Laboratory-scale Tests Research Articles

Process Improvement of Biogas Production from Sewage Sludge Applying Iron Oxides-Based Additives

Iron additives are effective in the anaerobic sewage sludge digestion process, but the composition and dosage of these additives are not precisely defined. This research investigates the effects of three iron oxides-based additives on the destruction of volatile solids, the production and quality of biogas, as well as the quality of the supernatant. Additive No 1 contained >41.5% of FeO and >41.5% of Fe2O3, additive No 2 contained ≥86% of Fe3O4, and additive No 3 contained ≥98% of Fe3O4. The best results were obtained by applying an iron oxides-based additive with a higher content of divalent iron oxide. The increase in efficiency of the VSs destruction was not significant and on average 2.2%. The increase in biogas production was on average 20% while the average increase in the content of methane in the biogas was 6.3%. Applying the additive, the reduction in the concentration of ammonium nitrogen in the supernatant was up to 28%, as well as a reduction in the concentration of phosphate phosphorus in the supernatant by up to 3.1 times could be expected compared to the case when the additive was not applied. The dose of additive No 1 was between 7.5 g/kg of dry solids and 15 g/kg of dry solids in the lab-scale test. The dose was specified in the full-scale test, and the recommended dose of the additive was 10 g/kg of dry solids to improve biogas production.

Gas diffusion electrode activity measurements of iridium-based self-supported catalysts produced by alternated physical vapour deposition

The scarce supply of Ir used to catalyze the sluggish oxygen evolution reaction in acidic water electrolysis calls for unconventional approaches to design more active catalysts with minimal resource usage for their commercial scaling. Industrial-ready production methods and laboratory scale tests that can reflect the catalyst behaviour realistically need to be included in this process. In this work, we benchmarked three series of self-supported Ir–Co catalysts with low Ir loading produced by physical vapour deposition under relevant current densities in a gas diffusion electrode setup. It was seen that after selective acid leaching of the Co, a nanoporous structure with a high electrochemically active surface area and a mixed oxide and metallic character was formed. Depending on the initial Co:Ir deposition ratio over ten times higher oxygen evolution mass activities could be reached as compared to a commercial, unsupported IrOx nanoparticle catalyst used as a benchmark in the same setup configuration. The presented integrative catalyst design and testing strategy will help to facilitate bridging the gap between research and application for the early introduction of next-generation catalysts for water splitting.

Metal organic frameworks (MOFs) for the removal of dissolved silica before reverse osmosis desalination

Freshwater scarcity in many arid regions necessitates brackish water desalination via reverse osmosis (RO). One of the key obstacles to lowering the cost of RO freshwater is scaling or fouling on the RO membrane caused by dissolved silica in the brackish water. Herein, a robust metal organic framework (MOF) material was produced with green production methods. During column tests, the MOF demonstrates a high and selective affinity toward silicic acid from the dominant species in brackish water (e.g., Cl-, SO42-, HCO3-, Ca2+, Mg2+). Further lab-scale desalination tests showed over 80% of the 10–15 µm sized stone-like scales on the membrane were reduced while a 28.1% increase in the permeate flux was observed compared to the RO membrane without MOF treatment. Plus, two regeneration methods based on the properties of the selected MOFs were developed and evaluated.

Impact of antioxidants in MgO–C refractory on steel cleanliness and refractory degradation

Magnesia-carbon (MgO–C) refractories are used in steelmaking processes as lining materials. We performed lab-scale tests at 1600 °C and a pO2 of 10−15 atm to determine the effect of Al and Si antioxidant level, time and slag composition on the amount and nature of inclusions in the steel and on the corrosion and infiltration of the refractory. In all steel samples, a pick-up of Al, Si and C was observed. For the refractories containing antioxidants, longer holding times seem to increase the number density of inclusions, especially in combination with a slag with lower MgO content. For the given experiments, the beneficial role of antioxidants against slag corrosion was not observed, possibly due to the low pO2, which prevented C oxidation. As both MgAl2O4 and SiC, formed in the refractory, react and dissolve in the slag infiltrating in the refractory, they do not play a protective role.

