= Total heat requirement, Btu/hr = Overall heat transfer coefficient (a value of 140 is used in the absence of other information) Btu/hr/°F/ft2 = Heat exchange surface area, ft2 = Diameter of sludge pipe, in = Logarithmic mean of the temperature difference / AT1 - AT2 \ 1 loge AT1/AT2J

Digester Sizing

The following equations predict the VSS destruction: Conventional digesters:

High-rate digesters:


These equations specifically apply to sludge with an initial VSS content of 65 to 70%. The quantity of solids remaining in the primary digester at the end of the digestion period can be calculated as follows:


MTt = Solids remaining in digester, lb

MTw = Daily solid waste input into digester, lb t1 = Digestion period, days

%V = VSS in the sludge received by the digester, %

The following equations calculate the required primary digester volume:

DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

Get My Free Ebook

Post a comment