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Incubation-derived calcium carbonate equivalence of papermill boiler ashes derived from sludge and wood sources
Environmental Pollution 79 (1993) 175-180
I N C U B A T I O N - D E R I V E D CALCIUM C A R B O N A T E EQUIVALENCE OF PAPERMILL BOILER ASHES D E R I V E D FROM S L U D G E A N D WOOD SOURCES Tsutomu Ohno & M. Susan Erich Department of Plant, Soil & Environmental Sciences, Deering Hall, University of Maine, Orono, ME 04469, USA (Received 29 July 1991; accepted 13 November 1991)
Abstract The burning of a papermill sludge and wood mixture and landspreading the resulting ash is a potential means of disposal of papermill sludge without the use of valuable landfill space. This study evaluated the effectiveness of ashes derived from a mixture of papermill sludge and wood sources to act as an alternative liming agent. The calcium carbonate equivalence of the material was determined using a 91-day laboratory incubation test with three mineral soils and one organic horizon soil. Application rates of soil-incorporated sludge-ash ranged from 2.30 to 32.2 g per kg soil. Soil pH increased linearly with increasing sludge-ash application rate. The calcium carbonate equivalence of the material varied temporally and the average value ranged from 19% to 28%. The fraction of total P, K and Mg added with the sludge-ash and extracted from the ash-amended soils using an NH4OAc based soil test method were 2.6, 3.8 and 17.6%, respectively. The low soil test extractability of ash-derived plant nutrients suggests that this material would provide only a modest increase in plant available nutrient levels in landspread fields.
potential means of disposing of this final by-product which would not require landfill space. Previous research has shown that wood-ash is an effective alternative liming agent for acid soils (Naylor & Schmidt, 1986; Ohno & Erich, 1990). In addition, wood ashes provide a modest quantity of plant nutrients (Erich, 1991; Erich & Ohno, in press). Landspreading of ash is subject to state regulations in the northeastern US. Currently a number of states including Maine, New Hampshire, Vermont, and New York have woodash utilization programs. In addition, some western US states (Idaho, Washington and Minnesota) are currently planning ash utilization regulations. Most state regulations are based on calcium carbonate equivalence (CCE) of the ash material. The objective of this study was to determine the CCE of sludgeash after a 3-month incubation in four different soils. Also, the potential nutrient supplying power of sludge-ash was evaluated by extraction of available plant nutrients from the sludge-ash amended soils at the end of the incubation. METHODS
INTRODUCTION
Soil and sludge-ash preparation Three soils were selected from the state of Maine that are potential sites for landspreading of sludge-ash. The surface organic horizon and the B horizon on a Marlow (coarse-loamy, mixed frigid Typic Fragiorthod) soil were collected from a forest site. The surface horizons of a Buxton (fine, illitic, frigid Aquic Dystric Eutrochrepts) and Adams (sandy, mixed frigid Typic Haplorthod) soils were collected from agricultural sites. All soils were sieved through a 5-mm screen to remove root fragments and gravel. The soils were homogenized by coning and quartering 5 times using a shovel and a plastic sheet. They were stored moist in large plastic bags and moisture percentages were determined before use for each. The papermill sludge-wood ash was collected monthly from October 1990 to January 1991 from the International Paper Corporation (Androscoggin) mill in Maine. The ash samples were dried and sieved through a 2-mm sieve to ensure a homogenous sample for use in this study.
Disposal of papermill sludge is a major solid waste problem for the pulp and paper industry. The estimated annual production of papermill sludge in 1985 was 2-1 million metric tons on a dry weight basis (Fuller & Warrick, 1985). In 1979, 86% of the papermill sludge was being landfilled (NCASI, 1984). With the cost of landfilling waste rising, alternative methods of disposal are being investigated. A new option for disposal of this residual is to burn the papermill sludge with a mixture of wood. This produces energy for the paper mill and also reduces the sludge:wood mix to a less voluminous ash material. Decrease in volume of the material by burning would save on landfill space required by the paper industry. Landspreading of the ash derived from burning a mixture of papermill sludge and wood [subsequently referred as sludge-ash] is a Environ. Pollut. 0269-7491/92/$05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain 175
176
Tsutomu Ohno, M. Susan Erich
Soil and ash characterization
Soil pH was determined using a 1 : 1 (soil:water) ratio for mineral soils and a 1 : 5 (soil : water) ratio for the organic horizon. The lime requirement was determined using the SMP single buffer method (McLean, 1982) with regressions developed locally (Glenn & Hoskins, 1989). The nutrient status of the soils was determined using a pH 3, 1 M NH4OAc extracting solution with subsequent determination of P, K, Mg and Ca concentrations using ICP (Glenn & Hoskins, 1989). Organic matter was determined using loss-on-ignition (Nelson & Sommers, 1982). The hydrometer method was used to determine the texture of all the mineral soils (Gee & Bauder, 1982). The ash was characterized for total elemental content by H F digestion (Lim & Jackson, 1982) and subsequent analysis by ICP. Acid extractable elements were determined by shaking overnight 1.000 g of ash with 50-0 ml of 0.1 N HC1 and determining the concentrations of the major cations in the filtered solution. The calcium carbonate equivalence was determined by AOAC protocol (Williams, 1984). Ash and lime incubations
