Biodegradable substance

Biodegradable- Substance capable of being decomposed by biological processes. 

Bioconversion Chemical conversion of a naturally occurring biodegradable substance using a biocatalyst. 

Ecotoxicology The good inertness of the perflourinated systems against most reaction conditions will lead to a critical accumulation of non-biodegradable substances in the environment [72]. This waste deposition may lead to ecological problems in the future. 

Surfactant concentrations also exert a negative influence on the bio-oxidation of certain substances, as evidenced in studies with even readily biodegradable substances [7]. It should be noted that this protection of substances from bio-oxidation is only temporary and it slowly reduces until its virtual disappearance in about a week for most substances. This phenomenon serves to retard the self-purification process in organically polluted rivers, even in the presence of high concentrations of dissolved oxygen. 

The modification of the sand surface allows the grains to simultaneously adsorb soluble heavy metals and remove particulate metals by filtration in a column packed with the media. Important factors to the performance of the adsorbent include pH of the solution to be treated, empty bed detention time (EBDT), and the presence of complexing agents, oil, surfactant, and biodegradable substances. 

Tag K, Lehmann M, Chan C, Renneberg R, Riedel K, Kunze G (2000) Measurement of biodegradable substances with a mycelia-sensor based on the salt tolerant yeast Arxula adeninivorans LS3. Sensors Actuators B67 142-148... 

Renneberg R, Kwong WK, Chan C, Kunze G, Riedel K (1999) Rapid measurement of biodegradable substances in water using novel microbial sensors. In Advances in biosensors, JAS Press, pp 195-213... 

Kwong W, Chan C, Renneberg R (1998) Monitoring biodegradable substances with high-molecular content with a microbial sensor. Anal Lett 31 2309-2325... 

Some studies suggest that biodegradation rates of substances at relatively higher concentrations are not extrapolatable to very low concentrations (see Figure 5.5). That could explain the persistence of very low residual levels of some biodegradable substances in water or soil. 

The work presented here takes as its starting point the need of disposal processes for organically contaminated waste water containing non-biodegradable substances or requiring a particularly high reaction efficiency. 

Tbe luminescence of GGA solutions were estimated using the bacterial chip system in order to produce a calibration plot for measurement of pollution containing biodegradable substances. The luminescent intensity was correlated with concentration of BOD standard (GGA) solution. The bioluminescence increased linearly with concentration up to approximately 50 ppm. Measurement of BOD values less than 50 ppm has been achieved. The bght intensity reached saturation at concentrations of over 100 ppm. Detection limit was approximately 1(X) ppm, and the minimum measurable BOD was 1 ppm. Based on the logarithmic curve which was obtained by the measurement with a chemi-imager, two linear calibration curves and equations were estimated and approximated... 

The results of assessment from the enforcement of law to the amendment, and from the amendment to present time, are shown in Table 7.4 [32], and we can find that biodegradable substances are nearly 20% of the assessed both a) and b). The substances judged as safe from the results of chronic toxicity tests were very few. This fact is attributed to high cost for chronic toxicity tests which are needed if the substance has highly bioaccumulative properties. 

Non-biodegradable substances are assessed for bioaccumulation potential. This may be done by measuring the n-octanol/water partition coefficient (Pow)- The pKa and a preliminary hydrolysis test are also required as part of the evaluation of bioaccumulation potential. If log P <3, the substance can be considered unlikely to bioaccumulate. A non-readily-biodegradable substance with a log P >3 is tested for bioaccumulation in carp. Alternatively, bioaccumulation can be assessed by analogy with chemically similar compounds which have already been tested. 

Biological treatment (favored for dilute wastewaters (< 5 %) and readily biodegradable substances). 

Biological waste gas scrubbers or compost filters The use of a biological waste gas scrubber can be considered if the gases to be treated contain readily biodegradable substances such as phenols, etc. Biological scrubbers generate less waste water than conventional wet scrubbers because biologically treated waste water can be recirculated more often. 

Non-biodegradable substances are those which show no evidence of primary or ultimate biodegradability. 

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