Respirometric measurements

A frequently used parameter for determining the toxicity of household and industrial sewage and of chemicals which affect the environment, is the change in rate of gas metabolism by microorganisms. Two basic variants are possible  

This method is usually used as a direct method of establishing the bio- 

The oxygen demand of microorganisms is reduced by the presence of toxic or inhibiting substances. The reduction serves as a means of measuring inhibiting effects, and for this purpose reference cultures must be prepared concurrently to which the substance under examination is not added. 

All respirometric measurements can be made with simple, barometric BOD measuring instruments. 

Discharge from a domestic-sewage treatment plant addition of 10 drops to the trial culture. 

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Suschka J, Ferreira E (1986) Activated sludge respirometric measurements, Water Res 20 137 Chem Abstr 104 (1986) 55663q... 

In 1998, BASF AG (Ludwigshafen, Germany) presented a respirometric measurement of the copolyester Ecoflex (approximately 45 mol% of terephthalic acid in the acid component), showing that this material was more than 90% metabolised in compost within three months [91]. 

An attempt to automate the turbidi-metric method for the determination of neomycin with K. pne.umon4.ae. has been reported by Gerke et al281 who obtained satisfactory assays with solutions containing 150-1200 yg/ml of neomycin. An automated respirometric method, which measured the amount of CO2 produced by interaction of antibiotic and the bacteria E.cot.i was also reported with a similar sensitivity. In both methods Auto Analyzer systems were employed. 

Among organic constituent measurements, that of aggregate properties (BOD and COD) and specific parameters (TOC for example) has been well developed for more than 20 years. Concerning BOD, a recent review on biosensors [33] has been published. BOD biofilm-based sensors as well as respirometric systems, other measuring principles, and the commercial BOD instruments are discussed and compared regarding their performance characteristics like linearity, response time, precision, agreement between BOD values obtained from the biosensors and the conventional 5-day test, as well as toxic resistance to various compounds and operational stability. 

From the analysis of the various respirometric curves recorded in both normal conditions and after exposure of the system to the toxic substance at several concentrations, we obtained a calibration curve to which reference can then be made to determine the toxicity of the selected sample. In practical terms, for each measurement record two different respirometric curves one in the presence of substrate alone and the other in the presence of substrate but after initial incubation with the toxic substance (for 8 min) the results can be processed using one of the two following experimental data ... 

Two very actual applications of respirometric test were performed on radon pollution and cellular phone field effect on biological system, both of great actuality and object of controversies due to contrasting conclusions reached by different authors, very often basing on unclear and poorly accurate measurements. Particularly for cellular phone field, it was concluded that 900 and 1800 MHz, corresponding to cellular... 

Figure 3. Cumulative measurement respirometric system (CMR) (Adapted with permission from reference 1. Copyright 2007 WILEY-VCH Verlag GmbH Co. KGaA).

Gong, P., Gasparrini, P., Rho, D., Hawari, J., Thiboutot, S., Ampleman, G. and Sunahara, G.I. (2000) An in situ respirometric technique to measure pollution-induced microbial community tolerance in soils contaminated with 2,4,6-trinitrotoluene. Ecotoxicology and Environmental Safety, 47, 96-103. 

Respirometric test on a solid anaerobic medium with the measurement of emitted biogases... 

Respirometric test in a liquid aerobic medium with the measurement of CO2 released ... 

Respirometric test on an aerobic solid medimn by measuring CO2 released... 

ENISO 14851 2004 Aqueous Not exceeding six months Preferably between 20and25 Aniline, microcrystalline cellulose powder, ashless cellulose filters or poly-(3-hydroxybutyrate as positive reference Oxygen consumption (by, for example, respirometric method or measurements of changes in volume or pressure)... 

The respirometric method meastues either CO2 produced or CO2 constuned or both of them in an enclosed system with proper maintenance or regulation of air or oxygen supply. This technique is especially suitable for confirmation on the extent of mineralization It can be used for measuring degradation of soluble powder from fragile pofymeric materials. This method is easily adapted to a whole range of envirorunental conditions and/or specified or mixed culture microorganisms. 

Kijchavengkul T, Auras R., Rubino M., Ngouajio M., Fernandez R.T. Development of an automatic laboratory-scale respirometric system to measure polymer biodegradability. Polymer Testing... 

The biodegradation rate can also be used to quantify the respirometric evaluations (Gou9alves and Franchetti 2013). In this case, the biodegradation rate is not measured by mass loss but by the amount of CO2 produced or the oxygen demand originated by microbial activity. This technique eliminates the aforementioned errors about the measurements of mass loss. 

Complete biodegradability of the product, measured through respirometric tests like ASTM D5338-92, ISO/CD14855 and CEN proposal xxl or the modified Sturm test ASTM 5209, in a time period compatible with the composting technology (few months). 

The extent of biodegradation is usually measured using respirometric methods, which detect CO2 evolution. Other parameters to assess are the rate of MW loss, the loss of polymer physical properties (e.g., tensile strength per ASTM standard D3826-98 [5]), the rate of increase of the microbial culture colony size in contact with the material, O2 uptake (e.g., biochemical oxygen demand) and radioactive tracer techniques that use labelling. 

Respirometric methods can be classified into a number of basic measurement principles depending on two criteria (i) The phase where oxygen is measured (gas or liquid) and (ii) the flow regime of bofh gas and liquid phase, which can be either flowing or static [4]. From these criteria the modalities are... 

A.K. Gemaey, B. Petersen, J.-P. Ottoy, and P. Vanrolleghem. Activated sludge monitoring with combined respirometric-titrimetric measurements. Water Res., 35 1280-1294, 2001. 

Further investigation of PLA biodegradation using the cumulative measurement respirometric (CMR) system (according to ASTM D5338 and ISO 14855-1) showed that the biodegradation of PLA bottles required >30 days buried in a compost pile to achieve 80% mineralization. CMR is a system designed to yield... 

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