All soils were incubated with both reagent-grade calcium carbonate and agricultural limestone (CCE = 93%, 42% retained by 80-mesh sieve) obtained locally to compare the effective liming potential of the sludge-ash to that of limestone. The mineral soil incubations consisted of moist soil equivalent to 300 g oven dry weight mixed with sludge-ash and the two limestone sources. The organic soil horizon incubations consisted of moist soil equivalent to 125 g oven dry weight mixed with sludge-ash and the two limestone sources. After mixing the soils with sludge-ash or limestone sources, the soils were transferred to plastic cups and weighed to determine the weight to which water would be added periodically to maintain field soil moisture levels. The cups were covered with paper to reduce evaporative loss. The soils were incubated for 91 days. The soils were dried for 48 h at 60°C prior to determining soil pH and nutrient content. R E S U L T S AND D I S C U S S I O N Chemical characteristics of soil and ash
Soil chemical properties are shown in Table 1. Soil pH of the selected soils ranged from 4.9 to 5.8 with
estimated lime requirement to attain pH 7 of 11.116-4 Mg ha ~ (Table 1). These soils were selected since acid soils would be used for landspreading materials which have acid neutralization capacity. In general, the nutrient status of the soils were in the low to medium range as determined by the University of Maine Soil Test. The Marlow, Buxton and Adams soil were classified as sandy loam, loam and loamy sand, respectively. The chemical composition of the sludge-ashes are shown in Table 2. The sludge-ash had higher total A1 content and lower total Ca content (Table 2) than wood ashes studied previously (Ohno & Erich, 1990). The elevated AI content is due to the use of aluminum sulfate in the paper making process. The elemental composition of the sludge-ashes differed from month to month which is typical of residual materials. The relative standard deviation (RSD) of the elements which were present in concentrations greater than 1 g kg 1 on a total basis ranged from 9.6% to 36.1%. The RSD of elements present in total concentrations less than 1 g kg~ ranged from 12.6% to 197%. The laboratory measured calcium carbonate equivalence using AOAC protocol of the October, November, December and January sludge-ashes were 22, 29, 21 and 18%, respectively. Extraction with 0.1 N HC1 was used to operationally define the fraction of the total concentration of elements (present in quantity greater than 1 g kg ~, except Ti) that was readily acid soluble (Table 3). Calcium, Mg, K and Mn were the most acid soluble elements with approximately half or greater of the total content being soluble in the acid solution (Fig. 1). Silicon, A1 and Fe which ranked as first, third and fourth most prevalent element present in the total elemental analysis had 0.1 N HC1 solubilities of 15% or lower. This suggests that these elements are part of a structural framework for the ashes and would be expected to be unreactive in acid soil environments. Less than 5% of total P content was acid soluble. Effect of sludge-ash and limestone on soil pH
The sludge-ash and limestone application rates for all soil treatments are shown in Table 4. The application rates for the mineral soils were based on 0, 1/3, 2/3 and 1 times the lime requirement for the soils and ranged from 2.30 g kg ~ at the 1/3 of lime requirement application rate to 11.47 g kg ~ for the full lime requirement application rate. The regression equation used by the Maine Soil Testing Service to calculate lime requirement
Table 1. Selected chemical and physical properties of the soils used
Soil
Marlow Marlow Organic Buxton Adams
pH
5-0 5.1 5.8 4-9
Lime req. (Mg ha t) 15.9 16.4 11.4 11.1
pH 3 NH4OAc Extraction P K Ca Mg (kg ha i) (kg ha L) (kg ha i) (kg ha l)
2.2 19.9 9.6 1-8
49 739 305 24
372 5 100 3 765 I 13
41 539 338 12
Loss-onignition (%)
Sand (%)
Slit (%)
Clay (%)
6-0 24.8 11.0 3.0
63 -43 83
32 -40 13
5 -17 4
Calcium carbonate equivalence of papermill boiler ashes 100
Table 2. Total elemental concentrations of the four papermill sludge-wood ashes used in the study Element
Ash Oct.
(g kg t) Si Ca AI Fe K Ti Mg Na Mn P (mg kg ~) Ba Zn Cu V Cr Ni Pb Sn Mo Cd
Nov.
Average RSD ~ (%)
Dec.
Jan.
"I"
Z
12.2 7.3 6.6 6.0 5.1 3-2 1.4
147 120 70-3 12.4 7.8 7.2 6-0 5.0 3-0 1-5
186 88.7 87-9 19.0 15-4 10.0 7-6 9.8 4-0 2.7
175 79.4 93-4 13.7 10.7 12.0 6-4 6.7 3-2 1-6
167 94.9 82.1 14-3 10.3 9-0 6.5 6-7 3.3 1.8
9.6 18.4 12-8
22.3 36-1 28-1 11-9 33-7 14.3 34.5
60
.,0
2
0
"~ E
40
IM U
"
kq
o Ca
455 300 95 86 81 57 41 <1 <1 <1
473 270 86 91 76 61 <20 <1 <1 <1
723 520 217 330 179 76 32 720 240 <1
546 600 207 230 75 66 33 9 <1 <1
549 423 151 184 103 65 32 183 61 <1
22-3 38.4 46-6 64.1 49.4 12-6 27.5 196 197 --
,, RSD = relative standard deviation. f r o m the S M P buffer m e t h o d was designed for m i n e r a l soils a n d u n d e r e s t i m a t e s the r e q u i r e m e n t for o r g a n i c soils. T h e a p p l i c a t i o n rates for the o r g a n i c soil were b a s e d on 0, 1, 2 a n d 3 times lime r e q u i r e m e n t a n d r a n g e d f r o m 10-3 to 32.2 g kg ~. These a m e n d m e n t rates which were s u b s t a n t i a l l y h i g h e r t h a n those for the m i n e r a l soils were selected to ensure a p H r e s p o n s e in the i n c u b a t i o n s ( T a b l e 4). F i g u r e s 2 - 5 s h o w the p H c h a n g e s which resulted f r o m the a d d i t i o n s o f ash, calcium c a r b o n a t e , a n d agric u l t u r a l l i m e s t o n e to the f o u r soils. L i n e a r regression e q u a t i o n s for each soil a n d s l u d g e - a s h c o m b i n a t i o n s are s h o w n in T a b l e 5. T h e c o r r e l a t i o n coefficients were 0.908 o r g r e a t e r for all c o m b i n a t i o n s except D e c e m b e r / A d a m s (r =- 0-875) a n d J a n u a r y / B u x t o n (r =
Element
Ash
Average (g kg ])
RSD, (%)
87,4 10,6 6.7 3-1 2.9 1-2 1.0 0.2 0.1
69.1 15-3 12.5 5.4 3.3 1-5 I-7 0.4 0.1
RSD = Relative standard deviation.
