A pilot scale treatment process for laying hen manure

J. agric. Engng Res. (1980) 25, 375-380

A Pilot Scale Treatment

Process A. T.

for Laying Hen Manure

SOBEL*

The use of carbonaceous additives to increase handling ease, alter the physical appearance and reduce the pollution potential of animal manures presents itself as an approach to solving many

waste management problems. The results of pilot scale studies concerned with the addition of wood shavings to laying hen manure indicate that the resulting product is storable and has an altered appearance. Introduction A horizontal batch mixer was adapted to process laying hen manure by the addition of wood sawdust. This mixer had a capacity of 0.5 m3 and was powered by a 2 hp, 3-phase electric motor. The motor was controlled by a time clock to run a preset time each hour. The mixer was insulated with 5 cm of polyurethane. The mixer was initially filled with approximately 9 1 kg of previously hand-processed material. At 3-4 day intervals approximately 22.7 kg of material was removed and 22.7 kg of manure and sawdust was added. The theoretical retention time was 14 days. The sawdust was a coarse material of mixed woods and had a moisture content between 20 and 40% on a wet basis (wb). The manure was from caged White Leghorn laying hens housed at the Agricultural Waste Management Laboratory, New York State College of Agriculture and Life Sciences, Cornell University. The manure had been partially dried using the slot-outlet system of undercage drying.’ The manure produced from this system had a moisture content of 30-50 % (wb). The oxygen content of the air within the manure-sawdust mixture was measured using an oxygen probe. The probe was placed within the material just after the material had been mixed and periodic measurements were taken. While this was a unique use of equipment designed for measuring the dissolved oxygen of a liquid, the information obtained indicated the uptake of oxygen by the microorganisms within the system. Fig. 2 shows such an oxygen uptake study and indicates that in 30 min the oxygen within the mixture had been reduced to 25 7: of that in the surrounding air. The mixing sequence was therefore set for the mixer to be on 10 s every 30 min. Temperatures were taken inside the mixer during operation. Fig. 2 shows this temperature for several cycles of feeding and weighing plus a time when the mixer was accidentally left switched on. The temperature reached an average maximum of 125°F. Mass balance After the mixer had been in operation for 20 days and after conditions had been established within the mixer, a detailed record was kept of the parameters of the process for a 35-day period. The operating procedure was similar for that followed in the initial period. The amount of sawdust added was calculated to produce an approximate 20% sawdust : 80% manure ratio by weight for 30% moisture manure. This is equivalent to 0.36 kg sawdust per kg of total solids. Adjustment was made for changes in moisture content of the manure added but not for changes in sawdust as this all came from a common supply. Water was added to the mixture in the mixer to replace evaporation. To keep an approximate equal amount in the mixer, during each feeding the entire contents of the mixer were removed, weighed, and a constant weight (68 kg) was placed back into the mixer. Tables I and II present the various parameters for this study including a *Department Received

of Agricultural 19 December

1978;

Engineering,

New

accepted

in revised

York

State

form

College

10 May

of Agriculture

and

Life

Sciences,

Cornell

University,

Ithaca,

New

York

1980

315 OW-8634/80/040375

t-06

SOZ.OO/O

fi? 1980 The

British

Society

for

Research

in Agricultural

Engineering

376

TREATMENT

OF HEN

Fig. 1. Oxygen uptake within mixer

4Ol 0

b

I I I 20 40

I

I 60

I, f:: 00

,

I

100

,

,

120

Tame (h)

Fig. 2. Temperature within mixer

,

,

I40

,

,

160

,

180

MANURE

Average

30 Nov. 197 1 3 Dec. 1971 7 Dec. 1971 10 Dec. 1971 14Dec. 1971 17 Dec. 1971 21 Dec. 1971 24 Dec. 1971 28 Dec. 1971 31 Dec. 1971

Date

92.26

94.80 99.34 87.54 100.24 95.26 94.35 96.16 92.99

72.58 89.36

68.04

68.04 68.04 68.04 68.04 68.04 68.04 68.04 68.04 68.04 68.04 0

Left in mixer ____~

I-

24.14

26.76 31.30 19.50 32.20 27.22 26.31 28.12 (92.99)

