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Pig manure secondary resource

Unincinerated manure generated by pig husbandry, represented here by fresh material collected from a pig farm in Tianjin, China, and studied as a diluted slurry. This heterogeneous agricultural residue contains nutrients and metals. Its origin is distinct from municipal sewage sludge, poultry litter, manure incineration ash and isolated fertilizer or metal products. The selected farm sample does not characterize all pig manure, and its liquid and solid fractions are not separate resource owners.

Microbial & Biochemical Mechanisms (1)

Sulfur-fed enrichment-associated acidification and metal mobilization

bioleaching Microbial

An indigenous sulfur-oxidizing enrichment was associated with acidification, sulfate accumulation and mobilization of copper, zinc and manganese from farm manure in laboratory flasks. Increasing sulfur dose accelerated the observed time courses, with little additional benefit from 8 to 10 g/L. The same treatment substantially reduced residual nutrient concentrations; no purified metal or nutrient product was recovered.

Experimental Context & Analytical Limits:
Fresh manure was stored at 4 degrees C and diluted to 2% solids (w/v). An active inoculum was developed through four transfers in sulfur-supplemented manure. The leaching assays used 200 mL manure slurry in 500 mL flasks, 5% v/v enrichment inoculum and nominal 2, 5, 8 or 10 g/L elemental sulfur, shaken at 180 rpm and 28 degrees C for 12 days in triplicate. Evaporative losses were replaced with distilled water. Centrifuged, 0.45 micrometre-filtered samples were analyzed by atomic absorption spectrometry. All reported dose arms were inoculated; no matched sterile, uninoculated or zero-sulfur arm is presented. A separate salt-medium enrichment used for community characterization reportedly gave clones with 98% 16S sequence similarity to A. thiooxidans; this does not establish a pure culture, confirmed species identity or species-specific causal contribution.
Curated Evidence Points:
Sections 2.1-2.4 and 3.1-3.3, Table 1 and Figures 1-4 establish the real feed, enrichment, conditions and dose-dependent liquid endpoints. Section 3.3 reports 48.5% Cu solubilization at 2 g/L sulfur after 12 days, versus approximately 90% or more for the higher-dose arms; the reported 12-day Zn and Mn ranges are 93.3-97.2% and 96.3-97.8%, respectively. Figure 4 shows the much slower low-sulfur Cu response and the similar 8 and 10 g/L endpoints. These are source-reported solubilization results, not independently closed mass balances or isolated yields.
Sections 2.3-2.4 and 3.4 do not fully resolve inoculum contributions, final-volume accounting or repeated sampling corrections. Methods describe sampling at two-day intervals, whereas Figure 4 includes daily points. Kinetic fits in Figures 3 and 5 and Tables 3-5 are empirical models, not direct evidence of growth or a unique molecular mechanism. Section 3.1's sulfur-dose ordering of times to exceed 200 mV conflicts with Figure 1b; Table 4 labels sulfur in mg/L whereas Methods and figures use g/L. Exact ORP crossing times and fitted sulfur optima are not adopted.
Section 3.5.3 and Figure 7 report residual nutrient-concentration decreases, including 68.5-71.0% for total phosphorus and 76.5-78.8% for potassium. These concentration comparisons are not nutrient recovery yields or a complete nutrient mass balance. Figure 7's caption says total nitrate and total phosphate, while the methods and axes identify total nitrogen and total phosphorus; nitrate or orthophosphate speciation is not inferred. Table 1/Figure 7 give TOC on an mg/kg basis that is not reconciled with the carbon wt% in Table 6. Figure 6's sequential extraction fractions are operational categories, and its post-treatment sulfur dose is unspecified. No direct demonstration of improved dewaterability, safe fertilizer use, complete detoxification or industrial operation is accepted.
Context_only Source: ncbi_930
The authority confirms the reference species name and rank, but does not verify the study's unnamed indigenous enrichment as that species; no organism identifier is assigned to the experimental community.

Sources & References

  1. wei_2018: Wei, Liu, Liao, Wang, Li and Huang (2018). Bioleaching of heavy metals from pig manure with indigenous sulfur-oxidizing bacteria: effects of sulfur concentration. Heliyon 4:e00778. DOI 10.1016/j.heliyon.2018.e00778; PMID 30211335, PMCID PMC6129760. Complete official JATS/HTML, Figures 1-7 and Tables 1-6 inspected; no separate supplementary document is announced in the inspected original.
    https://doi.org/10.1016/j.heliyon.2018.e00778 (accessed 2026-10-15)
  2. ncbi_930: NCBI Taxonomy 930, Acidithiobacillus thiooxidans, species. Identity context for the paper's sequence-similarity reference; not an identification of its enrichment.
    https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=930 (accessed 2026-10-15)

Curation History

Timestamp Curator Action Summary
2026-10-15T10:30:16.760666Z Codex (GPT-6; Codex) CREATE Created a farm-derived pig-manure secondary-resource record from the complete original microbial enrichment study, preserving sulfur-dose limits, nutrient tradeoffs, unresolved community identity and source assay contradictions.

Record source: data/records/pig-manure.yaml