63.4 17.4 14.1 6-1 3.7 1.9 2.0 0-7 0-1
73-2 15.0 11.3 4.7 3-3 1-6 1.4 0-4 0.1
14.0 20.2 28.4 29-1 10.5 17.7 37.7 57.5 --
Mn
K
Na
AI
m m
Si
P
Fe
0.653) i n d i c a t i n g t h a t there was a linear effect o f s l u d g e - a s h a n d l i m e s t o n e a m e n d m e n t on soil p H . T h e two c o m b i n a t i o n s with relatively low r values were i n c l u d e d in s u b s e q u e n t d a t a analysis. T h e C C E o f the s l u d g e - a s h e s was c a l c u l a t e d by c o m p a r i n g the slopes o f regression lines for soil p H as a f u n c t i o n o f ash a n d lime a m e n d m e n t ( T a b l e 6). T h e r e c i p r o c a l o f the slope o f the regression line is equal to the a m o u n t o f s l u d g e - a s h o r C a C O 3 in g kg~ soil n e e d e d to p r o d u c e a p H c h a n g e o f 1 unit. D i v i d i n g the s l u d g e - a s h slope by the C a C O 3 slope gives the Table 4. Application rates of papermill sludge-wood ash and limestone used in the study Source
Soil
Application rate Low Medium (g kg 1) (g kg i)
High (g kg-1)
Oct.
Marlow-Organic Marlow Buxton Adams
10.7 3.5 2.5 2.4
21.4 6-9 5.0 4-8
32.2 10.4 7-4 7.3
Nov.
Marlow-Organic Marlow Buxton Adams
11-5 3.7 2-7 2.6
23.0 7.4 5.3 5.2
34.6 11-1 8-0 7.8
Dec.
Marlow-Organic Marlow Buxton Adams
11.8 3.8 2-7 2.7
23,7 7.6 5.5 5.3
35.5 11.5 8.2 8.0
Jan.
Marlow-Organic Marlow Buxton Adams
10.3 3.3 2.4 2-3
20.6 6.6 4.8 4.7
31.0 9-9 7.1 6-9
Limestone u Marlow Organic Marlow Buxton Adams
7.4 2.4 1.7 1.7
14.7 4.7 3-4 3-3
22-1 7-1 5.1 5.0
Oct. Nov. Dec. Jan. (g kg 1) (g kg 1) (g kg ]) (g kg l) 72.7 16-5 11.9 4-1 3-5 1.7 1.0 0.3 0.1
Mg
Fig. 1. Percent of the total concentrations of the major elements in sludge-ash that are soluble in 0-1 N HC1.
Table 3. Concentrations of 0-1 N HCI extractable elements of the four papermill sludge-wood ashes used in the study
Ca Si AI K Mg Mn Na Fe P
80
"2. O
_.e
158 91.6 76-7
177
Same application rate for reagent grade CaCO 3 and agricultural limestone.
Tsutomu Ohno, M. Susan Erich
178
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0 AGL I OCT
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O AGL
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4 0
i
i
10 20 30 --1 Wood Ash Application Rote. g kg soil
5.0
40
....
I
0
I
,,- - - g
I
I
2 4 6 8 Wood ASh Application Rate. g kg -1 soil
Fig. 2. Soil pH as a function of sludge-ash and limestone application rates for the Marlow-Organic soil.
Fig. 4. Soil pH as a function of sludge-ash and limestone application rates for the Buxton soil.
incubation-derived CCE for the sludge-ashes (Ohno & Erich, 1990). Reagent grade C a C O 3 increased soil pH more than an equal amount of agricultural limestone, for all soils and addition rates. The limestone had a laboratory CCE of 93% but an incubation derived CCE across the four soils of 70%. The reason for the difference between these two values was probably a slower rate of reaction by the agricultural limestone than by the calcium carbonate due to greater particle size compared to reagent grade CaCO3. The coarser size of the agricultural limestone results in less reactive surfaces than for the finer reagent grade CaCO3 . In addition, the agricultural limestone had a C a : M g mole ratio of 2.85:1. Dolomitic limestone reacts at about half the rate of calcitic limestone (Barber, 1984). The incubation derived CCE values for each of the
sludge-ash samples averaged over the four soils used in the incubations were not significantly different at the 5% level and essentially identical to CCE determined in the laboratory using AOAC protocol (Table 6). The range of average CCEs obtained for the sludge ashes in this study (19-28%) was in general lower and less variable than the CCEs reported for wood-ash (14-56%) using similar incubation methods (Ohno & Erich, 1990). The tighter range in incubated CCEs was probably due to the samples being collected from the same plant with variation only over time. The earlier wood-ash study used ash collected from different plants.
Effect of sludge-ash on plant nutrientlevels The release of plant nutrients from the January sludge-ash to soils was quantified by determining the
7 • OCT
[] Nov
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r DEC •
• OCT
/
n
~, DEC
,/11
JAN
•
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e/ pH
o
//
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JAN
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//
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o / °
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pH
/
/
_
/ o /
/ / y ~ o . ~ . ~
I
0
I
I
3 6 9 --1 Wood Ash Application Rote, g kg soil
4
12
Fig. 3. Soil pH as a function of sludge-ash and limestone application rates for the Marlow soil.
I
0
.....
~<%fo
~-~--~"
v
-
I
3 6 Wood Ash Application Rote, g kg -1 soil
9
Fig. 5. Soil pH as a function of sludge-ash and limestone application rates for the Adams soil.
