CHAPTER FIVE

ASSOCIATED ENVIRONMENTAL IMPACTS

5.1 INTRODUCTION

The overview on the amounts of waste generated within the refining processes are

summarized on Table 5.1.

Table 5.1 Summary of the wastes to be generated during the refining process

at the ile-ife plant.

5.2 AIR POLLUTION

Most processes to be performed in the refinery will produce atmospheric emissions.

Speculation concerning the amounts and types of air pollutants emitted from refinery

operations has been widespread. Air pollution is the most difficult type of pollution to

sample, test, and quantify in an audit.

There are four main sources of air emissions from the Refinery, most of

which emit similar types of waste gases:

1. Flares

The Refinery’s two flares provide a safe pressure relief system in case of process upsets. In

the event of an incident at the Refinery, excess gas can be safely diverted to the flares,

protecting staff and equipment. Each flare has a continuous flame that safely combusts the

gases into carbon dioxide and water.

2. Furnaces

The refining process requires a precise balance between pressure and temperature, both of

which are supplied by furnaces. Fuel gas is produced as a supplementary product of refining

and the Refinery uses this fuel for energy for the furnaces which heat the hydrocarbons as

they flow through the refining units.

3. Residue Cracking Unit

The Residue Cracking Unit (RCU) is one of the most important process units at the Refinery

because it can process the heavy, low-value component of the crude oil. The RCU ’cracks’

the long chains of hydrocarbons into smaller compounds of greater value.

4. Sulphur Recovery Units

The Refinery has two Sulphur Recovery Units (SRUs) that remove hydrogen sulphide (H2S)

from the refinery’s fuel gas before the gas is burned in the furnaces. As well as reducing SO2

emissions, the H2S is converted into liquid sulphur which is on-sold for use in industrial

processes and to manufacture agricultural fertilisers.

Refinery plants usually generate nitrogen oxides and sulphur oxides from flaring.

Other significant sources of air emissions in oil refining operations include Volatile Organic

Compounds, particulates emissions from Residue Cracking Unit (RCU). These processes can

emit carbon monoxide, acids, and other volatile compounds.

The major sources of air pollution in the oil refinery plant are summarized on Table

5.2.

Table 5.2 Summary of the Air pollution sources and wastes to be generated

during oil Refining in Ile- Ife Refinery Plant.

5.3 WATER POLLUTION

The Ile- Ife oil refining unit is expected to use high volume of water throughout its

operations, from adding heat to the processes (steam), removing heat from the process

(cooling water), removing salt and impurities from crude, protecting equipment from

corrosion, generation of hydrogen (used to remove sulphur from motor fuels), equipment

cleaning and maintenance. The large amount of waste water generated also contain a wide

variety of chemicals, used throughout processing. These can cause damage if not properly

treated before discharge to the environment. As inappropriate discharge of this waste water

and residues could lead to contamination of water sources

The aquatic toxicity of the refinery wastewater varies considerably among production

facilities. The sources of aquatic toxicity can include salt, surfactants, ionic metals and their

metal complexes, toxic organic chemicals, biocides and toxic anions.

5.4 SOLID WASTE POLLUTION

The current environmental concerns have forced developed and developing countries

to reduce air, water and land pollution for sustainable growth. Solid refinery waste is cocktail

of hydrocarbons, water, oil mud, waste organic solvents, heavy metal and fine solids and is

substantial in quantity. The principal processes of waste management focus mainly on waste

source reduction, reusing, recycling, composting, incineration with or without energy

recovery, fuel production and land filling. Waste minimization can be achieved by

elimination of solid and hazardous waste generation through changes in product design and

manufacturing technology.

5.5 IMPACT OF THE MAJOR PROCESS CHEMICALS ON HUMAN HEALTH

The effects of the exposures to chemical substances, dust-laden and noise are

discussed further.

5.5.1 CHEMICAL SUBSTANCES

5.5.2 DUST AND FUMES

It has been general practice to discharge dust-laden air from stage 1 of the refinery

setup, to the atmosphere. Volatile organic emissions are largely uncontrolled and are used in

refining operations.

A summary of some of the most common dust and fumes and their effect on human

health is presented in table 5.5.

Table 5.5 The impact of dust and fumes on human health.

5.5.3 NOISE

The response of the human ear to sound depends both on the sound frequency

(measured in Hertz, Hz) and the sound pressure, measured in decibels (dB). A normal ear in a

healthy young person can detect sounds with frequencies from 20 Hz to 20 000 Hz. Speech

frequency ranges from 100 to 6000 Hz.