Bioassay and efficacy of clove flower stalk extract of Afo variety as a natural larvicidal

This study aims to test the larvicidal bioassay of clove stalk extract against Aedes aegypti on a laboratory scale and field scale efficacy test in a bath. Samples of sun-dried clove flower stalks were made into water extracts and coarse powder measuring 8-10 mesh for efficacy tests in the bath. The experimental method with a completely randomized design model was used to test the effectiveness of the larvicide, which consisted of two stages: The aqueous extract was tested against Ae. aegypti third instar larvae for three concentrations, namely 10%, 20%, and 30%, plus control treatment with three repetitions; observations were made at 30 minutes and 60 minutes after application to see the number of dead larvae as stage one. The second stage was the efficacy test in the bath which was carried out by inserting clove coarse powder in packs of 20 grams, 30 grams, and 40 grams, as well as the control treatment with five replicates, observed every day to see the time of emergence of mosquito larvae in a matter of days. The results of the first stage test showed an effect of the concentration of clove flower stalk extract on the mortality rate of the larvae, which was indicated by a positive relationship, where the mortality rate of the larvae reached 100% at 60 minutes after application. In comparison, the second stage test showed that there was an effect of clove flower stalk coarse powder on the time of larvae emergence, where the average time for larvae emergence was up to 8.8 days in the treatment of 40 g of clove flower stalk coarse powder, 1.83 times longer than the control (4 .8 days). Clove flower stalk extract is effective as a larvicidal mosquito Ae. aegypti.

Ethyl Formate Fumigation for Control of the Scale Insect Asiacornococcus kaki, a Quarantine Pest on Sweet Persimmon, Diospyros kaki: Efficacy, Phytotoxicity and Safety

Sweet persimmons are a valuable export commodity. However, the presence of live insects such as Asiacornococcus kaki limits their access to many export markets. Methyl bromide, traditionally used for pest control, is damaging to human health and the environment. Ethyl formate (EF) is a viable alternative; however, its effectiveness against A. kaki on sweet persimmon fruit is unknown. We evaluated the effectiveness of EF fumigation in controlling A. kaki present under the calyx of persimmon fruit. The hatching rate of eggs and the survival rates of nymphs and adults of A. kaki at low temperatures, its LCt50 and LCt99 after EF exposure, and phytotoxic damage caused by EF were evaluated in laboratory-scale and commercial-scale tests. The dose-response tests showed that the EF LCt99 at 5 °C was 9.69, 42.13, and 126.13 g h m-3 for adults, nymphs, and eggs, respectively. Commercial-scale tests demonstrated EF efficacy against all A. kaki stages without causing phytotoxic effects on persimmons, though the eggs of A. kaki were not completely controlled in linear low-density polyethylene (LLDPE)-packaged fruit. This study demonstrated that EF is a potential fumigant for quarantine pretreatment, especially before persimmon fruit is packed with LLDPE film, to control A. kaki infesting sweet persimmon fruit.

Investigation of the leak tightness of structural adhesive joints for use in battery housings considering mechanical and corrosive loads

ABSTRACT Due to increasing legal requirements to reduce emissions from vehicle fleets, vehicle manufacturers are focusing on the electrification of the powertrain. In entirely electrically driven vehicles, the energy is stored in traction batteries integrated below the passenger cell between the axles and thus located in the vehicle’s wet area. Therefore, high requirements apply to the protection of the sensitive cells against mechanical stress as well as against moisture penetration. In addition, one of the main requirements for the connections of the battery housing is to ensure gas tightness over the entire service life. Adhesive bonding technology as a planar joining process offers the potential to produce functionally tight connections. However, there is a lack of reliable test methods for validating the long-term tightness of structural adhesive joints under mechanical and corrosive loads. For this reason, the paper deals with developing a test concept with laboratory-scale test specimens for leak testing under mechanical loading. Various leakage test methods investigate the leakage rate of structurally bonded joints. An analysis of the leakage rate under superimposed cyclic mechanical shear tensile loading follows this. The test method is validated on a specially developed sample battery housing on a laboratory scale.