Calcium carbonate equivalence of papermill boiler ashes
179
Table 5. Linear regression equations of soil pH as a function of papermill sludge-wood ash and limestone application rates for the soils used in the study
Soil Marlow-Organic
Marlow
Source
Regression equation
CaCO 3 Ag. LimeP October November December January
pH pH pH pH pH pH
= 4.31 + = 4.36 + = 4.18 + = 4.30 + -- 4.17 + = 4-29 +
0.104 ApRate, 0-065 ApRate 0,023 ApRate 0.025 ApRate 0.022 ApRate 0.016 ApRate
0-995 0.969 0.991 0.994 0.997 0.993
CaCO 3
pH pH pH pH pH pH
= 4-80 + = 4-67 + -- 4.61 + -- 4.53 + = 4.56 + = 4,50 +
0.303 ApRate 0-189 ApRate 0.067 ApRate 0-084 ApRate 0-061 ApRate 0.088 ApRate
0-991 0.984 0.987 0.973 0.989 0-990
pH pH pH pH pH pH
= : -= = :
5,20 + 5-20 + 5.16 + 5.16 + 5.20 + 5.21 +
0.194 ApRate 0.119 ApRate 0.037 ApRate 0.051 ApRate 0.038 ApRate 0-017 ApRate
0.999 0-995 0.915 0.995 0.974 0.653
pH pH pH pH pH pH
-- 4.87 + : 4.26 + = 4.61 + -- 4-56 + -- 4.73 + -- 4.69 +
0.527 ApRate 0-369 ApRate 0-155 ApRate 0.174 ApRate 0.105 ApRate 0.118 ApRate
0-969 0-963 0-908 0.944 0.875 0.919
Ag. Lime. October November December January Buxton
CaCO 3
Ag. Lime. October November December January Adams
r
CaCO 3
Ag. Lime. October November December January
ApRate = application rate in g (ash or limestone) kg-1 dry soil. h Ag.Lime = agricultural limestone. percentage of the total nutrient added by the sludge-ash amendment that was extracted into the pH 3, 1 M NH4OAc soil test extraction (soil test level at highest sludge-ash rate minus control soil test levels). The percent availability indexes for P, K and Mg for the nutrients were 2.6%, 3.8% and 17.6%, respectively. The average nutrient availability of the sludge-ash were
lower than those found for wood ash (P -- 5.7% available, K -- 40% and Mg -- 48%) using the same soil test (Ohno & Erich, 1990). The lower nutrient availability of the sludge-ash in conjunction with lower total nutrient content suggests that the ability of sludge-ash to act as a supplemental fertilizer source is limited.
Table 6. Incubation-derived CCE values for each soil:papermill sludge-wood ash treatment combination and monthly averages relative to reagent grade CaCO3
SUMMARY
Ash
Soil
%CCE
Average % CCE
October
Marlow-Organic Marlow Buxton Adams
22 22 19 29
23
November
Marlow-Organic Marlow Buxton Adams
24 28 26 33
28
December
Marlow Organic Marlow Buxton Adams
21 20 20 20
20
January
Marlow-Organic Marlow Buxton Adams
15 29 9 22
19
This laboratory incubation study suggests that papermill sludge-wood ash which has an incubation-derived CCE of 19-28% could be landspread on both agricultural and forest soils which are low in pH. Since most states regulate ash spreading on the basis of CCE based application rate, higher loading rates are feasible due to the relatively low acid neutralizing capacities of this residual material. The variability in the CCE of sludgeash suggests that analysis of the actual material being landspread will be required to determine the correct loading rates. Due to the relatively low extractability of the sludge-ash derived plant nutrients, as measured by the NH4OAc extractant, this material is an acceptable alternative liming agent with essentially no supplemental fertilizer value.
ACKNOWLEDGEMENTS This work was funded by International Paper Corporation. Maine Agricultural Experiment Station Publication No. 1609.
180
Tsutomu Ohno, M. Susan Erich
REFERENCES Barber, S. A. (1984). Liming materials and practices. In Soil Acidity and Liming, ed. F. Adams. American Society of Agronomy, Madison, WI, pp. 171-209. Erich, M. S. (1991). Agronomic effectiveness of wood ash as a phosphorus and potassium source. J. Environ. Qual., 20, 576-81. Erich, M. S. & Ohno, T. (1992). Phosphorus availability to corn from wood ash-amended soils. Water, Air, Soil Pollut., (in press). Fuller, W. H. & Warrick, A. W. (1985). Soils in Waste Treatment and Utilization. Vol. I. Land Treatment. CRC Press, Boca Raton, FL, 81 pp. Gee, G. N. & Bauder, J. W. (1982). Particle-size analysis. In
Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods, ed. A. Klute. Soil Sci. Soc. Am., Madison, WI, pp. 383~,12. Glenn, R. C. & Hoskins, B. R. (1989). Soil Testing Handbook for Professional Agriculturalists. 2nd ed. Univ. of Maine Cooperative Extension, Orono, ME. Lim, C. H. & Jackson, M. L. (1982). Dissolution for total elemental analysis. In Methods" of Soil Analysis'. Part 2. Chemical and Microbiological Properties, ed. A. L. Page, R.
H. Miller & D. R. Keeney. Soil Sci. Soc. Am., Madison, WI, pp. 1-12. McLean, E. O. (1982). Soil pH and lime requirement. In
Methods of Soil Analysis. Part. 2. Chemical and Microbiological Properties, ed. A. L. Page, R. H. Miller & D. R. Keeney, Soil Sci. Soc. Am., Madison, WI, pp. 199-224. National Council of the Paper Industry for Air and Stream Improvement, Inc. (1984). The land application and related utilization of pulp and papermill sludges. Tech. Bull. 439. NCASI, New York. Naylor, L. M. & Schmidt, E. J. (1986). Agricultural use of wood ash as a fertilizer and liming material. Tappi J., 69, 11~19. Nelson, D. W. & Sommers, L. E. (1982). Total carbon, organic carbon, and organic matter. In Methods of Soil
Analysis. Part. 2. Chemical and Microbiological Properties, ed. A. L. Page, R. H. Miller & D. R. Keeney. Soil Sci. Soc. Am., Madison, WI, pp. 539-79. Ohno, T. & Erich, M. S. (1990). Effect of wood ash application on soil pH and soil test nutrient levels. Agric. EeosTstems Environ., 32, 223 39. Williams, S. (1984). Official Methods of Analysis" of the Association of Official Analytical Chemists. A O A C Inc., Arlington, VA. p. 1.
