Field Verification of Low-Level Biochar Applications as Effective Ameliorants to Mitigate Cadmium Accumulation into Brassica Campestris L from Polluted Farmland Soil

Farmland soils in China have been reported to be diffusely contaminated, Cd has been recognized as a significant contributor to this issue and biochars have been reported to be effective in mitigating soil Cd pollution. However, previous studies have shown contradictory outcomes. Furthermore, in general, laboratory experiments and unrealistically large amounts of biochar (>10 t/ha) have been used. In this study, three biochars: rice straw biochar (RS), pig manure biochar (PM) and rice husk biochar (RH) were produced from readily available farm residues and characterized. These were used in a field experiment, at low applications rates of 1.8 and 3.6 t/ha, with rape (Brassica campestris L.). Batch adsorption experiments indicated Cd adsorption in the order RS biochar > PM biochar > RH biochar. Field experiment indicated biochar amendments to slightly changes in soil pH and CEC; yet led to considerable and significant decreases in extractable Cd concentrations (reductions of: 43%-51% (PM), 29%-35% (RS) and 17%-19% (RH)). Reduced extractable Cd correlated with lower Cd concentrations in rape plants. PM and RS biochars were the most effective in decreasing Cd phytoaccumulation into edible parts of rape (>68% reduction). It is highlighted that biochars were produced using a pyrolysis unit with an output of 20 ton/yr. Thus, assuming a working application rate of 2 ton/ha, the pyrolysis unit could service 10 ha/yr. While at a modest scale, this research demonstrates the genuine reality of biochar-based remediation solutions to contribute to the mitigation of diffuse Cd contamination in some of China’s impaired farmland.

Impact of Deposition Temperature on Amorphous Zinc Oxide Thin Film Characteristics

In this paper, we discuss the deposition of amorphous zinc oxide (a: ZnO) thin film at two different temperatures by spray pyrolysis unit for Thin Film Transistor (TFT) application. The a: ZnO films were studied for its structural, morphology, composition, optical and electrical properties by means of XRD, SEM, EDAX, UV-Visible spectroscopy and I-V measurement system respectively. The film thickness characterized by optical Profilometer. The SEM images exhibit the variation in temperature leads to the crystallinity of the film. The XRD spectrum confirmed the films were amorphous in nature.

SPEAR (Solar Pyrolysis Energy Access Reactor): Theoretical Design and Evaluation of a Small-Scale Low-Cost Pyrolysis Unit for Implementation in Rural Communities

Energy access and waste management are two of the most pressing developmental and environmental issues on a global level to help mitigate the accelerating impacts of climate change. They are particularly relevant in Sub–Saharan Africa where electrification rates are significantly below global averages and rural areas are lacking a formal waste management sector. This paper explores the potential of integrating solar energy into a biomass pyrolysis unit as a potentially synergetic solution to both issues. The full design of a slow pyrolysis batch reactor targeted at biochar production, following a strict cost minimization approach, is presented in light of the relevant considerations. SPEAR is powered using a Cassegrain optics parabolic dish system, integrated into the reactor via a manual tracking system and optically optimized with a Monte-Carlo ray tracing methodology. The design approach employed has led to the development an overall cost efficient system, with the potential to achieve optical efficiencies up 72% under a 1.5° tracking error. The outputs of the system are biochar and electricity, to be used for soil amendment and energy access purposes, respectively. There is potential to pyrolyze a number of agricultural waste streams for the region, producing at least 5 kg of biochar per unit per day depending on the feedstock employed. Financial assessment of SPEAR yields a positive Net Present Value (NPV) in nearly all scenarios evaluated and a reasonable competitiveness with small scale solar for electrification objectives. Finally, SPEAR presents important positive social and environmental externalities and should be feasibly implementable in the region in the near term.

