How to compost sawdust?

Adaptability of the Technology

This technology is useful in the passive composting of manure piles in small-scale farming. Manure from dairy, swine, and poultry will not decompose well unless it is properly managed. Proper management includes making sure that the mixture is porous enough to allow air to penetrate. The pile must be periodically turned and mixed, to rebuild its porosity. The passive method of composting is essentially windrow composting, but the compost is turned less often. This method demands minimal labor and equipment.

The Technology

1. Preparation

The composting materials are prepared, using 50% wood chips and 50% poultry or other manure (on a per volume basis).

If this large quantity of wood chips (as a bulking material) is used, the air within the pile moves more easily through the composting materials. Therefore, during the active composting period, the temperature inside the pile does not fall even without frequent turning or aeration.

2. Advantages

Wood chips are a good bulking agent when handling animal wastes with a high moisture content. The wood chips increase microbial activity by supplying oxygen to the composting pile. An active composting pile containing wood chips generates considerable heat, and a large amount of vapor is released into the air. Therefore, composting reduces both the volume and mass of the raw materials within a short period of time. Aerobic composting does not generate evil-smelling gasses, as anaerobic processes tend to do. The main source of odors from compost heaps are usually ammonia lost from highly nitrogenous materials, and anaerobic conditions within windrows and piles. Anaerobic conditions can be minimized by proper management. Pungent ammonia odors can be controlled by including wood chips in the mixture. Application of wood chip compost can reduce disease incidence in plants, since it can enhance soil microbial activity. This is particulaly important in areas where vegetable crops are grown continuously.

Mulch made from wood chip compost reduces the number of weeds in field crops. The mulch suppresses weed germination and growth by covering the soil surface. Also,the phytotoxic compounds produced during the composting process seem to be an unfavorable environment for weed germination and growth.

Using wood chips in composting also gives farmers an extra supply of organic material for their crop lands.

Important Remarks

  • 1. Compost containing wood chips, which are a high carbon source, must be composted for at east six months. The large particle size (1-2 cm³) of the chips means that they are slow to decompose.
  • 2. The compost producer must keep an eye on the moisture content of the compost pile, and add more water when this is needed. A sufficient moisture content is needed for active composting. A compost pile containing more than 30% wood chips as a composting material may dry out more easily than a pile containing sawdust.
  • 3. Chips derived from wood which has been treated with preservatives or painted should not be used.
  • 4. The machinery used to shred timber into chips is expensive. The compost producer may also need to pay the cost of transporting wood from distant forested areas.

Index of Images

Figure 1 Compost Pile Containing Wood Ships and Swine Waste Is Easily Decomposed without Any System of Aeration

Figure 2 For Composting with Wood Chips to Be Economical, There Must Be a Cheap Source of Materials

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Building Garden Soil With Wood Mulch

Mycelium Madness

In the Maine apple orchard study, the research team observed that the wood chip plots became covered with white mycelium, which is the vegetative form of many fruiting fungi and is commonly known as white rot. The development of these fungi in the wood mulch increases the amount and enhances the character of organic matter in the soil, as well as helps the soil’s ability to retain moisture. The huge group of fungi known collectively as Basidiomycetes is a core player in wood chip decomposition. Many produce mushrooms — pretty, but not generally edible. Where moist wood chips and soil unite, these fungi use enzymes to access nutrients in the wood, which is their energy source for the growth of threadlike, white hyphae. The hyphae knit themselves together into mycelium, which is easy to see. In addition to fungi, several specialized types of bacteria are able to degrade high-cellulose materials such as wood chips, while others digest failing fungi. Seen this way, it’s easy to envision wood chips in soil as life rafts that support three major levels of soil life: the fibrous organic matter of the chips themselves, the biological mass of filamentous fungi that grows on them, and beneficial bacteria that come and go in waves.

Starter colonies of these microorganisms are usually present on the bark of chipped branches. Tradd Cotter, mycologist and owner of Mushroom Mountain in South Carolina, says fungi present on wood start growing quickly after wood has been cut or chipped. In moist climates, there may be no need to add a fungal inoculant to kick-start the process, but Cotter says providing inoculants in the form of sawdust spawn (sawdust covered with actively growing mycelium) can speed and enhance the soil creation process. Maybe you’ll get some edible mushrooms in the process, too. “The native edible species king stropharia (Stropharia rugoso-annulata) is by far our best wood-decomposing strain,” Cotter says. “It is spreading through our gardens, increasing soil depth, and attracting beneficials, such as earthworms.” Sawdust or wood chip spawn of stropharia (winecaps) and other species are available from Mushroom Mountain, Field and Forest Products and Fungi Perfecti.

Recovering Resources

Wood chips and sawdust are each byproducts of other activities, so finding good-quality, local resources is your first step. If you live near a sawmill, you can probably get sawdust cheap, though you’ll need assurance from the sawmill operator that it doesn’t include black walnut sawdust, which releases a toxin that can be murder on tomatoes and other sensitive vegetables. Also avoid sawdust from plywood and painted or treated wood in your garden because of the glues and other chemicals. With sawdust, the lower you go on the production chain (a sawmill that handles whole logs), the more likely you are to get garden-worthy sawdust. For soil-building purposes, coarse sawdust is better than fine because it’s less likely to pack into a mat, and it lasts longer as organic matter in the soil.

If kept moist, sawdust can decompose surprisingly quickly. In a study at Ohio State University, sawdust rotted faster than newspaper or straw, both of which were still recognizable after 16 weeks. To speed up rotting in a pile of sawdust, simply add moisture and nitrogen. This can be done by mixing up a big batch of fish emulsion, pouring it into an already damp, doughnut-shaped sawdust pile, and then covering it with a tarp or an old blanket to retain moisture. After sawdust turns black, you can use it to lighten up any soil — including potting soil — for seedlings and container gardening.

Most of the more recent studies with wood chips used what are called ramial wood chips, which are what you get when you put live, leafless hardwood branches, 2 to 3 inches in diameter, through a chipper to create pieces that are a half to 1 inch wide and 1 to 4 inches long. Ramial chips have relatively little bark and heartwood because of the size of the branches used, which is part of what makes them so attractive as a soil amendment. Superior batches also contain few leaves, cones, or other prickly parts.

