CHAPTER XV

ENVIRONMENT, WASTE PREVENTION AND TREATMENT

15.1 ENVIRONMENTAL ISSUES IN MALAYSIA

Environmental awareness is building up in Malaysia and with the 9th

Malaysia Plan

2006-2010 the Malaysian government has placed further emphasis on preventive

measures to mitigate and minimize negative environmental effects at source, to intensify

conservation efforts and to ensure a sustainable development of both the exhaustible

and the renewable energy resources.

The past decade of rapid economic growth and industrialization has caused

serious environmental challenges in Malaysia. The most prominent at the moment are

considered to be air pollution from industrial emissions, solid waste management,

ensuring long-term sustainability of the water supply and sewerage services industry and

overall improvements of energy efficiency to re-establish a clean Malaysia (Denmark

Ambassador, 2010).

15.1.1 Solid Waste Management

Due to growing population and increasing consumption, Malaysia generates waste at

19,100 tons per day. The disposal of solid waste has been done almost solely through

open landfills. The Committee on Solid Waste Management announced in 2006 the

closure of 16 open dumpsites and announced again in 2007 a closure of 16 open

landfills. Another 17 open landfills out of a total of 155 are expected to be shut down.

There will be a need to build further sanitary landfills and incinerator plants to prevent

water contamination and environmental pollution. The Government has now focused on

reuse, reduction and recycling of materials and promotes companies that undertake

these activities (Denmark Ambassador, 2010).

15-2

15.1.2 Water and Wastewater

The domestic and industrial water demand in Malaysia is expected to triple over the next

50 years and based on estimated doubling of the per capita water consumption by 2020

it is predicted that water shortages will occur within the next 5 years.

Currently more than 95% of the urban and 85% of the rural population are served

by piped water of which 45.746 km are Asbestos Pipes. During the 9th

Malaysia Plan the

Government plans to replace about 18.000 km of these pipes.

Sewerage systems will continue to be expanded to ensure the quality of effluent

discharged into receiving water bodies comply with environmental standard and

safeguard public health. A sum of USD 0.45 billion is allocated for the implementation of

environmental preservation projects and general water resource management.

Malaysia will continue to upgrade, rehabilitate and refurbish existing sewerage

treatment systems, and USD 860 million will be provided for repair of existing sewerage

plants and construction of new plants. The 9th Malaysia Plan will furthermore intensify

research and development on reuse of sludge for industrial, agricultural and landscape

purposes as well as wastewater reclamation for non-potable purposes.

At the recent mid-term review of the 9th Malaysia Plan it was highlighted that

from 2006 to 2008 the rural water coverage was expanded and another 177.760

households will benefit from the governments Water Supply Program. Another 650.000

people benefitted from the sewerage service and 308 small sewerage treatment plants

have been repaired and upgraded. In the 2009 budget RM308 million is allocated to

upgrade and supply clean water to rural areas (Denmark Ambassador, 2010).

15.1.3 Air Pollution

With the 9th Malaysia Plan a new Clean Air Action Plan will be undertaken to improve air

quality in urban areas. Reduced sulphur content in diesel and petrol is a main focus area

(Denmark Ambassador, 2010).

15-3

15.2 ENVIRONMENTAL ADMINISTRATION AND LEGISLATION IN MALAYSIA

15.2.1 Development of Environmental Policies and Environmental Quality Act

1974

Faced with worsening water pollution caused by the three traditional industries of tin

mining, natural rubber, and palm oil on the one hand, and by new industrial pollution on

the other, brought about by industrialization policies pursued since the late 1960s and

fostered by foreign capital inflow, Malaysia in 1974 enacted its first framework

environmental legislation in the form of the Environmental Quality Act 1974.

During the quarter of a century since the Environmental Quality Act was passed,

the Malaysian economy has achieved rapid growth. The industrial structure has altered

considerably with the development of the electrical and electronic industry, the increase

in small to mid-size companies that supply goods and services to large corporations, and

the expansion of other general support industries. Along with these changes,

environmental issues have gained far greater exposure than before. Malaysia now

faces a diverse range of environmental issues, such as hazardous and toxic waste

problems and air pollution in addition to water pollution which was the major concern

when the Act was passed. As a result, the government needed to implement inter-

agency environmental regulations that would cut across bureaucratic lines, and to

formulate policies for preventing, rather than curing, environmental pollution.

In fact, the 1974 Act has been amended three times since it was first enacted.

Preventive measures, in the form of environmental impact assessment, were introduced

in the 1985 amendment.

