An Introduction to Environmental Chemistry

on the control plots. Hydrocarbon consumption rate in the control plot was
0.052% d-^1 , but this increased to 0.45% d-^1 when the plot was fertilized, a rate
enhancement of 8.6 times.

Ex situ on-site bioremediation by composting—Finnish sawmills

Gardeners know that compost is added to soil to provide a source of nutrients
and to aid soil aeration by creating a more open soil structure. Gardeners might
not know, however, that most compost is also a rich source of microorganisms;
the compost effectively inoculates the soil with microbes. Under composting con-
ditions heat is generated though the processes of degradation (see eqn. 5.20). This
heat changes the microbial community and the rate at which it degrades organic
matter, including any bioavailable organic contaminants. Conditions within a

The Chemistry of Continental Solids 133

R(CH 2 )n-CH 2 -CH 2 -CH 3

R(CH 2 )n-CH 2 -CH 2 -CH 2 OH

R(CH 2 )n-CH 2 -CH 2 -CHO

R(CH 2 )n-CH 2 -CH 2 -COOH

R(CH 2 )n-CH=CH 2 -COOH

R(CH 2 )n-COOH + CH 3 COOH

Tricarboxylic acid

(TCA) cycle

Methyl-oxidation ß-oxidation

R(CH 2 )n-CH-CH 2 -COOH

OH

R(CH 2 )n-CH-CH 2 -COOH

O

Fig. 4.31Biodegradation pathways of hydrocarbon. Methyl-oxidation, by attack of the methyl
group (–CH 3 ) at the extremity of the hydrocarbon chain, results in formation of a carboxylic
acid group (–COOH). b-oxidation indicates that oxidation occurs at the second carbon atom
(counted from the end that bears the –COOH group, the a-carbon atom being immediately
adjacent to the –COOH group). b-oxidation continues removing C 2 units, and in effect unzips
the hydrocarbon chain until it no longer exists.