Sewage systems are one of the most of import substructures in building of residential, industrial or commercial undertaking as it determines the quality of life enjoyed by a community. It consists of a web of belowground cloaca pipes, pump Stationss, sewerage intervention workss and sludge intervention installations. This system normally operates based on by gravitation due to the incline of the pipe which reduces the high cost required for pumping.
Sewers are farther classified into a few classs, which depend on the type of effluent that each of it carries. For illustration, storm cloacas are designed to transport stormwater from roofs, paved countries, pavings and roads ; industrial cloacas are designed to transport effluent generate from the industry ; healthful cloacas are designed to transport the waste H2O from cooking and rinsing and the wastes from lavatories. There is another type of cloaca which is known as combined cloacas. These types of cloacas are designed to transport stormwater, industrial wastes, and domestic sewerage. In Malaysia, many towns and metropoliss use the separate cloaca system. The effluent is transported in separate pipes from storm cloacas, industrial cloacas and healthful cloacas. This system will non see CSOs ( Combine Sewer Overflows ) which normally happen to combined cloaca. The implosion therapy will do by stormwater merely.
Sewage system is really of import as it helps people to transport the wastes or sewage off from their topographic points. Therefore, the system must be working good because improper operation system will take to pollution and taint of assorted facets of our environing which affect human life and wellness. Hence, regular care must be done to the bing sewage system and appropriate design must be applied to the new sewage systems to guarantee the sewage systems are in good status.
The efficiency of the sewage system is affected by the flow of the effluent. In planing a sewage system, the type and size of the pipe to be used must be able to suit the extremum flow. The extremum flow is based on the population equivalent which is a direct measuring of the population in an country. When planing the sewage, there is a criterion and standards that should be followed. The standard codification of pattern for sewage design in Malaysia ( MS 1228:1991 ) was adopted from British Standard ; BS 8005:1987. However, British Standard may non be as applicable to Malaysia due to the season and clime factor which have direct consequence on the extremum flow. This is the chief ground of making this research to happen out whether the criterion is suited to be used in Malaysia.
Problem Statement
Any sewage system will be designed to transport a certain sum of sewerage based on the population equivalent ( PE ) . In sewage design, the per capita flow and the peak flow rate ( Qpeak ) are of import parametric quantities. Based on British Standard, the per capita flow is 225L/day/person and the extremum flow factor, K is 4.7. However, a old survey indicated lower per capita flow and peak flow factor in the sewage system in Malaysia although no conclusive consequences were obtained ( Dayalan, 2007 ) . A lower extremum flow factor will ensue in smaller pipes which will incur lower cost. Therefore, farther research is needed to analyze the suitableness of current design standard for sewage system located in tropical climes.
1.3Research Aims
The aims of the survey are:
To obtain flow informations from pre-determined cloaca tributary country.
To measure the parametric quantity in the extremum flow factor equation for medium graduated table sewage catchment system.
To find the relationship between population of an country to the extremum flow of sewage system.
1.4 Scope of Research
To roll up relevant information of sewage design from selected literatures.
To happen out relevant expression provided in selected codifications for sewage design.
To analyze the extremum flow factor in sewer line that serve the PE value of 1000-10000.
To mensurate flow features by utilizing flow metre with build-in detector in manholes at Tropicana Indah.
To compare the consequences obtained with the expression in the standard codification.
To do recommendation on the feasibleness of the codification expression to tropical clime.
Chapter 2: LITERATURE REVIEW
2.1 Sewage System in Malaya
The sewage system is designed to roll up effluent or disgusting sewerage generated from residential, industrial and commercial countries through sewer pipes and discharges it to the intervention workss or installations to guarantee the sewerage is released to the natural H2O organic structures in an appropriate status and quality ( Geoffrey, 2004 ) . In Malaysia, sewage systems range from simple lavatory with small or no intervention provided to modern sewerage intervention workss that treat the sewerage to the desired quality conformity to environment criterion. There are two chief types of sewage system in Malaysia. A premiss sewage system is either connected to a public sewerage intervention works or an single infected armored combat vehicle. Indah Water Konsortium ( IWK ) is responsible to supply service and care to public sewerage intervention workss and all the belowground pipes and besides provide desludging services to single infected armored combat vehicles ( Abd Aziz, 2006 ) .