I N C U B A T I O N - D E R I V E D CALCIUM C A R B O N A T E EQUIVALENCE OF PAPERMILL BOILER ASHES D E R I V E D FROM S L U D G E A N D WOOD SOURCES Tsutomu Ohno & M. Susan Erich Department of Plant, Soil & Environmental Sciences, Deering Hall, University of Maine, Orono, ME 04469, USA (Received 29 July 1991; accepted 13 November 1991)
Abstract The burning of a papermill sludge and wood mixture and landspreading the resulting ash is a potential means of disposal of papermill sludge without the use of valuable landfill space. This study evaluated the effectiveness of ashes derived from a mixture of papermill sludge and wood sources to act as an alternative liming agent. The calcium carbonate equivalence of the material was determined using a 91-day laboratory incubation test with three mineral soils and one organic horizon soil. Application rates of soil-incorporated sludge-ash ranged from 2.30 to 32.2 g per kg soil. Soil pH increased linearly with increasing sludge-ash application rate. The calcium carbonate equivalence of the material varied temporally and the average value ranged from 19% to 28%. The fraction of total P, K and Mg added with the sludge-ash and extracted from the ash-amended soils using an NH4OAc based soil test method were 2.6, 3.8 and 17.6%, respectively. The low soil test extractability of ash-derived plant nutrients suggests that this material would provide only a modest increase in plant available nutrient levels in landspread fields.
potential means of disposing of this final by-product which would not require landfill space. Previous research has shown that wood-ash is an effective alternative liming agent for acid soils (Naylor & Schmidt, 1986; Ohno & Erich, 1990). In addition, wood ashes provide a modest quantity of plant nutrients (Erich, 1991; Erich & Ohno, in press). Landspreading of ash is subject to state regulations in the northeastern US. Currently a number of states including Maine, New Hampshire, Vermont, and New York have woodash utilization programs. In addition, some western US states (Idaho, Washington and Minnesota) are currently planning ash utilization regulations. Most state regulations are based on calcium carbonate equivalence (CCE) of the ash material. The objective of this study was to determine the CCE of sludgeash after a 3-month incubation in four different soils. Also, the potential nutrient supplying power of sludge-ash was evaluated by extraction of available plant nutrients from the sludge-ash amended soils at the end of the incubation. METHODS
INTRODUCTION
Soil and sludge-ash preparation Three soils were selected from the state of Maine that are potential sites for landspreading of sludge-ash. The surface organic horizon and the B horizon on a Marlow (coarse-loamy, mixed frigid Typic Fragiorthod) soil were collected from a forest site. The surface horizons of a Buxton (fine, illitic, frigid Aquic Dystric Eutrochrepts) and Adams (sandy, mixed frigid Typic Haplorthod) soils were collected from agricultural sites. All soils were sieved through a 5-mm screen to remove root fragments and gravel. The soils were homogenized by coning and quartering 5 times using a shovel and a plastic sheet. They were stored moist in large plastic bags and moisture percentages were determined before use for each. The papermill sludge-wood ash was collected monthly from October 1990 to January 1991 from the International Paper Corporation (Androscoggin) mill in Maine. The ash samples were dried and sieved through a 2-mm sieve to ensure a homogenous sample for use in this study.
Disposal of papermill sludge is a major solid waste problem for the pulp and paper industry. The estimated annual production of papermill sludge in 1985 was 2-1 million metric tons on a dry weight basis (Fuller & Warrick, 1985). In 1979, 86% of the papermill sludge was being landfilled (NCASI, 1984). With the cost of landfilling waste rising, alternative methods of disposal are being investigated. A new option for disposal of this residual is to burn the papermill sludge with a mixture of wood. This produces energy for the paper mill and also reduces the sludge:wood mix to a less voluminous ash material. Decrease in volume of the material by burning would save on landfill space required by the paper industry. Landspreading of the ash derived from burning a mixture of papermill sludge and wood [subsequently referred as sludge-ash] is a Environ. Pollut. 0269-7491/92/$05.00 © 1992 Elsevier Science Publishers Ltd, England. Printed in Great Britain 175
176
Tsutomu Ohno, M. Susan Erich
Soil and ash characterization
Soil pH was determined using a 1 : 1 (soil:water) ratio for mineral soils and a 1 : 5 (soil : water) ratio for the organic horizon. The lime requirement was determined using the SMP single buffer method (McLean, 1982) with regressions developed locally (Glenn & Hoskins, 1989). The nutrient status of the soils was determined using a pH 3, 1 M NH4OAc extracting solution with subsequent determination of P, K, Mg and Ca concentrations using ICP (Glenn & Hoskins, 1989). Organic matter was determined using loss-on-ignition (Nelson & Sommers, 1982). The hydrometer method was used to determine the texture of all the mineral soils (Gee & Bauder, 1982). The ash was characterized for total elemental content by H F digestion (Lim & Jackson, 1982) and subsequent analysis by ICP. Acid extractable elements were determined by shaking overnight 1.000 g of ash with 50-0 ml of 0.1 N HC1 and determining the concentrations of the major cations in the filtered solution. The calcium carbonate equivalence was determined by AOAC protocol (Williams, 1984). Ash and lime incubations
