Paper Mill Boiler Ash and Lime By‐Products as Soil Liming Materials

Abstract

The pulp and paper industry in the southeastern USA produces ≈ 6500 t of boiler ash and lime by‐products (waste lime, grit, and dregs) daily. A survey of 88 pulp and paper mills indicated that most of these by‐products are placed in landfills, with only 10% being land‐applied. Seventeen boiler ash samples and 14 lime by‐products from 12 Alabama pulp and paper mills were analyzed and evaluated for their potential as soil liming materials. Most boiler ash resulted from the burning of wood or wood in combination with other materials and averaged 37% calcium carbonate equivalent (CCE), while 14 lime by‐products averaged 99% CCE. In an 84‐d incubation study, boiler ash and lime by‐products applied to an acid (pH = 5.2) Marvyn loamy sand (fine‐loamy, siliceous, thermic, Typic Kanhapludults) at equivalent rates based on CCE resulted in mean pH values significantly higher than values achieved with agricultural lime. All materials increased Mehlich‐1 extractable P, K, and Mg. In a field study conducted on an acid (pH = 5.1) Vaiden clay (very‐fine, montmorillonitic, thermic Vertic Hapludalfs), dallisgrass‐fescue (Paspalum dilatatum Poir.‐Festuca arundinacea Schreb.) herbage yield increased 62% the second year and 49% the third year after surface application of boiler ash, lime by‐products, and agricultural lime.

Nutrient leaching potential following application of papermill lime-sludge to an acidic clay soil

“…Limesludge had alkaline pH (9.7); low total organic matter (44 mg kg -1 ); high Ca, Na, S, Fe, and Mn concentrations (321, 39, 7, 2.6 g kg -1 , and 415 mg kg -1 , respectively); average Zn concentration (62 mg kg -1 ); low Mg concentration (2.5 g kg -1 ), and very low concentrations of other metals and other constituents (1.22 g kg -1 P, 1.33 g kg -1 K, and 3 mg kg -1 Cu); with the exception of S and Cu, concentrations were within ranges previously reported (Simson et al, 1981;Stappe & Balloni, 1988;Benedetti, 1994;Muse & Mitchell, 1995 (< 0.3 mm ≅ 97%), and this material is classified as industrial calcitic lime (Bergamin et al, 1994). The calcium carbonate equivalency of this lime-sludge was about 81%.…”

“…The calcium carbonate equivalency of this lime-sludge was about 81%. Taking into account the liming value of lime-sludge and the quantities produced by the pulp and paper industry (an average of 3,000 t per year was produced by each Brazilian mill), this material can be considered as under utilized as a soil liming amendment, due to the low number of land application programs in the southeast United States (Muse & Mitchell, 1995) and Brazil.…”

“…Leachate pH values were positively correlated with leachate PO 4 concentration (r = 0.709, P < 0.01), leachate SO 4 concentration (r = 0.915, P < 0.01), and leachate Na concentration (r = 0.925, P < 0.01) and negatively correlated with leachate NO 3 concentration (r = -0.511, P < 0.05) and leachate Mg concentration (r = -0.591, P < 0.05). These increases in the leachate pH values were due to the presence of carbonates, oxides, hydroxides, and other alkaline compounds (40 g kg -1 of Na, Table 2) in the lime-sludge chemical composition (Simson et al, 1981;Muse & Mitchell, 1995). At the end of the experiment (210 days), differences in leachate pH values between control and lime-sludge treatments were still significant, but no difference was observed between 4 t ha -1 treatment and 6 t ha -1 treatment.…”

“…One of these, limesludge, results from a process designed to recover high cost chemicals from the digestion liquor used in the kraft paper process (Simson et al, 1981;Muse & Mitchell, 1995). Calcium oxide reacts with spent (used) liquor, yielding mainly CaCO 3 , NaOH, and Na 2 S. These materials are filtered and washed to recover NaOH and Na 2 S. The CaCO 3 can be converted back to CaO in a lime-kiln.…”

Biomass ashes and their phosphorus fertilizing effect on different crops

“…Furthermore, biomass ashes can also be used as liming agents (Clapham and Zibilske 1992;Muse and Mitchell 1995;Mozaffari et al 2002;Nkana et al 2002;Odlare 2005;Mandre 2006). Ash application can stimulate the microbial activities and mineralization processes in the soil by amelioration of chemical and physical characteristics (Demeyer et al 2001).…”