Currently, while seeking to get tough on violations of the various environmental

regulations, the DOE is implementing progressive environmental programs that

emphasize pollution prevention. New initiatives taken by the DOE include the

establishment of the Environmental Fund, promotion of environmental management

systems, adoption of environmental audits, and introduction of new regulations for

controlling chemical substances (Ministry of Environment, Government of Japan, 2004).

15-4

15.2.2 Environmental Administrative Framework and the Department of

Environment

The supervisory agency in charge of environmental administration in Malaysia is the

Department of Environment (DOE) which was established in 1975 under the provisions

of the Environmental Quality Act 1974. The DOE has comprehensive authority over

environmental administration related to industrial activities and is charged with

formulating environmental rules and regulations; enforcing legislation and carrying out

monitoring in relation to water pollution, air pollution, and hazardous substances;

conducting environmental impact assessment of proposed development projects; and

carrying out Site Suitability Evaluation of proposed factories. The Environmental Quality

Act 1974 grants wide powers to the Director General of the DOE in order to promote

environmental programs (Ministry of Environment, Government of Japan, 2004).

15.2.3 Framework Environmental Legislation on Industrial Pollution

Malaysia's system of environmental legislation is based on the Environmental Quality

Act (EQA) 1974, which was introduced in 1974 and came into force in 1975. The EQA

1974 gives broad powers to the Director General of the DOE, including the authority to

oversee environmental regulations in general and to make proposals regarding law

enforcement, to issue various licenses for preventing discharge of pollutants, and to

monitor and prosecute cases of non-compliance with the regulations.

In addition, the EQA 1974 provides for the establishment of the Environmental

Quality Council as a national advisory body for environmental issues in Malaysia. It also

provides for the approval and licensing of prescribed projects that are subject to

environmental regulations, and states that no person shall cause air pollution, noise, or

contamination of inland waters or coastal waters by contravening stipulated limits. In

regard to scheduled wastes, the EQA 1974 prohibits disposal and transport without the

prior approval of the Director General of the DOE (Ministry of Environment, Government

of Japan, 2004).

15-5

15.2.4 Environmental Requirements for Industrial Operations in Malaysia

For a new project, such as plant construction, for example, environmental impact

assessment is required at the planning stage if the project is a prescribed activity. Even

if the project is a non-prescribed activity, Site Suitability Evaluation is required. At the

construction stage, the provisions of the abovementioned regulations about wastewater,

air pollution, and scheduled wastes state that prior written approval and written

permissions must be obtained from the Director General of the DOE if, for example, the

company is building a plant that will discharge industrial wastewater, or if the plant has

combustion or power generation facilities exceeding a certain size. If the proposed

facility is a palm oil mill, rubber mill, or scheduled waste-related facility, a separate

license to use and occupy the site is required. In addition, once a plant is operational,

the company must submit regular monitoring reports on wastewater and reports on

scheduled wastes generated in the plant.

Written permission must be obtained from the Director General of the DOE if a

new source of pollutant discharge will result from adding factory facilities or changing a

manufacturing process, or if the company is installing an incinerator or a combustion

facility exceeding a certain size. Prior consultation with the DOE is also required to

install facilities for preventing air or water pollution (Ministry of Environment, Government

of Japan, 2004).

15.3 ENVIRONMENTAL REQUIREMENTS FOR INDUSTRIAL OPERATION IN

MALAYSIA

Generally, the statutory requirement that needs to be complied is the Environmental

Quality Act 1974 (EQA 1974). Under this act, all industries in Malaysia have to comply

with the regulations stated under this act and the failure to do so will cause them penalty.

There are 3 main subsidiary regulations that need attention, namely:

1. Environmental Quality (Clean Air) Regulation 1978

2. Environmental Quality (Sewage and Industrial Effluent) Regulation 1979

3. Environmental Quality (Scheduled Waste) Regulation 1989

4. Other closely related regulations

(a) Environmental Quality (Compounding of Offences) Rules 1978

(b) Environmental Quality (Licensing) Regulations 1977

15-6

15.4 WATER POLLUTION REGULATION

Wastewater standards are prescribed as a set of nationally uniform standards divided

into two categories: Standard A is defined as the effluents which are released or

discharged into the inland water within the catchment areas. While Standard B is defined

as the effluents which are released or discharged into any other inland water under non-

catchment areas. Each standard covers 23 parameters, including general parameters

such as temperature, pH, and suspended solids (SS), as well as BOD, chemical oxygen

demand (COD), and various types of heavy metals. Standard B has more lenient limits

than Standard A. Table 15.1 shows Environmental Quality (Sewage and Industrial

Effluents) Regulations, 1978 [Regulation 8 (1), 8(2), 8 (3) Parameter Limits of Effluent of

Standards A and B.

