Equipment For Incorporating Sewage Sludge And Animal Manures Into The Soil

by Charles H. Reed

Professor of Agricultural Engineering, Rutgers Uni-v«$iiy. New Brunswick, New Jersey

For centuries, man has applied animal manures and human sewage to the soil to improve crop production. The principal technique was to spread it on the land and then work it into the soil.

With the expanding population, depletion of our natural resources, and intolerable pollution of the atmosphere and hydrosphere, there is an urgent need for techniques to recycle biodegradable wastes into the upper horizon of the soil where they are degraded and utilized, resulting in a beneficial effect upon die environment.1 Bohn and Cauthorn state, "In summary, compared to air and water, the soil has a vastly greater potential for waste disposal and transformation . . . and it has the capacity to absorb far more material than it can produce or than is added to it." 3

The incorporation of wastes directly hii<'. the soil is superior to surface spreading because there are no odors, no opportunity for flies or other pests to feed or breed, no runoff or surface erosion of wastes, and the wastes are placed in the best possible media for immediate degradation to plant nutrients and utilization by plant*. These techniques conform to the concept of land treatment as defined by Stevens etal.:'

Land treatment is any of several methods of waste water treatment and sludge application which consider the qualities of land, waste water, and sludge in the design of facilities. Land treatment conveys the reciprocal, beneficial relationship between the land and the waste. Most such facilities are designed to produce valuable end products, such as green crops and pure effluent as a result of the treatment processes.

Land treatment differs from land disposal, a term used to describe any method which applies sewage, raw or treated, to the earth; and land application, a term used by EPA [Environmental Protection Agency] to describe all methods of waste water disposal associated with the ground, that is, sewage farms, land treatment, septic systems, and underground disposal.

The design of an effective land treatment system and the selection of appropriate equipment necessitates the consideration of many factors, some of which are outlined below:

• Kind and previous treatments.

0 Physical and chemical properties, i.e., percent solids (wet basis) and rate of production (daily, weekly).

2. Storage available or required. Transportation.

e Distance to sites,

3. Site characteristics or limitations.

Q Topography,

« Existing vegetation.

• Soil characteristics.

• Location of human habitation. Distance. Prevailing wind.

4. Climatic Imitations.

• Temperature. Duration of frozen soil,

• Rainfall. Seasonal, normal, and extreme variations.

• End product desired. Crops to be raised, use of land, etc.

Irrigation of sewage sludge and effluent is receiving considerable attention at this time.4-'1 Only thin slurries with low-so'id contents can be irrigated. Because of the high water content (more than percent as it comes from the digesters), conveyance to disposal sites by pipeline may be the only practical transportation system. Storage structures at the sites will be required during periods of sub-freezing temperatures, frozen impervious soil, saturated soil, and other periods of shutdown. Unless thoroughly digested, surface applications of sewage sludge may generate odors and attract Hies. Any surface applications are susceptible to surface runoff. There is a possibility of soil clogging and waterlogging when sewage sludge is irrigated.3-6 Also, there may be damage to foliage when large quantities of sludge are repeatedly sprinkled on plants. There will be large power requirements. The aerosol effect may limit high-pressure irrigation on some sites.

Irrigation of effluent containing only dissolved solids can be managed without many of the above disadvantages of sewage sludge, and may be considered for irrigation of crops or ground water recharge when needed. The limiting factor usually is the amount of water which can be added to the soil at different seasons of the year; that is, ice buildup or saturated soil.

Composting is an ancient technique of recycling biodegradable wastes. Modern techniques and equipment have been developed to compost balanced mixtures of biodegradable wastes including sewage sludge, animal manure, and solid wastes, See Compost Science, Vol. 13, No. 3, May-June 1972, for information on General Motors' Terex-Cobey Composter. These techniques are relatively expensive and may generate some localized odor. Well-cured compost can be spread on the land without attracting Hies, is not as susceptible to surface runoff as is noncomposted waste, and is an excellent soil conditioner. An outstanding advantage of compost is that it can be readily stored in piles at low cost without nuisance until an appropriate time for application in the soil.

Land spreading is the most ancient method of utilizing both human and animal excreta. When plowed or disked immediately after application, it is an effective method of incorporating it into the soil. When large quantities are involved, this may be the most economical, but if not properly treated, it will not be the most sanitary technique.

The ridge-and-furrow technique might be considered a surface method of application unless covered immediately. The furrows can be made on the contour or slightly sloping to permit the water to filter into the soil, Ridge-and-furrows on the contour have been used experimentally at the New Jersey Agricultural Experiment Station as a low-cost winter storage. Aerobic conditions should be maintained in and at the bottom of the furrow.

