Pyrolysis is the thermal decomposition of biomass occurring in the absence of oxygen. It is the fundamental chemical reaction that is the precursor of both the combustion and gasification processes and occurs naturally in the first two seconds. The products of biomass pyrolysis include biochar, bio-oil and gases including methane, hydrogen, carbon monoxide, and carbon dioxide.
Depending on the thermal environment and the final temperature, pyrolysis will yield mainly biochar at low temperatures, less than 450 0C, when the heating rate is quite slow, and mainly gases at high temperatures, greater than 800 0C, with rapid heating rates. At an intermediate temperature and under relatively high heating rates, the main product is bio-oil.
Pyrolysis can be performed at relatively small scale and at remote locations which enhance energy density of the biomass resource and reduce transport and handling costs. Pyrolysis offers a flexible and attractive way of converting solid biomass into an easily stored and transported liquid, which can be successfully used for the production of heat, power and chemicals.
A wide range of biomass feedstocks can be used in pyrolysis processes. The pyrolysis process is very dependent on the moisture content of the feedstock, which should be around 10%. At higher moisture contents, high levels of water are produced and at lower levels there is a risk that the process only produces dust instead of oil. High-moisture waste streams, such as sludge and meat processing wastes, require drying before subjecting to pyrolysis.
The efficiency and nature of the pyrolysis process is dependent on the particle size of feedstocks. Most of the pyrolysis technologies can only process small particles to a maximum of 2 mm keeping in view the need for rapid heat transfer through the particle. The demand for small particle size means that the feedstock has to be size-reduced before being used for pyrolysis.
Pyrolysisprocesses can be categorized as slow pyrolysis or fast pyrolysis. Fast pyrolysis is currently the most widely used pyrolysis system. Slow pyrolysis takes several hours to complete and results in biochar as the main product. On the other hand, fast pyrolysis yields 60% bio-oil and takes seconds for complete pyrolysis. In addition, it gives 20% biochar and 20% syngas.
Bio-oil
Bio-oil is a dark brown liquid and has a similar composition to biomass. It has a much higher density than woody materials which reduces storage and transport costs. Bio-oil is not suitable for direct use in standard internal combustion engines. Alternatively, the oil can be upgraded to either a special engine fuel or through gasification processes to a syngas and then bio-diesel. Bio-oil is particularly attractive for co-firing because it can be more readily handled and burned than solid fuel and is cheaper to transport and store.
Bio-oil can offer major advantages over solid biomass and gasification due to the ease of handling, storage and combustion in an existing power station when special start-up procedures are not necessary. In addition, bio-oil is also a vital source for a wide range of organic compounds and speciality chemicals.
Zero Valent Iron (ZVI) was developed to eliminate chlorinated hydrocarbon solvents in the soil. Industrial solvents are replete with chlorinated hydrocarbon, so much toxic and bad for the environment. They get disposed in the soil along with other toxic elements to cause harm to our surrounding. In the current years, significant improvements have taken place in the realm of iron-based technology.
Zero Valent Iron can be effectively used in soil remediation
The result of years of research and significant improvement in the iron-based technology is the advent of nanoscale or polymer-supported iron-containing nanoparticles to remove contaminants from solvents and soil. This is all due to the high surface area to the volume ratio of such nanoscale particles that favor the reaction kinetics and sorption.
But, know one thing that high pressure drops may restrict fixed-bed column application. This is why we now have modified nanosized ferrous particles to facilitate arsenic removal. The fabulous reducing agent helps in pollution recovery, and thus it benefits our environment.
Applications of Zero Valent Iron
ZVI in recent times is used widely for wastewater treatment, groundwater, and soil treatment. If made through the physico-chemical process in combination, the ZVI may be very small particles, having a large surface area. ZVI is beneficial for the environment, for it has a strong reductibility, great purity, long aging property, and similar features.
Zerovalent Iron can boost the chlorine removal efficiency of the soil, groundwater, and six valent chromium. Thus, it reduces the time required for environmental remediation. Acting as a fabulous reducing agent, it facilitates pollution recovery. Indeed, you may also combine it to bioremediation to further improve the efficacy of environment pollution recovery. Use it in the soil, solvents and industrial wastewater confidently to get rid of the contaminants. The use of ZVI paves the way for pure water and soil.
What you should look for in ZVI?