15-7

Table 15.1 shows Environmental Quality (Sewage and Industrial Effluents)

Regulations, 1978 [Regulation 8 (1), 8(2), 8 (3) Parameter Limits of Effluent of

Standards A and B.

Parameter Unit Standard

A B

Temperature C 40 40

pH value - 6.0-9.0 5.5-9.0

BOD5 at 20C mg/L 20 50

COD mg/L 50 100

Suspended solids mg/L 50 100

Mercury mg/L 0.005 0.05

Cadmium mg/L 0.01 0.02

Hexavalency

Chromium mg/L 0.05 0.05

Arsenic mg/L 0.05 0.01

Cyanide mg/L 0.05 0.10

Lead mg/L 0.10 0.5

Trivalency

Chromium mg/L 0.20 1.0

Copper mg/L 0.20 1.0

Manganese mg/L 0.20 1.0

Nickel mg/L 0.20 1.0

Tin mg/L 0.20 1.0

Zinc mg/L 1.0 1.0

Boron mg/L 1.0 4.0

Ferum (Fe) mg/L 1.0 5.0

Phenol mg/L 0.001 1.0

Chlorine mg/L 1.0 2.0

Sulphide mg/L 0.50 0.50

Oil and Grease mg/L Cannot be detected 10.0

(Source: Department of Environment, Malaysia)

15-8

15.5 AIR POLLUTION REGULATIONS

An air pollution index (API) system normally includes the major air pollutants that could

cause potential harm to human health should they reach unsafe levels. The pollutants

included in Malaysia's API are ozone (O3), carbon monoxide (CO), nitrogen dioxide

(NO2), sulfur dioxide (SO2) and suspended particulate matter less than 10 microns in

size (PM10). Table 15.2 shows recommended air quality guidelines.

Table 15.2: Recommended Air Quality Guidelines (Ambient Standards)

Pollutant

Averaging time

Malaysia guidelines

(ppm) g/m3

Ozone

AS 2524

1 hour

8 hour

0.10

0.06

200

120

Carbon monoxide (mg/m3)

AS 2695

1 hour

8 hour

30

9

35

10

Nitrogen dioxide

AS 2447

1 hour

24 hour

0.17

0.04

320

-

Sulfur dioxide

AS 2523

10 minute

1 hour

24 hour

0.19

0.13

0.04

500

350

105

PM 10

AS 2724.6

24 hour

1 year

-

-

150

50

15-9

15.6 SCHEDULES WASTE LAWS AND REGULATIONS

Legislation regarding scheduled wastes in Malaysia is basically set forth in three

regulations and orders: Environmental Quality (Scheduled Wastes) Regulations 1989,

Environmental Quality (Scheduled Wastes Treatment and Disposal Facilities) Order

1989, and Environmental Quality (Scheduled Wastes Treatment and Disposal Facilities)

Regulations 1989.

The term "scheduled wastes," as used in Malaysia, refers to categories of solid

wastes ranging from hazardous wastes to toxic substances. There are currently 107

categories of industrial wastes listed as scheduled wastes under the environmental

regulations, including 28 types defined by their structure and composition rather than by

their source, and 30 types that can be identified by source, such as sludge generated by

wastewater treatment. The regulations on scheduled wastes do not prescribe any

permissible limits in terms of discharge volume or concentration of contaminants. This

means that even if a factory generates only a very slight amount of scheduled wastes,

final disposal in accordance with the laws and regulations is still required.

The regulations stipulate that scheduled wastes can only be finally disposed of at

"prescribed premises" approved by the Director General of the DOE, and the waste

generator is required to store the waste if no prescribed premise exists. At the moment,

since Malaysia's only prescribed premise is the final disposal facility operated by Kualiti

Alam, all scheduled wastes must be transported to Negeri Sembilan where the facility is

located (Ministry of Environment, Government of Japan, 2004).

15-10

15.7 WASTE MANAGEMENT HIREARCY

The best waste management is illustrated by the waste management hierarchy. Pollution

prevention or source reduction is always the top priority option in waste management

decisions. The waste management is lead by source reduction and followed by

recycling. Source reduction means the reduction of waste at the spot and this is most

preferable because in recycling the generation still occurs. If these two preferred options

are not possible then waste treatment should be considered before the final preferable

option disposal is considered. Figure 15.1 shows hierarchy of waste management. Table

15.3 defined more clearly on the four options of waste management.