Equipment hag been developed which will incorporate wastes directly into the soil, either in one or two operations by Sub-Sod-Injection or Plow-Furrow-Cover.

Sub-Sod-Inject ion (SSI) equipment is available which will inject any slurries that will flow by gravity or under pressure through a six inch diameter hose two feet long. Animal manures with up to 20 percent solids and sewage sludge with up to 10 percent solids can be injected by gravity into the soil at the rate of 400 gallons per minute in a band up to two inches thick and 28 inches wide and from six to eight inches beneath the surface without turning over the soil. The injector has a standard category two, three-point hitch with a spring-trip release for passing over subsurface objects. It is comparable to a two-bottom plow in weight and durability. This equipment is not yet available commercially, but can be assembled from existing components.

The-Plow-Furrow-Cover (PFC) method is the most adaptable of any of the previously mentioned techniques. Equipment is available, or can be assembled from manufactured components, to incorporate directly into the upper eight inches of the soil up to 300 tons per acre of biodegradable wastes, ranging from thin slurries (septic tank pumpouts) to semisolids (sewage cake). PFC leaves the soil plowed and ready for disking and seeding. Two types of equipment will be described for PFC: one for 25 percent solids or less, and the other for greater than 25 percent solids.

One of the two recently developed pieces of equipment was assembled by Agway, Inc., of Syracuse, New York. The first one was used at the University of Connecticut in a research demonstration pioject to study the effect of incorporating septic tank puinpouts into the soil, in this project more than 100,000 gallons of slurry were incorporated into the soil in two months. The capacity of the tank is 800 gallons A tun* inch auger with ample hydraulic power from an auxiliary hydraulic pump on the tractor, and 12 inch as welt as six inch valve openings will unload much heavier solids titan would the previous prototypes. The highest limit of solids content which it will unload has not yet been determined, This equipment will not unload low-moisture sewage cake, semisolid animal manures with bedding, or caked poultry manure reinforced with feathers. A gooseneck tongue is built permanently into the tank to provide easy maneuverability of either a 16 inch single-bottom moldboard plow or a sub-sod-injector which is mounted on the three-point hitch of the tractor.

A second unit, constructed in 1975, is identical, except that it has a capacity of 1,500 gallons, a nine inch ribbon auger, and a slurry spreader or. the rear. This unit has not yet been field-tested. The augers, valves, and spreader are powered by the hydraulic system on the tractor.

To plow-furrow-cover, a 16 inch single-bottom moldboard plow is mounted on the three-point hitch of a standard farm tractor. A slurry with up to 25 percent solids can be deposited into a six to eight inch deep plowed furrow. Immediately after deposition, and in the same operation, the plow covets the waste and opens the next furrow. With properly adjusted equipment, one and one-half to two inches of slurry can be completely covered. This is approximately 170 to 225 tons of slurry per acre. A well-formed Eurrow, 16 inches wide, seven to eight inches deep and 400 feet long with one and one-half inches of slurry, contains 500 gallons, or approximately two tons. PFC leaves the soil well plowed and ready for disking and seeding. The equipment has been designed to operate at three miles per hour and unload up to 200 gallons of slurry per minute. The axle of the trailer is adjustable so that the trailer is offset, permitting the right rear trailer wheel to travel in the newly formed clean furrow.

A combination transport and field unit was assembled by a tank on a four-wheel-drive, 1 i/j-ton truck chassis with flotation tires. It is equipped with a hydraulic pump, controls, and a category two, three-point hitch. The tank has a capacity of 500 gallons. With a 12 inch ribbon auger in the bottom of the tank and a 12 inch diameter valve, semisolid animal manures with up to 30 percent solids, and sewage sludge with up to 20 percent solids have been unloaded. Because the hydraulic power is limited, the full performance capabilities of the 12 inch auger have not been determined. A spreader can be installed on the rear for land spreading.

A ridge-and-furrow opener can be mounted on the three-point hitch of the tractor or mounted on the tongue of the trailer. This consists of right-hand and left-hand moldboard plows bolted together on the same trip-release beam. The 12 inch opening in the center of die trailer tank permits a high-capacity application of semisolids into the furrow, Presently the furrows are closed or covered in a second operation.

The best equipment field tested to date at the New Jersey Experiment Station, for unloading semisolids and cake with more than 25 percent solids, is a New Idea Flail Spreader, It can be adjusted for a wide range of surface applications, which are plowed under in a second operation. A conveyor similar to the one on a forage wagon is being adapted to this spreader to convey the waste into a furrow for PFC.

