum bagasse were investigated using scanning electron microscope and Fourier transform infrared, and the effects on pyrolysis using thermogravimetric analyzer and a fast pyrolysis device. The results indicated acid treatment obviously changed the surface morphology of the cell walls of sweet sorghum bagasse, effectively removed most metals from sweet sorghum bagasse, and increased the volatiles and bio-oil yields. The results showed that bio-oil produced from pretreated sweet sorghum bagasse contained less components categories, lower contents of phenols, aldehydes, furans and alcohols, while much higher contents of d-allose and ketones than that from the original sample. Hydrochloric acid-washing pretreatment of sweet sorghum bagasse can increase the contents of some high-value chemicals in bio-oil.

Evaluation of the effectiveness and mechanisms of acetaminophen and methylene blue dye adsorption on activated biochar derived from municipal solid wastes.

The adsorption potential and governing mechanisms of emerging contaminants, i.e. acetaminophen or acetyl-para-aminophenol (APAP) and methylene blue (MB) dye, on activated carbon derived from municipal solid waste were investigated in this work. Results showed that MB adsorption was significantly more effective, with a maximum removal of 99.9%, than APAP adsorption (%Rmax = 63.7%). MB adsorption was found to be unaffected by pH change, while the adsorption capacity of APAP drastically dropped by about 89% when the pH was adjusted from pH 2 to 12. Surface reactions during APAP adsorption was dominated by both physical and chemical interactions, with the kinetic data showing good fit in both pseudo-first order (R2 = 0.986-0.997) and pseudo-second order (R2>0.998) models. On the other hand, MB adsorption was best described by the pseudo-second order model, with R2>0.981, denoting that chemisorption controlled the process. Electrostatic attractions and chemical reactions with oxygenated surface functional groups (i.e., -OH and -COOH) govern the adsorption of APAP and MB on the activated biochar. Thermodynamic study showed that APAP and MB adsorption were endothermic with positive ΔH° values of 16.5 and 74.7 kJ mol-1, respectively. Negative ΔG° values obtained for APAP (-3.7 to -5.1 kJ mol-1) and MB (-11.4 to -17.1 kJ mol-1) implied that the adsorption onto the activated biochar was spontaneous and feasible. Overall, the study demonstrates the effectiveness of activated biochar from municipal solid wastes as alternative adsorbent for the removal of acetaminophen and methylene blue dye from contaminated waters.

Improving the surface properties of municipal solid waste-derived pyrolysis biochar by chemical and thermal activation: Optimization of process parameters and environmental application.

Biochar produced from the slow pyrolysis of municipal solid waste was activated with KOH and thermal treatments to enhance its surface and adsorptive properties. The effects of KOH concentration, activation temperature and time on the specific surface area (SSA) of the activated biochar were evaluated and optimized using central composite design (CCD) of the response surface methodology (RSM). Results showed that the activation of biochar enhanced its SSA from 402.8 ±â€¯12.5 to 662.4 ±â€¯28.6 m2 g-1. The adsorptive capacities of the pristine biochar (PBC) and activated biochar (ABC) were compared using methylene blue (MB) dye as model compound. For MB concentrations up to 25 mg L-1, more than 99% dye removal was achieved with ABC, while only a maximum of 51% was obtained with PBC. Results of the isotherm study showed that the Langmuir model best described MB adsorption on ABC with adsorption capacity of 37.0-41.2 mg g-1.

Correction: Effects of Pyrolysis Temperature on Product Yields and Energy Recovery from Co-Feeding of Cotton Gin Trash, Cow Manure, and Microalgae: A Simulation Study.

[This corrects the article DOI: 10.1371/journal.pone.0152230.].

Effects of Pyrolysis Temperature on Product Yields and Energy Recovery from Co-Feeding of Cotton Gin Trash, Cow Manure, and Microalgae: A Simulation Study.

The intensive search of new and cleaner energy catches interest in recent years due to huge consumption of fossil fuels coupled with the challenge of energy and environmental sustainability. Production of renewable and environmentally benign energy from locally available raw materials is coming in the frontline. In this work, conversion of the combined biomass (cotton gin trash, cow manure, and Microalgae [Nannochloropsis oculata]) through batch pyrolysis has been investigated. The effect of temperature to the production of energy fuels such as bio-oil, char, and biogas have been simulated considering the yield and energy content as responses. Result of the investigation generally revealed that the proportions of the different biomass did not significantly affect the product yield and energy recovery. Significant effect of temperature is evident in the simulation result of energy recovery whereby maximum conversion was achieved at 400°C for char (91 wt%), 600°C for syngas (22 wt%), and 551°C for bio-oil (48 wt%). Overall energy conversion efficiency of 75.5% was obtained at 589°C in which 15.6 MJ/kg of mixed biomass will be elevated to pyrolysis products.

Evaluation of particulate matter abatement strategies for almond harvest.

Almond harvest accounts for substantial PM10 (particulate matter [PM] < or =10 microm in nominal aerodynamic diameter) emissions in California each harvest season. This paper evaluates the effects of using reduced-pass sweepers and lower harvester separation fan speeds (930 rpm) on lowering PM emissions from almond harvesting operations. In-canopy measurements of PM concentrations were collected along with PM concentration measurements at the orchard boundary; these were used in conjunction with on-site meteorological data and inverse dispersion modeling to back-calculate emission rates from the measured concentrations. The harvester discharge plume was measured as a function of visible plume opacity during conditioning operations. Reduced-pass sweeping showed the potential for reducing PM emissions, but results were confounded because of differences in orchard maturity and irrigation methods. Fuel consumption and sweeping time per unit area were reduced when comparing a reduced-pass sweeper to a conventional sweeper. Reducing the separation fan speed from 1080 to 930 rpm led to reductions in PM emissions. In general, foreign matter levels within harvested product were nominally affected by separation fan speed in the south (less mature) orchard; however, in samples conditioned using the lower fan speed from the north (more mature) orchard, these levels were unacceptable.

