Potential use of wood ash in South African forestry: a review

Scheepers, G.P.; Toit, Ben du

doi:10.2989/20702620.2016.1230716

Cited by 23 publications

(27 citation statements)

References 49 publications

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“…The combustion temperature largely affects the chemical properties and quantity of ash produced. The amount of organic matter and heavy metal contents in the ash are also associated with the combustion temperature [6,15]. Due to the oxidation of carbon and nitrogen compounds during the combustion process, which form gaseous compounds, their quantity in PPFA is generally low [32].…”

Section: Chemical Propertiesmentioning

confidence: 99%

“…Currently, pulp and paper mill fly ash (PPFA) is often treated as a nonhazardous commercial waste product and is landfilled at a cost to producers and to society at large. However, landfilling will tend to be reduced or banned in the future due to stringent environmental regulations, rising disposal costs, and the scarcity of landfill space [3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

“…More than 35% of the wood chips entering a pulp mill becomes residue, mainly in the form of sludge and reject material [30]. The primary sludge generated in the pulp mills is commonly landfilled at the source point itself, while the dry sludge is sometimes reused to fuel the boilers [6]. The liquid waste undergoes primary treatment in sedimentation tanks to remove suspended solids.…”

Section: Introductionmentioning

confidence: 99%

“…It was identified from a literature review that modified pulp and paper mill fly ash can be environmentally and economically advantageous over commercial coal-based fly ash in various sustainable applications.Sustainability 2019, 11, 4394 2 of 16 use of compost products, etc., are drawbacks of composting [10]. Contaminant-free PPFA has great significance as a soil liming agent and fertilizer in agriculture and forestry [6,11]; however, its direct application requires safety precautions due to its undesirable handling and spreading characteristics and associated health risks [12,13]. Further, high pH and electrical conductivity values of pore water in wood ash might have perturbing effects on the microbial community [14].…”

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Pulp and Paper Mill Fly Ash: A Review

Cherian

Siddiqua

2019

Sustainability

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The continual growth of pulp and paper industry has led to the generation of tremendous volumes of fly ash as byproducts of biomass combustion processes. Commonly, a major part of it is landfilled; however, updated environmental regulations have tended to restrict the landfilling of fly ash due to rising disposal costs and the scarcity of suitable land. The pulp and paper industries are therefore urgently seeking energy-efficient mechanisms and management for the beneficial use of fly ash in an ecological and economical manner. This paper offers a comprehensive review of existing knowledge on the major physicochemical and toxicological properties of pulp and paper mill fly ash to assess its suitability for various bound and unbound applications. The current state of various methods used for the valorization of pulp and paper mill fly ash into more sustainable geomaterials is briefly discussed. This paper also presents promising and innovative applications for pulp and paper mill fly ash, with particular reference to agriculture and forestry, the construction and geotechnical industries, and the immobilization of contaminants. It was identified from a literature review that modified pulp and paper mill fly ash can be environmentally and economically advantageous over commercial coal-based fly ash in various sustainable applications.Sustainability 2019, 11, 4394 2 of 16 use of compost products, etc., are drawbacks of composting [10]. Contaminant-free PPFA has great significance as a soil liming agent and fertilizer in agriculture and forestry [6,11]; however, its direct application requires safety precautions due to its undesirable handling and spreading characteristics and associated health risks [12,13]. Further, high pH and electrical conductivity values of pore water in wood ash might have perturbing effects on the microbial community [14]. In order to withstand extreme conditions, the bacteria may enter a dormant stage, thereby decreasing the microbial population and diversity and ultimately disturbing the ecological balance. PPFA and value-added materials also have multifunctional engineering applications, such as supplementary cementitious material (SCM) in concrete systems, aggregate in pavement construction, binder for soil stabilization, and adsorbent for the immobilization of toxic heavy metals [15][16][17][18][19][20][21][22][23]. Based on a statistical survey conducted on the management and utilization of boiler ashes generated at Canadian pulp and paper mills, it was reported that more than 50% of ash is landfilled, 20-25% is used as a soil amendment (direct application or compost), and less than 20% is used for other beneficial applications such as the construction of embankment fills, the stabilization of pavement layers, and the solidification of wastes. [1,2].This paper reviews the existing knowledge on physicochemical and toxicological properties of PPFA in order to assess its suitability as a sustainable geomaterial for various bound and unbound applications. The bound applications of fly ash in...

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Section: Chemical Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Pulp and Paper Mill Fly Ash: A Review

Cherian

Siddiqua

2019

Sustainability

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“…The potential risks of heavy metal contamination, water contamination, immobilisation and volatilisation of essential macro and micro nutrients and possible nutrient imbalances is greatly influenced by site conditions, soil properties, wood ash application rate and abiotic factors (Demeyer et al 2001, Pitman 2006. It is evident from the reviewed literature that the effects of wood ash applications on stand nutrition and development tends to be highly sitespecific (Scheepers & du Toit 2016). The Zululand coastal plain of South Africa has more than 50 000 ha of industrial plantation forests and many wood-burning processing plants.…”

Section: Introductionmentioning

confidence: 99%

Potential for utilization of wood ash on coastal arenosols with limited buffer capacity in KwaZulu-Natal and its effect on eucalypt stand nutrition and growth

Scheepers¹,

Toit²

2017

iForest

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A field trial was established to test the effects of various wood ash and fertilizer application rates on the nutrition and early growth of a clonal Eucalyptus grandis × urophylla stand near Richards Bay, KwaZulu-Natal province, South Africa. The trial consisted of wood ash treatments of 0, 0.3, 0.6 and 1.2 t ha -1 , combined with fertilizer treatments of no fertilizer (control), 150 g tree -1 of conventional ammonium sulphate fertilizer or 320 g tree -1 of controlled release fertilizer mixture containing N, P and a balanced suite of several plant nutrients. The experiment was conducted on a young sandy soil of aeolian origin with a very low buffer capacity. Ash application rates were chosen after a pilot study was conducted to test the effect of CaCO3 on the soil reaction. At 4 and 8 months after treatment, soil heavy metal concentrations for cadmium (Cd), mercury (Hg), chromium (Cr) and lead (Pb) levels were substantially lower than toxic levels. Foliar heavy metal concentrations (for the same elements) were less than 1mg kg -1 at both time intervals. The wood ash induced a temporary liming effect up to 8 months after application. Foliar nutrient assessments revealed sub-optimal nutrient concentrations for phosphorous (P), potassium (K) and zinc (Zn) at 4 months and K at 8 months of age. The positive growth responses (expressed as a biomass index) at 8 months, ranged between 13% and 683% relative to the untreated control. At 21 months, the growth response to ash and fertilizer combinations ranged from -0.5% to 50% relative to the control. This research demonstrated that 1.2 t ha -1 of wood ash can safely be disposed of on a typical, poorly buffered Zululand coastal sand with little environmental risk and minimal growth suppression, provided that it is balanced with an appropriate NPS plus trace element fertilizer mixture.

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