The use of respirometry for the evalutation of an industial wastewater toxicity over activated sludge
DOI:
https://doi.org/10.15626/Eco-Tech.2007.044Keywords:
Toxicity, Respirometry, Formaldehyde, Activated Sludge, Industrial WastewaterAbstract
The discharge of industrial wastewaters with toxic substances in wastewater treatment plants may cause relevant inhibition of microbiological metabolism. A number of toxicity tests available mostly focus on ecological impacts on water recipients by using macro invertebrates as bio-indicators. However, toxic effects occurring in wastewater treatment plants cannot be properly addressed with this approach. A promising method that has been used to investigate microbiological inhibition caused by industrial wastewaters is,.the respirometric test. As part of a treatability study, the present investigation aimed to assess the toxic effects of an industrial wastewater generated in a wood-floor industry, located in Nybro, Sweden over activated sludge microorganisms. The wastewater results from washing/cleaning of machineries that continuously apply urea-formaldehyde resins on wood particle boards. The respirometric method was able in a short time to assess both the inhibition and the stimulation of microbial metabolism caused by this particular tested effluent. Metabolic inhibition was positively correlated with dilution factors and formaldehyde concentrations within the aqueous phase. Whereas 1,989.4 mg L"1 of formaldehyde caused 50% of metabolic inhibition, concentrations below 156 mg L"1 did stimulate it. High EC50 values suggest that in thepresence of other compounds, antagonistic processes are taking place, reducing toxic effects of formaldehyde. Finally it was concluded that toxicity tests carried out with single substances in synthetic waters have limited value if the ultimate goal is to develop real wastewater treatment systems. It is important to highlight that formaldehyde was here used as an indicator and the correlation between inhibition of respiration and formaldehyde concentration is actually reflecting the effect of not only this particular substance but the complex mixture of substances presented in the glue wastewater.
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Copyright (c) 2007 Fabio Kaczala, Marcia Marques, William Hogland
This work is licensed under a Creative Commons Attribution 4.0 International License.