IWK decided to split the belowground pipe into two subdivisions, public pipe and private pipe ( Figure 2.1 ) to do certain that all belowground pipes operate without any job. Public pipe is under the duty of IWK and the private pipe is under single duty. An person have to pay for the IWK services when the private pipe demand for serving. ( Abd Aziz, 2006 ) .
hypertext transfer protocol: //www.usj23.com/planet_free/sewage_system/Sewage % 20System.jpg
Figure 2.1 Flow of effluent from private pipe to public pipe ( USJ 23 Residence
2.2 Transportation of Wastewater
Wastewater is normally transported through sewer pipes that are connected to the cloaca brinies by clay, cast-iron, or polyvinyl chloride ( PVC ) pipes that scope from 80-100mm diameter. The big cloaca brinies can be located about 1.8m deep or more than that along the center line of a street or tract. The little and big cloaca pipes are made by different stuff, in which the smaller cloaca pipes are made of clay, concrete, or asbestos cement, and the big cloaca pipes are made of strengthened concrete building. The flow of effluent is different from water-supply system. The H2O supply is transported to each house by the application of force per unit area. However, the effluent from each house is flows through sewer pipes by gravitation. Therefore, the cloaca pipe must put on incline surface to let the effluent to flux at a speed of at least 0.8m/s and non more than 4m/s. ( MS1228:1991 ) . If the effluent flows at speed lower than 0.8m/s, the solid stuff tends to settle in the pipe which will take to blockage. Storm-water brinies have similar construction as healthful cloacas but they have a much larger diameter than healthful cloacas. In certain topographic points, the urban cloaca brinies are connected to interceptor cloacas, which can so fall in to organize a bole line. The bole line will so dispatch the effluent into the wastewater-treatment works. This transit procedure is shown in Figure 2.2. As the interceptors and bole lines will transport the effluent discharge from sewer chief, they are normally made of brick or reinforced concrete which can transport more burden than the other pipe. Sometimes, they are big plenty for a truck to go through through them. ( Norhan Abd Rahman et.al, 2007 )
hypertext transfer protocol: //techalive.mtu.edu/meec/module21/images/CombinedSewer.jpg
Figure 2.2 Transportation system of Wastewater ( Michigan Environmental Education Curriculum,
Wastewater Treatment )
2.3 Concept & A ; Theory
In planing a sewage pipe web, the pump Stationss and sewerage intervention workss are required to transport and pump volumetric flow rate. The flow rates are normally measured in three-dimensional metre per second ( m3/s ) and need to be calculated for both bing land usage and for expected hereafter development. There are two parametric quantities that are used to cipher expected flow rates. One of the parametric quantities is per capita flow. This per capita flow of 225L/person/day is an mean day-to-day flow, which means a individual will bring forth 225 litres of sewerage in a twenty-four hours. Another design parametric quantity named “ population equivalent ” ( PE ) of a catchment can besides be used to cipher the flow rate. PE is non a step of population. However, it is used to mensurate the estimated figure of people that use the sewerage installations. In residential countries, the PE is a direct measuring of the population in an country which is calculated as five per home. The PE has a different method of measuring in commercial country. It is calculated from the floor country and this PE value is considered to be relative to the figure of people utilizing a premiss during the twenty-four hours which does non reflect the population life in an country.
2.4 Measure for Effluent
2.4.1 Tributary Area
Tributary country is an country from where the effluent is being transported to a peculiar cloaca subdivision. The types of activities in that country determine the measure of effluent being collected by a peculiar subdivision. A study has to be done when there is no information available on bing countries in order to find the figure and categorization of individuals and the types of industries. ( Guyer, 2010 )
Table 2.1 shows the method of ciphering the PE.
Table 2.1 Equivalent Population, PE ( MS1228:1991 )
No.
Type of Premises/Establishment
Population Equivalent ( recommended )
1
Residential
5 per unit
2
Commercial:
A
A
( include entertainment/recreational Centres, eating houses, cafeteria, theaters )
3 per 100m gross country
3
School/Educational Institutions:
A
A
– Day schools/institutions
0.2 per pupil
A
– Full moon residential
1 per pupil
A
– Partial derivative residential
0.2 per pupil for non-residential pupil and 1 per pupil for residential pupil
4
Hospitals
4 per bed
5
Hotels ( with dining and wash installations )
4 per room
6
Factories ( excepting procedure wastes )
0.3 per staff
7
Market ( Wet Type )
3 per stall
8
Petrol kiosks/Service Stationss
18 per service bay
9
Bus terminus
4 per coach bay
2.4.2 Sanitary/Domestic Wastes
2.4.2.1 Lending Population
In planing the flow, the population to be used depends on the location of the cloaca. The design population in a residential country is based on the figure of houses served. However, the design population for an industrial country is the maximal figure of staff of all time employed. The design population for cloacas that serve both residential and industrial countries include occupants and non-residents. Designing of these cloacas denote that no individual should be counted more than one time. Allowances should be made for future population alterations caused by maestro planning projections and installation forces demands. ( Guyer, 2010 )