International Harvester sells an attachment to convert one of their heavy-duty manure spreaders into a self-unloading forage wagon. At this time it has not been demonstrated for unloading a gummy, sticky semisolid into a furrow.

There should be no difficulty to adapt either of these pieces of equipment to PFC for either one or two operations. Plans are underway at the New Jersey Agricultural Experiment Station to make these adaptations.

There are outstanding advantages in handling dewatered sludge with a solids content of 15 percent or greater.

1. As solids content »meases, volume and weight decrease. For example, to inject one ton of solids in a ;» percent solution, 20 tons of slurry must be handled; for one ton of solids in a 15 percent solution, 6% tons; and only 3i/s tons if a semisolid with 30 percent solids, dry-weight basis.

2. It can be stored in contoured furrows or piles on well-drained sites to be incorporated into the soil when weather and soil conditions are optimum.

3. It ran be transported in regular dump trucks without leakage on the highway.

■J. Sludge with a solids content of 15 percent represents the minimum solids content which can be incorporated into the soil by PFC at the rate of 40 tons dry-weight equivalent per acre in one application: that is, 2-27 inches of depth in the furrow can be completely covered. Greater rates of application can be achieved in one operation if the sludge contains less moisture and more solids, and also because greater depths can be covered in the furrow. This rate of application represents the performance capabilities of the equipment and not necessarily the optimum or safe amount which the soil can tie up, degrade, and recycle. Smaller quantities can he applied.

In order to utilize the continuous output of sewage treatment plants, daily PFC applications at the desired annual rate may be made in contiguous strips or furrows, resulting in the entire plot receiving the total annual treatment. At any time when there is sufficient area of contiguous strips of plowed ground, it may be disked and seeded to the crop appropriate for that particular season. After some forage crops, that is, hybrid Bermuda grass, have been established, one or 'wo applications can be made annually by PFC or SSI without replanting. For maximum recycling and utilization of nutrients from the sludge, crops should be raised on and harvested from the treated sites when mature or at the end of the period of their maximum assimilation. Numerous crop management plans and rotations are possible, depending upon the sites and the end product desired.

REFERENCES

1. Meadows, Dunella H.; Meadows; Randers; and Bchrcns. "The Limits to Growth." A report for the Club of Rome's project on the Predicament of Mankind. New York: Universe Books, 1972.

2. Bohn, Hinrich L„ and Qiuthorn. Pollution: The Problem of Misplaced Waste." American Scientist. Vol. 60, Sept .-Oct, 1972, pp. 561-565.

3. Stevens, R. Michael; Elazar, D.|,; Schlesinger. Jeanne; I.ockard, J, F,; and Stevens, B. A. "Green Land-Clean Streams," Center for the Study of Federalism, Philadelphia, Pa. 1972.

4. Hinaly, Thomas l>„ and Sottwitz, Ben, "Digested Sludge Disposal on Crop Land." 41st Annual Convention Water Pollution Control Federation. Chicago, Illinois, Sept., 1068.

5. "Recycling Sludge and Sewage Effluent by Land Disposal." Environmental Science and Technology. Vol. 6, No. 10, Oct. 1972.

6. Reed; Murrman, S.C.; Kom; Rickard; Hunt: Buzzeli; Carey; Bilello: Buda; Outer; and Sorbor. "Wastewater Management by Disposal on Land." .Special Re|>ort 171, Corps of Engineers. Cold Regions Research and Engineering Laboratory, Hanover, N.H., 1972.

SOURCES OF EQUIPMENT TO ADD ORGANIC MATERIAL TO THE SOIL

Big Wheels

Big Wheels is a 1,600-gallon tank truck used for distributing sludge in either surface or subsurface applications. It is not built for road transport; it must be used in conjunction with sludge transport systems. For surface application, sludge is sprayed from the rear of the truck.

For subsurface application, soil-slicing coulters precede chisel-plowing tines to cut a narrow path for application hoses. Injection is possible at adjustable depths usually between 6 and 9 inches. Furrow coverers are available but are usually unnecessary.