You can get ramial wood chips for free by connecting with tree-trimming crews working in your area. In some towns, such as Oshkosh, Wis., you can take small limbs to a chipping center on certain Saturdays and go home with your own homegrown wood chips. Wherever you live, a few phone calls to local utility companies or tree service companies should be all it takes to find a free supply. Wood chips often end up in landfills; let’s put them to use enriching our garden soils instead.

Chipper-Shredder Options

If you have lots of trees to tend on your property, you may want to buy a chipper-shredder and make your own soil-building mulches. You could use the machine to shred fall leaves, too. If a storm brings a tree down, you can rent a chipper, or hire someone to come in and chip it up for you. Companies that make chipper-shredders include BCS, Country Home, Echo and MacKissic.

Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on Google+.

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One thing that’s in plenty of supply around here is sawdust. It’s a shame to let that beautiful fluff go to waste, so here’s 17+ ideas to put it to good use. Remember…these apply to REAL wood sawdust, not MDF. Also, you’ll want to use common sense when it comes to using sawdust from pressure treated wood as well.
1. Mix it with white paint to make fake snow.
2. Use it for traction on slippery roads.
3. Soak up spills in the shop or garage.
4. Feed your plants with it, except if it’s walnut sawdust.
5. Make fire starters.
6. Fill holes and defects in wood.
7. Use it to pack a path.
8. Use walnut sawdust to kill weeds.

9. Lighten the heft of mixed cement.
10. Use it as a floor cleaner.
11. Use it as animal bedding, except for walnut.
12. Put it in a meat smoker for some interesting results
13. Use it as fuel.
14. Stuff homemade pincushions with it, or….
15. Stuff a dog’s bed with it.
16. Mix it with mud for a facial.
17. Absorb used turpentine and mineral spirits with it. (In many cities you can throw these away if they are dry. Otherwise, in liquid form, they have to go to a recycling center.)
To go about putting the first 10 ideas practice, go to thisoldhouse.com. For the remaining hints–and many more–check out toolcrib.com.

‘Key and Sawdust’ by Le Consul via flickr.

World Journal of Engineering and Technology Vol.05 No.03(2017), Article ID:78658,14 pages
10.4236/wjet.2017.53045

Potential Utilization of Sawdust in Energy, Manufacturing and Agricultural Industry; Waste to Wealth

O. L. Rominiyi1*, B. A. Adaramola1, O. M. Ikumapayi1, O. T. Oginni2, S. A. Akinola3

1Department of Mechanical and Mechatronics, Afe Babalola University (ABUAD), Ado-Ekiti, Nigeria

2Department of Mechanical Engineering, The Federal University of Technology, Akure, Nigeria

3Department of Electrical/Electronics, Ekiti State University, Ado-Ekiti, Nigeria

Copyright © 2017 by authors and Scientific Research Publishing Inc.

This work is licensed under the Creative Commons Attribution International License (CC BY 4.0).

Received: June 9, 2017; Accepted: August 20, 2017; Published: August 23, 2017

ABSTRACT

Sawdust which is basically considered as a timber-industrial waste that pollutes the environment can become a valuable commodity which is considered in three ways: Manufacturing, Energy and Agricultural utilization. The sawdust is burnt in an updraft gasifier under a limited supply of air to obtain producer gas which is carbon II oxide and hydrogen as main components. The sawdust and other biomass materials are mixed in certain proportions, then bound together and palletized to a small blocks called briquettes. The material was also considered to be composted by mixing it with animal digestion or wood ashes and calcium carbonate to form fertilizers. The sawdust and wood shavings can be used for particle board as well as oil production.

Keywords:

Sawdust, Industrial Waste, Producer Gas, Biomass, Briquette, Utilization

1. Introduction

Sawdust is a tiny piece of wood that fall as powder from wood as it is cut by a saw . In other words, sawdust is basically a waste of small particles available in saw-milling industries, pulp plant and paper industries as well as wood processing industries particularly, in the southern part of Nigeria in a quite large volume in form of heaps and mostly burnt off resulting in the environmental pollution . Sawdust is generally considered as a timber-industrial waste that pollutes the environment but can become a valuable commodity either as a raw material in manufacturing industries for wood boards, light construction materials such as shelves, notice boards, wall and roof sheeting for mobile houses, as an insulator in the refrigerating system and cold conservation of in Energy industries as fuel burned directly or indirectly to produce wood gas, briquette, pellet, etc. Some aspects of the technologies used for the mentioned above shall form part of the discussions in this paper.

Sawdust possesses characteristics similar to wood but due to the fact that it is in particles, some structural properties have been altered. It can however recover this so that it can be used again as wood. Consequently, in utilizing sawdust as a source of energy, its heating value can be compared with that of other fuels. It has a very low thermal conductivity and hence used as insulating material so as to reduce heat losses through conductor. This material is however capable of producing briquettes with density above 100 kgm−3. More precisely, the bulk density of sawdust could be as low as 150 – 200 kgm−3 . High pressure and temperature are essential to agglomerate to make a very dense briquette without a binder.

The technological development of sawdust proves its positive use, for instance, it is a requirement for improvement in various forms in different kinds of materials, chemicals such as methanol ; as a fuel for instance, it can be burnt directly to obtain heat in three distinct ways :

1) As household fuel energy by burning in special stones for cooking and in fire places for spaces for cooking and in fire places for space heating.

2) For drying and curing, space heating and heating chicken brooders in the agriculture industry.

3) Direct burning in black-smiting, brick making and poultry making in the industrial sector.

Most researchers agreed that all readily recovered waste being generated at present could be absorbed by the industry either for energy supply or for additional raw material for processing chipboards and fine board . Therefore all prime timber is likely to find a ready market for the foreseeable future. For instance, a number of pulp plants in the United States already use their processed wastes to produce other chemicals and beverages quality alcohol.