Pd and Pd-Cu supported on different carbon materials and immobilized as flow-through catalytic membranes for the chemical reduction of NO3-, NO2- and BrO3- in drinking water treatment

Powdered catalysts are commonly used in lab-scale tests for the catalytic reduction of oxoanions in drinking water, but their powder nature limits their application at full scale. In this work, Pd and Pd-Cu catalysts (5% wt.) supported on carbon materials with different structural properties, in powder form, were used to prepare catalytic membranes that were tested in a reactor with flow-through configuration (FTCMR) to study their performance in the reduction of NO3-, NO2- and BrO3-. Pd catalytic membranes showed high activity in the reduction of NO2-, being the selectivity to NH4+ lower than 2% at 80% NO2- conversion in all cases. In BrO3- reduction, they exhibited a wide range of conversions being the catalyst supported on materials with high conductivity the most active ones, which may be ascribed to the charge distribution at the metal-carbon interface. NO3- reduction using Pd-Cu catalytic membranes showed that catalysts supported on materials with small nanoparticle size and low electrical conductivity exhibited higher selectivity to NH4+. FTCMR led to a good control of H2 transfer and availability in the active sites, facilitating the tuning of H2 availability conditions to preserve the activity, while maintaining/diminishing selectivity to NH4+. In simultaneous oxoanions reduction tests, NO3- reduction was inhibited by Br species, probably by affection of the Pd-Cu redox cycle. This fact could be crucial to the future development of drinking water treatment processes, as conditions the order of the disinfection and NO3- reduction steps.

Interplay between membrane imperfections and external concentration polarization

Reverse osmosis membranes provide a highly effective and efficient barrier against various kinds of pollutants. Their reliability depends on the integrity of the active layer: in case the active layer is damaged and contains imperfections, unfiltered feed solution can contaminate the permeate. Various types of integrity monitoring techniques have been developed to verify membrane performance, of which the rejection of fluorescent dyes is a well-established technique. Fluorescent dyes are however relatively small solutes for which the membranes can display non-zero diffusive permeability, such that not all dye passage can be attributed to membrane imperfections. Additionally, fluorescent dyes are subject to external concentration polarization (ECP) during filtration, causing a flux-dependent enrichment at the membrane surface, further complicating the analysis of dye rejection data. This study presents a model to discern between membrane permeability, enrichment by ECP and passage through imperfections. The consequences of imperfections on solute passage are explored, showing that imperfections only contribute significantly to the passage of solutes with a low membrane permeability. This leads to underestimates of the external mass transfer coefficient, with the error being increasingly large with decreasing membrane permeability coefficient, relative to the case of an imperfection-free membrane. This error is then related to the proportionality of the Sherwood number, used to calculate external mass transfer coefficients, with solute diffusivity, allowing the quantification of the contribution of imperfections to water flux. The model was experimentally verified using Pyranine rejection in two membrane types, both operated in a lab-scale flat sheet crossflow test system, finding proof of imperfections in one membrane type.

Corrosion of 1.4016 Ferritic Steel by Urea at High Temperature

The corrosion behavior of a ferritic unstabilized stainless steel 1.4016 during decomposition of aqueous urea solution at high temperature has been investigated. Corrosion was obtained from 100 h of cyclic heating (from room temperature up to 600 °C) and injection of aqueous urea solution on the steel plate in a laboratory-scale test bench. The evaluation procedure covered the metallographic analysis of corroded steel samples by high-resolution scanning electron microscopy (HR-SEM) and transmission electron microscopy (TEM). Uniform corrosion underneath deposits was found as one of the drivers for degradation of the steel. Damage happened by high-temperature depassivation of stainless steel due to the excess of the aggressive medium. Besides uniform corrosion, a nitridation layer underneath surface oxides together with chromium carbonitride particles precipitated through the whole depth of the sample was identified resulting in intergranular attack.