4.54 21.32

Removed from mixer

I

I

Total in mixer

-

Wet weights, kg

TABLE

I

30.28

31.28

68.02 68.59

30-45 27.02 30.94 30.07 30.07 31.48 30.82 30.71 29.99

Ash, %

66.24 68.45 65.69 67.87 66.85 72.35 70.68 69.7 1 70.06

Total solids, %

mixer

47.36

51.97

39.56 41.34 40.31 45.13 49.15 45.31 48.39 50.46 62.03

Organic-N

14.74

16.09

15.20 14.35 13.94 13.88 15.32 13.23 14.42 14.74 16.27

NH,-N

Nitrogen mg/g ts

Mixture removedfrom

Measured parameters of pilot manure treatment process

67.03

63.27 69.19 69.04 65.95 66.44 67.01 63.10 70.53 68.73

-

Total solids, ‘%

25.37

2544 21.00 24.34 27.71 27.16 24.42 26.96 25.78 25.53

Ash, %

54.41

57.95 57.19 52.25 63.41 54.41 46.28 41.40 49.00 67.80

Organic-N .___

9.20

9.92 7.79 8.38 12.38 9.49 7.80 8.99 7.60 10.42

NH,-N

Nitrogen mg/g ts

Manure added to mixer

24.14* - 9.34

Mixture Change

68.59*

66.19

67.03 * 60,OOt

0y /lJ solids

7.58 - 3.74

16.56 - 5.60

Nitrogen;

NEG-Negligible

in

- 25.3 out

11.32

22.16

equals ash

9.71 1.61

19.75 2.41

kg

Moisture kg

30.28*

22.61

25.37* 1.00*

“/, ash

0

5.01 0

5.01

5.01 NEG

Ash, kg

- 32.6

11.55 -5.60

__\-___. 17.15

14.74 2.41

Volatile solids, kg

Wet weight of manure added Wet weight of sawdust added Water added Wet weight of mixture removed Evaporation [153,0+ 10 (3.74)] Water evaporated/kg volatile solids lost

Totals during test period

Solids,

other values are calculated ash remains constant and ash

- 27.9

33.48

Total

‘A Change

29.46 4.02

Manure Sawdust:

* Measured values--all : ~;plations assume 0 by weight TKN-Total Kjeldahl

OUT

IN

Wet weight, kg

TABLEII

92.0 3.5 13.0 35.0 10

62.10

56.68

63.61 NEG

mglg

kg kg kg kg kg kg

I

g

-18.1

1028 - 228

1256

1256 NEG

kg days days days

TKN

294.6 40.2 153.0 241.4 190.4 3.4

~~

balance on pilot manure process

Average total wet weight in mixer Time between feedings Theoretical retention time Time of test period Number of feedings

Mass

784 - 290 - 27.0

1074

48.46 47.36* ’

1074

NEG

NEG

g 54,41*

mglg

Organic-N

I

14.74*

8.21

NEG

9.20*

mglg

NH,-N

244 +62 + 34.1

182

NEG

182

g

A.

T.

379

SOBEL

The comparison was made based on the mass balance on the solids and forms of nitrogen. assumption that the fixed solids (ash or inorganic matter) remained constant and did not accumulate within the mixer, i.e. equal amounts of fixed solids were added and removed during each feeding.2 The mass balance indicates that there was a loss of nitrogen and a substantial conversion of organic nitrogen to ammonia. This was apparent during the operation of the unit by a strong ammonia odour. Considerable evaporation occurred with 3.4 kg of water evaporated per kg of volatile solids lost. Assuming all the heat for evaporation to come from the decomposition of manure solids, the energy used for the evaporation of water was approximately 2000 kcal/kg organic matter destroyed. The energy potential of laying hen manure is 4000 kcal/kg of volatile solids3 The portion of the released energy used for evaporation was therefore 50”;.

Storage of processed material-uncovered The processed manure from the mass balance study was placed as removed from the mixer into an outside storage. This storage was a simple 2.5 x 2.5 m plywood frame 0.6 m high. No cover was provided and the manure was exposed to the rain, snow and sun. The mixture remained in the storage for 5 months after the last material was added. At this time samples were taken from various areas of the pile and the material was utilized for a home vegetable garden. Table III presents the analysis of the manure at the end of the storage period. A fertilizer analysis on the material from the storage indicated 2.9 % P and 2.14 y/, K. With an average nitrogen content of 4f,; and expressing the P and K as P,O, and KzO. the fertilizer value was therefore 4.0-6.6-2.6. The material was of granular nature and easy to handle. The material did not resemble manure, but was similar in appearance to high organic soil or leafmould. TABLE III

