Rusanescu and Rusanescu 2023 - MSWI fly ash in agriculture

Rusanescu and Rusanescu review whether fly ash from municipal solid waste incineration (MSWI) can be used as an agricultural soil amendment. The source is not a primary market-food or crop-occurrence study: its metal concentrations are secondary ranges from cited literature. Its routeable value is context evidence for waste-derived soil amendments, including the high variability of As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, and other elements in MSWI fly ash and the dose-dependent rise of several metals in amended soil.

Key numbers

Fly ash composition

Table 1 compiles MSWI fly-ash and soil composition ranges from cited sources. The fly-ash values below are reported as mg/kg unless noted:

The same table reports major nutrient or matrix elements in MSWI fly ash, including Ca 0.11-22.2%, S 0.1-1.5%, Al 0.1-17.3%, Na 0.01-2.03%, K 0.15-3.5%, Mg 0.04-7.6%, P 0.004-0.8%, and B 10-618. The review states that MSWI fly-ash chemistry depends on the waste burned and the ash treatment method.

Table 2 compiles oxide compositions in fly ash as wt% from several cited studies. Heavy-metal-bearing oxide examples include Cr2O3 0.19 wt%, CuO 0.25 wt%, PbO 0.57 wt%, and ZnO reported as 2.32 wt% in one cited source and 0.71-3.11 wt% in another. These oxide values are not directly interchangeable with elemental mg/kg concentrations.

Soil amendment tables

Table 3 summarizes one onion/soil amendment study in which ash was added at 0, 1, 2.5, 5, 10, and 15 t/ha. Across that sequence, pH rose from 7.0 to 8.2, electrical conductivity rose from 210 to 346 micro mhos/cm, and water-holding capacity rose from 33.68 to 42.93. The cation-exchange-capacity values did not move monotonically.

Table 4 reports another soil mixture in which fly ash was added from 0 to 100% of the mixture. The soil-only pH was 6.65 and EC was 281 microS/cm; fly-ash-only pH was 7.56 and EC was 600 microS/cm. At 50% fly ash, pH was 6.96 and EC was 358 microS/cm.

Table 5 reports soil elemental concentrations after adding fly ash at 0, 1, 2.5, 5, 10, and 15 t/ha. Selected endpoints:

The same table reports K rising from 3900 to 10,150 mg/kg and P rising from 45.5 to 70.0 mg/kg by the 15 t/ha condition, while Fe is comparatively stable at 263-340 mg/kg across the ash-amendment sequence.

Table 6 compares physical properties of fly ash and soil: bulk density <1.0 g/cc for fly ash versus 1.33 g/cc for soil, water-holding capacity 35-40% versus <20%, and porosity 50-60% versus <25%.

Plant-growth and risk framing

The review summarizes cited studies in which lower fly-ash application rates increased plant biomass by 11.6-29.2%, while high application rates of 50-100% of soil mass decreased biomass by 45.8% due to heavy-metal toxicity. It also summarizes yield increases of 20-30% at MSWI ash doses from 20 to 100 t/ha, a recommendation in one cited source to keep MSWI fly ash below 5-10% of soil depending on soil acidity and crop, and several cited reports that metal uptake depends on ash dose, soil pH, crop, and ash treatment.

Methods (brief)

This is a narrative review, not a primary sampling study. The authors synthesize published literature on MSWI generation, fly-ash composition, heavy-metal and salt treatment methods, soil physical and chemical changes after ash amendment, and plant-growth outcomes. The paper does not report a search strategy, inclusion/exclusion flow, quality scoring, or new chemical analysis. Tables are explicitly labeled as data adapted or compiled from cited references.

Implications

Certification: This source should not enter product or ingredient occurrence pools. It supports supply-chain due diligence for land-applied waste amendments: MSWI fly ash can carry very high and highly variable As, Cd, Cr, Cu, Hg, Ni, Pb, Zn, and other element burdens, and treatment history matters before agricultural use.

Courses: Useful as context for how circular-economy soil amendments can improve soil pH and water retention while also introducing contaminant-management problems. It is a good cautionary example for separating soil-amendment evidence from edible-product occurrence evidence.

App: Route as context for waste-derived soil amendments and soil-to-plant transfer risk. Do not convert the review’s crop-yield or soil-amendment summaries into food concentration benchmarks.

Wiki pages this source may touch

• arsenic
• cadmium
• chromium
• copper
• mercury
• nickel
• lead
• zinc
• soil-to-plant-transfer
• agronomic

Verification notes

The PDF has author attribution and DOI 10.3390/app13053246; no DOI conflict was observed. Names in the frontmatter are ASCII transliterations of the byline. The PDF labels the article type as “Review,” and the tables cite prior literature rather than reporting new samples. Table 5’s heading prints the ash dose as “t/h,” while the surrounding text describes t/ha; this page uses t/ha and flags the source as secondary context. Table 1’s unit column is blank for several minor elements, including Hg, Mn, B, and Se; this page treats them as part of the table’s concentration context rather than as product-benchmark values. The review uses total elemental symbols without speciation; tAs and tHg in frontmatter mean unspecified total arsenic and total mercury, not inorganic arsenic or methylmercury.

Page history

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