WasteWater Engineering Treatment Principles and Design Session132930961 1. EAP 582.4 WasteWater Engineering Treatment Principles and Design Session1

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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

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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

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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

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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)



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)

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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

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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.

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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.

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Polluted river

world's most polluted river ??


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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


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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.

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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.


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Sources


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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

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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?

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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

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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.

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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.

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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.


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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.

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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.

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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))

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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)

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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)

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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.

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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)


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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.


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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.


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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

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Important Definition-Wastewater Quality

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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

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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.

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WasteWater Engineering Treatment Principles and Design Session132930961 1. EAP 582.4 WasteWater Engineering Treatment Principles and Design Session1