The exact conditions under which sawdust can be economically viable are hereby highlighted:

1) Energy industries,

2) Manufacturing industries,

3) Agricultural industries.

1.1. Energy Industries

The increasing costs, crisis and depletion of energy from convectional sources over past few years have reawakened interest in the development of alternative sources of energy. Many years ago, the world’s energy requirements were gases, running water and nuclear energy. Apart from the fact that most of these conventional energy sources are non-renewable, world energy planners have realized that these sources alone would be inadequate to meet the increasing need of the world both now and the future. This led to greater attention being paid to the development of wood gas from sawdust which otherwise would be wasted. The technological development of sawdust brought about briquettes which are good alternatives for using wood as fuel . The specific energy content of the wood waste and charcoal are 16,795.96 kJ/kg, charcoal 18,711.70 kJ/kg respectively . It can however be converted to bitumen or heavy oil due to the presence of cellulose in it by processing it with water, sodium carbonate and a gas rich in carbon (ii) oxide (CO) at a temperature of 250˚C – 400˚C . Sawdust is beneficial also as insulating materials in the refrigerating system and in cold conservation.

1.2. Manufacturing Industries

Application of modern technology in the areas of pulp and paper making, particle board, water board, oriented strand board plywood has resulted in several benefits such as availability of high quality product for making materials such as shelves, wall and roof sheathings, light construction materials and employment opportunities for the populace to mention a few. Several structural wood panels such as mentioned above shall be the focus of this paper under the manufacturing industry.

1.3. Agricultural Industries

Sawdust is a useful factor in agricultural industry in making fertilizer called sawdust compost as well as food in chicken brooders. Several million tons of sawdust and other wood residues are produced annually in the Southwest Nigeria. While most of this is burned, an increasing amount is being used for mulches, growers of small fruit, and nurserymen. It is also find an increasing use as litter in barns and feed lots, and as a soil conditioner in general agriculture. Usage has been largely on a trial and error basis, usually with good results. Like other highly carbonaceous organic matter, however, sawdust under certain conditions can cause a deficiency of available nitrogen in soils and thus retard plant growth. Certain woods or bark also contain tannins and other extractives that may have more or less toxic influence on plants and soil microorganisms. To obtain information and fundamental knowledge on these and other problems arising in connection with agricultural uses of wood wastes. It is well known that mulching can increase crop yields, but it is essential that mulches be low-cost, readily available materials. In addition, it is desirable that materials used should not require costly applications of nitrogenous fertilizers during the process of decomposition. Most of our soils are greatly in need of organic matter because the usual crop rotations seldom maintain soil humus at high level as desirable. Wood residues should be utilized for humus maintenance wherever it is economically feasible to do so. Although the emphasis is on sawdust, this material reacts much as do chips, shavings, and bark, except that decomposition is more rapid in the more finely divided material. Sawdust mulches: Improve structure and aeration of heavy soils. Increase water absorption and penetration. Conserve moisture through weed control and reduced evaporation.

1.4. Environmental Concerns

Technological advancement is an important desirable and necessary ingredient of economic and social growth but the environmental consequences can be unpleasant. For example burning sawdust in an open space causes atmospheric pollution landing leading to the problem of acidic rain and the emission of carbon (iv) oxide which is of concern as greenhouse gas . Sawdust seriously affects the soil and water, being a very dangerous threat to the environment. It has three major negative effects on the soil, these include: reduction of the hydrogen content of the soil when used as mulch and reduces soil phosphorous when incorporated. Soil acidity increases and therefore unsuitable for crop germination unless it is composted not good to be used as a fertilizer. Sawdust pollutes the soil with phenol compound. All together these effects reduce the soil productivity .

Sawdust reuse is promoted by waste legislation. There is no specific legislation regarding sawdust but there is legislation for wastes in general. As a by-product of timber industry, sawdust is considered by the environmental authorities as a recyclable waste.

1.5. Sawdust Technology

1.5.1. Sawdust Briquetting

Sawdust and other biomass materials such as palm kernel shell, rice bran, alfalfa straw, olive pits, wheat straw, rice husks, walnut shells, sunflower straw, soybean stalks. Maize cabs, maize stalk etc. are mixed in certain proportions and then bond together with some binding materials. There are various types of binding agents; these include starch, tar, pitch, thermoplastic resin. The use of thermoplastic resin as binding agent is called “Franja” However the addition of binding agent increases the energy content of the material. It is claimed from 800 Btu/lb for raw wood to at least 1800 Btu/lb for pellets. These pellets burn at higher temperatures than untreated wood; resulting in more complete burning and less ash residual . Subsequently, the mixtures of sawdust, biomass materials and the binding agents are then molded into small block cubes and cured (by drying out the water content in a drying oven). These cubes are called the briquettes which can then be burned in a special stove for cooking.

1.5.2. Briquette Techniques

A screw press was used for destruction of the cell walls to generate heat and a high pressure which is the prerequisite for briquetting of sawdust consequent of the force needed to overcome the natural springiness of these materials (i.e., sawdust, biomass and the binding agents).

1.5.3. Densification Process of Briquetting

The process whereby there is a considerable reduction in the volume of the loose sawdust and its aggregates by the application of compressive stress and thereafter leading to its agglomeration so that the product remains in the compressed state is referred to as densification . If the material is compacted with low to moderate pressure (0.2 – 5 MPa); thus reducing the space between particles. As the pressure is increased there will be a stage when the cellulose cell wall of the constituent will collapse . After the densification the material remains as solid until it serves its function well as a fuel. The densification also reduce the moisture content, increase the bulk density, increase the calorific value of the fuel and as well as improving the handling and transporting characteristics. The handling characteristics depend on the following properties:

1) Density,

2) Resistance to humidity,

3) Resistance to mechanical action.

Advantages of Sawdust Briquettes:

1) Combustion device: It can be combusted more efficiently when briquette then unprocessed sawdust or wood.

2) Briquette is easily fed into the plant unlike the loose sawdust which may be blown out of the combustion zone and may not completely burn.

3) Sawdust briquettes emit little or no smoke when burnt and also burns with high flame.

