LYCOS RETRIEVER 
Digestion: Acids
built 628 days ago
In a two-stage or multi-stage digestion system different digestion vessels are optimised to bring maximum control over the bacterial communities living within the digesters. Typically hydrolysis, acetogenesis and acidogenesis occur within the first reaction vessel. The organic material is then heated to the required operational temperature (either mesophilic or thermophilic) prior to being pumped into a methanogenic reactor. Acidogenic bacteria produce organic acids and more quickly grow and reproduce than methanogenic bacteria. Methanogenic bacteria require stable pH and temperature in order to optimise their performance.
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Several designs are used to keep Parr acid digestion bombs tightly sealed during consecutive heating and cooling cycles when conventional seals might leak. One of these designs uses a tapered closure between the PTFE cup and cover with an unusually long sealing face that tends to become self-sealing. This long path ... minimizes the tendency for acid migration through the joint. Bombs using this design can be sealed by simply turning down a knurled cap by hand without using a wrench or spanner. For applications requiring higher temperatures and pressures, the PTFE liners are made with a broad, flanged closure and sealed by tightening the bomb cap with a spanner or, in a larger design, by using cap screws to develop the sealing force. Tight closures for the PTFE cup in Parr microwave bombs are developed and maintained with self- sealing PTFE O-rings.
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The reason for this is that, for best digestion, proteins require an acid digestive medium and starches an alkaline one. When eaten together, they interfere with each other’s utilization, so that digestion takes longer and is inefficient.
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Parr acid digestion bombs have added a new alternative to the task of preparing analytical samples for analysis. By combining the unique chemical inertness of PTFE with the advantages of a sealed pressure vessel, these convenient bombs offer a rapid procedure for sample dissolution or digestion that has several important advantages over more traditional methods of sample preparation. By providing a convenient means for holding strong mineral acids or alkalis at temperatures well above normal boiling points, these sturdy digestion bombs will:
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Acids