Noise can cause hearing impairment, interfere with communication, disturb sleep, cause

cardiovascular and psycho-physiological effects, reduce performance, and provoke

annoyance responses and changes in social behaviour. The many and varied sources of noise

in industrial machinery and processes include: rotors, gears, turbulent fluid flow, impact

processes, electrical machines, internal combustion engines, pneumatic equipment, drilling,

crushing, blasting, pumps and compressors. Furthermore, the emitted sounds are reflected

from floors, ceiling and equipment. Noise is a common occupational hazard in many

workplaces.

5.6 Impact Quantification and Determination of Significant Impacts

The identified, associated and potential impacts of the proposed Ile- Ife oil refining

Plant were quantified using the Risk Assessment Matrix and the ISO 14001 Procedure for

evaluation and registration of Environmental Aspects and identifying significant

environmental aspects/impacts.

Criteria and Ratings for Identifying Significant Environmental Impacts of the project

are as follows:

Legal / Regulatory Requirements (L) – is there a legal/regulatory requirement or a

permit requirement?

0 = There is no legal/regulatory requirement

3 = There is a legal/regulatory requirement

5 = There is a permit required

Risk (R) – What is risk/hazard rating based on Risk Assessment Matrix (RAM)

(Table 5.6)

1= Low risk

3 = Medium/intermediate risk

5 = High risk

Environmental Impact Frequency (F) – What is frequency rating of impact based on

RAM?

1 = Low frequency

3 = Medium / intermediate frequency

5 = High frequency

Importance of Affected Environmental Component and Impact (I) – What is the rating

of importance based on consensus of opinions?

1 = Low importance

3 = Medium/intermediate importance

5 = High importance

Public Perception (P) – What is the rating of public perception and interest in

proposed project and impacts based on consultation with stakeholders?

1 = Low perception and interest

3 = Medium/intermediate perception and interest

5 = High perception and interest

The significant potential impacts of the proposed project were identified as those

impacts in the checklist that satisfy the following criteria.

I. (L+R+F+I+P) _>15: Sum of weight of legal requirements, Risk factor, frequency of

occurrence, importance and public perception greater than or equal to the benchmark

(15).

II. (F+I) is >6: Sum of weight of frequency of occurrence and importance of affected

environmental component exceeds the benchmark (6).

III. P=5: The weight of the public perception/interest in the potential impact exceeds the

benchmark (5).

Table 5.6: Risk Assessment Matrix for Environmental Consequences

5.7 Environmental Assessment

5.7.1 Land Acquisition

During the design/planning stage, land acquisition would be planned for. Land

acquisition entails loss of farmland by the indigenous farmers who use the land to cultivate

various crops such as cassava and maize. However, if adequate compensation is paid, it

would improve the personal income of landlords/indigenes. The impact is significant,

irreversible and of long-term effect.

5.7.2 Site Preparation

Site preparation shall involve removal of limited amount of vegetation to provide path

for survey. The removal of wildlife habitat (vegetation) will lead to temporal migration of

wildlife. The effect is not significant in the short term since the survey routes would be re-

vegetated naturally.

Bush clearing activities during site preparation shall involve the removal of the

vegetation, which would lead to exposure of the soil to adverse weather conditions. The

width of the plant ROW shall be one kilometre. The removal of the vegetation shall lead to

migration of wildlife from the area. The effect is significant; irreversible (since the ROW

shall be maintained at a low height), and permanent until the life span of the project (> 25

years).

5.7.3 Waste Disposal

A number of waste types shall be produced during the construction and operational

phases of the project. These include metal scraps, gaskets, lubricant filters, domestic waste

associated with base camp etc. Improper waste disposal would lead to loss of aesthetics, risk

of accidents by sharp objects/scrap piles, and contamination of soil and water bodies (through

run-offs). The effects of improper waste disposal are significant, can be reversed and are of

short term.

5.8 Abandonment

When the use of the plant is no longer required, it would be decommissioned and

abandoned. The abandonment process involves removal of all surface facilities.

Technical Report Writing Group shall maintain a record of the abandoned facility and

a copy will be given to the Osun State Environmental Management Board), FMENV,

communities, and other stakeholders. The impact from abandonment programme is

significant, long term and restores the environment to its original form as much as possible.

The effects are significant positive and long term.