Analysis of mixture stored outside uncovered

Location

Centre of pile Centre cross section, dry portion 10 cm from surface, high manure content 18 cm from surface, high sawdust content, some fly larvae Outside edge, very wet Average

Moisture content, % (wb) __~_ 34.48

31.06 67.54 66.94 70.77 ______ 54.16

Total solids, 0, 0

solid.s, “I 0

Fixed

65.52 68.94 32.46

Nitrogen,

rng/x t.v

TKN ___~~

NH,-N

21.30 28.88 42.35

25.66 39.11 54.41

IO.81 15.48 34.60

33.06 29.23

35.27 41.28

47.92 34.38

31.68 13.37

45.84

33.82

39.90

21.19

Analysis of overall system The overall system of treating laying hen manure would include predrying the manure under the caged birds, moving this to the mixer for combination with a carbonaceous additive such as sawdust, a period of time in the mixer for treatment, storage of the treated mixture, possible bagging of the stored material, and final use of the material as a soil conditioner. Based on analysis during the various components of such a system, the overall losses and concentrations are presented in Table IV. The composition of the “As Produced” manure was taken from References (4) and (5). The losses have been calculated based on the assumption that the fixed solids (ash) remain constant.

TREATMENT

380 TABLE

OF

HEN

MANURE

IV

Overall concentrations and losses for laying hen manure treatment system

As produced

Wet weight, W, units Moisture, m, % Total solids, S, %(100/A) Volatile solids, V, % of S (V/A) Fixed solids, A, % of S

Nitrogen: TKN, % of S (N/A) Organic N, % of S (ON/A) NH,-N, % of S (AN/A)

Predrying

Treatment

100~00 35.28 75.004 32.97 25.004 (4.167) 67.03 (3.942) 76.00’ (3.167) 74.63 (2.942) 24.004 25.37 7.5005 (0.3 125) 6.361 (0.2507) 6.97S (0.2906) 5.441 (0.2145) 0.5255 (0.0219) 0.920 (0.0368) _ _

Storage*

28.89 31.41 68.59 (3.302) 69.72 (2.302) 30.28 6,210 (0.2051) 4.736 (0.1564)

1.474 (0.0487)

___._

38.70 54.16 45.84 (2.957) 66.18 (1.957) 33.82 3.990 (0.1180)

1,871 (0.0553) 2.119 (0.0627) _--__-

% loss (or gain) from “As Produced”t

Wet weight

- 64.72 - 5.40 - 7.10 0 - 19.78 -26.19 + 65.75

0 0 0 0 0 0 0

Total solids Volatile solids Fixed solids Nitrogen: TKN Organic-N NHS-N

71.11 - 20.76 -27.31 0 - 34.37 -46.18 + 122.37

-61.30 - 29.04 - 38.21 0 - 62.24 - 80.97 + 186.30

Values presented are for the uncovered storage based on assumption that fixed solids remain t Calculations 4,s Data taken from References (4) or (5) as indicated ??

constant

The major losses occurred during the storage portion of the system. There was a great increase in ammonia during the treatment and storage portions resulting in the ammonia being released. Whilst these losses resulted in a stable material, the decrease in nitrogen (62 7:) represented a significant nutrient loss. Conclusions A manure treatment system was investigated that provided a storable product. This product had the advantages of granular nature making it easy to handle, low pollution potential, and altered appearance, making it more acceptable as a soil conditioner. The product had the disadvantage of being low in nitrogen due to losses during treatment and storage. REFERENCES

Sobel, A. T. Undercage

drying

of laying hen manure.

Proc.

Cornell Agricultural

Waste Management

Conf., Ithaca, New York, 1972 187-200 Sobel, A. T.; Ludingion, D. C. Management research

investigations.

Sobel, A. T.; Ludington, D. C. Destruction animal

of laying hen manure

Proc. Cornell Agricultural

wastes. ASAE Pub]. Sobel, A. T. Physicalproperties

by moisture

Waste Management

of chicken

manure

removal-results

of several

Conf., 1977 549-579

by incineration.

Management

of farm

No. SP-0366. Proc. nat. Symp. Animal Waste Management, 1966 95-98 of animal manures associated with handling. ASAE Pub]. No. SP-0366. Proc. natn. Symp. Animal Waste Management, 1966 27-32 Hashimoto, A. G. Characterization of White Leghorn manures. Proc. Cornell University Agricultural Waste Management Conf., Ithaca, New York, 1974 141-152