2.4.2.2 Average Daily Flow
The mean day-to-day flow is counted by multiplying the population equivalent from occupant and non-resident with the appropriate per capita flow and adding the two flows generated from both resident and non-resident. The mean day-to-day flow shows the entire volume of waste generated over a 24-hour period. It can non be used for wastes that were generated over shorter periods of 8, 10, 12 hours, etc. Therefore, it can merely be used for planing cloacas that generate effluent over a 24-hour period ( e.g. residential country ) . In Malaysia, the mean day-to-day flow for residential country is normally taken as 225L/person/day. In industrial countries, the mean day-to-day flow is taken every bit 115L/person/day as non-resident forces and employees is working for 8-hour displacements. These measures are normally used in planing effluent intervention installations. However, they are besides used for sizing interceptors, bole cloacas and pumping Stationss functioning big parts of the installing. ( Guyer, 2010 )
2.4.2.3 Average Hourly Flow Rate
Average hourly flow rate is used for planing cloacas that serve little countries of the installing ( e.g. industrial country ) , where most of the effluent is generated by non-residents or other short term residents. The mean hourly flow rate is counted based on the existent period of waste coevals. For illustration, 1000 non-residents with an mean day-to-day flow of 115L/person/day would bring forth 115,000 litres in 8 hours which is tantamount to an mean hourly flow rate of 14,375 L/h or 345,000 L/d. However, the mean day-to-day flow would still be 115,000 L/d. Therefore, the cloaca must be designed hydraulicly to transport 115,000 litres of waste in 8 hours alternatively of 24 hours ( Guyer, 2010 ) . If the cloaca is designed to transport a waste of 115,000 litres in 24 hours, so the cloaca pipe will non be able to transport the wastes as the existent volume of wastes generated is more than the design waste. This will take to the obstruction of sewer pipes and flood in the lavatory.
2.5 Design Wastewater Flow
The design flow of effluent must be determined for any subdivision of a proposed cloaca. The design flow is non merely based on healthful sewerage ; industrial flows, inflow and infiltration must besides be taken into history. The followers shows the equation to find the extremum flow factor and the factor to be considered in sewage design.
2.5.1 Design Equations
The extremum flow required to plan cloacas, pumping station and intervention installations are calculated by the undermentioned equation:
Peak flow factor = 4.7 ten p-0.11
p – Estimated tantamount population, in 1000.
The cloacas are designed based on extremum flow to guarantee that the sewer pipes would be able to suit the effluent generated at any clip.
2.5.2 Factors Affecting Sewer Design
In planing cloacas, there are a few factors as stated in MS1228:1991 that must be taken into consideration:
Economy in the design
The cloacas should be kept every bit short as possible and avoid unproductive lengths.
Shallow rider cloacas can be laid under main roads holding expensive foundations and surfaces to have the local house connexion, and to link the riders at convenient points into the chief cloacas.
Location of cloacas
The cloacas should be placed within streets or right-of-way to ease the care work.
If topography dictates, the cloaca is to be located within private belongingss, and supply equal entree for care intents.
Location or the place of other bing or proposed service lines, constructing foundation, etc for care intents.
A lower limit at 3 thousand horizontal and 1m perpendicular separation from the H2O chief should be provided to avoid the sewerage from come ining the H2O chief.
The impact of sewer building and subsequent care activities towards route users.
Hydraulic Design
The cloacas should be laid at such gradients to bring forth equal speeds to convey the solid affair. The gradient should bring forth a minimal speed of non less than 0.8 m/s and a maximal speed of non more than 4.0 m/s to avoid scouring of cloaca by eroding action of suspended solid.
Structural Design
The deepness of cloacas must be equal to suit the sewerage from bing and future belongingss. The minimal deepness should be 1.2 m.
The minimal size of the cloaca should be 200 millimeter in diameter in order to convey natural sewerage.
Straight alliance and unvarying gradient between back-to-back manholes should be laid for cloacas of 600 millimeter or less in internal diameter while curves can be laid for cloacas of larger than 600 mm internal diameter.
Flexible type and watertight articulations should be provided between cloacas, sewer manhole or other gear construction to avoid infiltration and breakage due to differential colony.
The foundation should be able to keep the pipe in proper alliance and carry the weight of dirt above the cloaca and any other overlying burden.
Service Connection
The diameter of the connexion must be equal plenty to forestall obstruction jobs.
The cloaca must hold a minimal gradient of 2 % .
The minimal size of the connexion should be 150 millimeter.
Tee junction should be used to link service connexion to the chief cloaca.
