Environmental Engineering Reference
In-Depth Information
temperature. Total solids (TS) includes total suspended solids (TSS) and total
dissolved solids (TDS), i.e., TS¼TSSþTDS.
Total Suspended Solids and Total Dissolved Solids
TSS is the portion of total solids retained by a filter (0.45
m in pore size is the most
common), while TDS is the portion that passes through the filter. The temperature at
which the residue is dried has an important bearing on results, because weight losses
due to volatilization of organic matter, mechanically occluded water, water of
crystallization, gases from heat-induced chemical decomposition, as well as weight
gains due to oxidation, depend on temperature and time of heating. Each sample
requires close attention to desiccation after drying. Note the different temperatures
used for TSS (1041 C) and TDS (1802 C) measurement. Because the
temperature difference, in practice, the equation TS¼TSSþTDS may not work out
for some samples.
m
Volatile Solids (VS)
This is the difference between the dried solids and the same sample further ignited at
55050 C in a muffle furnace. VS is useful in control of wastewater treatment
plant operation because it approximates the amount of organic matter in the solid
fraction. Thus, TVS¼TS - TS ash ; TVSS¼TSS - TSS ash ; TVDS¼TDSTDS ash .
''Ash'' is the residue at 55050 C in a muffle furnace.
Settleable Solids
Settleable solids can be measured either gravimetrically or volumetrically. The
common volumetric method is defined as the volume (mL) of settleable solids per
liter of wastewaters after 1 h settling under quiescent conditions (mL/L). It is
normally performed in a Imhoff cone, which is simply a cone-shaped plastic
container with a holding volume of 1 L and the side of the cone graduated in mL.
Settleable solids can be used to estimate the sludge volume index (SVI), which
represents the volume (mL) occupied by 1 g of activated sludge after 30-min
settling, i.e, SVI (mL/g) ¼settleable solids (mL/L)/TSS (g/L). A high SVI (
100)
indicate poor settling quality and possible bulking problem in secondary clarifier of
the wastewater treatment plant.
>
6.3.3 Acidity, Alkalinity, and Hardness of Waters
1. Acidity
All waters having pH lower than approximately 8.3 should contain acidity. Acidity
is the capacity of water to neutralize a base (OH ). Sources of acidity in natural
water include CO 2 (air, bacterial degradation), H 2 PO 4 ,H 2 S, protein, fatty acids,
and salt of
such as hydrated Fe and Al (e.g.,
trivalent metals
Search WWH ::




Custom Search