estimate the mass and volume of sludge produced from unreated wastewater without and with the use of ferric chloride for the enhanced removal of TSS. Also, estimate the amount of lime required for the specified ferric schloride dose. assume that 60% of the TSS is removed in the primary settling tank without the addition of chmicals, and that the addiction of ferric chloride results in an increased removal of TSS to 85%. also assume that the following data apply to this situation:

1- wastewater flowrate (m3/day) =1000
2- wastewater TSS (mg/L) = 220
3- wastewater alkalinity as CaCO3 (mg/L) = 136
4- Ferric chloride (FeCl3) added (kg/m3) = 0.04
5- raw sludge specific gravity = 1.03
6- raw sludge moisture content % = 94%
7- Chemical sludge specific gravity = 1.05
8- chemical sludge moisture content = 92.5%

when ferric chloride is added to wastewater, the following reactions take place

2 FeCl3 + 3 Ca(HCO3)2 -> 2 Fe(OH)3 + 3 CaCl2 + 6 CO2

if lime is added to supplement the natural alkalinity of the wastewater, the following raection can be assumed to occur:

2 FeCl3 + 3 Ca(OH)2 -> 2 Fe(OH)3 + 3 CaCl2