MadSci Network: Environment & Ecology

Re: Can a chemical oxidizer speed up the process of biodegadation?

Date: Mon Dec 14 15:59:18 1998
Posted By: Harry Adam, Staff, Research Division, Research Division, Kodak Limited
Area of science: Environment & Ecology
ID: 910126304.En

Hi, Stephanie - biodegradation is a process in which organic or carbon-
based molecules are broken down into smaller, more simple molecules which 
are ordinarily found in the environment. This breaking down, or 
degradation, is called biodegradation when it is reliant on simple 
organisms – bacteria most commonly, to make it happen. All chemical 
reactions involve oxidation and reduction – one reagent gets oxidised, the 
other reduced – and biodegradation reactions are no different. Oxidative 
biodegradation is one kind, and reductive is the other, and you will often 
see these referred to as “aerobic” and “anaerobic” degradations. Aerobic 
simply means that it occurs in the air, or on the presence of oxygen – it 
requires oxygen as a key reagent, whereas anaerobic reactions will 
continue happily in the complete absence of oxygen. An common example is 
in our landfill sites where while the air (and water) are available, most 
organic wastes decompose rapidly, but if the landfill is sealed, and fresh 
air cannot get to the wastes, the air gets used up, and is replaced by 
methane, and everything slows down, with only anerobic processes of 
degradation occurring.

You may have heard of a couple of terms used: BOD and COD – as 
characteristics of wastes. These stand for biological oxygen demand and 
chemical oxygen demand. The first is actually a measure of 
biodegradability – and is measured by observing the consumption of oxygen 
when a sample is allowed to react under controlled conditions for a 
specific length of time (e.g. 28 days) with a carefully prepared sample of 
acclimatised “bugs”. Chemical oxygen demand simply measures the amount of 
oxygen required to convert the organic wastes such that all the carbon in 
it ends up as carbon dioxide and the rest is water and a few other 
residuals. This works with chemicals that are not very biodegradable or as 
they say, persistent, and might accumulate in the environment.

Of course, biodegradation is not the only degradation route for chemicals 
to break down in the environment – photolysis is a common route by which 
some chemicals are degraded – the sun’s energy can break up wastes as well 
as give you sunburn.

So, the question of oxidation in the sea is really about the ability of 
the air and oxygen to get to the chemicals that need to be degraded in the 
sea. Because the sea is so vast, there is no practical way we could 
compete with the mechanisms that already exist between air and sunlight by 
adding oxidising chemicals to the sea. Fortunately, though, nature has 
provided the oceans with a very effective self-cleaning mechanism which 
means we don’t have to treat sea water to keep it clean – there is an 
awful lot of it! We just have to be careful we don’t overload the system 
and give it more work than it can cope with.

So the fundamental answers to your two questions are:
1. Can a chemical oxidizer speed up the process of biodegadation? - Yes
2.   Are there any oxidizers that would be effective in the ocean? – No ( 
just because of the volume of      water)

I hope this all helps, and here is a web-site you may find of interest. E-
mail me for more help if you need it. 
Biodegradation web-site:

My e-mail:

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