Toxicity and Bioremediation of Heavy Metals Contaminated Ecosystem from Tannery Wastewater: A Review

Table 2

Factors that influence bioremediation of heavy metals [45].

Factors	Activities
Microbial	(i) Production of toxic metabolites
	(ii) Enzymes induction
	(iii) Mutation and horizontal gene transfer
	(iv) Enrichment of capable microbial populations
Substrate	(i) Chemical structure of contaminants
	(ii) Too low concentration of contaminants
	(iii) Toxicity of contaminants
	(iv) Solubility of contaminants
Environmental	(i) Inhibitory Environmental conditions
	(ii) Depletion of preferential substrates
	(iii) Lack of nutrients
Mass transfer limitations	(i) Oxygen diffusion and solubility
	(ii) Solubility/miscibility in/with water
	(iii) Diffusion of nutrients
Growth substrate vs. co-metabolism	(i) Microbial interaction( competition, succession, and predation)
	(ii) Concentration
	(iii) Alternate carbon source present
Biological aerobic vs. anaerobic process	(i) Microbial population present in the site
	(ii) Oxidation/reduction potential
	(iii) Availability of electron acceptors