Reclamation of heavy metals from contaminated soil using organic acid liquid generated from food waste: removal of Cd, Cu, and Zn, and soil fertility improvement

Abstract

Food waste fermentation generates complicated organic and acidic liquids with low pH. In this work, it was found that an organic acid liquid with pH 3.28 and volatile low-molecular-weight organic acid (VLMWOA) content of 5.2 g/L could be produced from food wastes after 9-day fermentation. When the liquid-to-solid ratio was 50:1, temperature was 40 °C, and contact time was 0.5-1 day, 92.9, 78.8, and 52.2% of the Cd, Cu, and Zn in the contaminated soil could be washed out using the fermented food waste liquid, respectively. The water-soluble, acid-soluble, and partly reducible heavy metal fractions can be removed after 0.5-day contact time, which was more effective than that using commercially available VLMWOAs (29-72% removal), as the former contained microorganisms and adequate amounts of nutrients (nitrogen, phosphorous, and exchangeable Na, K, and Ca) which favored the washing process of heavy metals. It is thus suggested that the organic acid fractions from food waste has a considerable potential for reclaiming contaminated soil while improving soil fertility.

Innovative Integrated Technique for Nutrient Acquisition: Simultaneous Recovery of Carbon and Nitrogen Sources from the Anaerobic Fermentation Liquid of Food Waste

“…The pH, OM, cation exchange capacity (CEC), total N (TN), total P (TP), total Ca (hereafter, Ca), total Mg (hereafter, Mg), and exchangeable K and Na of soil samples were determined following standard analytical methods …”

Evaluation of Soil and Ambient Air Pollution Around Un-reclaimed Mining Bodies in Nižná Slaná (Slovakia) Post-Mining Area

“…Ore mining is inevitably connected with the excavation of huge amounts of dump rocks that disrupt environment balance, cause irreversible changes in landscape structure, and are the source of undesirable substances releasing the soil, water, and air. The state of the soil quality is reflecting on soil conditions, which are responsible for soil fertility and its correct functionality [13].…”

Successful Outcome of Phytostabilization in Cr(VI) Contaminated Soils Amended with Alkalizing Additives

“…The availability of mobile heavy metal species in the soil solution is increased in highly acidic and acidic soils [ 33 ]. This is associated with an increase in the solubility of these element compounds and a decrease in their adsorption on soil colloids when the soil pH is low [ 34 ]. Therefore, the additives proposed by the authors can be used in the remediation of soil in which the acceptable levels of heavy metal pollution are exceeded because of the alkalizing properties.…”