1.5.4. Oxygen Gasification of Sawdust

Gasification of sawdust is the process by which sawdust is burnt with limited supply of air or oxygen. Sawdust gas is composed of carbon (ii) oxide, carbon (iv) oxide, hydrogen and methane. The liquid and the gas are combustible and are potential fuel or fuel feedstock except carbon (iv) oxide. The typical composition from gasification in air, omitting water vapour is as shown in the Table 1 below.

There are some variations, in general the composition of the gas largely independent of the composition of the feedstock because the end product is a mixture of simple gases. In some cases, if there is significant sulphur content in the feedstock hydrogen sulphide may be generated. This can be easily removed by passing the gas through water.

Furthermore, if the air supply is replaced by pure oxygen as it is in the proxy process, the nitrogen content is eliminated and the energy density can be as high

Table 1. Typical composition from gasification of sawdust in air.

Source: .

as 9 MJ/m3. Another route to produce the higher BTU gas is by hydro gasification where hydrogen is added to react with the carbon (ii) oxide to give hydrocarbons.

1.5.5. Production of Oil from Sawdust

The fact that sawdust consists of predominantly carbohydrates (cellulose and hemicellulose), the technology of hydrogenation and carbon (ii) oxide is readily adaptable to converting sawdust to oil. The conversion of cellulose to liquid material requires high pressure hydrogenation and to a bitumen-like material, this requires treatment with caustic at elevated temperatures and pressures.

This process involved heating the feedstock (sawdust), water and catalyst in an autoclave in the presence of carbon(ii) oxide at a desire pressure and to an operating temperature of about 250˚C – 400˚C . Water is needed because it supplies the hydrogen for the reaction and also for the hydrolysis of the high- molecular weight carbohydrate present. It also acts as a solvent and vehicle for the reaction. It decreases the extent of polymerization of some of the highly reactive water soluble intermediates.

However, the disadvantages of water in the system are as follows:

1) Using steam at high partial pressure raises the operating pressure to the levels where capital cost tends to be high.

2) The operating costs depend largely on the sum of the heat required to bring water to the operating temperature and pressure.

The separation of the oil and water phases during the product recovery step is sometimes encountered by emulsions. At a temperature of about 250˚C – 400˚C, the reaction can be flushed from the autoclaves with solvent and the product oil extracted in a soxhlet unit .

The extraction can be done using acetone or benzene depending on the temperature at which the reaction occurs. The solvent can then be separated by a rotary evaporated heater in a hot water bath.

1.6. Sawdust in Manufacturing Industry

1.6.1. Composite Structural Panels

All wood-based structural panels are composite materials. There are a lot of wood panels that can be made from sawdust, these include: Particle board, Oriented strand board, water board, plywood, etc., the strength of which depends on the grain size of the sawdust used.

1.6.2. Fabrication of Particle Board

Wood dust in the form of flakes, shavings, chips fibres mixed with resin and other binding agents. This mixture is laid down in a mat which is hot-pressed to increase the density of the mat and to cure the adhesive. The sawdust particles may be oriented to some degree to provide some directionally of strength properties along and across the panels. Particles may be laid down in orthogonal layers similar to plywood veneer. Different types of particles may be used in the same panel to improve surface properties and create a more layered particle product .

1.6.3. Hot-Pressing of Particle Board

In order to overcome the problem associated with spring back and stabilization of the material hot pressing of the sawdust can be carried out for consolidating the particle board to the required thickness and density. It has a direct effect on the product quality and the production efficiency. The function of hot-pressing is to consolidate the material to a desirable panel density and thickness. Modern plants use single-opening or continuous presses for adhesive and furnish to be bonded together to overcome the spring back and heat stabilize the panel for the targeted thickness and density . Production of better panel thickness, controlled density profiles and lower losses in sanding and trimming are assured than for multi opening presses .

1.6.4. Factors Influencing Hot-Pressing

1) The temperature of the press,

2) The press closing speed,

3) The moisture of the mat and its distribution,

4) The press pressure,

5) The time of pressing,

6) The profile of the thickness .

2. Design Methodology

2.1. Typical Machines for Sawdust Utilization

The aim of this design is to provide a model for the following:

1) A reactor and a storage unit for the production of producer gas during oxygen gasification of sawdust.

2) A manual pressing machine for the production of a particle board of 500 mm by 600 mm board and sawdust briquette.

Design Considerations for the

Reactor

1) Material Selections and their adequacy for the purpose.

2) Dimensions of the components and unit.

Storage Tank

1) Volume of gas to be stored.

2) Pressure generated in the storage tank.

3) Dimension of the components and unit.

4) Materials of construction and their adequacy for the purpose.

Pressing Machine

1) Materials of construction and their adequacy for the purpose.

2) Torque on the screw to be used.

3) Dimensions of the components and unit.

In the designing of unit, efforts were made to use simple manufacturing and engineering techniques to produce units which will serve as a model and which is relatively cheap and easily available.

2.2. The Reactor for Oxygen Gasification of Sawdust

2.2.1. Dimension of the Unit

The dimension of the reactor unit is based on a portable unit that will compose 2 kg of sawdust biomass at each feeding rate. The specific value of heat content cannot be ascertained. But assertion can be made during the oxygen gasification of wood. The range of the calorific value of both pyrolysis gas and oxygen gasification obtained tends to 11 MJ/m3 – 19 MJ/m3wood .

2 kg of sawdust will produce = 0.19 MJ/kg.

The density of sawdust which varies from species to species, moisture content is approximately = 750 kg/m3 .

(1)

(2)

This is the volume that 2 kg mass of sawdust will occupy.

The volume of the producer gas that can be produced during oxygen gasification of sawdust is the addition of the two principal constituents: Carbon (ii) oxide (CO) and hydrogen (H2) by percentage of the total volume of gas produced per feeding rate of 2 kg of sawdust. A specific value cannot be ascertained due to the following conditions:

1) The moisture content.

2) The properties of each wood from which sawdust is being produced.

3) Climatic region under which the tree is grown.

