ESE2401: WATER SCIENCE AND
TECHNOLOGY
SEMESTER 2, AY2014/15
TUTORIAL SESSION 9
TUTORIAL 5
SHI XUEQING
ERISX@NUS.EDU.SG
DEPARTMENT OF CIVIL AND
ENVIRONMENTAL ENGINEERING
NATIONAL UNIVERSITY OF SINGAPORE
Coagulation indicates the process through which colloidal particles and very
fine solid suspensions are destabilized so that they can begin to agglomerate
if the conditions are appropriate
Flocculation refers to the process by which destabilized particles actually
conglomerate into larger aggregates so that they can be separated from the
wastewater
Sedimentation
Filtration
In a sewage (or industrial wastewater) treatment plant, the
activated sludge process is a biological process that can be
used for one or several of the following purposes:
•oxidizing carbonaceous biological matter.
•oxidizing nitrogenous matter:
mainly ammonium and nitrogen in biological matter.
•removing phosphates.
•generating a liquor that is low in dissolved or suspended
material.
SUMMARY
•
Unit conversion
•
Material balance
•
Residence time
•
Molarity/normality
•
Water quality parameters
•
1. Alkalinity
2. Hardness (TH, CH, NCH)
3. TS, TDS, TSS, VSS
4. Ionic strength
Henry’s Law
•
Relative humidity
SUMMARY
1.
Equations
1.
2.
3.
4.
Mass conservation
Equilibrium
Electroneutrality (Charge balance)
Proton condition
2.
Solid dissolution/precipitation
3.
Acid base equilibrium
1.
2.
Strong acid/base
Weak acid/base
4.
Open/closed carbonate system
5.
Solving equilibrium problems
1.
2.
Analytical approach
pC-pH diagram
SUMMARY
PROTON CONDITION （PRL）
ELEMENTRAY REACTION KINETICS （expression of rate, k, Ƭ）
REDOX STOICHIOMETRY (element oxidation state, element balance, charge
balance)
BIOCHEMICAL OXYGEN DEMAND (BOD(t)=BODu-BODt, first order kinetics)
BATCH REACTOR KINETICS (sequential first-order reaction
A →B →C, d[B]/dt=R1-R2=k1 [A]-k2 [B])
THREE CLASSIC MODELS (batch reactor, CMFR, PFR)