-
AAMH 1
EAP582/4: Wastewater Engineering
Wastewater Treatment Plant Principles' and Design
Dr. ABU AHMED MOKAMMEL HAQUE School of Civil Engineering,
Engineering Campus, Universiti Sains Malaysia
14300 Nibong Tebal, P. Pinang, Malaysia.
E-mail: [email protected] August 09 , 2010
1
-
AAMH
Pre-Requisite Knowledge and/or Skills
Basic Principles of Environmental Engineering
Basic Principles of Environmental Fluid Mechanics
Mass Balance Techniques
Basic Organic and Inorganic Chemistry
Understanding of Environmental Engineering unit Processes
Basic Computer Spreadsheet Application
-
AAMH 3
Outline Objectives
Introduction - Plant Classifications (Aerobic, Anaerobic, Fixed Media, Suspended Culture etc)
Type of Treatments - Primary, Secondary, Tertiary (Management Aspect, Biological oxidation, Kinetics of BOD etc) - Design Aspects- Physical & Chemical Plant (Screen, Grit Removal, Comminutor, Skimming & Equalization Tanks, Sedimentation Tank, Coagulation & flocculations) - Design of biological Plant (Activated Sludge, RBC, Anaerobic Digester etc)
Advance Wastewater Treatment
Reclamation and Reuse
-
AAMH
AAMH Teaching Plan
SECTION TOPICS
W1 Introduction Concept, Sources, Objectives, Plant Classification (Aug 09/10)
W1 Introduction Concept, Source, Objectives, Plant Classification (Aug 11/10)
W2 Type of Wastewater Treatments (Aug 16/10)
W2 Type of Wastewater Treatments (Aug 18/10)
W3 Type of Wastewater Treatments (Aug 23/10)
W3 Advance Wastewater Treatment (Aug 25/10)
W4 Wastewater Reclamation & Reuse (Aug 29/10)
W4 Wastewater Reclamation & Reuse (Sep 01/10)
W5 Revision (Sep 06/10)
-
AAMH
Text Book
Wastewater Engineering: Treatment, and Reuse, Metcalf and Eddy, Inc., 4rd Edition, McGrawhill, 2004.
Wastewater Engineering: Treatment, Disposal, and Reuse, Metcalf and Eddy, Inc., 3rd Edition, McGrawhill, 1991.
Wastewater Treatment Technologies: A General Review, Economic and Social Commission for Western Asia, United Nations, New York, 2003
Some PhD Thesis will be supplied By AAMH
-
AAMH 6
Objectives
To learn how to do a preliminary design of the most widely used wastewater treatment unit operations and how to organize these into a functioning treatment system.
To provide experiences in realistic civil and environmental engineering design and construction practice.
To develop teamwork and communication skills required for multi-disciplinary civil and environmental engineering objectives.
-
AAMH
Introduction: Wastewater Treatment
Wastewater Engineering
Branch of Environmental Engineering in which the basic Principles of Science and Engineering are applied to solve the problems of Water related pollution control.
Goal Wastewater Management, Protection of environment in a manure commensurate with economic, Social and Political concerns.
-
AAMH
Polluted river
world's most polluted river ??
Introduction: Wastewater Treatment
-
AAMH
Introduction: Wastewater Treatment
Sources of Generation Water carried wastes removed from Residence, Institutions, Commercial and Industrial establishment.
Technically, wastewater contains organic and inorganic matter, rich in microorganisms (some are pathogenic) and mainly made up of 99.9% water and 0.1% solids.
wastewater
Liquid (99.9%) Solid (0.1%)
Organic (70%)
Protein
(65%)
Carbohydrate
(25%)
Fat
(10%)
Inorganic (30%)
grit salt metal
Introduction: Wastewater Treatment
-
AAMH
Introduction: Wastewater Treatment
Most water that we used ends up as wastewater that needs to be disposed.
Wastewater collected from cities and towns which returned to receiving water bodies and or land as well as in ground water aquifers. Scientific knowledge, Engineering judgments based on experience, local conditions and regulations are very important issues on how we conserve our environment from water pollution.
A wastewater treatment plant functions to treat wastewaters from any source such as from a community, locality or township.