Figure 15.1: Hierarchy of waste management

Table 15.3: Ways of Waste Management

Source reduction Procedures that either reduce or eliminate the generation

of hazardous waste before the waste is produced.

Recycling Reuse of waste stream as an ingredient in a productive

process or recovery of a reusable product.

Treatment

The use of, physical, chemical, biological or thermal

technologies to reduce the volume, toxicity and/or mobility

of waste.

Disposal The placement of waste into landfill or the underground

injection of waste.

15-11

15.8 WASTE MINIMIZATION

The waste minimisation and treatment plant should fulfilled the following objectives

below:

Save in operating cost by reducing waste treatment and disposal cost,

raw material purchases, and other operating costs including utility costs.

Meet state and national waste minimisation policy goals.

Reduction of ecological damage and also reduce potential environmental

liabilities.

Reduction of Civil and Criminal Liability.

Improved company image.

In the Tetradecene monomer production plant, waste minimization started from

the bottom of hierarchy, which is the minimization of the source of waste production.

This is done by increasing the conversion of raw material to the maximum achievable

conversion. So, the unreacted raw material is reduced to the minimum level. The

condition of the reactor is also modified to achieve maximum selectivity for the desired

reaction to avoid the unwanted by-product being produced.

15.9 PROCESS DESCRIPTION OF WASTE TREATMENT FACILITY

The main process in the Tetradecene monomer plant is thermal cracking. The

production only involves cracking of raw material which is Palmitic Acid into Tetradecene

and Acetic Acid. There is side reaction occurred during the thermal cracking process that

produced gum. The desired product is Tetradecene. Acetic Acid and Gum are the

byproduct. Acetic Acid will be sold as the quantity is quite significant. Gum will be the

scheduled waste for the production. Furthermore, the bottom stream of T-103 distillation

must be treated before being discharge. The air pollution is not significant in this

Tetradecene monomer plant as it only involve thermal cracking inside a closed vessel.

15-12

15.10 SOLID WASTE POLLUTION CONTROL

Thermal Cracking of Palmitic acid will produce gum as a waste. In the room temperature

gum exist as a solid. However, in the process flow, gum will remain in liquid form as

depending on the temperature of the stream (320°C-.240°C) While the gums discharge

from the process flow, the physical properties of the gum change immediately.

Gum will be removed by using Bag Filter Housing fabricate by Eaton

Corporation. The diagram for the installation of the Bag Filter Housing into the process

flow shows in Figure 15.2.

6 7

8

10

14

13

15

16R

T 300

PFR

F100

F300

T100

F200

7a

7b

7c

Figure 15.2: Process Flow Diagram for removal of Gum by filtration

15-13

Figure 15.3: Typical design of Bag Filter Housing (Source from Eaton Corporation)

15.10.1 Mechanism of the Removal Gum from Process Stream

Bag Filters Housing is one of the type filtration units. Bag Filters Housing

by Eaton Corporation is build from the material of stainless steel. The

temperature condition at stream flow into Bag Filters is 240°C. The filter bag

design as it can face high temperature condition. 216 kmol/h of molar flowrate

will feed to the inlet of the Bag Filter Housing, the filter will trap the gum and the

remaining liquid which contain of Palmitic Acid and Acetic Acid will flowing out to

the outlet of bag filter with the amount of gum remove is 0.2386 kg/h (see table

11.1). The process will occur continuously. After the volume filter is filled up by

disposal gum, it can be clean by manually. During the cleaning time, opening

valve to the second Bag Filter will open, and the process will flow continuously

without destruction. Other than that, bag filter will be install to the outlet stream

of T300 before enter to the mixer. As known before, the purposed to install T300

is for the safety factor if the stream contains gum composition. Meanwhile, the

bag filter attached to the outlet stream of T300 same a safety factor in order to

totally removed gum from the process stream.

15-14

15.10.2 Mass Balance on Filter

157.81 kmol/h palmitic acid

58.140 kmol/h tetradecene

58.141 kmol/h Acetic Acid

0.0006kmol/h gum

9

n palmitic acid

n tetradecene

n Acetic Acid

n gum

F100

7 8

Figure 15.4: Bag Filter Housing

Assume the efficiency, η, of the filter is 100%

Therefore,

Table 15.4: Mass Balance on Bag Filter Housing

Component MW In Out

7 8 9

Palmitic Acid 256.42 157.81 kmol/h 40399.36 kg/h 40399.36 kg/h -

Tetradecene 196 58.140 kmol/h 11395.44 kg/h 11395.44 kg/h -

Acetic Acid 60 58.141 kmol/h 3488.46 kg/h 3488.46 kg/h -

Gum 394.71 0.0006 kmol/h 0.2368 kg/h - 0.2368 kg/h

15.10.3 Conclusion

According to the mass balance on filter, gum will be removed with amount of 0.2368

kg/h. After the removal of gums, it will be dry in the dryer in order to minimize the

volume. The dry solid of gum will be packing and sent to the Kualiti Alam.

