Inhibition of heavy metals on fermentative hydrogen production by granular sludge

doi:10.1016/j.chemosphere.2006.11.005

Chemosphere

Volume 67, Issue 4, March 2007, Pages 668-673

https://doi.org/10.1016/j.chemosphere.2006.11.005 Get rights and content

Abstract

This study was conducted to investigate the toxicity of six electroplating metals on the H₂-producing activity of a granular sludge sampled from an H₂-producing upflow reactor treating sucrose-containing wastewater. The H₂ production activities of the sludge were measured in serum vials using wastewater containing not just sucrose and proper nutrient, but also individual heavy metals at concentrations ranging 0–5000 mg l⁻¹. The relative toxicity to H₂ production was found in the following order: Cu (most toxic) ≫ Ni ∼ Zn > Cr > Cd > Pb (least toxic). The C_I,50 values, at which the bioactivity of the sludge was reduced to 50% of the control, for individual heavy metals were Cu 30 mg l⁻¹, Ni and Zn 1600 mg l⁻¹, Cr 3000 mg l⁻¹, Cd 3500 mg l⁻¹, and Pb >5000 mg l⁻¹. Compared with the literature data, H₂-producing sludge exhibited in general higher resistance to metal toxicity than methanogenic granular sludge.

Introduction

Heavy metals are present in significant concentrations in some industrial wastewaters and municipal sludge, and are often the leading cause for the upset of the wastewater treatment process (Lester et al., 1983, Stronach et al., 1986, Fang and Chan, 1997). Heavy metals can be stimulatory, inhibitory, or even toxic in biochemical reactions depending on their concentrations. A trace level of many metals is required for activation or function of many enzymes and co-enzymes. Excessive amounts, however, can lead to inhibition or toxicity. This is mostly due to the chemical binding of heavy metals to the enzymes, resulting in the disruption of enzyme structure and activities (Vallee and Ulmer, 1972).

Sludge and concentrated wastewater are conventionally treated by anaerobic processes leading to the production of methane (Gallert et al., 2003). More recently, a new anaerobic technology has been developed to convert organic wastes into H₂ (Li and Fang, 2007). Recent research has shown that the H₂-producing sludge may agglutinate into granules, similar to methane-producing sludge, in upflow reactor to facilitate H₂ production with high biomass concentration (Li et al., 2006). Although the effects of heavy metals on the anaerobic methane-producing process have been widely studied (Fang and Hui, 1994, Fang and Chan, 1997, Lin and Chen, 1999), little is known on their effects on fermentative H₂ production.

A series of batch experiments were conducted in this study to investigate the inhibition effect of heavy metals on the production of H₂ from a sucrose-containing wastewater by granular sludge. The six heavy metals selected were those commonly found in electroplating effluents, including Cd, Cr, Cu, Ni, Zn, and Pb.

Section snippets

Inoculums

H₂-producing granular sludge was sampled from a packed-bed upflow reactor which has been operated at 26 °C treating sucrose-containing wastewater for over 500 d. This sludge had a H₂ production yield and rate of 1.22 mol-H₂ mol⁻¹-sucrose and 6.17 l-H₂ l⁻¹ d⁻¹, respectively. Detailed characteristics of this granular sludge have been reported in a previous study (Li et al., 2006).

Batch tests

Six series of batch tests were conducted in duplicate for Cd, Cr, Cu, Ni, Zn and Pb, respectively, in 250 ml glass serum

Results and discussion

In all experiments, the biogas produced contained only H₂ (35–56%), CO₂ (44–65%) and residual N₂ from the initial purging. The biogas was free of methane due to the lack of methanogenic activity in the sludge. The VFA and alcohol residues in the mixed liquor were mainly acetate, butyrate, ethanol and propanol, plus small amounts of butanol, valerate and caproate.

Inhibition of individual metal to H₂ production was represented by concentration C_I,50, at which the H₂-producing activity of the

Conclusion

Inhibition of six heavy metals commonly found in electroplating effluent inhibited the bioactivity of H₂-producing sludge in the following order: Cu (most toxic) ≫ Ni ∼ Zn > Cr > Cd > Pb (least toxic). The C_I,50 values for individual heavy metals were Cu 30 mg l⁻¹, Ni and Zn 1600 mg l⁻¹, Cr 3000 mg l⁻¹, Cd 3500 mg l⁻¹, and Pb >5000 mg l⁻¹. H₂-producing sludge exhibited in general higher resistance to metal toxicity than methanogenic granular sludge.

Acknowledgements

The authors wish to thank the Hong Kong Research Grant Council for the financial support of this project (HKU7007/02E), and Chenlin Li wishes to thank HKU for the postgraduate studentship.

References (23)

C. Gallert et al.
Scale-up of anaerobic digestion of the biowaste fraction from domestic wastes
Water Res.
(2003)
J.J. Lay et al.
The influences of pH and moisture content on the methane production in high-solids sludge digestion
Water Res.
(1997)
J.N. Lester et al.
Significance and behavior of heavy metals in wastewater treatment process
Sci. Total Envion.
(1983)
C.Y. Lin et al.
Effect of heavy metals on the methanogenic UASB granule
Water Res.
(1999)
H. Liu et al.
Extraction of extracellular polymeric substances (EPS) of sludge
J. Biotechnol.
(2002)
APHA
Standard Methods for the Examination of Water and Wastewater
(1992)
H.H.P. Fang
Inhibition of bioactivity of UASB biogranules by electroplating metals
Pure Appl. Chem.
(1997)
H.H.P. Fang et al.
Toxicity of electroplating metals on benzoate-degrading granules
Environ. Technol.
(1997)
H.H.P. Fang et al.
Effect of heavy metals on the methanogenic activity of starch-degrading granules
Biotechnol. Lett.
(1994)
H.H.P. Fang et al.
Characterization of a hydrogen-producing granular sludge
Biotechnol. Bioeng.
(2002)

H.H.P. Fang et al.

Acidophilic hydrogen production from rice slurry

Int. J. Hydrogen Energy

(2006)

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Inhibition of heavy metals on fermentative hydrogen production by granular sludge

Abstract

Introduction

Section snippets

Inoculums

Batch tests

Results and discussion

Conclusion

Acknowledgements

Water Res.

Water Res.

Sci. Total Envion.

Water Res.

J. Biotechnol.

Standard Methods for the Examination of Water and Wastewater

Inhibition of bioactivity of UASB biogranules by electroplating metals

Pure Appl. Chem.

Toxicity of electroplating metals on benzoate-degrading granules

Environ. Technol.

Effect of heavy metals on the methanogenic activity of starch-degrading granules

Biotechnol. Lett.

Characterization of a hydrogen-producing granular sludge

Biotechnol. Bioeng.

Acidophilic hydrogen production from rice slurry

Int. J. Hydrogen Energy