Cleaning Cyanide Wastewater Using Algae and Bacteria in a Light-Powered Reactor

Jenn Hoskins
10th January, 2025

Cleaning Cyanide Wastewater Using Algae and Bacteria in a Light-Powered Reactor

Microscopic analysis identified the two key organisms for the study's bioremediation microcosm as the bacterium Bacillus licheniformis, seen as Gram-positive rods (a, c), and the microalga Chlorella spp., seen as small spherical cells (b, d).

Image adapted from: AbdelMageed et al. / CC BY (Source)

Key Findings

  • Researchers at Cairo University studied microorganisms from an Egyptian wastewater treatment station to clean industrial wastewater
  • The bacteria Bacillus licheniformis can remove significant amounts of harmful chemicals like potassium cyanide and benzonitrile from wastewater
  • The algae Chlorella spp. is sensitive to these pollutants, but when combined with the bacteria in a special reactor, they effectively detoxify the wastewater without harming plant growth
Wastewater from industrial activities often contains harmful pollutants, including heavy metals and toxic compounds, which pose significant threats to the environment and public health. Conventional methods of treating such wastewater can be expensive and sometimes introduce new chemicals into the ecosystem. Recent research conducted by Cairo University has explored the use of highly resistant bacterial and microalgal strains to address this issue[1]. The study focused on isolating and characterizing strains from an Egyptian wastewater treatment station that could degrade cyanide-containing compounds. The bacterial strain identified was Bacillus licheniformis, and the microalgal strain was identified as Chlorella spp. These microorganisms demonstrated a remarkable ability to detoxify synthetic wastewater containing various pollutants. Bacillus licheniformis was able to remove up to 1 g/L of potassium cyanide, 3 g/L of benzonitrile, and 1 g/L of sodium salicylate when incubated in a specific medium at 30°C. However, it could not degrade potassium thiocyanate at any tested concentration. The Chlorella spp. strain showed high sensitivity to these pollutants, with significant inhibition of growth at relatively low concentrations. Specifically, 0.05 g/L of potassium cyanide inhibited 93% of algal growth, while 1.5 g/L of benzonitrile, 5 g/L of potassium thiocyanate, and 5 g/L of sodium salicylate inhibited 96%, 75%, and 21% of growth, respectively. The combination of these microorganisms in a continuous stirred photobioreactor demonstrated effective detoxification of synthetic wastewater containing 0.2 g/L of potassium cyanide, 0.1 g/L of benzonitrile, and 0.5 g/L of sodium salicylate within 3.5 days. However, the system failed when the concentration of potassium cyanide was increased to 0.25 g/L. Importantly, the treated effluent did not inhibit the germination of Lepidium sativum seeds, indicating the absence of phytotoxicity. This study builds on previous research that has demonstrated the potential of using microorganisms for pollution degradation. For instance, earlier studies have shown that various bacteria and fungi can reduce heavy metal concentrations in industrial effluents[2]. Additionally, the use of an algal/bacterial microcosm has been investigated for treating organic pollutants in wastewater, with varying degrees of success depending on the presence of inorganic pollutants[3]. The current study by Cairo University expands on these findings by highlighting the specific capabilities of Bacillus licheniformis and Chlorella spp. in degrading cyanide-containing compounds. The methods employed in this study involved isolating the microorganisms, characterizing them using genetic and microscopic techniques, and testing their pollutant degradation capabilities in controlled environments. The use of a continuous stirred photobioreactor allowed for the assessment of the microorganisms' performance in a dynamic system, simulating real-world wastewater treatment conditions. Overall, this research underscores the potential of using specific microbial strains for the bioremediation of industrial wastewater. The findings suggest that Bacillus licheniformis and Chlorella spp. could be effective components of a biological treatment system for cyanide-containing pollutants. This approach offers an environmentally friendly and cost-effective alternative to conventional wastewater treatment methods, aligning with the need for sustainable solutions in pollution management[2].

EnvironmentSustainabilityBiotech

References

Main Study

1) Algal-bacterial bioremediation of cyanide-containing wastewater in a continuous stirred photobioreactor.

Published 9th January, 2025

https://doi.org/10.1007/s11274-024-04230-5

Related Studies

2) Biodegradation of Pollutants in Waste Water from Pharmaceutical, Textile and Local Dye Effluent in Lagos, Nigeria.

https://doi.org/10.5696/2156-9614-6.12.34

3) Remediation of the effect of adding cyanides on an algal/bacterial treatment of a mixture of organic pollutants in a continuous photobioreactor.

https://doi.org/10.1007/s10529-014-1557-7


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