The height and the circumference of the reactor can be calculated using the following assumption:

The diameter to be 0.15 m, therefore, the height of the combustion chamber which is expected to be of the whole reactor that will gasify the sawdust could be calculated as thus.

(3)

The reactor chamber is expected to have a minimum height of

(4)

Therefore, the height and the circumference of the grate that will conveniently gasify the sawdust are 610 mm and 470 mm respectively having equal distance between the four major components namely: heating unit, combustion chamber, Gas outlet and feeding unit. The outlet unit where hose can be tightly fixed is assumed to have a diameter of 20 mm and about 60 mm long.

2.2.2. The Storage Unit

The storage method to be used is the low pressure storage mild steel tank under a pressure slightly higher than the atmospheric pressure.

2.2.3. Materials Selection

The materials for construction are a mild steel of 3 mm thickness gauge 14 SWG (Standard Wire Gauge) which is readily available and relatively cheap.

2.2.4. Dimensions of the Storage Tanks

The dimension of the tank is based on the following:

The volume of gas to be stored.

1) The gas production rate from the reactor chamber.

The height “H” of 200 mm and diameter “D” of 100 mm are used for the storage tank

(5)

(6)

2.2.5. Generated Pressure “P” in the Storage Tank

(7)

where:

is the atmospheric pressure (N/m2)

is the density of air ( kg/m3)

g is acceleration due to gravity (m/s2)

h is height of the tank (m)

P is the permissible pressure (kN/m2)

From the Table 2 above the Atmospheric N2/O2,ratio = = 3.73

Table 2. Composition of dry air by volume.

Source: .

2.2.6. The Stress of the Cylindrical Vessel “δ”

(8)

where:

is the stress of the cylindrical vessel (Design Pressure)

P, is the permissible pressure

t, is the thickness of the material

d, is the diameter of the storage tank = 100 mm

Factor of safety = 3

(9)

where;

is the working stress

Yield Stress of the mild steel = 200 N/mm2

Therefore a mild steel of 2 mm thickness will be adequate to store the gas under a pressure of 101.327 kN/m2.

2.2.7. The Pressing Machine

A mild steel of 3 mm thickness, gauge 18 SWG, (Standard Wire Gauge), a steel rod of thickness 10 mm and a screw and nut that is readily available and relatively cheap are used.

The dimensions of the pressing machine and the mould that will produce a sizeable particle board and briquette are based on the following:

1) The volume of the mould that will produce the particle board of 500 mm × 600 mm × 20 mm in dimension.

2) The internal bonding stress that will be generated inside the sawdust.

3) The work done by the screw on the biomass.

(10)

where:

Vs is the Volume and the mass of sawdust and binder

is length of the particle board

is the breadth of the particle board

is the thickness of the particle board

Density of sawdust is taken to be 750 kg/m3

(11)

2.2.8. The Internal Bonding Pressure “Pi”

(12)

2.2.9. The Torque of the Screw Used

(13)

where: T is the Torque of the screw

Co is the Torque coefficient 0.2 ± 0.06

is the thickness of the bolt in (mm)

, is the initial tightening force in the bolt (N)

where: is the stress area

is the proof stress

The proof strenght for steel screw thread=350 MPa

The thickness of the bolt is 10 mm

The stress area (mm2) = 58 mm2

The tightening tension “” =

Then the tightening torque “T” =

The work done on the biomass to keep the keep the particle board in a thickness of 20 mm depends on the force on the screw and the screw distance to maintain that thickness.

(14)

2.3. Contact Stress

When surface are placed in contact they touch at one or few discrete points. When the surface of the wood (the top materials) is loaded, the contacts flatten elastically and the contact area grows until failure of some sort occurs :

1) Failure by crushing caused by compressive stress “δc”

(15)

where, f is the tightening force of the screw = 18,270 N

a is the radius of contact = 50 mm ( i.e.)

2) Tensile fracture caused by the tensile stress “δt”

(16)

3) The yielding stress caused by the shear stress

(17)

3. Sawdust Utilization for Feed Meal, Compost and Mushrooms Production

Uncontaminated sawdust and wood shavings are useful for soaking up excess moisture in wet compost heaps and as a dry “brown”, are useful for balancing out “green”-heavy compost heaps that might otherwise go sludgy. Stir them into the existing compost so they get damp and to also stop them either forming a dense layer on top (which might reduce the air flow in the heap) or blowing around the garden. (If the heap has a tendency to be on the dry side, extra moisture is added when adding sawdust otherwise it might dry up all together). Sawdust or wood shavings used as animal bedding can be added as long as the animal is vegetarian―for example, rabbits or most chickens droppings feathers or fur can be added to the heap along with the sawdust―it will all compost down nicely together. Ruminant animals can also utilize cellulosic materials as food because of a valuable symbiotic relationship with microorganisms present in the rumen section of their digestive tract.

Cellulose pulps and wood waste have been fed as maintenance rations to cattle and horses during times of great national emergencies. Another potential agricultural uses of wood waste is in the rations for flattering cattle. Feeding trials were conducted with and sheep using based all concentrate formula with and without sawdust and oyster shell.

The addition of inexpensive source of cellulose to a purified experimental chick ration resulted to a significant increase in growth. Spruce wood flour fed to chicks at a level of 20.2 percent of the diet in a practical-type ration without detrimental effects and brought about slight increases of growth at 28 weeks of age when compared with the control group.

4. Conclusions

Sawdust that ordinarily constitutes a menace in sawmills is a good source of fuel, biogas, animal feed meal, organic manure, weed killer and particle board and briquettes. The flame-purified gas is found useful to power internal combustion engines.

Also, the particle boards and plywood products are prefer to other materials like asbestos in roof and wall sheathings for safety and health reasons. Finally, composting sawdust with livestock droppings can be of a great prospect for soil conditioning.

5. Recommendations

Government should create enabling environment for the manufacturing of pressing machine and briquetting machines locally. If briquetting machines as well as pressing machines are developed here in Nigeria, for local consumption and export, we would have gained more money in foreign exchange.

Indiscriminate burning of sawdust directly should be discouraged through government supported seminars and workshop within the country.