Big Wheels, Inc. 1-57 and Rt. 9 Paxton, IL 60957

DTS-100 .Stationary Manure Pump Unit

This is a stationary unit comprising (lie HSP-HHI electrically driven screw pump as well as the delivery pipe with three-way valve and mixing nozzle. It is mounted on a supporting rail made of channel sections which should he fixed permanently at the place of pump installation. ft is possible to mix the manure in tanks, to pump it over from initial tanks to main tanks, tu pump over from the tank to the water cars, and to deliver from the tank directly to the sprinkling system, when the area to be sprinkled is nearby the farm. The unit can be used with even very dense liquids for which no other pump can find application. The stationary unit is best suited for large pumping jobs.

Sewage Equipment

Specifications:

It will deliver at a rate of 40 cubic meters

Delivery of pump

—40 meters over S hours

per hour.

Pressure of pump

—100 m H 0

Speed of pump

—■560 rpm

Agromet-Motoimpori

Electric motor

—type SZJfVe-64 b

Foreign Trade Enterprise

Total weight

—807 kilograms

00-950 Warszawa. ul.

Depth of tank

—3.5 meters

Przemyslown 26, Poland

10- Woodlot and Orchard Management by Jim Ritchie by Jim Ritchie

For most homestead timbering purposes, you wit! need to make a small investment in tools: a lightweight chain saw or how saw, an a> at least «vo steel wedges lor splitting logs and rails, and a »ledge to drive the wedges. You may prek : i splitting hammer: a sledge with a hammer lace on one side and a wedge-shaped splitting blade on tin other: once you get the hang of using it, this tool can speed up timber chores.

You may also find a use for a machete, brush hook, grub hoe, mattock, power circular saw, and bucksaw. Other, more specialized tools and equipment are occasionally called in for particular jobs around the homestead, but unless you use a specialized piece of equipment enough to justify the Investment, you may ivant to borrow or rent, rather than buy.

Handling wood with a peavy. \

Handling wood with a peavy. \

m&mmm

* Reprinted from Trees for the Yard, Orchard, and IVoodlot, edited by Roger B, Yepsen, Jr. Rodale Press, 1976. 428

All woodcutting tools should he kept sharp and out of the rain. Well-maintained equipment is not only easier to work with, hut safer as well. A sledge or axe that is loose on the handle is a hazard both to die operator and to fellow workers or bystanders. A dull axe blade may bounce or glance off the log aitd into a human limb.

SAWS

For most homestead work a lightweight chain saw with a 14 or 16 inch cutter bar is sufficient. You can buy heavier, more powerful models if you need to do a lot of heavy work. But by notching and undercutting with smaller saws, you can fell trees up to three feet in diameter. If you've never operated a chain saw, try out two or three different models and sizes. Also, consider the availability of parts and service before you buy.

Chain saws aren't for everybody. Many people object to the cash investment, the stink or the noise, or the gas and oil consumed. You may prefer to work with a crosscut saw—either the two-man variety (if you have a steady helper) or a one-man saw. The rhythmic sound of a crosscut has a soothing quality, something that certainly cannot be said of a chain saw.

Two-man saws are typically six to seven feet long and have cutting teeth alternated with drag teeth to remove sawdust from the saw kerf (or slot). These saws are made of high-quality steel and are too limber and springy for handy operation by one man. However, it is possible to use a two-man saw by

The proper stance at a sawhorse.

yourself if you remove the handle from one end atul support thai end of the saw with a slender, timber stick cut to just the right length. Poke the stick into the ground at the midpoint of the saw's travel, on the opposite side of the log (or tree) from tire sawyer, and lie the upper end ol the stick to the saw where the handle was removed. The stick then supports the saw so the blade doesn't [lop and wobble. It's not as handy as a sawing partner, but it works.

One-man crosscut saws are shorter, about five feet in length, and are made of heavier metal than two-nian crosscuts. They are not as likely to buckle when pushed and pulled from one end.

Because of the chain saws's great popularity, manual crosscut saws have all but disappeared from some ureas—even in regions of heavy timbering. And, as with most steel products, prices have climbed rapidly in the past few years. To find a used saw, cheek classified ads in local newspapers and visit a few farm sales. (Often you can also find reasonably priced axes, sledges, wedges, Hies, and other limber equipment at these sates.)

For lighter work, a bow saw or bucksaw is more convenient than a crosscut. These have two- or three-foot saw blades stretched in a metal or wooden frame, hacksaw fashion. They're ideal lor bucking off cordwood cuts, limbing, and other light timber work and can be used to fell smaller trees. They also come in handy for pruning fruit and ornamentals.

With all saws, power or manual, the condition of the cutting teeth has a big inllucnec on the condition of the sawyer at the end of a day's work. There's an art to filing and setting saw teeth, and no two timbennen file a saw the same way. You'll need a good, c lean file—about a number ten bastard Hat file for crosscut saws. Cluunsaw chains have teeth of various si/es, so you'll need to buy a file to lit your particular saw. Bow saw blades can be easily replaced.