All soils were incubated with both reagent-grade calcium carbonate and agricultural limestone (CCE = 93%, 42% retained by 80-mesh sieve) obtained locally to compare the effective liming potential of the sludge-ash to that of limestone. The mineral soil incubations consisted of moist soil equivalent to 300 g oven dry weight mixed with sludge-ash and the two limestone sources. The organic soil horizon incubations consisted of moist soil equivalent to 125 g oven dry weight mixed with sludge-ash and the two limestone sources. After mixing the soils with sludge-ash or limestone sources, the soils were transferred to plastic cups and weighed to determine the weight to which water would be added periodically to maintain field soil moisture levels. The cups were covered with paper to reduce evaporative loss. The soils were incubated for 91 days. The soils were dried for 48 h at 60°C prior to determining soil pH and nutrient content. R E S U L T S AND D I S C U S S I O N Chemical characteristics of soil and ash
Soil chemical properties are shown in Table 1. Soil pH of the selected soils ranged from 4.9 to 5.8 with
estimated lime requirement to attain pH 7 of 11.116-4 Mg ha ~ (Table 1). These soils were selected since acid soils would be used for landspreading materials which have acid neutralization capacity. In general, the nutrient status of the soils were in the low to medium range as determined by the University of Maine Soil Test. The Marlow, Buxton and Adams soil were classified as sandy loam, loam and loamy sand, respectively. The chemical composition of the sludge-ashes are shown in Table 2. The sludge-ash had higher total A1 content and lower total Ca content (Table 2) than wood ashes studied previously (Ohno & Erich, 1990). The elevated AI content is due to the use of aluminum sulfate in the paper making process. The elemental composition of the sludge-ashes differed from month to month which is typical of residual materials. The relative standard deviation (RSD) of the elements which were present in concentrations greater than 1 g kg 1 on a total basis ranged from 9.6% to 36.1%. The RSD of elements present in total concentrations less than 1 g kg~ ranged from 12.6% to 197%. The laboratory measured calcium carbonate equivalence using AOAC protocol of the October, November, December and January sludge-ashes were 22, 29, 21 and 18%, respectively. Extraction with 0.1 N HC1 was used to operationally define the fraction of the total concentration of elements (present in quantity greater than 1 g kg ~, except Ti) that was readily acid soluble (Table 3). Calcium, Mg, K and Mn were the most acid soluble elements with approximately half or greater of the total content being soluble in the acid solution (Fig. 1). Silicon, A1 and Fe which ranked as first, third and fourth most prevalent element present in the total elemental analysis had 0.1 N HC1 solubilities of 15% or lower. This suggests that these elements are part of a structural framework for the ashes and would be expected to be unreactive in acid soil environments. Less than 5% of total P content was acid soluble. Effect of sludge-ash and limestone on soil pH
The sludge-ash and limestone application rates for all soil treatments are shown in Table 4. The application rates for the mineral soils were based on 0, 1/3, 2/3 and 1 times the lime requirement for the soils and ranged from 2.30 g kg ~ at the 1/3 of lime requirement application rate to 11.47 g kg ~ for the full lime requirement application rate. The regression equation used by the Maine Soil Testing Service to calculate lime requirement
Table 1. Selected chemical and physical properties of the soils used
Soil
Marlow Marlow Organic Buxton Adams
pH
5-0 5.1 5.8 4-9
Lime req. (Mg ha t) 15.9 16.4 11.4 11.1
pH 3 NH4OAc Extraction P K Ca Mg (kg ha i) (kg ha L) (kg ha i) (kg ha l)
2.2 19.9 9.6 1-8
49 739 305 24
372 5 100 3 765 I 13
41 539 338 12
Loss-onignition (%)
Sand (%)
Slit (%)
Clay (%)
6-0 24.8 11.0 3.0
63 -43 83
32 -40 13
5 -17 4
Calcium carbonate equivalence of papermill boiler ashes 100
Table 2. Total elemental concentrations of the four papermill sludge-wood ashes used in the study Element
Ash Oct.
(g kg t) Si Ca AI Fe K Ti Mg Na Mn P (mg kg ~) Ba Zn Cu V Cr Ni Pb Sn Mo Cd
Nov.
Average RSD ~ (%)
Dec.
Jan.
"I"
Z
12.2 7.3 6.6 6.0 5.1 3-2 1.4
147 120 70-3 12.4 7.8 7.2 6-0 5.0 3-0 1-5
186 88.7 87-9 19.0 15-4 10.0 7-6 9.8 4-0 2.7
175 79.4 93-4 13.7 10.7 12.0 6-4 6.7 3-2 1-6
167 94.9 82.1 14-3 10.3 9-0 6.5 6-7 3.3 1.8
9.6 18.4 12-8
22.3 36-1 28-1 11-9 33-7 14.3 34.5
60
.,0
2
0
"~ E
40
IM U
"
kq
o Ca
455 300 95 86 81 57 41 <1 <1 <1
473 270 86 91 76 61 <20 <1 <1 <1
723 520 217 330 179 76 32 720 240 <1
546 600 207 230 75 66 33 9 <1 <1
549 423 151 184 103 65 32 183 61 <1
22-3 38.4 46-6 64.1 49.4 12-6 27.5 196 197 --
,, RSD = relative standard deviation. f r o m the S M P buffer m e t h o d was designed for m i n e r a l soils a n d u n d e r e s t i m a t e s the r e q u i r e m e n t for o r g a n i c soils. T h e a p p l i c a t i o n rates for the o r g a n i c soil were b a s e d on 0, 1, 2 a n d 3 times lime r e q u i r e m e n t a n d r a n g e d f r o m 10-3 to 32.2 g kg ~. These a m e n d m e n t rates which were s u b s t a n t i a l l y h i g h e r t h a n those for the m i n e r a l soils were selected to ensure a p H r e s p o n s e in the i n c u b a t i o n s ( T a b l e 4). F i g u r e s 2 - 5 s h o w the p H c h a n g e s which resulted f r o m the a d d i t i o n s o f ash, calcium c a r b o n a t e , a n d agric u l t u r a l l i m e s t o n e to the f o u r soils. L i n e a r regression e q u a t i o n s for each soil a n d s l u d g e - a s h c o m b i n a t i o n s are s h o w n in T a b l e 5. T h e c o r r e l a t i o n coefficients were 0.908 o r g r e a t e r for all c o m b i n a t i o n s except D e c e m b e r / A d a m s (r =- 0-875) a n d J a n u a r y / B u x t o n (r =
Element
Ash
Average (g kg ])
RSD, (%)
87,4 10,6 6.7 3-1 2.9 1-2 1.0 0.2 0.1
69.1 15-3 12.5 5.4 3.3 1-5 I-7 0.4 0.1
RSD = Relative standard deviation.
