Effect of trace metals on halophilic and mixed cultures in anaerobic treatment

Abstract

ABSTRACT:Trace metals are known to stimulate the activity of anaerobic methanogenic bacteria involved in the degradation of organic matter. The objective of this research was to investigate the effect of three trace metals, iron, nickel and cobalt on the activity of halophilic methanogens, digester sludge and a mixed culture of halophilic bacteria and digester sludge, at various salt concentrations. Iron slightly stimulated both initial and maximum specific methanogenic activity (SMA) of halophilic methanogens at all salt concentrations. Iron addition was also able to increase both initial and maximum SMA of the mixed culture. Iron could not stimulate either initial or maximum SMA of digester sludge at salt concentrations of more than 10 g/L. Adding cobalt showed no benefit on the initial and maximum SMA of halophilic methanogens. A slight increase in the initial SMA was observed in mixed culture when cobalt was injected to the system containing sodium concentrations of 10-30 g/L. At salt concentrations above 40 g/L, cobalt could stimulate the maximum SMA of mixed culture. No benefits were found when cobalt was added to the digester sludge at sodium concentrations higher than 20 g/L. Nickel was observed to increase the initial SMA of digester sludge at all salt concentrations, and the maximum SMA of mixed culture at salt concentrations of 30-50 g/L.

Influence of heavy metal supplementation on specific methanogenic activity and microbial communities detected in batch anaerobic digesters

“…Moreover, a stimulation of the activity and population of halophilic methanogens was also reported after adding Ni 2+ and Co 2+ during the anaerobic degradation of organic matter at different salt concentrations. [39] In the same way, it was reported that the methanogenic activity of Methanosarcina sp. increased considerably after the addition of trace nutrients (Ni 2+ and Co 2+ ) in sulphide-containing media during the anaerobic treatment of wastewaters containing methanol.…”

New insights on improved growth and biogas production potential of Chlorella pyrenoidosa through intermittent iron oxide nanoparticle supplementation

“…The observed differences in biogas yield and digestibility of microalgal biomass grown at different IONPs concentration clearly signify the active role of IONPs in improving the digestion of microalgal biomass. As discussed above, the improvement in the biogas production with increasing the IONPs concentration could be attributed to the fact that the iron nanoparticles act as a catalyst for simulating the activity of anaerobic microflora 41 , 42 . Overall, 25.14% enhancement in biogas production was observed with an increase in IONPs dose to 30 mg L −1 as compared to control.…”

Intensification of biogas production using various technologies: A review

“…The solution is highly recommended because of environmental benefits such as potentially lower air pollution by H 2 S/SO 2 emission and lesser impact on human health. Krongthamchat et al 83 reported that the addition of iron as a trace metal could reduce the lag time of a mixed culture. Liu et al 75 stated that iron ions released from the dissolution of magnetic NPs can stimulate bacterial activities.…”