Recovery of Ammonium from Biomass-Drying Condensate Via Ion Exchange and Its Valorization as a Fertilizer

In this study, an industrial biomass-drying wastewater condensate containing > 3200 mg/L NH4+ and >8900 mg/L CH3COO− was treated in ion-exchange columns for the recovery of NH4+. Two commercial resins (CS12GC and CS16GC) were studied on laboratory and pilot scales. CS16GC outperformed CS12GC by achieving better separation at the condensate temperature (60 °C), which was energy-efficient regarding NH4+ removal. K3PO4 was used for regeneration to produce a liquid compound fertilizer containing nutrient elements (N, K, and P) as a byproduct. The N/K ratio in the byproduct was found to be adjustable by varying the operating parameters. Regeneration with 2 mol/L K3PO4 gave a higher regeneration efficiency (97.67% at 3 BV and ~100% at 4 BV). The stability tests performed on a laboratory scale showed that the cyclic runs of the column separation process were steady and repeatable. Based on the outcomes of the laboratory-scale tests, the pilot-scale tests applied a loading volume of 7 BV. The pilot column purified the feed and achieved the target NH4+ level in the treated effluent within the seven tested cycles, revealing that the industrial application of the cation ion-exchange resin CS16GC is worth further study.

A non-linear viscoelastic material model with progressive damage based on microstructural evolution and phase transition in polycrystalline ice for design against ice impact

This study presents a nonlinear viscoelastic material model incorporating a progressive damage framework with an iterative algorithm for glacial/freshwater polycrystalline ice subject to compressive impact load induced by ice-structure interaction. The damage model accounts for microcracking, dynamic recrystallisation, pressure melting, and high-shear elastic failure with a pressure- and rate-dependent convex failure locus. The constitutive laws are written in Fortran and implemented as a vectorised user material (VUMAT) in Abaqus with three different numerical methods, Lagrangian FEM, coupled FEM-SPH, and ALE-FEM. The constitutive model together with the implemented numerical methods are validated against two different types of laboratory-scale physical tests, indentation of cone-shaped ice and triaxial creep. The proposed model implemented with the coupled FEM-SPH method enables simulation of the cyclic transition from solid-like intact ice to the fluid-like pulverised/granular substance, progressively extruded with viscous rheology.

Intensive carbon combustion in sintering packed bed via steam spraying: An experimental study on carbon monoxide emission reduction.

Improving the combustion efficiency of solid fuels is important for reducing carbon monoxide emissions in the iron ore sintering process. In this paper, the surface steam spraying technology is introduced in the sintering process based on the auxiliary combustion effect of steam on coke, and its potential to reduce carbon monoxide emissions is demonstrated. Thermogravimetric analysis experiments of coke breeze in air and air-steam mixed atmosphere are carried out, and the results show that the introduction of steam can reduce the concentration of carbon monoxide in the exhaust gas from 183×10-6 to 78×10-6. At the same time, the mechanisms of carbon monoxide emission reduction by surface steam spraying technology are analyzed from the thermodynamic and kinetic perspectives. Then, a series of laboratory-scale sintering pot tests are carried out under no spraying operation, interval spraying operation, and continuous spraying operation. The results indicate that both interval and continuous spraying operations can reduce carbon monoxide emissions. The optimal mode of steam spraying under the present experimental conditions is continuously spraying for 13 min at a volume rate of 0.053 m3/min. Compared with no spraying, the average carbon monoxide concentration in the exhaust gas is reduced from 7565×10-6 to 6231×10-6, and total carbon monoxide emissions for per ton sinter are reduced from 13.46 m3/t to 9.51 m3/t.