Cost of the equipment:

With 5ft2 filter area, type of filter is drum filter the estimates cost is RM332928.

15-15

15.11 WASTEWATER POLLUTION CONTROL

Waste treatment refers to the activities required to ensure that waste has the least

practicable impact on the environment. Waste is unwanted or useless materials. In

industry, waste is also an unavoidable problem in a chemical plant which can be found in

three physical states such as solid, liquid, gases or mixture form which must not exceed

the maximum levels at which they will harmful to environment.

The waste water treatment plant unit receives, neutralizes and treats the various

waste effluents from the process area in the plant. The final discharged waste water

must comply with the regulations and guidelines imposed by Malaysia government under

the Department of Environment. This wastewater treatment plant only caters for the

waste stated below. Classifications of waste contributed from this plant are:

1) Storm water (from rain, roofs of buildings, car parks, undeveloped areas

outside the process area).

2) Accidentally oil contaminated water (pipe tracks, roads, vehicle

filling/unloading bays, rail loading/unloading facilities, yard areas, drum

storage areas).

3) Utilities effluent (heating and cooling system).

15.11.1 Wastewater Discharge Composition

The composition of each component of at the bottom stream of T-103 distillation column

are taken from HYSYS and showed in the table 15.5 below.

Table 15.5: Mass and moles out of wastewater from distillation column

Component Mass out (kg/hr) Moles out (kg mole/hr)

Palmitic Acid 2.4434 0.0095

Gum 0.4158 0.0011

15-16

The conditions of wastewater stream are listed in Table 15.6 below.

Table 15.6: Condition of wastewater stream

Conditions Stream 16

Temperature, K 625.15

Pressure, kPa 95

Table above shows the composition of wastewater produced from Tetradecene

monomer plant. The wastewater comes from single streams which are come from T-103

distillation column.

15.11.2 Calculation procedure for wastewater treatment

Data required for calculate the Biological Oxygen Demand (BOD) and Chemical Oxygen

Demand is shown in Table 15.7.

Table 15.7: Data required for calculate BOD and COD

Component Mol fraction Mass out (kg/h) Flowrate (L/h) MW

Palmitic Acid 0.900 2.4434 3.288

256

Gum 0.100 0.4158 392

General equation:

OHCOOCOOHHC 2223115 161623

Hence, 1 mole of Palmitic Acid required 23 moles of Oxygen.

Mass of Palmitic Acid, C15H31COOH:

COOHHCkgCOOHHCkmolkmol

kg31153115 2561

256

Mass of Oxygen, O2:

22 7362332

OkgOkmolkmol

kg

15-17

Mass of O2 consumed:

COOHHCkg

consumedOkg

m

m

COOHHC

O

3115

288.2256

736

3115

2

So, 1 mol C15H31COOH required 2.88 mol of O2.

Oxygen demand

2

16.9221688.2Ohr

mg

Molecular weight of C15H31COOH = 256 g/mol

Mass of waste:

LmghrL

hrmg/03.28

/288.3

/16.92

Thus, mol of [H+] in wastewater:

molg

Lmg

molg

Lmg

/

/11.0

/256

/03.28

So, COD calculation:

Lmgmolgmolg

Lmg/52.3/32

/

/11.0

BOD calculation is assuming about 1/3 from the COD value.

Thus, BOD:

Lmg /17.152.33

1

15-18

Generally, the value of total oxygen related with Biological oxygen demand (BOD) and

chemical oxygen demand (COD). Based on the Environmental Quality (Sewage and

Industrial Effluents) Regulation 1979 the BOD discharge must below 50 mg / l and COD

100 mg / l in standard B. From calculation above it shows that the COD and BOD

concentration is below the parameter standard which can be discharge directly to the

environment but treatment must be done for utilities effluent which is from heating and

cooling system.

15.11.3 Wastewater Treatment Process Description

The main objective of the wastewater treatment is to treat all the waste which considers

as waste effluent from bag house filter backwashing, heating and cooling system before

it is being discharge to the water reservoir near the plant. A wastewater plant in a small

scale is build, which to treat the wastewater from Tetradecene monomer plant. The

process flow diagram for the wastewater treatment process had been shown below.