PROCESSING OF WASTE COAL FINES WITHOUT ACCESS TO OXYGEN

The subject of research in this work is the processing of waste coal fines using a pyrolysis plant. The aim of the study is to obtain semi-coke and pyrolysis gas in the process of processing waste coal fines without oxygen. The process of thermochemical processing of coal fines is carried out by the principle of embedding a pyrolysis unit in a pyrolysis unit, or a second pyrolysis unit of a reduced size is installed inside the improved design of the pyrolysis unit using a specially withdrawn hole. To obtain the result of the study, the main pyrolysis unit, first, we will load the main pyrolysis unit with coal and then install the built-in (new) pyrolysis unit by preloading it with coal fines, and then we will make connections with the outlet pipe and fully load the main pyrolysis unit. We attach a distributor tee, a waste material container and a receiver for collecting pyrolysis gas to the outlet pipe. Experimental research is carried out on the coals of the Abshyr-ata and Kozho-kelen deposits, and for the reliability of the obtained research result, we will measure the main parameters of the studied coals until the final product is obtained. To obtain the result of the study, the main pyrolysis unit, first, we will load the main pyrolysis unit with coal and then install the built-in (new) pyrolysis unit by reloading it with coal fines, and then we will make connections with the outlet pipe and fully load the main pyrolysis unit. We attach a distributor tee, a waste material container and a receiver for collecting technical gas to the outlet pipe. Experimental research is carried out with coals of the Abshyr-ata and Kozho-kelen brands, and for the reliability of the obtained research result, we will measure the main parameters of the studied coal grades until the final product is obtained. With the help of this unit, the process of upgrading waste of coal fines and low-grade coals of Kyrgyzstan is carried out. The developed installation can be used in the heat and power industry of the Republic and research institutions.

CLEARANCE OF SOLID HOUSEHOLD WASTE WITH THE RECEPTION OF ALTERNATIVE TYPES OF ENERGY CARRIERS

The research is devoted to improving the technology of obtaining alternative types of energy carriers by applying methods of pyrolysis of unclaimed types of solid domestic wastes of biological origin, which also allow solving the tasks of improving the ecological situation in the places of formation. The practical value and relevance of this research lies in the development of advanced technology for obtaining alternative fuels. The proposed pyrolysis unit allows producing gaseous and liquid hydrocarbons in a continuous cycle. In the atmosphere of the gasifying agent (air, oxygen, water vapor, carbon dioxide or their mixture), the gasification process is primarily performed in vortex reactors or fluidized bed furnaces at temperatures of 600-1100°C. Accordingly, the production (extraction) of AT from them requires pre-treatment, often quite serious: separation, grinding, mixing, drying, etc., which ultimately guarantees the consistency of its composition and quality.

Mathematical Modelling of Pyrolysis of Hardwood (Acacia)

This paper emphasises on the analogous modelling of hardwood (Acacia) pyrolysis. The effect of physical characteristics of hardwood chips on the pyrolysis is examined through the conservation of solid mass fraction of biomass. The chip size of G30 and G50 are used in the pyrolysis reactor. In the analogous situation, the fixed bed is assumed to be a wooden slab with a porosity equivalent to the voidage of bed. The bulk density, the length of the bed and the porosity are some of the physical attributes of a fixed bed used to determine the variation of solid mass of the hardwood across the fixed bed. The four-temperature sensors separated from each other by 80 mm are used to determine the temperature along the length of the pyrolysis unit. The heating element of 2 kWe is used to initiate the pyrolysis of biomass. The experiments are conducted in three different stages. The ONORM standard chips, G30 and G50, and the combination of them are separately pyrolysis to determine the validity of a model for different sizes of chips. The proposed model is also used to establish the relationship between the kinetics of pyrolysis and decomposition of the hardwood.

Fabrication of Custom-Designed and Cost-Effective Spin-Spray Pyrolysis Unit

In this paper, an efficient, spin-spray pyrolysis unit is designed and constructed for the deposition of oxide thin films. The system is an effective combination of two independent techniques such as spin and spray methods. The rotation of the substrate by keeping the spray nozzle stationary makes the system unique. The system allows the decomposition of the solution before reaching the substrate. Spin-spray pyrolysis unit is capable of coating thin films on different substrates like float glass, FTO coated glass, and Aluminum coated glass, Teflon, and kepton, of dimensions up to 4-inch diameter, any contour and scalable to industrial applications. Metal oxides like Al2O3, GZO, ZnO etc., can be coated for many applications such as solar cells, thin-film transistors, sensors, etc. The elements required for construction of spray pyrolysis units are a heater, spray nozzle, thermocouple, solution feeding unit, airflow assembly, substrate rotator, and exhaust assembly. The elements of the system are discussed in accordance with the cost estimation. The working principle of each element of the system is explained in a separate block diagram. The system is optimized for deposition of ZnO thin films on a glass substrate and is characterized. The thinfilms can be used for development of TFT’s, heaters, thermistors, piezo-electronics devices, sensors, antireflection coatings and solar cell.