63.4 17.4 14.1 6-1 3.7 1.9 2.0 0-7 0-1
73-2 15.0 11.3 4.7 3-3 1-6 1.4 0-4 0.1
14.0 20.2 28.4 29-1 10.5 17.7 37.7 57.5 --
Mn
K
Na
AI
m m
Si
P
Fe
0.653) i n d i c a t i n g t h a t there was a linear effect o f s l u d g e - a s h a n d l i m e s t o n e a m e n d m e n t on soil p H . T h e two c o m b i n a t i o n s with relatively low r values were i n c l u d e d in s u b s e q u e n t d a t a analysis. T h e C C E o f the s l u d g e - a s h e s was c a l c u l a t e d by c o m p a r i n g the slopes o f regression lines for soil p H as a f u n c t i o n o f ash a n d lime a m e n d m e n t ( T a b l e 6). T h e r e c i p r o c a l o f the slope o f the regression line is equal to the a m o u n t o f s l u d g e - a s h o r C a C O 3 in g kg~ soil n e e d e d to p r o d u c e a p H c h a n g e o f 1 unit. D i v i d i n g the s l u d g e - a s h slope by the C a C O 3 slope gives the Table 4. Application rates of papermill sludge-wood ash and limestone used in the study Source
Soil
Application rate Low Medium (g kg 1) (g kg i)
High (g kg-1)
Oct.
Marlow-Organic Marlow Buxton Adams
10.7 3.5 2.5 2.4
21.4 6-9 5.0 4-8
32.2 10.4 7-4 7.3
Nov.
Marlow-Organic Marlow Buxton Adams
11-5 3.7 2-7 2.6
23.0 7.4 5.3 5.2
34.6 11-1 8-0 7.8
Dec.
Marlow-Organic Marlow Buxton Adams
11.8 3.8 2-7 2.7
23,7 7.6 5.5 5.3
35.5 11.5 8.2 8.0
Jan.
Marlow-Organic Marlow Buxton Adams
10.3 3.3 2.4 2-3
20.6 6.6 4.8 4.7
31.0 9-9 7.1 6-9
Limestone u Marlow Organic Marlow Buxton Adams
7.4 2.4 1.7 1.7
14.7 4.7 3-4 3-3
22-1 7-1 5.1 5.0
Oct. Nov. Dec. Jan. (g kg 1) (g kg 1) (g kg ]) (g kg l) 72.7 16-5 11.9 4-1 3-5 1.7 1.0 0.3 0.1
Mg
Fig. 1. Percent of the total concentrations of the major elements in sludge-ash that are soluble in 0-1 N HC1.
Table 3. Concentrations of 0-1 N HCI extractable elements of the four papermill sludge-wood ashes used in the study
Ca Si AI K Mg Mn Na Fe P
80
"2. O
_.e
158 91.6 76-7
177
Same application rate for reagent grade CaCO 3 and agricultural limestone.
Tsutomu Ohno, M. Susan Erich
178
6.5 •
CC
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0 AGL I OCT
7
/
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•
6
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/Buxton
O AGL
/
I OCT 0 NOV v DEc
/
/
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•
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/'/~ ~
/ 0/
/
/
/
/
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J
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t
4 0
i
i
10 20 30 --1 Wood Ash Application Rote. g kg soil
5.0
40
....
I
0
I
,,- - - g
I
I
2 4 6 8 Wood ASh Application Rate. g kg -1 soil
Fig. 2. Soil pH as a function of sludge-ash and limestone application rates for the Marlow-Organic soil.
Fig. 4. Soil pH as a function of sludge-ash and limestone application rates for the Buxton soil.
incubation-derived CCE for the sludge-ashes (Ohno & Erich, 1990). Reagent grade C a C O 3 increased soil pH more than an equal amount of agricultural limestone, for all soils and addition rates. The limestone had a laboratory CCE of 93% but an incubation derived CCE across the four soils of 70%. The reason for the difference between these two values was probably a slower rate of reaction by the agricultural limestone than by the calcium carbonate due to greater particle size compared to reagent grade CaCO3. The coarser size of the agricultural limestone results in less reactive surfaces than for the finer reagent grade CaCO3 . In addition, the agricultural limestone had a C a : M g mole ratio of 2.85:1. Dolomitic limestone reacts at about half the rate of calcitic limestone (Barber, 1984). The incubation derived CCE values for each of the
sludge-ash samples averaged over the four soils used in the incubations were not significantly different at the 5% level and essentially identical to CCE determined in the laboratory using AOAC protocol (Table 6). The range of average CCEs obtained for the sludge ashes in this study (19-28%) was in general lower and less variable than the CCEs reported for wood-ash (14-56%) using similar incubation methods (Ohno & Erich, 1990). The tighter range in incubated CCEs was probably due to the samples being collected from the same plant with variation only over time. The earlier wood-ash study used ash collected from different plants.
Effect of sludge-ash on plant nutrientlevels The release of plant nutrients from the January sludge-ash to soils was quantified by determining the
7 • OCT
[] Nov
j-
r DEC •
• OCT
/
n
~, DEC
,/11
JAN
•
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o
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pH
/
/
_
/ o /
/ / y ~ o . ~ . ~
I
0
I
I
3 6 9 --1 Wood Ash Application Rote, g kg soil
4
12
Fig. 3. Soil pH as a function of sludge-ash and limestone application rates for the Marlow soil.
I
0
.....
~<%fo
~-~--~"
v
-
I
3 6 Wood Ash Application Rote, g kg -1 soil
9
Fig. 5. Soil pH as a function of sludge-ash and limestone application rates for the Adams soil.
