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II. Types of Organic Wastes

II. Types of Organic Wastes

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G. S. TOOR ET AL.



6



Animal manures can be grouped, based on their moisture content, into

three broad categories: solid, semisolid, slurry or liquid. Manures that have

greater than 20% solids can be handled as a solid. For example, poultry litter

(mixture of feces and bedding material) will usually have 70% or more solids.

Manures with 10–20% solids fall in the semisolid category and

are represented by most dairy farm wastes. Manures with less than 10%

but greater than 4% solids can be treated as slurry. These are typical of deep

swine lagoon pits; however, dairy manure with milking parlor washwater

is also handled as slurry. Liquid manure with less than 4% solids can be

handled with common irrigation equipment. Properly designed and managed lagoon pits and wastes generated from washing of dairy milking

operations (milkhouse and milk parlor) will have typically less than 1%

solids. Table III includes most common types of manures (solid, lagoon,



Table III

Estimated Solid, Semisolid (Lagoon), and Liquid Manure and Total Phosphorus Produced per

Animal per Year (in kg yearÀ1) in the United Statesa

Solid

Animal

Dairy



Livestock stage



Dairy herd

Dairy cow

Dairy heifer

Dairy calf

Veal calf

Feeder calves

Finishing cattle

Fattening cattle

Beef

Cow

Poultry Layer

Broiler

Turkey

Duck

Swine

Farrowing

Nursery

Grow‐finish

Farrow‐finish

Breeding‐gestation

Total

a



Semisolid (Lagoon)



Manure Total P



Manure



Total P



Manure



Total P



18,090

12,600

5,850

1,350

990

3,150

5,310



6,030

18

8

41

27

2,160

216

945

7,713

900

65,357



62,100

40,950











19,800





59





7,425



3,600

28,800

5,175

167,909



5.9

3.7











4.1





0.01





1.2



0.4

4.5

0.8





32,850

24,300

11,250

2,700

1,575

5,850

11,475



13,500

59

37

231b

112.1

5,175

450

4,275d

16,875

3,150

129,358



25.8

19.1

8.3

2.0

1.8

5.1

10.8



11.4

0.2

0.1

0.2c

0.1

3.3

0.4

2.7e

21.2

4.1





15.7

8.3

3.9

1.0

0.6

2.8

8.1



5.3

0.2

0.1

0.2

0.1

2.8

0.4

1.8

13.6

1.4





Adapted from Mid West Plan Service (1988).

Sum of Tom and Hen turkeys.

c

Average of Tom and Hen turkeys.

d

Sum of deep pit, wet/dry feeder, and earthen pit.

e

Average of deep pit, wet/dry feeder, and earthen pit.

b



Liquid



CHARACTERIZATION OF P IN ORGANIC WASTES



7



and liquid) and their annual generation by dairy, beef, poultry, and swine in

the United States. Most of the wastes generated by all animal species (total

of dairy, beef, poultry, swine) fall in the semisolid (167,909 kg yearÀ1) and

liquid (129,358 kg yearÀ1) categories, although dairy, beef, and swine (farrow‐finish, farrowing) contribute considerable quantities of solid manure

(65,357 kg yearÀ1).

The discussion on other wastes generated by agricultural operations, including crop residues, food processing wastes, wood harvesting

and milling (paper mill sludge, woodchips, sawdust), and public and private horticulture (composts, lawn and leaf clippings) is not covered in this

review.



1.



Dairy and Beef



Dairy operations produce both solid and liquid wastes. Solid manure is

generated from confined dairy or beef facilities, whereas liquid manure

(mixture of feces, urine, and washwater) is a waste generated from a dairy

parlor and in some confined dairy operations. Large dairy operations (>200

milk cows) and some medium sized farms (80–200 cows) tend to use liquid,

rather than solid or semisolid, manure handling systems (Dougherty et al.,

1998) because of the eYcient automated systems that are employed for

watering, cleaning, and sanitizing. Use of automated flushing systems has

also reduced the need of bedding materials thereby producing manures with

lower solids content. However, smaller livestock farms commonly employ

traditional solid or semisolid manure‐handling procedures due to the higher

costs associated with installing automatic flushing systems. In rotational

grazing (mostly for dairy and sheep), manure is naturally spread on land

as the animals graze, while in an open feedlot (mostly for beef) manure may

be occasionally scraped or temporarily stored as pile before land spreading.

The amount and type of bedding material not only aVects manure solids

content but also alters the physical, chemical, and biological composition of

the manure. The most commonly used bedding materials in dairy operations

are sand, sawdust, and straw, although some operations use paper sludge or

shredded newspaper.



2.



Poultry



Major poultry wastes are poultry manure and poultry litter (mixture of

poultry manure and bedding material) and are principally generated by

broilers, turkeys, layers, and ducks. There are two types of manure generation systems: (i) liquid or semisolid manure is generated from caged pit



8



G. S. TOOR ET AL.



systems (layers) where manure falls into a pit and is then either scraped or

flushed (no bedding material is used) and (ii) solid manure is generated from

floor/litter systems (broilers, turkeys) on earthen or concrete floors covered

with bedding material such as sawdust, wood chips, or other materials. In

the United States, complete waste removal for broilers is usually accomplished after 12–24 months with partial cleaning after each flock (approximately 49 days). This poultry waste is usually directly applied to land after

its removal, but solid manure can also be stored in roofed or covered

structures. Field storage of poultry manure as stockpiles or in lagoons and

manure pelletizing are also common. Comprehensive reviews of broiler

waste generation and issues related to its management can be found in

Cabrera and Sims (2000), Sims and Wolf (1994), and Williams et al. (1999).