2.5.2.1 Gravity Sewer Design
Sewers are designed to convey the effluent flows as required. By and large, it is non recommended to plan the cloacas for full flow, even at peak rates as the opportunities for job arising are high. The flows that cover above 90 % to 95 % of full deepnesss are considered unstable which may take to sudden loss of transporting capacity with surcharging at manholes as shown in Figure 2.2 ( Guyer, 2010 ) . Surcharging means that the pipe that is designed to flux full or partially full, is now transporting the flow under force per unit area. When the flow exceeds the design capacity, there will be surcharge in the manholes ( David and John, 2011 ) . Besides that, big bole and interceptor cloacas laid on level inclines experience less fluctuation in flow. If it is designed to flux full, the cloacas may miss sufficient air infinite above the liquid for proper airing. Ventilation in cloaca is of import in forestalling the buildup of explosive, caustic or odorous gases, and for cut downing the formation of H sulphide. Therefore, the deepness of design flow for bole and interceptor cloacas should non transcend 90 % of full deepness ; laterals and chief cloacas, 80 % ; and edifice connexions, 70 % . Regardless of flow and deepness, the minimal sizes of sewer pipes to be used are 150 millimeters for service connexions and 200 millimeter for all other sewer types. The sewer pipes for service connexions are normally smaller than 150 millimeters as they merely convey liquids with small or no solids ( e.g. condensate lines ) . A condensate line of more than 100 millimeter is recommended for most state of affairss. Same design standards as healthful cloacas can be applied to industrial application except pipe stuff that is immune to the waste are to be specified. ( Guyer, 2010 )
Figure 2.2 ( a ) Part-full pipe flow without surcharge
( B ) Pipe flow with surcharge ( David and John, 2011 )
2.6 Pipe Materials for Gravity Sewer
There are many types of stuff which can be used for sewage building. However, the type of stuffs that we choose must depend on its life anticipation, old local experience, raggedness coefficient, structural strength and local handiness. Table 2.2 shows the common stuffs that are suited for healthful cloacas. Sewer pipes made by different stuff have different diameters and lengths.
Table 2.2 Pipe Materials for Gravity Sewer
Types of Pipe Material
Length ( m )
Diameter ( millimeter )
Pipe Joints
Vitrified clay pipe ( VCP )
0.6 – 1.0
100 – 300
Flexible
Reinforced concrete pipe
A
A
A
& lt ; 375mm diameter
1.83
150 – 3000
Spigot & A ; socket type with gum elastic rings
& gt ; 375mm diameter
3.05
Fabricated steel with sulfates resistance cement liner
9
100 – 1500
A
A
A
A
& lt ; 750mm diameter
A
A
Spigot & A ; socket, rim and mechanical
& gt ; 750mm diameter
A
A
Welded articulations
Cast Fe
3.66
Vary
Flange and spigot & A ; socket type
Asbestos cement pipe
4
100 – 600
A
Plastic pipe
6
110 – 630
Spigot terminal and socket type with gum elastic seals, jointing by rims, welding and solvent cementing
A
A
A
A
A
A
Other stuff
A
A
A
Chapter 3: RESEARCH METHODOLOGY
3.1 Introduction
In this research, a field work will be conducted to acquire the information that will be used to make the aims of this research.
3.2 Preliminary Plants
This is the initial plants that has to be done before carry oning the field work at site. It includes information assemblage on the subject of sewage design and self-study on similar and related subjects in order to larn more.
3.2.1 Information Gathering
A series of books, articles and online information has to be studied to obtain information on the subject of sewage design. Beginnings for sewage design largely come from abroad. However, the information on the method to measure the design standard is obtained from related research by a local university.
3.2.2 Standard Code of Practice for Design and Installation of Sewerage Systems
( MS1228:1991 )
With the mention to this codification book, the design standard and the factors to be considered for sewage design is obtained. The equations to cipher the extremum flow which depend on the population equivalent are all available in this standard codification of pattern.
3.3 Site Work
A site has been identified for the field work informations aggregation. The location of this site is in Tropicana Indah. Approval is still pending from IWK for entree to their manholes.
3.3.1 Flow Characteristics Measurement
The flow feature of a subdivision of sewage pipe systems can be measured by utilizing a flow metre. This flow metre is provided with detector which will automatically enter the flow, speed and H2O tallness at a specific clip interval, which in this instance is 5 proceedingss. Once the measuring is completed, the information from the flow metre will be linked to a computing machine that has Flowlink4 package. This package would help the plotting of graphs for the 3 parametric quantities ( flow, speed and tallness ) every bit good as transportation of informations to other package. From the information, the upper limit and minimal hourly flow rate can be obtained. The mean flow rate can be used to cipher per capita flow.
Flow per capita = Average day-to-day flow ( m3/day ) / Entire population equivalent ( PE )
= m3/day/person
The rating of peak factor and per capita flow for sewage can besides be done through the informations obtained from field experiment. The equations that are used for sewage design are as follow:
a. Peak flow factor = 4.7 A- p-0.11
B. Average day-to-day flow = Flow per capita A- Pe
= m3/day
c. Peak domestic flow = Peak flow factor A- Average day-to-day flow
= 4.7 A- p-0.11 A- Flow per capita A- Pe
= m3/day
From MS 1228:1991, the ‘p ‘ value is an estimated PE in 1000s and the mean flow per capita is 225 L/day/person.
