Direct toxicity assessment of wastewater: Baroxymeter, a portable rapid toxicity device and the industry perspective

Abstract

Direct toxicity assessment of wastewater is becoming necessary, and new legislation may render it compulsory for the water industry. At present such assessment is performed at a laboratory away from a site, at considerable cost, and results often come too late, after a toxic event has occurred and the toxin has been released into the environment. Some of the rapid toxicity tests available today require certain conditions to function properly, or their results do not always correlate with other methods. The objective of this study was to assess a portable device, the Baroxymeter, for its suitability as an instrument to test wastewater toxicity. The way the device works is based on monitoring respiration of a bacterial culture by pressure measurements and using respiration inhibition as a toxicity alert. It has been shown that it is possible to detect toxic substances such as 3,5-dichlorophenol and bronopol within 5 min from a 1-mL sample. The benefits and future applications of the Baroxymeter as a high-throughput, cost-effective alternative for toxicity screening are discussed in this article.

Direct toxicity assessment with a mini portable respirometer

“…However, the system has two components: (a) the limits and resolution for the physical measurement; (b) the kinetics and transport properties in the gas, liquid and biomass; too great a reduction in headspace can lead to oxygen limitation. We have shown previously [15,16] that for the headspace/sample (V G /V L ) volumes used here and surface area of the sample/gas phase interface, the respiration is not limited by the headspace O 2 concentration during each 30 s closed respiration window, but further significant decreases in volume do appear to influence the signal measured. In previous work [15] we have also shown that simple scaling of a 'large' respirometer does not necessarily give a comparable respirometric measurement.…”

“…The microorganism pellet preparation allows reproducible respiration to be recorded immediately on contact with the sample [15,16], but the bacteria typically require 130-160 min to reach their full respiration rate, once a sample is introduced. Fig.…”

“…Pressure change measurements were made with respect to an empty control chamber included in the unit underneath the sample chamber. This was based on sequential respiration rate monitoring cycles [16], monitoring the pressure change in discrete respiration "windows": cycles of closed respirometry (30 s) separated by periods of open respirometry (30 s) for pressure equilibration. The pressure drop rate value (Pa/min) was obtained during each closed respiration window (30 s).…”

“…Exploitation of portable manometric respirometry with microbacteria begins here to evaluate the potential and identify measurement protocols and information that could be available. We have presented some initial results from a portable toxicity monitoring device, the 'Baroxymeter', based on the rapid monitoring of bacterial respiration [16]. In this paper we explore further the use of small volume rapid respirometry to detect a range of potentially toxic substances.…”

Toxin detection based on action potential shape analysis using a realistic mathematical model of differentiated NG108-15 cells

“…In the areas of environmental protection, toxicology and drug development there are increasing demands for high-throughput functional screening methods (Rogers 1995;Paddle 1996;Ohlstein, Ruffolo et al 2000;Heck, Roy et al 2001;Croston 2002;Tzoris, Fearnside et al 2002). For monitoring of the environment, whole-cell biosensors could be more effective than physico-chemical methods to assess the global toxicity of the wide variety of chemicals that are possible pollutants (Evans, Briers et al 1986;Rogers 1995;Bousse 1996;Paddle 1996;.…”