First of all, the wastewater was sent to a collection tank. The wastewater from the

collection tank is then pumped into equalization tank. Before entering the equalization

tank, the wastewater from the collection tank needs to pass through fine screen to

remove small particle first. Equalization tank acts as temporary storage of flow to

equalize flowrates and mass loadings of BOD and suspended solid. At this point the pH

of the wastewater is adjusted to neutral condition. If the pH is too acidic, lime should be

added to reduce the pH.

Then, the wastewater is pumped into coagulation tank where at this point

coagulation process will take place. The wastewater now is added with coagulant. In

general, coagulant is the chemical that is added to destabilize the colloidal particles in

wastewater so that floc formation can result. Alum is used as the coagulant. Next,

flocculant tank will be the next point for further treatment. This process promotes the

aggregation of small particles into larger particles to enhance their removal by gravity

sedimentation. Flocculant will be added into the wastewater. Flocculant is a chemical,

typically organic, added to enhance the flocculation process. The most commonly used

flocculant is polyaluminium chloride (PAC). Polyaluminium chloride (PAC) is used as the

flocculant because it is cheap and easy to obtain.

15-19

The wastewater from the coagulation tank is then pumped into clarifier for

removal of settleable solids which is the flocs from the flocculant tank. Efficiently

designed and operated clarifier should remove from 50 to 70 percent of the suspended

solids and from 25 to 40 percent of the BOD (Metcalf and Eddy, 2004). Sludge that

accumulates at the bottom of the clarifier will be sent to filter press to remove the sludge

moisture before the sludge is being disposed. After that, the wastewater is pumped into

aerator. Surface mechanical aerator with vertical axis is used in aerated tank. Surface

aerator consists of submerged impeller that is attached to motors mounted on floats. The

purpose of aerated tank is to allow the wastewater for direct contact with oxygen and

simultaneously allow aerobic process. In aerobic process, degradation of organic matter

in wastewater is then resulted in decreasing of BOD level in water.

Finally, if the parameter of wastewater from the aerated tank complied with the

standard from Department of Environment, the wastewater can directly discharge. But, if

not the wastewater will undergo final treatment which is filtration process. Multimedia

filter will be used for the filtration process. The multimedia filter consists of 3 layer of

medium which are anthracite, sand and gravel. Backwash must be done periodically to

increase the efficiency of the multimedia filter. The wastewater from the backwash

process is recycled back to equalization tank. Figure 15.5 shows the layout of

wastewater treatment plant.

15-20

E-1

P-2 P-5

P-6

P-7

Figure 15.5: Design of wastewater treatment

Equalization

tank

Coagulation

tank

Filter press

Flocculant

tank

Treated

effluent

Sludge

Effluent

Fine

screen

Multimedia

filter Clarifier

Aerator

Recycle wastewater

Recycle wastewater

Oxygen

15-21

15.11.4 Design of Fine Screen

Fine screen is selected for preliminary treatment of wastewater. Fine screen is used to

retain solids found in the influent wastewater to the treatment plant. Furthermore, by

having the preliminary treatment, it can protect process equipment and increase the

wastewater treatment plant efficiency. Fine screens used for preliminary treatment are of

the static, drum and step type. Typical removal rates of BOD and TSS are reported in

Table 15.8.

Table 15.8: Typical data on the removal of BOD and TSS with fine screens used

to replace primary sedimentation.

Type of screen Size of openings Percent removed

In Mm BOD TSS

Fixed parabolic 0.0625 1.6 5 – 20 5 – 30

Rotary drum 0.01 0.25 25 – 50 25 – 45

(Source: Metcalf and Eddy, 2004)

Based on Table 15.8, it shows that drum type fine screen is more efficient

in removing BOD and TSS. So that, drum screen is selected for the tetradecene

monomer wastewater treatment plant. For the drum type screen, the screening or

straining medium is mounted on a cylinder that rotates in a flow channel.

Internally fed screens are applicable for flow ranges of 0.03 to 0.8 m3/s per

screen (Laughlin and Roming, 1993). Drum screens are available in various

sizes.

An installation should have a minimum of two screens, each with the

capability of handling peak flowrates. Flushing water should be provided nearby

so that the buildup of grease and other solids on the screen can be removed

periodically. The calculation of headloss through fine screen is shown below.