A Monte Carlo simulation study of L-band emission upon gamma radiolysis of water

Several studies have confirmed visible light and ultraviolet emission during water molecule radiolysis; however, radiofrequency emission has been scarcely investigated. This simulation study has revealed that the gamma radiolysis of water creates excited hydrogen atoms which emit radio recombination L-band (1 GHz–2 GHz) radio waves of sufficient strength that a radio-imaging device can detect. The physical and physicochemical stages of radiolysis of water have been modeled via application of Monte Carlo simulation techniques (utilizing Geant4) up to 1 ps from the onset of gamma photon interaction with water molecules. Subsequently an L-band emission analysis up to a few ms duration was accomplished to obtain and understand RF power emission characteristics as a function of gamma radiation dose rate. The generated L-band 1.4 GHz RF power is 19 dBm per one Gy/h of absorbed dose rate. The generated RF power varies linearly with absorbed dose rate up to 3.38 Gy/h, beyond which non-linearity manifests due to line broadening. Unlike conventional gamma radiation detectors, the proposed RF-based gamma radiation detection model indicates that the detection sensitivity of the RF detector does not deteriorate rapidly with an increase in altitude above radiation source at ground. Consequently, source-detector standoff distances are increased significantly at least up to two orders of magnitude higher than the current gamma radiation detection scenario. Preliminary experiments were conducted using an experimentally simulated signal, an RF transmitter and an RF receiver along with suitable data acquisition unit. This was performed to determine the sensitivity of the RF receiver, which would enable laboratory scale testing with safe gamma sources of dose rate less than 0.1 mGy/h.

On the influence of hydrocarbons solvents on the inhibition efficiency of some organic corrosion inhibitors: Theoretical and validation studies

Injecting inhibitors into industrial equipment and piping systems is an effective way to control corrosion. Before application of corrosion inhibitors on an industrial scale, small scale laboratory testing is necessary to define the performance of inhibitors in specific corrosive media. To achieve low inhibitor concentrations for the laboratory, the inhibitor often needs to be pre-diluted before addition to the corrosive media by solvents. However, corrosion inhibitors may be affected by the solvents used. In this study, some cases that make the researchers get fake results in inhibitor science have been discussed by investigating ten organic compounds in different states (vacuum and solvents). Three hydrocarbon solvents, acetone, benzene, and diethyl ether, were selected. Inhibition performance can be improved by pre-design and theoretical simulations. The Density Functional Theory (DFT) was used in this study. Some physical values were used to find a link between the calculated quantum chemical parameters and the effectiveness of inhibition. The theoretical outcomes were confirmed via experimental tests. The corrosion of aluminum in 1 M HCl in the absence and presence of three hydrocarbon solvents was evaluated. Electrochemical measurements were used to estimate the corrosion parameters. It was found that each solvent affected the corrosion rates. Inhibition efficiencies ranged from 31.43 to 81.42 %. The maximum effect was related to acetone. Furthermore, SEM and AFM techniques were used to determine the effects of solvents. Theoretical and experimental results proved that the solvents used with inhibitors produced fake values of inhibitor efficiency.

Evaluation of Polyelectrolyte Complex Nanoparticles for Prolonged Scale Inhibitor Release in Porous Media