Are you planning to procure zero valent elemental metallic ions for wastewater treatment or soil remediation? Zerovalent metals or ZVI has a wide range of applications that range from electrodes and trenches to filters. Yes! It helps in the water filtration process, and thus we have pure drinking water. It gets rid of every trace of impurity or contaminant from the solvent or soil. It is important to look for a reliable company to procure ZVI.
Watch out for the following properties of ZVI
The particles must be fine enough to be customized as per your application
Look for the great adsorption performance and sound chemical activity
A large surface area for that very strong reductibility
Make sure the duration of its effect is very long to reduce the injections
Very fine ZVI particles to remediate pollution and to save remediation time and effort
Must be environment-friendly, deprived of any toxic compound
Enhanced nitrate-removing potential
Zero-valent metal has an enhanced nitrate removal capacity. It eliminates nitrate from the groundwater to facilitate remediation. Hence, biochar-supported ZVI can facilitate nitrate removal while the ones with wider pH can remove larger nitrates. Biochar composite eliminates nitrate from the groundwater without leaving any harmful by-products. But, biochar has a variable nitrate-removal capacity.
ZVI biochar has a potential to reduce nitrate by mediating the redox potential, the electron transfer, pH and thus facilitates enhanced removal or reduction of nitrate from the solvent or soil. Everything revolves around the logic of intensifying chemical reduction in order to eliminate nitrate from the soil or groundwater.
Nitrate and How it Accumulates
Nitrate is the form of nitrogen, which lies beneath the cultivable land. Nitrate is water soluble and may move through the soil quite easily. Owing to its high mobility, it moves to the groundwater table. Once it has moved to the groundwater table, it persists there and deposits to a very high level.
Thus, shallow groundwater is also at a risk of contamination from chemicals of land surfaces. This is a matter of concern, and indeed, nitrate in water may harm human health, aquatic life, livestock life and contaminate the surface water. We can say that it is not that harmful to adult humans, but it can significantly affect the health of the infants. It may reduce the level of oxygen in the blood to cause ‘blue baby’ disorder.
Hence, biological denitrification, ion exchange, and reverse osmosis are the treatment processes to handle this issue. The use of ZVI is a way to denitrification and the key to attaining a safe nitrate level in the water. A zero-valent metallic reduction is an effective way to refine dirty and polluted water. As soon as ZVI is placed in the flowing water or is added to the flowing water, there starts the process of oxidizing. The resultant chain reaction will purify water or remove the contaminants.
A Tool to Remediate Acid Mine Drainage
AMD or Acid Mine Drainage is the most common source of metal in places like the Appalachians, Tennessee, and Kentucky. It is important to remediate acid mine drainage for it is highly acidic and toxic. It is the major contributor to the arsenic environment and something needs to be done. AMD is a rich source of heavy and corrosive metals, acidic in nature. Biological treatment of Acid Mine Drainage is cost-effective, efficient and environment-friendly.
Biotechnological processes are an asset when it comes to treating Acid Mine Drainage in an effective manner. ZVI is environmentally sustainable. When it is very complicated and difficult to treat or remediate Acid Mine Drainage, ZVI eases the process. It gets rid of harmful elements or potentially hazardous substances from AMD to separate metal from acid and toxic compounds. There isn’t a need to abandon a mine site just because there are acidic metal deposits. Mine metals can be reclaimed with ZVI, and herein lays the environmental benefit.
Recycling of metallurgical waste
It is important to treat AMD or Acid Mine Drainage. The ecological solution to separate toxic metals, to reclaim water in large quantities is gaining a lot of attention. ZVI and zero valent metals save our natural resources and prepare the toxic metals for the recycling process. This is only possible through the separation of the acidic part.
We can recycle gallons of water that lay in the pond and other water bodies. It drops the acid level in the water and metal while also prevents heavy metallic reactions. When Acid Mine Drainage is one of the serious concerns in the realm of coal mining, zero valent metals prevent any exposure of sulfur-rich mineral to the water and atmospheric oxygen.
Final Thoughts
Zero-valent metals can help in the treatment of contaminated zones through the process of remediation. Zero valent iron is the highly reactive powder for remediation of wastewater and soil and works fabulously on environmentally contaminated areas. This remediation solution is highly efficient and benefits our environment in multiple ways.
Waste-to-energy (also known as energy-from-waste) is a complicated technology in the realm of renewable energy. There are a lot of hidden truths and myths about this technology that people need to be aware of. Renewable energy technologies, like solar and wind, have much more simple processes and gain most of the attention from media outlets.