You'll also need gauges to show the length and set of the saw teeth. (Turn the saw teeth up and sight lengthwise along the blade or chain; the angle of the cutting teeth from the plane of the saw blade is called the set.) For cutting fibrous wood, such as green oak or hickory, you'll need lo set a greater angle than norma! into the saw's teeth.

For clearing brush and small trees from land to be cultivated, a wheel-mounted circular power saw can come in handy, particularly if you're clearing large areas. These saws are fast and effective in cutting top growth. Some models are self-propelled but shouldn't be used on steep slopes.

A good single- or double-bitted axe is a necessary homestead tool. Keep the blade sharp on the job with a small pocket whetstone.

Older circular saws, like this PTO-run model, often appear at farm sales and auctions.

Older circular saws, like this PTO-run model, often appear at farm sales and auctions.

AXES

Saint' woutUmt'ii prefer to use a double-bitted axe, with one blade lionet! sharp and the other allowed to dull slightly; the dull blade serves well for grubbing out roots and cutting off sprouts below ground level, white the sharp blade is never used for such rough work.

Leaving one blade slightly dulled gives a measure of protection when chopping among limbs tlvit might catch the axe and divert your swing. H the axe glances into your leg 01 loo! (an occurrence to be avoided at alt costs) at least you have an even chance that the dull blade will make contact.

A homestead wooillot can provide shelter, fuel, tools, equipment, ami outbuildings—depending on the si/c of the woods, the kind of trees grown, and the imagination and skill of the landowner.

FIREWOOD

Trees arc; most often tul lor burning. Even it you cut timber lor other purposes, you'll lind that much oi vottr firewood supply perhaps all of it can come from the leftover portions ul the harvested trees.

Wood varies in healing value with species used and the degree ol seasoning. Wood that has been allowed to air-dry for a year or more alter cutting lias a moisture content ol 2(1 to 25 percent and will burn better and proditie ¡note beat pet unit ol wood than freshly tut. green wood. Also, dried wood does not deposit as much creosote on Hue walls, lessening the chatico of a chimney fire.

The best firewood burns steadily but not too quickly, product", a lot of heat lor the amount of wood used, and Inirits cleanly with little creosote deposit and little ash. The table below gives the beat equivalents of the most common firewood species (based on air-dried wood) as compared with fuel oil. The heat values are given in millions ol lltu's (British thermal unit—the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit) per cord of wood.

Softwoods generally make poor firewood. They burn too quickly, produce relatively little heat, and often give off unpleasant odors. For example, air-dried red pine has but 12.S million lint's per cord as compared with 24 million Htu's per cord of white oak.

r HEAT EQUIVALENTS OF WOOD, BY SPECIES

Wood

Available heat of

No. 2 fuel

(1 standard cord)

1 cord of wood (Bill's)

oil (gallons)

Hickory, shagbark

2'1,000,0(H>

251

l .-x itit, black

'Ji.tUMMo

251

Ironwood (hardback)

24,100,000

246

Apple

23,877,000

'¿44

Elm, rock

23,188,000

240

Hickory or butternut

23,'177,000

240

Oak, white

22,700,000

232

Beech, American

21,800,000

222

Oak, red

21, ¿00,000

217

Maple, sugar

21,300,000

217

Birth, yellow

21,300,000

217

Ash, white

20,000,000

201

Walnut, black

10,500,000

198

Birch, white

18,900,000

193

Cherry, black

18,770,000

191

Tamarack (Eastern larch)

18,650,000

190

Maple, red

18,600,000

190

I oiltimted on next j»>nr

I oiltimted on next j»>nr

Wood i i standard cord)

Ash, green Pine, pitch Sycamore. American Ash, black Elm, Amt-nYan Maple, silver Spruce, red Hemlock Willow, 1) lack Pine, red Aspen (poplar) Pine, white Bass wood Fir, balsam

HEAT EQUIVALENTS OF WOOD, BY SPECIES

Available heat of 1 cord of wood (Btu's)

18,360,000 17,970,00!) 17,950,000 17,300,000 17,200,000 17,000,000 13, (¡32,000 13,500,000 13,206,000 12,765,000 12.500,000 12,022,000 11,700,000 11,282,000

No. 2 fuel oil (gallons)

187 183 183 177 176 173 139 138 135 130 128 123 119 115

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