Letter 35044

Wastewater treatment  

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I'm an undergraduate University student doing an assignment about wastewater treatment. The analysis report shows that the sulphide content in the wastewater is 7.760 mg/l and there is 1 mg/l of oil and grease. BOD is 780 mg/l and the COD is 1900 mg/l. I wish someone could help me as I do not know what is the cause of that, and give some opinions on how to reduce the BOD and COD. Thank you in advance.

Phing Voon Chung
student - Malaysia

These are real numbers from an actual physical installation or a hypothetical example, Phing?. If real, it would be foolish to speculate in lieu of actually determining the situation. But if sheerly a hypothetical as a learning experience, sulfide could come organic installations like egg processing or from industrial use of sulfide chemicals. Oil and grease should be rather obvious. Hopefully you know what BOD and COD are, rather than just retyping the acronyms, but domestic treatments plants with trickling filters or activated sludge are designed to reduce BOD and COD.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

Oil and grease is an organic compound, so, by adding oxidation reagent such as ozone, hydrogen peroxide, chlorine dioxide, potassium permanganate into the wastewater could reduce the BOD and COD. However, physical method such as adsorption with activated carbon also could reduce the BOD and COD. Ozone and hydrogen peroxide are the most environmental friendly reagent because after being reduced, it converts to carbon dioxide and water. While chlorine dioxide would produce a by product, called chlorite that has to be removed by adding ferrous ion salts or reduced sulfur compounds. Potassium permanganate would produce black insoluble manganese dioxide after the treatment. It could be removed by conventional filtration. Activated carbon that had been used to adsorb the oil and grease has to be reactivated by heating or burning. Apart from these methods, biological method is one of the cheaper methods. Bacteria seed or yeast is adding into the wastewater and leave the bacteria to degrade the oil and grease using their secreted enzyme. Beside, oil and grease could also be decomposed using titanium dioxide when irradiated under UV light. By using hydrogen peroxide, ion sulphide will be oxidized to ion sulfate.

Alexander Chong
PhD student in USM - Penang, Malaysia

Pollution prevention priorities, discuss the constraint factors that contribute to selectivity of pollution prevention method. Give pros and cons of selected method.
more specified towards water recycles.

Nagentheran
- Kuantan, Pahang

Ed. note: You lost us, Nagentheran. Is this advise for the other inquriers about what to include in their work, or are you asking someone to do your homework for you?

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