On the converse, renewable energy sources that are highly complex like nuclear energy have a bunch of media attention as well.
So, why don’t we discuss a bit more about this relatively unknown technology and asset class? Here I’ll discuss a number of the most important facts about waste-to-energy (abbreviated as WTE).
Interesting Facts About Waste-to-Energy
Let’s get into our facts about waste-to-energy that you need to know.
Waste-to-Energy Can Provide Baseload Power
The most familiar renewable energy resources such as wind and solar can only provide power if the sun is shining or the wind is blowing. WTE projects can actually provide baseload power that is used to serve consumers and the grid no matter the time of day or if the sun is shining or not.
Baseload power is essentially when intermittent resources like solar and wind become more prevalent.
Not All WTE Projects are Clean and Green
While waste-to-energy projects would seem to be green and clean because they turn trash into power or gas. However, some projects require long hauling of trash to bring to the actual incineration facility. This actually ends up require much more emissions from the trash haulers than alternatives.
One solution to this would be to help promote the use of electric vehicles and electric vehicle technology to be installed in trucking, like waste hauling.
WTE Projects Are Crucial to Help Reduce Landfills
Landfills have increased at an exponential pace the in last 100 years. Waste-to-energy projects are an awesome alternative to landfills as the trash is used to provide electricity or fuel.
WTE projects reduce waste volumes by approximately 90%, which results in fewer landfills that are needed to process ash. This ends up protecting our natural resources and land in a dramatic fashion.
Most WTE Projects have Multiple Revenue Streams
Waste-to-energy projects are extremely complicated and expensive to build. Most of the investor economic interest is driven by financial incentives, renewable identification numbers, tax credits, etc. to help these projects get financed.
Beyond these other financial incentives, some of the waste-to-energy projects produce a byproduct, named biochar, which has multiple applications and fetches good prices. The biochar can usually end up providing the most value in the revenue stream or investability of the project itself.
In addition to other economic streams, waste-to-energy projects usually require high tipping fees. A tipping fee is what the trash hauler has to pay in order to dump the trash at the facility. With WTE projects, the tipping fee can end up being 50-60% of the overall revenue stack.
WTE Facilities are Net Greenhouse Gas Reducers
Methane has more than 20 times the potency of carbon dioxide and is ranked as a very dangerous contributor to climate change and warming of our planet. WTE facilities avoid the productions of methane and end up producing up to 10 times more the electricity than landfill gas projects. If you didn’t know, landfills can actually end up producing electricity by capture the methane gas and compressing it into a consumable natural gas for power.
Sweden is one of the best proponents of waste-to-energy in the world
WTE projects will usually have much more capacity than any landfill gas projects.
Conclusions
You can’t use waste-to-energy projects at your home similar to solar or even wind to get free electricity. However, knowing about projects in your area and the relevant suppliers will help you understand whether or not the technology is a perfect fit for your community. If you see a project coming online in your surrounding area, you should know how to ask the right questions.
At the end of the day, WTE projects are green and clean. They just need to have the right systems in place to make them more efficient and less risky to appeal new investor appetite. What fact was your favorite about waste-to-energy?
Do you know much about waste-to-energy projects? Let us know in the comments below. We’d love to hear from you.
Biochar is a carbon-rich, fine-grained residue which can be produced either by ancient techniques (such as covering burning biomass with soil and allowing it to smoulder) or state-of-the-art modern biomass pyrolysis processes. Combustion and decomposition of woody biomass and agricultural residues results in the emission of a large amount of carbon dioxide. Biochar can store this CO2 in the soil leading to reduction in GHGs emission and enhancement of soil fertility. Biochar holds the promise to tackle chronic human development issues like hunger and food insecurity, low agricultural productivity and soil depletion, deforestation and biodiversity loss, energy poverty, water pollution, air pollution and climate change. Let us have a close look at some of the most promising applications of biochar.
Use of biochar in animal farming
At present approx. 90% of the biochar used in Europe goes into animal farming. Different to its application to fields, a farmer will notice its effects within a few days. Whether used in feeding, litter or in slurry treatment, a farmer will quickly notice less smell. Used as a feed supplement, the incidence of diarrhoea rapidly decreases, feed intake is improved, allergies disappear, and the animals become calmer.