Sawdust briquette should be used as an alternative fuel in place of kerosene and firewood.

Cite this paper

  1. 1. Hornby, A.S. (1998) Advance Learner Dictionary. Special Priced Edition, Oxford University Press, Oxford.
  2. 2. Adegoke, C.O. and Mohammed, T.I. (2002) Investigation of Sawdust Briquettes as High Grade Fuels. The West Indian Journal of Engineering, Faculty of Engineering, University of West Indies.
  3. 3. Alexandru, R.S. (2002) Putting Sawdust to Work in Romanian. Planet’s Voice Article, Planet Voice Org.
  4. 4. FAO (1989) The Briquetting of Agricultural Wastes for Fuel. FAO Production Environmental Energy Paper II.
  5. 5. Goodger, E.M. (1980) Alternative Fuel Chemical Energy Resources. Macmillan, London Bagsing Stock.
  6. 6. Adegoke, C.O. (2003) Available Alternative Energy Source for Domestic Use: A Case Study of Solar Cookers, Dryers and Sawdust Briquettes. Paper Work.
  7. 7. Thomas, E.M. (1975) Wood Engineering and Construction Hand Book. Southern Illinois University Press.
  8. 8. Adegoke, C.O. (2002) Energy a Veritable Tool for Sustainable Environment. A Lecture Delivered at a Conference in Federal University of Technology, Akure.
  9. 9. Rominiyi, O.L. (2015) Evaluation of Energy Content of the Municipal Solid Waste of Ado-Ekiti, Metropolis, M. Eng Thesis, Department of Mechanical Engineering, The Federal University of Technology, Akure.
  10. 10. Vis Viva Renewable Energy Plot 38-b, RD&E Cooperative Housing Society, Kalas, Pune, Maharashtraph.
    http://www.vvenergy.com
  11. 11. El-Gayar, M.S. (1997) Shellsol as a Processing Liquid in Biomass Liquefaction. Energy Sources Part a Recovery Utilization and Environmental Effects.
    https://doi.org/10.1080/00908319708908881
  12. 12. Okebola, F.O. (1985) Modern Wood—Work Technology for Polytechnics and Technical Colleges. Ilesanmi Press Limited.
  13. 13. Moslem, A.A. (1974) Particle Board. Vol. 1, Materials, Southern Illinois University Press, Carbondale.
  14. 14. Chrisis (2002) Applying Research in Forestry. Department of Horticulture, University of Missouri.
    http://mdc.mo.gov.www.google.com
  15. 15. Ashby (1999) Wood Density and Modulus of Elasticity.
  16. 16. ASHREA (1977) Handbook of Fundamentals. American Society of Heating Refrigerating and Air Conditioning Engineers, Inc.
  17. 17. Ryder, G.H. (1982) Strength of Material. 3rd Edition, Macmillan Press, Hong Kong.
  18. 18. Fogiel, M. (1989) The Machine Design Problem Solver Research and Education Association.
  19. 19. Ashby, M. (2000) Design Formulae for Simple Structure. Metal Foams.

Using Sawdust In Your Compost Pile

Most people who keep a compost pile know about the typical things you can add to it. These things may include weeds, food scraps, leaves and grass clippings. But what about some of the more unusual things? Things that may not come out of your garden or your kitchen? Things like sawdust.

Using Sawdust in Compost

These days, woodworking is a popular pasttime (though not as popular as gardening). A great many people enjoy putting objects together with their own two hands and enjoy the feeling of accomplishment that comes from taking a pile of wood planks and turning them into something lovely and useful. Besides a feeling of pride, the other byproduct of a woodworking hobby is a whole lot of sawdust. Since trees are plants and plants make good compost, the logical question is “Can I compost sawdust?”

The quick answer is yes, you can compost any kind of sawdust.

For composting purposes, sawdust would be considered a “brown” composting material. It is used to add carbon to the mix and to balance the nitrogen from the “green” composting materials (like food).

Tips for Composting Sawdust

When composting sawdust, you will want to treat the sawdust just as you would dry leaves, meaning that you will want to add it in an approximately 4:1 ratio of brown to green materials.

Sawdust actually makes a great amendment for your compost pile, as it will add a filler that is somewhat absorptive and will wick up water from rain and juices from the green material, which help with the composting process.

It does not matter what kind of wood your sawdust is from. Sawdust from all types of trees, soft or hard, can be used in your compost pile.

The one thing to be mindful of is if you will be composting sawdust from chemically treated wood. In this case, you will want to take a few extra steps to ensure that these chemicals work their way out of the compost before you use it in your vegetable garden. The best way to do this is to just douse your compost pile with water a few extra times during the summer. This, along with normal rainfall, should leech any harmful chemicals out of your compost pile and will dilute the chemicals being leeched out to levels that will not harm the surrounding area.

Composting sawdust is an excellent way to reclaim some value from what otherwise would be a waste product. Think of it as using one hobby to feed another.

How to Compost Chicken Manure

Chicken manure contains more nitrogen than almost any other type which aids in strong leaf and stem growth. Gardeners call it black gold. However, adding fresh chicken manure to gardens can burn the leaves and the roots of plants. Composted chicken manure mellows out the nitrogen and will not harm your plants. Each chicken produces approximately one cubic foot of manure every six months.

Decide where on your property you will locate your chicken manure composting area. Once composting begins, the pile will not emit odors, but fresh chicken manure will have a smell that nearby neighbors may not appreciate so keep this in mind when finding a spot. You can compost in an open pile or in an enclosed area. A garbage bin can be used if necessary, but because of the volume of used chicken bedding you are likely to acquire, a larger space will be more useful.

Collect manure and bedding. Chicken owners normally use bedding such as untreated pine shavings, sawdust, dry leaves, or straw to provide a dry cushion for chickens and to control odor and pests. The coop bedding can be collected with the manure and dumped into a composting bin. Some owners prefer to pick manure and soiled bedding out of the coop on a daily basis; others will add new bedding over droppings and collect on a less frequent basis. I personally clean about three times during the week. Chicken poop (green which is the nitrogen) mixed with bedding (brown which is the carbon), air and moisture. You can also add coffee grounds and vegetation that breaks down such as old lettuce and grass clippings. Don’t add citrus rind. It will never break down and can be harmful to some plants. If you are wanting to throw in eggshells, they need to be crushed into a powder to be useful.

