Ammonia Emission Assessment After Buffalo Manure And Digestate Application

Quite recently, considerable attention has been paid to the effect of anaerobic digestion on ammonia emissions from digestate spreading in the field, due to the growing interest in NH3 emission monitoring. Unfortunately, there are still some different studies finding about the effect of anaerobic digestion on ammonia emissions. Thus, more research into this topic is still necessary before obtaining a definitive answer to the increment or not in emission. For this purpose, this paper proposes comparison study between ammonia emissions from buffalo raw (Farmyard) manure and digestate on bare soil under Mediterranean climate, using the wind tunnel equipped with acid traps, to assess the ammonia emission fluxes. The sampling campaign, in three replicates, lasted each time, for 6 days to ensure that most of the ammonia has been emitted before the end of each campaign. The results obtained indicate that a diurnal correlation between emission and external temperature occurs, especially during the first days. Specifically for both fertilizers, ammonia volatilization increased with air temperature raising. Overall, the total digestate cumulative NH3 emission is 54% higher than raw manure emission. This is certainly due to the Total NH4+-N rate, which was 55,8kg ha-1 for the raw manure and 107 kg ha-1 for the digestate, around 1,9 times higher for the digestate TAN content. Finding suggests the need for adjusting digestate application rate based on TAN content, in order to reduce the impact on the environment

NH3 Emissions From Treated Buffalo Manure Application In Mediterranean climate And Comparison To ALFAM Model

Ammonia volatilization is widely recognized as one of the major environmental European problems, due to the increase in livestock farming activities. As a consequence, accurate ammonia assessment is needed in order to control ammonia emissions and to update national emission inventories. Besides some uncertainties still related to the measurement methods, another important issue is the necessity of investigating a different kind of fertilizers. In the last few years, considerable attention has been paid to many manure treatments prior to field application. This study aims to assess ammonia emissions from the field application of separated buffalo manure digestate in the Mediterranean climate, in order to improve the emission inventory for this animal species, reared mostly in South Italy. Two measuring methods were used: wind tunnel (WT) and Integrated Horizontal flux (IHF). Moreover, ammonia emission measured were compared to those obtained running the statistical regression model ALFAM. This model based on Michaelis-Menten type equation is often used to predict cumulative ammonia loss and since it is based on a significant dataset is useful to discuss the effectiveness of the emission measured. The total ammonia losses measured in 7 days were 26.39 and 49.24 kg N ha-1, for WT and IHF, respectively. Although the predicted total emissions were 40.99 and 36.56 kg N ha-1, for IHF and WT, respectively, it is possible to observe the good accordance of the ALFAM model with the temporal pattern of both methods

Aerodynamically Efficient Rotor Design for Hovering Agricultural Unmanned Helicopter

Unmanned aerial vehicles, especially agricultural unmanned helicopters (AUH), are nowadays extensively used in precision agriculture. AUHs have recently become responsible for spraying fertilizers and pesticides for crop yields. The strong downward rotating flow produced by the main rotor helps very uniform crop spraying which determines that how important is the aerodynamics of rotor blade in AUH. In this work, the aerodynamic performance of AUH rotor blades is evaluated and an efficient blade is obtained by numerically investigating the influence of design variables on the aerodynamics of rotor blades. The design variables consist of airfoil shape, pitch settings, and twist angle. The limited power available in hover and aerodynamic requirements (lift and drag) are the aerodynamic constraints. This analysis only considers the hovering flight condition at a constant rotational speed. The aerodynamically efficient rotor blade which is based on gradually varying and linearly twisted airfoil shapes, show a significant improvement in hover performance with relatively uniform blade loading. After testing, the optimum blade can be used as the main rotor in the AUH to perform precision farming

An investigation of sqrt 2 conjecture inspired drag induced vertical axis wind turbine blade