Calcium carbonate equivalence of papermill boiler ashes
179
Table 5. Linear regression equations of soil pH as a function of papermill sludge-wood ash and limestone application rates for the soils used in the study
Soil Marlow-Organic
Marlow
Source
Regression equation
CaCO 3 Ag. LimeP October November December January
pH pH pH pH pH pH
= 4.31 + = 4.36 + = 4.18 + = 4.30 + -- 4.17 + = 4-29 +
0.104 ApRate, 0-065 ApRate 0,023 ApRate 0.025 ApRate 0.022 ApRate 0.016 ApRate
0-995 0.969 0.991 0.994 0.997 0.993
CaCO 3
pH pH pH pH pH pH
= 4-80 + = 4-67 + -- 4.61 + -- 4.53 + = 4.56 + = 4,50 +
0.303 ApRate 0-189 ApRate 0.067 ApRate 0-084 ApRate 0-061 ApRate 0.088 ApRate
0-991 0.984 0.987 0.973 0.989 0-990
pH pH pH pH pH pH
= : -= = :
5,20 + 5-20 + 5.16 + 5.16 + 5.20 + 5.21 +
0.194 ApRate 0.119 ApRate 0.037 ApRate 0.051 ApRate 0.038 ApRate 0-017 ApRate
0.999 0-995 0.915 0.995 0.974 0.653
pH pH pH pH pH pH
-- 4.87 + : 4.26 + = 4.61 + -- 4-56 + -- 4.73 + -- 4.69 +
0.527 ApRate 0-369 ApRate 0-155 ApRate 0.174 ApRate 0.105 ApRate 0.118 ApRate
0-969 0-963 0-908 0.944 0.875 0.919
Ag. Lime. October November December January Buxton
CaCO 3
Ag. Lime. October November December January Adams
r
CaCO 3
Ag. Lime. October November December January
ApRate = application rate in g (ash or limestone) kg-1 dry soil. h Ag.Lime = agricultural limestone. percentage of the total nutrient added by the sludge-ash amendment that was extracted into the pH 3, 1 M NH4OAc soil test extraction (soil test level at highest sludge-ash rate minus control soil test levels). The percent availability indexes for P, K and Mg for the nutrients were 2.6%, 3.8% and 17.6%, respectively. The average nutrient availability of the sludge-ash were
lower than those found for wood ash (P -- 5.7% available, K -- 40% and Mg -- 48%) using the same soil test (Ohno & Erich, 1990). The lower nutrient availability of the sludge-ash in conjunction with lower total nutrient content suggests that the ability of sludge-ash to act as a supplemental fertilizer source is limited.
Table 6. Incubation-derived CCE values for each soil:papermill sludge-wood ash treatment combination and monthly averages relative to reagent grade CaCO3
SUMMARY
Ash
Soil
%CCE
Average % CCE
October
Marlow-Organic Marlow Buxton Adams
22 22 19 29
23
November
Marlow-Organic Marlow Buxton Adams
24 28 26 33
28
December
Marlow Organic Marlow Buxton Adams
21 20 20 20
20
January
Marlow-Organic Marlow Buxton Adams
15 29 9 22
19
This laboratory incubation study suggests that papermill sludge-wood ash which has an incubation-derived CCE of 19-28% could be landspread on both agricultural and forest soils which are low in pH. Since most states regulate ash spreading on the basis of CCE based application rate, higher loading rates are feasible due to the relatively low acid neutralizing capacities of this residual material. The variability in the CCE of sludgeash suggests that analysis of the actual material being landspread will be required to determine the correct loading rates. Due to the relatively low extractability of the sludge-ash derived plant nutrients, as measured by the NH4OAc extractant, this material is an acceptable alternative liming agent with essentially no supplemental fertilizer value.
ACKNOWLEDGEMENTS This work was funded by International Paper Corporation. Maine Agricultural Experiment Station Publication No. 1609.
180
Tsutomu Ohno, M. Susan Erich
REFERENCES Barber, S. A. (1984). Liming materials and practices. In Soil Acidity and Liming, ed. F. Adams. American Society of Agronomy, Madison, WI, pp. 171-209. Erich, M. S. (1991). Agronomic effectiveness of wood ash as a phosphorus and potassium source. J. Environ. Qual., 20, 576-81. Erich, M. S. & Ohno, T. (1992). Phosphorus availability to corn from wood ash-amended soils. Water, Air, Soil Pollut., (in press). Fuller, W. H. & Warrick, A. W. (1985). Soils in Waste Treatment and Utilization. Vol. I. Land Treatment. CRC Press, Boca Raton, FL, 81 pp. Gee, G. N. & Bauder, J. W. (1982). Particle-size analysis. In
Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods, ed. A. Klute. Soil Sci. Soc. Am., Madison, WI, pp. 383~,12. Glenn, R. C. & Hoskins, B. R. (1989). Soil Testing Handbook for Professional Agriculturalists. 2nd ed. Univ. of Maine Cooperative Extension, Orono, ME. Lim, C. H. & Jackson, M. L. (1982). Dissolution for total elemental analysis. In Methods" of Soil Analysis'. Part 2. Chemical and Microbiological Properties, ed. A. L. Page, R.
H. Miller & D. R. Keeney. Soil Sci. Soc. Am., Madison, WI, pp. 1-12. McLean, E. O. (1982). Soil pH and lime requirement. In
Methods of Soil Analysis. Part. 2. Chemical and Microbiological Properties, ed. A. L. Page, R. H. Miller & D. R. Keeney, Soil Sci. Soc. Am., Madison, WI, pp. 199-224. National Council of the Paper Industry for Air and Stream Improvement, Inc. (1984). The land application and related utilization of pulp and papermill sludges. Tech. Bull. 439. NCASI, New York. Naylor, L. M. & Schmidt, E. J. (1986). Agricultural use of wood ash as a fertilizer and liming material. Tappi J., 69, 11~19. Nelson, D. W. & Sommers, L. E. (1982). Total carbon, organic carbon, and organic matter. In Methods of Soil
Analysis. Part. 2. Chemical and Microbiological Properties, ed. A. L. Page, R. H. Miller & D. R. Keeney. Soil Sci. Soc. Am., Madison, WI, pp. 539-79. Ohno, T. & Erich, M. S. (1990). Effect of wood ash application on soil pH and soil test nutrient levels. Agric. EeosTstems Environ., 32, 223 39. Williams, S. (1984). Official Methods of Analysis" of the Association of Official Analytical Chemists. A O A C Inc., Arlington, VA. p. 1.