Understanding carbon to nitrogen balance:

A combination of 30 parts Carbon to 1 part Nitrogen creates the ideal environment for microbes to break down organic material to produce compost. Since the different beddings have their own carbon nitrogen ratio, the proportion of bedding to manure will vary depending on the type of bedding used. To keep things simple most composters follow the general rule of 1 part brown to 2 parts green. However, because chicken manure is so high in Nitrogen you may be more successful using a 1:1 or even a 2:1 mixture.

Combine the correct ratio of bedding and manure at one time to form a pile, approximately one cubic yard. Then spray the pile down with water(material should be about as wet as a well wrung sponge). It is recommend that the compost pile gets up to 130-150 degrees F and maintain that temperature for 3 days. Heating is necessary to destroy pathogens but temperatures above 160 degrees F can kill beneficial microorganisms and slow the process. To help you achieve appropriate temperature you can purchase a compost temperature gauge from a local nursery.

Repeat the heating process. Once the center of your compost pile has reached 130-150 degrees for three days it will start to cool. After it cools, pull the center apart and move the core material to the edges and bring the edge material into the center to heat. For 1 cubic yard of material repeat the process of bringing edges into the core at least 3 times.

Let it cure. Monitor the pile and once you are satisfied that the entire contents of your bin has been heated, loosely cover and let cure for 45-60 days before using. Your composted chicken manure is ready when most of the material has become a dark brown loam. Don’t worry if there is still some of the bedding visible. This will provide air pockets in your soil which is beneficial to plants. You can either dig in the compost to empty beds or encircle plants with it and allow the nutrients to be carried into the soil by rain.

If you have larger empty beds that you will not be using for two or more months, simply spread the uncomposted chicken bedding over it and allow it to compost right where it is. Then till it in when ready to plant. Chicken manure makes a fantastic soil amendment for both vegetables and flowers, even better than expensive fertilizers available at garden stores. With just a little work, you can have the best soil on your block in no time.

Manure Safety Tips. Fresh chicken manure may contain disease organisms that could contaminate root crops (carrots, radishes, beets) and leaves (lettuce, spinach), so DO NOT spread uncomposted manure on the soil in your vegetable garden.

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PHOTO: iStock/Thinkstockby Maurice Pitesky March 31, 2017

Backyard chicken keeping has many benefits aside from farm-fresh eggs. If you garden, chicken manure is black gold when composted and applied appropriately, returning nutrients to the soil and helping produce better plants, fruits and vegetables for you and your family.

In a 2014 survey conducted by UC Davis Animal Science Master’s student Carine Elkhoraibi and her adviser, Dr. Joy Mench, more than 1,400 backyard chicken-keepers responded. When asked the major reasons they kept backyard chickens, 95 percent of the respondents mentioned food for home use followed by 63 percent who listed their chickens as gardening partners: Think pest control and manure as a fertilizer. While this suggests that composting is common, we need to be careful how we handle, compost and apply compost in order to avoid contamination of the fruits and vegetables we are growing in our gardens.

Manure Macronutrients

Aside from macronutrients nitrogen, phosphorus and potassium, which are essential for plant growth, chicken manure also contains calcium, magnesium and sulfur, which are not found in synthetic fertilizers. In its raw form, however, poultry manure also has high concentrations of bacteria, including pathogenic salmonella, meaning that you should never apply raw poultry manure to your edible garden. The bacteria can come into contact with your growing produce and either stick to the surface or move inside the plant’s cells, making cleaning impossible.

In addition, if you apply raw, noncomposted manure to your plants, they may very well die due to excessive available nitrogen and salts. The best way to dispose of the manure is to first compost it and then use it correctly and safely.

Step 1: Collect Materials

Think bedding material, such as rice hulls and wood shavings, and put it in a composting bin. You’re aiming for approximately 25 percent manure and 75 percent other materials, which can include the aforementioned bedding material, leaves, plant material or kitchen scraps, and lawn clippings. You should have at least 1 cubic foot of material to allow the composting process to heat the pile up to an internal temperature of 140 to 160 degrees F, which will kill pathogenic bacteria.

Step 2: Add Water

You’re looking for the pile to match the texture of a wet sponge.

Step 3: Monitor Temperature

Do this daily with a composting thermometer, which you can find online or at a home-improvement store, and keep a temperature log to refer to. Your goal is to reach a temperature between 140 to 160 degrees F and maintain that temperature for three days.

The temperature is key: Submitting compost samples to a lab for detection of pathogens is not practical or effective. However, temperatures of 160 degrees F or higher will kill salmonella and common bacterial pathogens found in poultry manure. If you don’t achieve that temperature, the chances of pathogen survival for an extended period of time will increase.

Step 4: Repeat

While the internal part of your pile is treated, the outside is not. Therefore, repeat the process at least two more times to make sure all parts of the pile have been treated.

Step 5: Cure

Put the compost in a covered pile for at least 80 days. This waiting period helps to ensure that the pathogenic bacteria have been killed.

How To Use It

On commercial farms, farmers match the nutrient requirements of the crop with the application rate, which helps mitigate any issues related to nitrogen leaching into groundwater. This approach is not practical for backyard gardeners, but it’s important to recognize that more is not always better and the timing of application is important.

In general, always apply compost as near as possible to planting time and apply it between 1 and 2 inches deep to your garden crops or 1/2 inch deep to your lawn. If you want your compost samples analyzed for macronutrients, such as nitrogen, phosphorus and potassium, and E. coli and salmonella levels, you can collect a sample and send it to a private diagnostic lab.