-
AAMH
Reasons for treating: Protect public health Protect surface-water quality. Managing the wastewater well. Protect ecosystem Meet legal requirements and regulations Specific concern: Pathogenic organisms Pathogen = specific agent causing disease Pathogenic = capable of causing disease Wastewater treatment as part of the main infrastructure.
Indicator of civilization. As important as other basic need of development, such as
water supply, drainage, transportation, electricity, telecommunication, etc.
Introduction: Wastewater Treatment
-
AAMH
Sources
Introduction: Wastewater Treatment
-
AAMH
Introduction: Wastewater Treatment
Pollution Prevention
Wastewater contains high pollutants
Example : BOD5 = 250 mg/L
BOD std = 50 mg/L
SS = 360 mg/L
SS std = 100 mg/L
Leachate contains : Temp = 27oC
COD = 1925 mg/L
Color = 3869 PtCo
-
AAMH
Introduction: Wastewater Treatment
Collection Treatment Discharges
Preventing water-borne diseases. Reducing outbreak of diseases. Wastewater contains pathogenic organisms (bacteria, viruses, worms, protozoa, helminthes, etc.)
Collection company : Indah water, Alam Flora, Idaman bersih, Jalutong (WWE Holdings BHD) What will happen if there is no company to do collection, treatment and discharge??? How about Reclamation and Reuse / Irrigation?
-
AAMH
Objectives: Wastewater Treatment
Objective of wastewater treatment is to get the quality of final effluent to be in a good standard A or B (Malaysia).
To reach this standard, the design of wastewater treatment plant must be compliance in removing wastewater loads in order to get a high quality of final effluent within the fix specification
Therefore, a civil and environmental engineer has a responsible to design a suitable plant
The important of treatment showed in Following Figure 1.1
-
AAMH
Criterias : Wastewater / Sewage
Figure 1.1, shows the thickness/density of wastewater from nearby town is 280mg/L of BOD and 360mg/L of SS respectively.
If standard B is followed, value of BOD and SS is < 50mg/L and < 100mg/L respectively
Therefore, the treatment plant which can removed these recorded wastewater loads data should be followed.
-
AAMH
Compositions: Wastewater / Sewage
Organic Solid (1)
Non-Organic
(2)
Total Organic
(3)
BOD5
Suspended Solid
(settle-able)
39
15
54
19
Suspended solid (unsettle-able)
26
10
36
23
TOTAL 90 42
Dissolved solid 80 80 160 12
Data from Table 1.1, taken from the analysis of sewage sample, x. Tested to the organic, inorganic and BOD5 concentration.
-
AAMH
From Table 1.1:
Total composition (1+2), consist of organic substances (1), inorganic (2). In this case, mineral is inorganic substance. e.g: sodium, sulfate and others
BOD5 is the value within the total space which evaluation of oxygen on the day 5.
Concentration of organic load in sewage can be SS and DS. SS can be both settleable and unsettle-able.
Compositions: Wastewater / Sewage
-
AAMH
Compositions: Wastewater / Sewage
From Table 1.1, can be concluded:
(54/90)*% = 60% out of total SS can be settled.
(19/42)*% = 45% from BOD5 can be removed through sedimentation process.
This data is to prove that sedimentation (physical treatment) only unable to remove all the BOD5.
In other words, if only sludge pond is used to the eliminate sewage, then there will be 55% (100-45%) That is the BOD5 concentration in our final effluent.
Therefore, the biological treatment is essential in removing organic concentration in wastewater.
-
AAMH
Wastewater Quality
The design of a wastewater treatment plant requires knowledge of:
Quantity or flow rate of wastewater.
Required to determine the size of the various unit operations and unit processes.
Quality of raw wastewater.
Required to determine which unit operations and processes to be used.
Quality required for the effluent (treated wastewater).
Required to determine the degree of treatment needed to produce the required quality of the effluent.
-
AAMH
Wastewater Quality
The quantity of wastewater produced varies in different communities and countries, depending on a number of factors such as water uses, climate, lifestyle, economics, etc.
A typical wastewater flow rate from a residential home in the US
might average 70 gallons (265 L) per capita per day. Approximately 60 to 85 percent of the per capita consumption of water becomes wastewater.