The formation of inorganic scales on the surfaces of porous media, production wells, and pipelines can substantially reduce the efficiency of oil production and damage reservoir formations. Scale inhibitors (SIs) are often applied to prevent or mitigate scale formation using a “squeeze treatment”, where the SI is injected into a formation and allowed to equilibrate, and then the flow is reversed (return phase). Although organic polymers, such as poly(vinyl sulfonic acid) (PVS), can tolerate high temperatures and have been effective for scale control, repeated applications may be required because they exhibit weak adsorption (retention) in most reservoir formations. To address this limitation, the release performance of a polyelectrolyte complex nanoparticle (PECNP) loaded with PVS was evaluated in laboratory-scale squeeze tests and compared to PVS alone. After injection of the PECNP into a Berea sandstone core and a 24 h shut-in period, a brine solution was introduced to the core. Following injection, the free or “active” PVS concentration in the effluent spiked to approximately 600 mg/L, decreased to 10 mg/L after 10 pore volumes (PVs), and then gradually declined to concentrations between 1 and 3 mg/L over the remaining 450 PVs of the test. Minimal PECNPs were detected in effluent samples during the return phase, indicating that PECNP attachment was irreversible under these experimental conditions. In contrast, the PVS-only squeeze test exhibited elevated PVS concentrations that approached the applied concentration immediately after a brine solution was introduced during the return phase, and the PVS return concentration decreased to below the detection limit (0.5 mg/L) after only 70 PVs. A mathematical model that incorporated nanoparticle attachment and rate-limited release of the SI successfully reproduced the experimental results and can be used to predict PECNP squeeze lifetime. These findings demonstrate the potential application of PECNPs for scale control in reservoir formations.

Isobaric storage of compressed air: Introduction of a novel concept based on phase change materials and pressure equalizing modules

In industrial compressed air systems (CAS), compressed air receivers have a significant impact on the overall energy efficiency. Isobaric compressed air receivers have the potential to increase the amount of stored air significantly and, hence, the energy efficiency can be improved compared to the usage of conventional isochoric compressed air receivers. In this work, we propose a novel concept of an isobaric compressed air receiver based on pressure equalizing modules (PEQM). These PEQM are filled with a condensable gas – in this work called phase change material (PCMl/g) – and are placed inside the receiver. During the charging and discharging of a compressed air receiver equipped with PEQM, the PCMl/g condenses or evaporates, respectively. Due to the large volume change during the phase change of the PCMl/g air can be stored isobarically. However, a proper selection of suitable PCMl/g is crucial for efficient and safe use. Therefore, we introduce a three-step selection process based on an adapted digital-logic method. In this selection process, qualitative (e.g. flammability) and quantitative (e.g., heat of condensation) properties are considered. As a result, R-1234ze(E) is selected as PCMl/g which owns a vapor pressure of 800 kPa at a temperature of 314.7 K. First experiments with the novel PEQM filled with R-1234ze(E) have been conducted in a lab-scale test plant and the results are shown in this work. The storage capacity of the test plant has been increased by 37.9 %. Additionally, the phase change of the PCMl/g during charging and discharging has been observed. However, the phase change is not isobaric yet. Temperature changes during the phase change inside the PEQM hinder the isobaric storing of the working gas. Therefore, proper heat management inside the PEQM is necessary, for example, by using a second phase change material for heat storage.

1,2,3-Triazole mediated, non-halogenated phosphorus containing protective coatings from castor oil: Flame retardant and anti-corrosion applications

