EAP582/4: Wastewater Engineering
Wastewater Treatment Plant Principles' and Design
1
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
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
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
Outline - Plant Classifications (Aerobic, Classifications (Aerobic, Anaerobic, Fixed Media, Suspended Culture etc)
- Primary, Secondary, Tertiary (Management 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 Plant (Activated Sludge, RBC, Anaerobic Digester etc)
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)
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 –
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.
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. –
Polluted river
Introduction: Wastewater Treatment world's most polluted river ??
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%)
Inorganic (30%)
Organic (70%) Protein
Carbohydrate
Fat
(65%)
(25%)
(10%)
grit
salt
metal
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.
Introduction: Wastewater Treatment 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 Sources
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
Introduction: Wastewater Treatment Collection
Treatment
Discharges
Preventing water-borne diseases. Reducing outbreak of diseases. contains pathogenic Wastewater
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?
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
Criteria’s : 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.
Compositions: Wastewater / Sewage Organic Solid (1)
NonOrganic (2)
Total Organic (3)
BOD5
39
15
54
19
26
10
36
23
90
42
160
12
Suspended Solid (settle-able) Suspended solid (unsettle-able) TOTAL Dissolved solid
80
80
Data from Table 1.1, taken from the analysis of sewage sample, x. Tested to the organic, inorganic and BOD 5 concentration.
Compositions: Wastewater / Sewage 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 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 BOD 5.
•
In other words, if only sludge pond is used to the eliminate sewage, then there will be 55% (10045%) That is the BOD 5 concentration in our final effluent.
•
Therefore, the biological treatment is essential in removing organic concentration in wastewater.
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.
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))
Wastewater Quality
Dry Weather Flow (DWF)
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.
Wastewater Quality
Dry Weather Flow (DWF)
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: D x A DWF
DWF D A
375
= dry weather flow (L/s) = population density (person/hectare) = 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.
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.
Wastewater Quality Identification of Quantity of DWF 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) –
Wastewater Quality Identification of Quantity of DWF 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.
–
Wastewater Quality Identification of Quantity of DWF 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.
Wastewater Quality Example : a) b)
The rate of water usage for 10000 people is 250 L/capita.day, calculate the value for DWF. 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 m 3 /day) = 3350 m3 /day
AAMH
Important Definition-Wastewater Quality
Wastewater Quality Land application: kg of BOD applied per day
We know, LBOD = (area loaded per day) * (cycle time) 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