In Germany, researchers conducted a controlled experiment in a dairy that was experiencing a number of common health problems: reduced performance, movement disorder, fertility disorders, inflammation of the urinary bladder, viscous salivas, and diarrhoea. Animals were fed different combinations of charcoal, sauerkraut juice or humic acids over periods of 4 to 6 weeks.
Experimenters found that oral application of charcoal (from 200 to 400 g/day), sauerkraut juice and humic acids influenced the antibody levels to C. botulinum, indicating reduced gastrointestinal neurotoxin burden. They found that when the feed supplements were ended, antibody levels increased, indicating that regular feeding of charcoal and other supplements had a tonic effect on cow health.
Biochar as soil conditioner
In certain poor soils (mainly in the tropics), positive effects on soil fertility were seen when applying untreated biochar. These include the higher capacity of the soil to store water, aeration of the soil and the release of nutrients through raising the soil’s pH-value. In temperate climates, soils tend to have humus content of over 1.5%, meaning that such effects only play a secondary role.
Indeed, fresh biochar may adsorb nutrients in the soil, causing at least in the short and medium term – a negative effect on plant growth. These are the reasons why in temperate climates biochar should only be used when first loaded with nutrients and when the char surfaces have been activated through microbial oxidation.
The best method of loading nutrients is to co-compost the char. This involves adding 10–30% biochar (by volume) to the biomass to be composted. Co-composting improves both the biochar and the compost. The resulting compost can be used as a highly efficient substitute for peat in potting soil, greenhouses, nurseries and other special cultures.
Because biochar serves as a carrier for plant nutrients, it can produce organic carbon-based fertilizers by mixing biochar with such organic waste as wool, molasses, ash, slurry and pomace. These are at least as efficient as conventional fertilizers, and have the advantage of not having the well-known adverse effects on the ecosystem. Such fertilizers prevent the leaching of nutrients, a negative aspect of conventional fertilizers. The nutrients are available as and when the plants need them. Through the stimulation of microbial symbiosis, the plant takes up the nutrients stored in the porous carbon structure and on its surfaces.
A range of organic chemicals are produced during pyrolysis. Some of these remain stuck to the pores and surfaces of the biochar and may have a role in stimulating a plant’s internal immune system, thereby increasing its resistance to pathogens. The effect on plant defence mechanisms was mainly observed when using low temperature biochars (pyrolysed at 350° to 450°C). This potential use is, however, only just now being developed and still requires a lot of research effort.
Biochar as construction material
The two interesting properties of biochar are its extremely low thermal conductivity and its ability to absorb water up to 6 times its weight. These properties mean that biochar is just the right material for insulating buildings and regulating humidity. In combination with clay, but also with lime and cement mortar, biochar can be added to clay at a ratio of up to 50% and replace sand in lime and cement mortars. This creates indoor plasters with excellent insulation and breathing properties, able to maintain humidity levels in a room at 45–70% in both summer and winter. This in turn prevents not just dry air, which can lead to respiratory disorders and allergies, but also dampness and air condensing on the walls, which can lead to mould developing.
As per study by the Ithaka Institute’s biochar-plaster wine cellar and seminar rooms in the Ithaka Journal. Such biochar-mud plaster adsorbs smells and toxins, a property not just benefiting smokers. Biochar-mud plasters can improve working conditions in libraries, schools, warehouses, factories and agricultural buildings.
Biochar is an efficient adsorber of electromagnetic radiation, meaning that biochar-mud plaster can prevent “electrosmog”. Biochar can also be applied to the outside walls of a building by jet-spray technique mixing it with lime. Applied at thicknesses of up to 20 cm, it is a substitute for Styrofoam insulation. Houses insulated this way become carbon sinks, while at the same time having a more healthy indoor climate. Should such a house be demolished at a later date, the biochar-mud or biochar-lime plaster can be recycled as a valuable compost additive.
Biochar as decontaminant
As a soil additive for soil remediation – for use in particular on former mine-works, military bases and landfill sites.
Soil substrates – Highly adsorbing and effective for plantation soil substrates for use in cleaning wastewater; in particular urban wastewater contaminated by heavy metals.
A barrier preventing pesticides getting into surface water – berms around fields and ponds can be equipped with 30-50 cm deep barriers made of bio-char for filtering out pesticides.
Treating pond and lake water – bio-char is good for adsorbing pesticides and fertilizers, as well as for improving water aeration.