Governments and research agencies are providing support and resources to facilitate the growth of renewable energy sector (RES). Today wind turbines (WT) are the prominent form of renewable energy for direct energy harvesting. It is found that traditional Savonius wind turbine (SWT) requires design modification or integration supportive design feature in order to improve the drag attributes and power output performance. Generally conventional WTs are design to operate at high wind speed ranging from 10-15 m/s. This constrains the WT to harvest adequate power at low wind speed condition. Research shows that, design configuration adjustment and optimization has improved the efficiency in Cp. Hence, in this study drag driven WT configuration namely SWT is adapted for the construction of proposed design. The research process flow is segregated into four phases specifying the strategies utilized to carry out the investigation namely bio-hybridization, experimental fluid dynamics, computational fluid dynamics and optimization. The selected bio-elements are reconfigured and altered to fit the design problem and criteria of WT. Since the study involves analyzing and recognizing complex morphologies of bio-elements, computational based framework is utilized for the geometry extraction process namely OpenCV. The proposed drag induced wind turbine (DIWT) is a result of hybridization of two bio-elements namely nautilus spiral configured shell and barnacle marine organism. The aim of primary stage of the design process is to construct the mainframe of the WT blade shape which is extracted from a non-aerodynamic element which is Nautilus shell. The initial design is modelled with barnacles and blade morphology inspired by mathematical conjecture but without endplates. The proposed conjecture and ratio provide an alternative approach in calculating the parametric values of a geometry with regards to √2. It appears that irrational number √2 is fundamental in the creation of circle and spiral. In addition, multiple combinations of blade curvatures is also possible to be constructed with the newly found conjecture, ratio and method. Meanwhile, relative to experimental fluid dynamics procedure the rotational properties of the rotor is investigated using a digital torquemeter coordinated by Arduino. The credibility of the fabricated torquemeter is investigated by comparing the generated moment magnitude with computational numerical model which is executed in CFD. The percentage of error between computational and instrumentational torque is 15.6 %. As for CFD framework for this research, the initially proposed design is comprehensively investigated based on computational numerical model analysis conducted in Ansys CFX. Preliminary investigation indicated that the performance of the initial design is affected by the absence of endplate. The barnacle geometry and its configuration introduce early turbulence and consequently reduces the pressure drag. The reconfiguration of the design is based on the proposed optimization process. The basis of the optimization technique is the Gf which governs the drag attributes of a body relative to flow. If the researcher would like to further investigate reconfigure the existing morphology, it is required to determine the body geometric factor in order to preliminary determine the drag condition. Since Gf 1 (positive volume) minimizes the drag attributes if the orientation of the body is perpendicular the flow. It is found that the implementation of the barnacle geometry aligned perpendicular to flow effectively reduces the pressure attributes. Hence, the technique inspired for the removal of the barnacle geometry. It is found that the blockage corrected peak Cp value of the reconfigured turbine is 0.201 which is 15.4 % of deviation from the uncorrected CFD result. Hence the new corrected data of Cp is utilized to compare with available literature to measure the performance of the proposed design. It can be concluded that the optimized design improved the quality of Cp by 19.2 % in comparison to conventional SWT at λ = 0.67. Meanwhile the author also presented a novel design with shaft and adjoin blade. It is found that the optimized design outperformed both the models by 15.51 % and 6.34 % respectively. Hence, it is evident that blade morphology modification via the proposed conjecture with the presence of endplate improves the performance of the rotor in terms of rotational characteristics and power output

Study of aerodynamic performances of different wind tunnel configurations and air inlet velocities, using computational fluid dynamics (CFD)

