The materials balance for the insolubles produced is presented in
Table 11, "SLUDGE BALANCE". The input considers only the chemicals
(soda ash and lime) which were added to cause precipitation. Their
addition has been calculated to a total input of 2671 pounds as CaC03•
The output is in the insolubles of the sludge. Chemical analysis of
the sludge indicated that the 900 gallons of sludge contained 2985
pounds of solids. Although the insolubles are a mixture of calcium
carbonate and magnesium hydroxide, the amount of the latter precipitate
is small and will not appreciably affect the balance. The deviation
is shown as 5.5%, which is reasonable.