Use of biochar in wastewater treatment – Our Project
The biochar grounded to a particle size of less than 1.5 mm and surface area of 600 – 1000 m2/g. The figure below is the basic representation of production of bio-char for wastewater treatment.
We conducted a study for municipal wastewater which was obtained from a local municipal treatment plant. The municipal wastewater was tested for its physicochemical parameters including pH, chemical oxygen demand (COD), total suspended solids (TSS), total phosphates (TP) and total Kjeldahl nitrogen (TKN) using the APHA (2005) standard methods.
Bio filtration of the municipal wastewater with biochar acting as the bio adsorbent was allowed to take place over a 5 day period noting the changes in the wastewater parameters. The municipal wastewater and the treated effluent physicochemical.
The COD concentration in the municipal wastewater decreased by 90% upon treatment with bio-char. The decrease in the COD was attributed to the enhanced removal of bio contaminants as they were passed through the bio char due to the bio char’s adsorption properties as well as the high surface area of the bio char. An 89% reduction in the TSS was observed as the bio filtration process with bio char increased from one day to five days
The TKN concentration in the wastewater decreased by 64% upon treatment with bio char as a bio filter. The TP in the wastewater decreased by 78% as the bio filtration time with bio char increase. The wastewater pH changed from being alkaline to neutral during the treatment with bio char over the 5 day period
Use in Textiles
In Japan and China bamboo-based bio-chars are already being woven into textiles to gain better thermal and breathing properties and to reduce the development of odours through sweat. The same aim is pursued through the inclusion of bio-char in shoe soles and socks.
Date palm trees produce huge amount of agricultural wastes in the form of dry leaves, stems, pits, seeds etc. A typical date tree can generate as much as 20 kilograms of dry leaves per annum while date pits account for almost 10 percent of date fruits.
Date palm biomass is found in large quantities across the Middle East
Date palm is considered a renewable natural resource because it can be replaced in a relatively short period of time. It takes 4 to 8 years for date palms to bear fruit after planting, and 7 to 10 years to produce viable yields for commercial harvest. Usually date palm wastes are burned in farms or disposed in landfills which cause environmental pollution in dates-producing nations.
The major constituents of date palm biomass are cellulose, hemicelluloses and lignin. In addition, date palm has high volatile solids content and low moisture content. These factors make date palm residues an excellent biomass resource in date-palm producing nations.
Date palm biomass is an excellent resource for charcoal production in Middle East
A wide range of physico-chemical, thermal and biochemical technologies exists for sustainable utilization of date palm biomass. Apart from charcoal production and energy conversion (using technologies like combustion and gasification), below are few ways for utilization of date palm wastes:
Conversion into fuel pellets or briquettes
Biomass pellets are a popular type of alternative fuel (analogous to coal), generally made from wood wastes and agricultural biomass. The biomass pelletization process consists of multiple steps including pre-treatment, pelletization and post-treatment of biomass wastes. Biomass pellets can be used as a coal replacement in power plant, industries and other application.
Conversion into energy-rich products
Biomass pyrolysis is the thermal decomposition of date palm biomass occurring in the absence of oxygen. The products of biomass pyrolysis include biochar, bio-oil and gases including methane, hydrogen, carbon monoxide, and carbon dioxide.
Depending on the thermal environment and the final temperature, pyrolysis will yield mainly biochar at low temperatures, less than 450 0C, when the heating rate is quite slow, and mainly gases at high temperatures, greater than 800 0C, with rapid heating rates. At an intermediate temperature and under relatively high heating rates, the main product is bio-oil.
Bio-oil can be upgraded to either a special engine fuel or through gasification processes to a syngas which can then be processed into biofuels. Bio-oil is particularly attractive for co-firing because it can be more readily handled and burned than solid fuel and is cheaper to transport and store.
Conversion into biofertilizer
Composting is the most popular method for biological decomposition of organic wastes. Date palm waste has around 80% organic content which makes it very well-suited for the composting process. Commercial-scale composting of date palm wastes can be carried out by using the traditional windrow method or a more advanced method like vermicomposting.
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Pyrolysis is the thermal decomposition of biomass occurring in the absence of oxygen. It is the fundamental chemical reaction that is the precursor of both the combustion and gasification processes and occurs naturally in the first two seconds. The products of biomass pyrolysis include biochar, bio-oil and gases including methane, hydrogen, carbon monoxide, and carbon dioxide.