3.



Swine



Swine manure is handled as solid or liquid depending upon the type of

housing and manure handling system. In the United States, swine are fed

diets that are very similar to poultry and that are formulated with corn or

grain sorghum and soybean meal. Greater than 50–60% of swine operations

in the United States use total confinement systems where hydraulic water

flushing systems are used and the manure is typically handled as slurry in

anaerobic lagoons. Approximately 15% of the swine raised in the United

States have solid manure handling systems, whereas very few (<5%) of the

swine are raised on pasture or in open feedlot. The methods of manure

collection, dilution, and storage are the major factors aVecting composition

of nutrients in swine manure.



B. MUNICIPAL WASTES

The major municipal wastes are municipal solid waste (MSW) and biosolids, with the former accounting for 95% of the total (National Research

Council, 2002). While the other municipal wastes are wastewaters produced

from sewage treatment, MSW composts, and drinking water residuals

(solids from drinking water treatment). The MSW is a mixture of paper

and cardboard products (35%), yard wastes (20%), and metals, plastic, glass,

wood, and food wastes (each comprises about 6–9%). Approximately 60% of

MSW is biodegradable (paper, cardboard, food wastes) and can be potentially recycled by means of composting. The term ‘‘biosolids’’ is a relatively

new name for sewage sludge. According to the US Environmental Protection

Agency (1995), biosolids are ‘‘the primarily organic solid product yielded by

municipal wastewater treatment processes that can be beneficially recycled.’’



CHARACTERIZATION OF P IN ORGANIC WASTES



9



Considerable amounts of biosolids are produced each year and this figure is

increasing. For example, in 1998 biosolids production in the United States

was 6.3 million dry Mg and is expected to increase by 19% (7.5 million dry

Mg) in 2010 (US Environmental Protection Agency, 1999). Increases in

biosolids production require greater resources to beneficially reuse them

by means of land application. In 2000, 40.1% of the biosolids were land

applied followed by incineration (21.9%), landfilling (17.2%), composting

(5.4%), lime stabilization (4.1%), surface disposal (3.8%), heat drying and

pelletization (1.4%), and lagoon storage (0.90%).



III. FACTORS AFFECTING PHOSPHORUS

COMPOSITION IN ORGANIC WASTES

Phosphorus forms in organic wastes can be influenced by a number of

factors, ranging from the origin (animals, industries) to practices that occur

during the generation, treatment, handling, and storage (e.g., the type of P

fed to animals, bedding materials, the addition of lime and metal salts to

biosolids).



A. DIETARY EFFECTS

Over the last few years, the P content and/or forms of P in some manures

has been significantly changed due to changes in animal nutrition. The

driving force for these changes has been to increase the cost eYciency of

feed consumption, animal performance, and the need to better manage

organic wastes by reducing P excretion in manures.



1.



Poultry and Swine Diets



Dietary manipulation by feeding P closer to animal requirement and by

using feed additives, such as phytase and vitamin D metabolites, is an

emerging area of research because imported feedstuVs are the principal

P inputs on many farms in the United States and Europe. For example,

imported feedstuVs supplied 5859 kg P haÀ1 in the form of concentrates on a

Belgian pig farm that raised 5000 pigs per year (Table IV). The P surplus on

this farm was 1056 kg P haÀ1 and was much higher than other European

farms (14–41 kg P haÀ1). Similarly, concentrates were the major P input on

some European dairy farms that had P surpluses of 8–23 kg P haÀ1.



10



Table IV

Farm Gate Phosphorus Balances for Selected European Pig and Dairy Farmsa (in kg P haÀ1)

Pig



Dairy



Denmarkc



Spaind



Francee



Swedenf



Belgiumg



Denmarkh



Spaini



0

0

0

5859

561

0



21

0

0

182

9

1

0

213



9

0

94

0

0.4

0

0

103



4

0

49

0

5

0

0

58



13

0

10

31

5

1

0

60



5

0

43

0

0

0

7

55



22

0

0

11

0

1

0

34



6

13

0

7

0.2

0

0

27



1

0

17

0

0

0

0

18



141

12

46

0

199

14

93



40

0

49

0

89

14

86



0

0

17

0

17

41

29



12

2

23

0.2

37

23

61



0

23

10

0

33

22

60



0

18

5

0

23

11

68



0

7

7

0

14

13

52



0

1

9

0

10

8

55



Input

Mineral fertilizer

Manure

Fodder

Concentrates

Animal products

Atmospheric deposition

Net stock exchangel

Total input



6420



1

0

95

0

0

0

À27

69



Output

Organic fertilizers

Arable products

Animals and animal products

Other

Total output

Surplus

Utilization (%)



2945

0

2355

64

5364

1056

84



0

16

30

0

46

23

67



Francej



Swedenk



G. S. TOOR ET AL.



Belgiumb



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