Answer to Question #337484 in Chemical Engineering for Vhadau

Question

One of the products of sewage treatment is sludge. After microorganisms grow in the activated sludge

process to remove nutrients and organic material, a substantial amount of wet sludge is produced.

This sludge must be dewatered, one of the most expensive parts of most treatment plant operations.

Disposing off the dewatered sludge is a major problem. Some organizations sell dry sludge for

fertilizer, some spread the sludge on farmland and in some places, it is burned. To burn a dried sludge

fuel oil is mixed with it, and the mixture is burned in a furnace with air.

As part of the design evaluation of the furnace the following analysis for the sludge and product gases

was collected:

Sludge (%) Product gas (%)

S 32 SO2 1.52

C 40 CO2 10.14

H2 4 O2 4.65

O2 24 N2 81.67

CO 2.02

a) Determine the weight percent of carbon and fuel oil

b) Determine the ratio of pounds of dry sludge to pounds of fuel oil in the mixture fed to the

furnace. [20]