15-22

Calculation of headloss:

2

2

1

CA

Q

ghL

Where hL = headloss, m

C = coefficient of discharge for the screen, 0.6

g = acceleration due to gravity, 9.81 m/s2

Q = discharge through screen, m3 /s, Q = 0.5 m3/s

A = effective open area of submerged screen, m2

Area

222

16.04

)45.0)(1416.3(

4m

DA

Headloss

mhL 38.116.06.0

5.0

81.92

12

Material of construction of fine screen is stainless steel and polyester

screen cloths. Size of screen particle is 6 – 35 µm. This type of screen also can

be used as grit removal (Metcalf and Eddy, 2004).

Costing for fine screen:

Screen type = Drum screen

Deck area = 1.5 m x 3 m

= 4.5 m2

Material = Stainless steel

Cloth = Polyurethane screen

Cost 2007 US $ = $ 36800

= RM 111369

(Source: Screen cost, 2003)

15-23

15.11.5 Design of Equalization tank

Flow equalization is a method used to overcome the operational problems caused by

flowrate variations, to improve the performance of the downstream processes, and to

reduce the size and cost of downstream treatment facilities (Metcalf and Eddy, 2004). In-

line equalization arrangement is chosen as all of the flow must passes through before

further treatment. This arrangement can be used to achieve a considerable amount of

constituent concentration and flowrate damping.

The proper operation of in-line equalization tank generally requires proper mixing

and aeration. Mixing equipment should be sized to blend the contents of the tank and to

prevent deposition of solids in the tank. Aeration is required to prevent wastewater from

becoming septic and odorous. Mechanical aerator is used to ensure proper mixing,

particularly with a circular tank configuration. To protect the aerator in the event of

excessive level drawdown, low-level shutoff controls should be provided. The capacity of

equalization tank is 100 m3.

Costing for equalization tank:

Tank type = Vertical, cone roof and flat bottom, field fab

Tank volume = 100 m3

Material = Stainless steel

Pressure = Atmospheric

Cost 2007 US $ = $ 78100

= RM 236356

(Source: Tank cost, 2003)

15-24

15.11.6 Design of Coagulation Tank

Colloidal particle found in wastewater typically have a net of negative surface charge.

The size of colloids is such that the attractive body forces between particles are

considerably less than the repelling forces of the electrical charge. Under these stable

conditions, Brownian motion keeps the particles in suspension (Metcalf and Eddy, 2004).

Coagulation is the process of destabilizing colloidal particles so that particle growth can

occur as a result of particle collisions. Alum is added as coagulant in the coagulation

tank to destabilize the colloidal particles in wastewater so that floc formation can result.

In the coagulation tank, mixing is important to mix the coagulant with the

wastewater. Continuous rapid mixing is used for the process. Rapid mixing usually

occurs in the regime of turbulent flow in which inertial forces predominate. As a general

rule, the higher the velocity and the greater the turbulence, the more efficient the mixing.

Type of impeller used for this mixing process is propeller. The design of coagulation tank

is shown below.

Width = 4 m

Depth = 3.5 m

Volume = 44 m3

(Source: Metcalf and Eddy, 2004)

Costing for coagulation tank:

Tank type = Vertical tank

Tank volume = 44 m3

Tank cost = $ 24300

Propeller cost = $ 8500

Total cost = $ 32800

= RM 99264

(Source: Tank cost, 2003)

15-25

15.11.7 Design of Flocculant Tank

The purpose of wastewater flocculation is to form aggregates or flocs from finely divided

particles and from chemically destabilized particles. Flocculation is a transport step that

brings about the collisions between the destabilized particles needed to form larger

particles that can be removed readily by settling or filtration. Flocculation typically follows

rapid mixing where chemicals have been added to destabilize the particle. In the

flocculant tank, polyaluminium chloride (PAC) is added to enhance the flocculation

process. Typical detention time for flocculation process used in wastewater treatment is

about 30 – 60 minutes.

The flocculation device that is selected is static mixer. The design is suitable for

horizontal flow. The flocculation tank is equipped with an axial-flow impeller mixer.

Increased particle contact promotes floc growth, but, if the mixing is too vigorous, the

increased shear forces will break up the floc into smaller particle. Agitation should be

controlled carefully so that the floc particles will be of suitable size. The design of

flocculant tank is shown below.