Wastewater flow rates Commercial developments: 800 to 1500 gal/(acre.d) (7.5 to 14 m3/(ha.d)) Industries - light industry: 1000 to 1500 gal/(acre.d) (9.4 to 14 m3/(ha.d)) - medium industry: 1500 to 3000 gal/(acre.d) (14 to 28 m3/(ha.d))
-
AAMH
Wastewater Quality
Definitions: Daily measured flow at a sewage works during a period of dry weather, or The rate of flow of sewage (domestic & industrial wastes), together with infiltration
if any, in a sewer in dry weather measured after a period of seven consecutive days of dry weather during which the rainfall has not exceeded 0.25 mm
_______________________________________________________________
DWF from municipal catchments can be divided into waters from household, institutions, business areas, industries, drainage of buildings and infiltration.
In the absence of flow measurements, the DWF is computed from the population and per capita sewage flow or water consumption.
For example: A community of 100 persons with an average per capita sewage flow of 200 L/d DWF = 20,000 L = 20 m3 This represents a flow of 20,000 L/24 h or 0.23 L/s At a large sewage works the flows entering the works in dry weather are like to be
50% of the DWF at any point in time.
Dry Weather Flow (DWF)
-
AAMH
Wastewater Quality
When the available information is in terms of population densities, and
assuming that maximum domestic sewage DWF is 230 L per capita per
day (Code of Practice 2005), the DWF can be calculated from the
following equation:
DWF = dry weather flow (L/s)
D = population density (person/hectare)
A = area (hectare)
Definition: Dry Weather Flow Rate is the rate of average sewage
that is calculated based on the total population and their water usage daily per capita.
375
AxDDWF
Dry Weather Flow (DWF)
-
AAMH
Wastewater Quality
Identification of Quantity of DWF
Through some calculation methods.
Usually can be calculated from the quantity of
water per capita.
In the operating plant, DWF is determined by
measurement of the actual flow rate of
wastewater to the plant for certain of period
using flow rate meter.
For future plants, the design flow rate is base
on the total usage of water per capita multiply
by total residents.
-
AAMH
Wastewater Quality
Calculation method (i) Quantity of water * population equivalent DWF = (q, water usage)(PE, populations) = (225 L/capita.day)*(1000 capita) = 225 m3/day (ii) (Water supplied * populations)-lost DWF = (i) (20~30% lost) = 70~80% (supplied water* populations)
Identification of Quantity of DWF
-
AAMH
Wastewater Quality
Calculation method
(iii) (Water supplied * populations) + other sources lost
DWF = (i) + (other source such as well) (20~30% lost)
(iv) Sewage record of short period
measurement of actual flow rate at site in a short term.
accurate, but for its long term there is no actual data.
i.e.: record for 3 days is 1000 l/min and it is only for 3 days period.
Identification of Quantity of DWF
-
AAMH
Wastewater Quality
Calculation method
(v) Sewage record of long period
same as for the previous one.
base on minimum and maximum value of the sewage it is suitable for design purpose.
Identification of Quantity of DWF
-
AAMH
Wastewater Quality
Example :
a) The rate of water usage for 10000 people is 250 L/capita.day, calculate the value for DWF.
b) Rate of water usage for 20000 people is 250 L/capita.day and the fraction of sewage/water is 0.67, calculate the value for DWF.
Solution:
a) DWF = q*P
= (250 L/capita.day) (10 000 people)
= 2 500 000 liter/day
= 2500 m3/day
b) DWF= (0.67*20 000 x 0.25 m3/day)
= 3350 m3/day
-
AAMH
Important Definition-Wastewater Quality
-
AAMH
Wastewater Quality
Land application:
We know, LBOD = Where,
LBOD = kg/ha-day
kg of BOD application per day = Concentration, mg/L Flow, m3/day Conversion Factor (CF);
Conversion Factor = [1000 L/ m3 0.001 kg/g 1g/1000mg]
Area Loaded = Total wetted area receiving wastewater per day, ha
Cycle time = time between subsequent applications to a given plot, days
time)(cycle*day)per loaded (area
dayper applied BOD of kg
-
AAMH
Land Application
Calculation:
A wastewater treatment plant discharged effluents for land treatment purpose which contented BOD of 200 mg/L. The slow-rate land treatment field area was 2 ha/day and the daily effluent flow rate was 1000 m3/day. The land treatment effluent application cycle time was 5 days between two applications. Findout cycle average BOD loading rate.