Livestock and agricultural activities contribute significantly to atmospheric ammonia emission in Europe. The volatilization process depends on many factors, especially wind speed and rainfall. The most important methods to evaluate ammonia volatilization are the wind tunnel and micrometeorological methods. The tunnels are more flexible and simple to use in every situation. Few studies have been carried out to determine, which conditions are established inside the chamber and how they influence the ammonia volatilization and measurement. The aim of this research was to investigate the effects of the wind tunnel configuration and flow inlet velocity, by means of CFD simulations and wind speed measurements, in order to achieve a better aerodynamic performance. The SST k–ω model used for simulations was first validated in order to prove the consistency of the model itself. Several configurations were simulated and compared. In particular, in order to overcome the asymmetric flow conditions that occurred in all wind tunnel configurations, four flow distribution devices were proposed and simulated. The best setup was chosen with the purpose of reaching both the best uniform velocity distribution (to ensure homogeneous volatilization from the emitting surface) and easy transport for field applications. It consists of an emission chamber 40 cm wide, 25 cm high and 80 cm long, situated between a divergent diffuser and a convergent duct, respectively 50 cm and 25 cm long. Moreover, structures similar to honeycombs, namely guiding channels, were introduced in the divergent diffuser, because they showed the best aerodynamic performance. These 20 channels, located in the divergent diffuser, prevent flow from separating, by means of the reduction of the expansion angle, obtaining the desired flow conditions inside the wind tunnel. Finally, it was verified that CFD confirmed its usefulness as a decision-support instrument to design and simulate possible solutions, reducing design time

LIVESTOCK MANURE TREATMENT FOR NUTRIENTS REMOVAL: CONSOLIDATED TECHNIQUES, EMERGING PROBLEMS AND NEW APPROACHES

Intensive farming practices and their continuous spread generate a large amount of livestock manure that cannot be disposed properly. This can cause water, air and soil contamination. Therefore, the identification of strategies for correct management of livestock manure is necessary for limiting environmental pollution. Nitrification/denitrification process (NDN) represents one of the most applied solutions. However, at real scale, many of those facilities that adopt this process suffer from managing issues and malfunctioning. Recently, alternative techniques have been applied to the recovery of nutrients along with their removal. An example is solid/liquid separation using chemicals to remove phosphorus and concentrate it into solid fraction, easier to handle. Other concerns are ammonia and greenhouse gases emissions derived from the management and the treatment of livestock manure. Their assessment is the first step to identify and apply proper mitigation strategies focused on limiting emissions. In this thesis, the application of biological processes for the removal of nitrogen from livestock manure was investigated to find possible improvements. First, a review of the state of the art of nitrification/denitrification process applied in the sequencing batch reactor system (SBR) to livestock manure was carried out to produce an overview on the SBR technology, monitoring parameters and process optimization. This can help the identification of SBR strengths and weaknesses when these systems are adopted for the livestock manure treatment and can support the definition of the best operation settings to adopt for reaching desired removal rates. Several treatment plants were monitored to attest operational and removal efficiencies achieved. The aim of these monitoring campaigns was the identification of possible improvements for NDN (nitrification/denitrification) plants. Eventually, the application of the NDN process in laboratory SBR systems was analysed to study how the nitrogen removal rate changes with the variation of the slurry inlet characteristics and of the applied operational settings. Concerning emissions, the use of different types of dynamic hoods and static chamber for estimating GHGs and NH3 emissions derived from livestock manure was investigated. Regarding recovery of phosphorus (P), the dissertation dealt with the evaluation of the effect of two additives (calcium hydroxide Ca(OH)2 and aluminium sulfate Al2(SO4)3) on the solid/liquid separation process of P, Copper and Zinc from raw slurry and co-digested slurry before and after a physico-chemical ammonia stripping treatment. The results outlined that the performance of monitored SBR treatment plants at real scale are less than expected. Rarely TAN removal exceeds 50% even if at lab-scale observed removal rates were higher (up to 95%). Pre-treatments are necessary to improve performance of treatment plants. Moreover, the upgrading of proper process control system and its correct use are required. These should be considered also if a new SBR is designed. Ammonia and GHGs emissions occur during the entire livestock manure management chain and their evaluation is possible applying the direct method. In particular, dynamic hoods can be useful tool for measuring site-specific NH3 and GHGs emissions except for CH4. The application of solid/liquid separation process for phosphorus removal using aluminium sulphate allowed to reach removal rates higher than 70%. This additive enhanced also the removal of suspended solids (58%), copper (up to 94%) and zinc (up to 93%)