Width = 4 m

Depth = 3.5 m

Volume = 44 m3

(Source: Metcalf and Eddy, 2004)

Costing for flocculant tank:

Tank type = Vertical tank

Tank volume = 44 m3

Tank cost = $ 24300

Propeller cost = $ 8500

Total cost = $ 32800

= RM 99264

(Source: Tank cost, 2003)

15-26

15.11.8 Design of Clarifier

The wastewater from the flocculant tank is then pump into clarifier. The objective of

treatment by sedimentation is to remove settleable solids which are the flocs from

flocculation process and thus reduce the suspended solids content. Efficiently designed

and operated clarifier should remove from 50 to 70 percent of the suspended solids and

from 25 to 40 percent of the BOD. The design of clarifier is shown below. The capacity of

the clarifier is assumed to be 1500 m3. The retention time for particle sedimentation is

about 2 hours. The design of flocculant tank is shown below.

Type of tank = Circular

Depth = 4.3 m

Diameter = 12 m

Bottom slope = 1/12

Flight speed = 0.03 r/min (Source: Metcalf and Eddy, 2004)

Costing for Clarifier:

Material of construction = Cement

Capacity = 1500 m3

Clarifier cost = RM 10000

15.11.9 Design of Aerator

Surface mechanical aerator with vertical axis is used in aerated tank. Surface aerator

consists of submerged impeller that is attached to motors mounted on floats. The

impeller is used to agitate the wastewater vigorously, entraining air in the wastewater

and causing a rapid change in the air-water interface to facilitate solution of the air. High

speed aerator is used for aeration process.

For surface high speed aeration system, the transfer rate of oxygen is 1.4 kg

O2/kW.h. Aerator size is 20 hp. The design of aerator is shown below.

Depth = 3.5 m

Width = 10 m

Costing for aerator = RM 10000

15-27

15.11.10 Design of Filter Press

Filtration is the most widely used method in the treatment of sludge produced

by wastewater treatment. Filter presses generally work in a "batch" manner. They are

loaded with slurry before completing a filtering cycle and producing a batch of solid

filtered material, called the filter cake. The solid is removed, the press re-loaded with

slurry and the filtering cycle repeated. Figure 15.6 shows figure of plate filter press.

Figure 15.6: Plate filter press (Source: Lenntech, 2009)

Costing for plate filter press:

Material = Cast iron

Cost of filter press = RM 15000

(Source: Nanxing Machinery Manufacturing Co., Ltd.)

15-28

15.11.11 Design of Multimedia Filter

Multimedia Filtration is designed so that the larger grain particles are at the top of the

filter and the smaller to the bottom of the filter. This has several advantages over a

single media filter.

Increased filtration rates

Longer filter runtimes

Reduced backwash water consumption

A bed of anthracite placed on top of the sand layer provides the filter with:-

Larger grain particles on the surface of the filter which delays binding and

pressure drop across the filter.

A larger reservoir in which the floc may be held before backwashing.

A prefilter for the filtration sand below.

The grades of media used in a multimedia filter are chosen to have similar backwash

expansion characteristics.

Table 15.9: Dimension of multimediafilter

Duel Media Filter

Media Grade Depth Bulk Density

Anthracite 1.18 - 2.50 mm 600 mm 0.74 tonne/m3

Sand 0.60 - 1.18 mm 600 mm 1.56 tonne/m3

Gravel 6.7 - 13.2 mm 150 mm 1.60 tonne/m3

Figure 15.7: Multimedia filter

(Western Carbons Multimedia filtration, 2010)

Anthracite

Sand

Gravel

15-29

15.12 TOTAL COST FOR WASTE TREATMENT

Waste treatment cost that required to treat the waste from Tetradecene monomer plant

is shown in Table 15.10.

Table 15.10: Overall costing for waste treatment

Type of waste Equipment Price (RM)

Solid waste Bag House Filter 332928.00

Water

Fine screen 111369.00

Equalization tank 236356.00

Coagulation tank 99264.00

Flocculant tank 99264.00

Clarifier 10000.00

Aerator 10000.00

Filter press 15000.00

Multimedia filter 15000.00

TOTAL 929181.00

15.13 CONCLUSION

In the Tetradecene monomer plant the waste water treatment discharge must be

followed the standard B in Environmental Quality (Sewage and Industrial Effluents)

Regulation 1979 which the value of BOD not exceed 50 mg/L and COD 100 mg / L.

Table 15.11 shows the comparison of wastewater discharge from T-103 distillation

column which the parameter is comply with the regulation but treatment must be done

for utilities effluent which is from heating and cooling system. While for the dry solid

which is the gum, it will be packed and sent to the Kualiti Alam.

Table 15.11: Government waste standard

Parameter Maximum Permitted Value

B Waste discharge

BOD5 at 20⁰C, mg/L 50 1.17

COD, mg/L 100 3.52