Halogenated flame retardants are under regulatory scrutiny despite their outstanding flame retardancy. The present study focuses on the development of non-halogenated flame retardant and corrosion-resistant polyurethane coatings from castor oil. Towards this attempt, a non-halogenated, hydroxy functionalized, triazole and phosphorus-containing reactive flame retardant (HTP-FR) with anti-corrosive properties was designed and synthesized by azide-alkyne cycloaddition of 2-azidoethanol, and Diphenyl prop-2-yn-1-yl phosphate. By adding HTP-FR to castor oil in 50 and 100 weight percentages, CO-HTP-PUs (CO-HTP-50, CO-HTP-100, where HTP-FR was loaded as 50 and 100 wt%, respectively) were made and their flame-retardant and corrosion resistance properties were tested. The parent castor oil and MDI-based polyurethane (CO-PU) was concurrently synthesized and investigated as control for comparative appraisal. The FR behaviour of the PUs was examined using bomb-calorimetric testing and lab-scale flame tests. From the lab-scale flame test, it was found that the intumescent char length of the CO-HTP-100 after burning is longer than that of the CO-HTP-50 due to its high HTP-FR content. A substantial decrease in gross heat of 8.23, and 13.17 % was observed for the CO-HTP-50, and CO-HTP-100, respectively compared to the control CO-PU. The intumescent FR mechanism of CO-HTP-PUs was studied using Thermogravimetric Analysis coupled with Mass Spectroscopy (TGA-MS) analysis and Energy-dispersive X-ray spectroscopy (EDX) elemental analysis with mapping. The increase in P content of the post-burn sample in comparison to their unburn counterparts, and the expulsion of nitrogen gas from the triazole moiety from CO-HTP-PUs corroborated the intumescent FR mechanism. High char yields at 700 °C of CO-HTP-100 (20.3 wt%) and CO-HTP-50 (15.5 wt%) when compared to control CO-PU (3.6 wt%) also substantiated the FR behaviour of CO-HTP-PUs. The performance of these protective coatings against corrosion was investigated by the electrochemical methods. The significantly low corrosion current (Icorr) values (2.60 × 10−9 A/cm2), high polarization resistance (42.7 × 104 Ω cm2), bulk resistance values (10.4 × 106 Ω cm2) and low corrosion rate (3.0 × 10−5 mm/year) of CO-HTP-100 demonstrate the excellent corrosion resistance property of HTP-FR.

H2S Emission and Microbial Community of Chicken Manure and Vegetable Waste in Anaerobic Digestion: A Comparative Study

In order to solve the problem of H2S corrosion in biogas utilization, it is necessary to understand the characteristics and mechanisms of H2S production in chicken manure anaerobic digestion (CMAD) and vegetable waste anaerobic digestion (VWAD). In this study, lab-scale batch tests of CMAD and VWAD were conducted for 67 days at 35 °C. The results showed that sulfide was found to be the major form of sulfur in CMAD (accounting for 90%) and VWAD (70%). The average concentration of H2S was 198 ± 79 ppm in CMAD and 738 ± 210 ppm in VWAD. Moreover, 81% of total H2S was produced at 20 days of methane production in CMAD, but 80% of total H2S was produced in the first day in VWAD because of the rapid production of biogas and fermentation acidification. The sulfide ion equilibrium model could universally and feasibly predict the H2S production in CMAD and VWAD. The abundance of Firmicutes, Bacteroidetes, Proteobacteria and Euryarchaeota accounted for about 95% of the total microbes in both CMAD and VWAD; the influence of the fermentation stage on the microbial community was greater than that of the difference between CM and VW; the abundance of SRB was 0.01~0.07%, while that concerning organosulfur compounds fermentation was 22.8~30.5%. This study indicated that the H2S concentration of CMAD biogas was more than five times that of VWAD because CM is alkalescent but VW is acidic.

A microcontroller - Based Irrigation Scheduling Using FAO Penman-Monteith Equation

This study uses the Food and Agricultural Organization (FAO) Penman-Monteith equation to develop a crop water algorithm needed to automate the supply of specific amount of water to crops, depending on their different crop water requirements. This was done to deviate from the practice of supplying the same amount of water to different crops during irrigation practices which could lead to over-irrigation or under-irrigation resulting in pest infestation and eventually low yield. The crop water requirement for cocoyam, spinach and tomatoes were estimated using data from FAO. A microcontroller-based smart irrigation device incorporated with real-time clock was developed to supply the right amount of water to crops at the right time and duration daily. The implementation was done using a laboratory-scale irrigation test bed and experimental results reveal the effectiveness of the developed system in the automation of crop-specific irrigation systems and in line with their Crop Water Requirement (CWR). Possible applications include greenhouses where researchers have to apply a specific amount of water to crops for experiments; horticultural gardens and nurseries to mention a few.