I\'m looking at Waste Water treatment, and how with aeration a reaction occurs w

Question

I'm looking at Waste Water treatment, and how with aeration a reaction occurs with the biology inside of the tank.

I'm looking for the delta H of the reaction taking place, but clearly there is no neat equation of formation (like there is for glucose, for example). I can't simply find values in the back of a text book for delta H of reactions and add up.

Does anyone have any suggestions on calculating a theoretical delta H value for sludge reacting with oxygen in order to compare to expirimental data?

Explanation / Answer

In waste water treatment,aeration known as the secondary treatment process.

Aeration in an activated sludge process is based on pumping air into a tank, which promotes the microbial growth in the wastewater.

The microbes feed on the organic material, forming flocs which can easily settle out. After settling in a separate settling tank, bacteria forming the activated sludge flocs are continually recirculated back to the aeration basin to increase the rate of decomposition.

Aeration provides oxygen to bacteria for treating and stabilizing the wastewater.

Oxygen is needed by the bacteria to allow biodegradation to occur. The supplied oxygen is utilised by bacteria in the wastewater to break down the organic matter containing carbon to form carbon dioxide and water.

Without the presence of sufficient oxygen, bacteria are not able to biodegrade the incoming organic matter in a reasonable time. In the absence of dissolved oxygen, degradation must occur under septic conditions which are slow, odorous, and yield incomplete conversions of pollutants.

Under septic conditions, some of the biological process convert hydrogen and sulphur to form hydrogen sulphide and transform carbon into methane.

Other carbon will be converted to organic acids that create low pH conditions in the basin and make the water more difficult to treat and promote odour formation. Biodegradation of organic matter in the absence of oxygen is a very slow biological process.

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