Bioremediation of Heavy Metals and Organic Toxicants by Composting

Abstract

Hazardous organic and metallic residues or by-products can enter into plants, soils, and sediments from processes associated with domestic, municipal, agricultural, industrial, and military activities. Handling, ingestion, application to land or other distributions of the contaminated materials into the environment might render harm to humans, livestock, wildlife, crops, or native plants. Considerable remediation of the hazardous wastes or contaminated plants, soils, and sediments can be accomplished by composting. High microbial diversity and activity during composting, due to the abundance of substrates in feedstocks, promotes degradation of xenobiotic organic compounds, such as pesticides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). For composting of contaminated soils, noncontaminated organic matter should be cocomposted with the soils. Metallic pollutants are not degraded during composting but may be converted into organic combinations that have less bioavailability than mineral combinations of the metals. Degradation of organic contaminants in soils is facilitated by addition of composted or raw organic matter, thereby increasing the substrate levels for cometabolism of the contaminants. Similar to the composting of soils in vessels or piles, the on-site addition of organic matter to soils (sheet composting) accelerates degradation of organic pollutants and binds metallic pollutants. Recalcitrant materials, such as organochlorines, may not undergo degradation in composts or in soils, and the effects of forming organic complexes with metallic pollutants may be nonpermanent or short lived. The general conclusion is, however, that composting degrades or binds pollutants to innocuous levels or into innocuous compounds in the finished product.

A comprehensive overview of elements in bioremediation

“…Rev Environ Sci Biotechnol (2010) 9:215-288 245 bioremediation technique for degrading toxic organic compounds and perhaps lowering their persistence and toxicity in organic residues and wastes (Barker and Bryson 2002). The biochemical and physicochemical processes of remediation in composts are similar to those that usually occur biologically in soil.…”

Sewage sludge use in bioenergy production. A case study of its effects on soil properties under Cynara cardunculus L. cultivation

“…CO 2 effect on climate change) have led to strategies oriented towards sustainability, as the Directive 2009/08/EC, which established legally binding targets within the European Union (EU) for 2020 in order to reach a 20% share of renewable energy on the final energy consumption. Within the renewable en-2 which reduces heavy metal availability and diminish the presence of plant pathogens and organic toxicants (Barker & Bryson, 2002;Noble & Roberts, 2004). As observed for SS, when sewage sludge compost (SSC) is applied to the soil, fertility and plant growth are enhanced (Casado-Vela et al, 2006;Larchevêque et al, 2006;Song & Ju Lee, 2010).…”

Evidence for the importance of litter as a co-substrate for MCPA dissipation in an agricultural soil

“…Pre-exposure to 2,4-D and MCPA has been reported to boost degrading populations, thereby increasing the dissipation of these herbicides in agricultural soils (Baelum et al 2008;Smith and Aubin 1991). Differences in dissipation between both MCPA levels underline the importance of initial herbicide concentrations in Several studies have shown that degradation of organic compounds in soils can be improved by adding raw organic matter or compost (e.g., Barker and Bryson 2002;López-Piñeiro et al 2013). In our study, litter addition significantly accelerated MCPA dissipation only in soils exposed to the high MCPA concentration ( Fig.…”