Here are a few other items of note:

  • Do not add dog, cat or human feces to your compost pile, as they can’t be safely composted.
  • You shouldn’t smell ammonia associated with manure inside the coop; aside from being bad for our lungs, it can cause ulcers in the chickens’ corneas. If you do, you need more bedding material. Straw, though commonly used, isn’t the best choice for bedding, as it’s relatively nonabsorbent compared to wood shavings or rice hulls, and can contribute to that strong ammonia smell. Clean your coop as needed, but ideally, if you have the right density of birds and the correct amount of bedding material, you shouldn’t need to clean your coop more than once every couple of months. (The birds often will “till” their manure with their bedding as part of their normal scratching behavior.)
  • Remember that after you compost the material can still contain low levels of salmonella, E. coli and other pathogens, which is fine. This is a numbers game in that your starting material had millions of these bacteria per gram of manure. Very low levels of these bacteria will not cause disease if you have a normal immune system. It’s still recommended to always wash freshly picked fruits and vegetables.

Compost is a safe and ideal fertilizer for your home garden—if processed correctly. Aside from providing nutrients to your plants, the manure adds organic matter to the soil and increases the water-holding capacity and the beneficial bacteria present in the soil, but processing it properly is paramount.

This article is written by Pramod Pandey and Maurice Pitesky, faculty members at the UC Davis School of Veterinary Medicine at the University of California, Davis, and the University of California Cooperative Extension. Dr. Pandey’s research focus is on composting and microbial waste management, and Dr. Pitesky’s research focus is on poultry health and food safety epidemiology.

This article appeared in the March/April 2017 issue of Chickens.

Using Sawdust in Your Garden

Article: Nine Ways To Use Sawdust In Your Garden

April 21, 2011

Sawdust is inexpensive, readily available, and has many practical uses in the garden. It often gets a bad rap for “stealing” nitrogen from growing plants, but when used properly it can actually support the growth of your plants by helping to improve your soil. Sawdust can also be used to store crops, repel pests, deter weeds, and is handy for cleaning up accidental spills.

  1. Amend Your Soil: Add small amounts of sawdust to your soil to increase organic matter and improve its texture. Because sawdust is very slow to decompose, it works especially well in moist, heavy soils like clay, where soil amendments tend to break down quickly. Advertisement
  2. Compost It: For composting purposes, sawdust is considered a “brown” (carbon) material, which can be added in alternating layers to balance out the “green” (nitrogen) materials like grass clipping and food scraps. Sawdust also acts as a bulking agent, allowing air into the pile. It takes approximately a year to transform raw sawdust into finished compost.
  3. Discourage Weeds: Not many gardeners know this, but sawdust (especially from hardwoods like walnut trees) is a natural weed killer. Sweep it between the cracks and crevices of concrete sidewalks and in between stepping stones to help prevent weeds from popping through.
  4. Grow Mushrooms: If you have ever considered growing your own mushrooms, sawdust can make a good growing medium. Unlike green garden plants, mushrooms lack chlorophyll and rely on other organic materials for their food. In nature, logs work well for this. In the garden, you can use a mixture of sawdust and woodchips. Growing mushrooms successfully requires monitoring temperature and light. For information and supplies, check out: http://www.mushroompeople.com Advertisement
  5. Mulch With It: Sawdust has an acidifying effect on the soil, and is a good choice for mulching around acid-loving plants like conifers, blueberries, strawberries and rhododendrons. Keep in mind that fresh, non-composted sawdust will hog nitrogen as it decomposes, so using too much of it without adding supplemental fertilizer to the soil can cause a nitrogen deficiency in your plants.
  6. Pave a Path: Sawdust is the ideal material for creating an inexpensive garden path. It’s soft, looks natural, helps control erosion, and it smells really great! Start by marking out your path. Clear away existing grass and weeds to expose the soil. Apply a thick layer of sawdust and tamp it firmly into place. Walked-on sawdust compacts quickly, so expect to refresh your path every few years. Advertisement
  7. Repel Slugs: Sawdust (especially coarser sawdust) can help keep slugs at bay. Raise the foliage around susceptible plants and apply several inches around the base of stems.
  8. Soak Up Spills: Sawdust is highly absorbent, which great for cleaning up occasional drips and leaks from lawn and garden equipment. Keep a bucket handy in your garage or garden shed. Toss a handful of sawdust over the spillage, wait for it to be absorbed, then sweep it up cleanly with a broom.
  9. Store Root Crops: Root vegetables like carrots, beets, and turnips can be placed in a single layer and kept over the winter in a box filled with fresh sawdust. To maximize their shelf-life, store the box in a cool place like a semi-heated garage or unheated basement at approximately 35-40 degrees F.

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Warning: Sawdust Can Rob Soil of Nitrogen

Using sawdust in the garden is not without its problems. Like other wood products, as sawdust breaks down and decays it locks up important nutrients in the soil – namely nitrogen. Spreading raw or “green” sawdust in the garden can lead to a nitrogen deficiency resulting in the malnutrition of your plants. Fortunately, there are a couple of ways around this:

  • Let the sawdust simmer in the compost pile for at least a year before using it in the garden.
  • When using raw or “green” sawdust, provide regular applications of a slow-release organic fertilizer to counteract any nitrogen deficiencies.
  • Avoid using large quantities of sawdust around plants at one time. Start with small amounts and see how your plants react.

If your soil is low in organic nutrients to being with, pay extra attention to your plants during the growing season. If they start to appear light yellow in color, they may be suffering from nitrogen deficiency. You can counteract this by side-dressing them with an organic fertilizer such as alfalfa meal or blood meal, compost, or manure. Advertisement

Sourcing Sawdust

The best sawdust for garden use has a slightly course texture – the type created as a byproduct of sawmills or chain saws. Very fine sawdust, like the dust created from sanding furniture or cabinets, has a tendency to become packed down and anaerobic so it’s not a good choice. Also, make sure you know what type of wood was used to create the sawdust.

Walnut, cedar, and chemically treated wood should never be used on garden plants, but may be suitable for soaking up spills or creating garden paths. To source sawdust in your area, check with local lumberyards and tree removal companies. Many will offer sawdust for free (or at least very inexpensively), especially if you’re willing to pick it up and haul it home yourself.

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