Particulate matter emission factors for almond harvest as a function of harvester speed.

Almond harvest accounts for substantial particulate matter less than 10 microm in aerodynamic diameter (PM10) emissions in California each harvest season. This paper addresses the reduction of harvester ground speed from a standard 8 km/hr (5 mph) to 4 km/hr (2.5 mph) as a possible mitigation measure for reducing PM10 emissions. Ambient total suspended particulate (TSP) and PM10 sampling was conducted during harvest with alternating control (8 km/hr [5 mph]) and experimental (4 km/hr [2.5 mph]) treatments. On-site meteorological data were used in conjunction with both Industrial Source Complex-Short Term version 3 (ISCST3) and the American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model (AERMOD) dispersion models to back-calculate emission rates from the measured concentrations. Baseline annual emission factors for nut pickup of 381 +/- 122 and 361 +/- 123 kg PM10/km2 x yr were determined using ISCST3 and AERMOD, respectively. Both of these values are substantially lower than the current PMIo emission factor for almond pickup of 4120 kg PM10/ km2 x yr. The particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5) emission factors for nut pickup developed from this study were 25 +/- 8 kg PM2.5/km2 x yr and 24 +/- 8 kg PM10/km2 x yr were determined using ISCST3 and AERMOD, respectively. Reducing harvester speed resulted in an emissions reduction of 42% for TSP, but no differences were detected in emissions of PM10 and PM2.5. Differences detected in the emission factors developed using ISCST3 and AERMOD were not statistically significant, indicating that almond harvest emission factors previously developed using ISCST3 may be applied appropriately in AERMOD.

Seasonal and spatial variations of ammonia emissions from an open-lot dairy operation.

There is a need for a robust and accurate technique to measure ammonia (NH3) emissions from animal feeding operations (AFOs) to obtain emission inventories and to develop abatement strategies. Two consecutive seasonal studies were conducted to measure NH3 emissions from an open-lot dairy in central Texas in July and December of 2005. Data including NH3 concentrations were collected and NH3 emission fluxes (EFls), emission rates (ERs), and emission factors (EFs) were calculated for the open-lot dairy. A protocol using flux chambers (FCs) was used to determine these NH3 emissions from the open-lot dairy. NH3 concentration measurements were made using chemiluminescence-based analyzers. The ground-level area sources (GLAS) including open lots (cows on earthen corrals), separated solids, primary and secondary lagoons, and milking parlors were sampled to estimate NH3 emissions. The seasonal NH3 EFs were 11.6 +/- 7.1 kg-NH3 yr(-1)head(-1) for the summer and 6.2 +/- 3.7 kg-NH3 yr(-1)head(-1) for the winter season. The estimated annual NH3 EF was 9.4 +/- 5.7 kg-NH3 yr(-1)head(-1) for this open-lot dairy. The estimated NH3 EF for winter was nearly 47% lower than summer EF. Primary and secondary lagoons (approximately 37) and open-lot corrals (approximately 63%) in summer, and open-lot corrals (approximately 95%) in winter were the highest contributors to NH3 emissions for the open-lot dairy. These EF estimates using the FC protocol and real-time analyzer were lower than many previously reported EFs estimated based on nitrogen mass balance and nitrogen content in manure. The difference between the overall emissions from each season was due to ambient temperature variations and loading rates of manure on GLAS. There was spatial variation of NH3 emission from the open-lot earthen corrals due to variable animal density within feeding and shaded and dry divisions of the open lot. This spatial variability was attributed to dispirit manure loading within these areas.

The recovery of ammonia and hydrogen sulfide from ground-level area sources using dynamic isolation flux chambers: bench-scale studies.

Controlled bench-scale laboratory experiments were conducted to evaluate the recovery of ammonia (NH3) and hydrogen sulfide (H2S) from dynamic isolation flux chambers. H2S (80-4000 ppb) and NH3 (5000-40,000 ppb) samples were diffused through the flux chamber to simulate ground level area source emissions while measuring the inlet and outlet flux chamber concentrations simultaneously. Results showed that the recovery of H2S during a 30-min sampling time was almost complete for concentrations >2000 ppb. At the lowest concentration of 80 ppb, 92.55% of the H2S could be recovered during the given sampling period. NH3 emissions exhibited similar behavior between concentrations of 5000-40,000 ppb. Within the 30-min sampling period, 92.62% of the 5000-ppb NH3 sample could be recovered. Complete recovery was achieved for concentrations >40,000 ppb. Predictive equations were developed for gas adsorption. From these equations, the maximum difference between chamber inlet and outlet concentrations of NH3 or H2S was predicted to be 7.5% at the lowest concentration used for either gas. In the calculation of emission factors for NH3 and H2S, no adsorption correction factor is recommended for concentrations >37,500 ppb and 2100 ppb for NH3 and H2S, respectively. The reported differences in outlet and inlet concentration above these ranges are outside the fullscale sensitivity of the gas sensing equipment. The use of 46-90 m of Teflon tubing with the flux chambers has apparently no effect on gas adsorption, because recovery was completed almost instantaneously at the beginning of the tests.