Every industry usually produces waste which it is expected to dispose off in a manner that is environment friendly. The refinery will be no exception. It is projected that during the construction of the refinery, construction solid wastes and domestic sewage will contaminate the soil if not properly treated.
Refineries generate solid wastes and sludges with a range of 0.01-2kg per tone of crude processed (before waste treatment). According to the World Bank, 80% of those solid wastes may be considered hazardous because of the presence of toxic organs and heavy metals. Sludges originate from various sources such as crude and product tanks bottoms, desalters, alkylation units, boiler feed water preparation, bio reactors, the cleaning of heat exchanger bundles and equipment, oil spills and soil remediation.
In terms of volume, oily sludges represent the largest waste category from refineries. Partly this is due to the presence of basic sediment and water in the crude, which can carry from crude to crude. Other wastes are generated from many of the refining processes, petroleum handling operations and waste water treatment. Both hazardous and non hazardous wastes are generated.
Spent catalysts originate from reformers, catalytic crackers, hydro crackers, hydrometalization, hydrosulphurization and hydro treating units. The regeneration of catalysts is a well established technique.
Liquid wastes from worker camps, slop oil, lost fuel will also cause soil pollution if inappropriately treated.
The operation of the refinery will produce solid and liquid wastes from processing, maintaining and repairing. These are sources of a negative impact on air, soil leading to impact on surface and ground water in the area. The environmental pollution will obstruct the growth of the vegetation and affect animal husbandry around the Refinery area.
Besides, during the construction of the refinery the process of plant clearance, razing, and unloading soil to prepare the project area will change the soil structure and natural environment of the area in which the refinery will be. The area clearance is a factor causing erosion.
Similarly, movement of vehicles will cause soil compression and decrease soil quality.
During the design activities sources of waste shall be reviewed in order to identify expected waste generation and to establish the storage, treatment and disposal infrastructure required. This review will also highlight any risks such as the sources of hazardous waste and identify opportunities for waste prevention, minimization, recycling and re-use of materials.
Some of the methods that the World Bank EHS general guidelines have recommended to minimize the quantity of waste generated are the need to substitute material for less hazardous materials and for lower waste generating material, the need to employ efficient processes to obtain higher yield and less waste and efficient inventory control to reduce waste from out of date materials.
In addition to waste prevention, the total amount of waste produced can be significantly reduced through re-use and recycling e.g returning containers to manufacturers for re-use
It is also recommended that the refinery implement a solid waste management system.
It is therefore expected that the refinery will carry out annual monitoring and reporting on waste quantities, implement a plan with measures for waste reduction including recycling and/or recovery operate the WWTP so as to maximize performance, with the minimum of sludge production and generally implement good house keeping activities.
The oil refinery should minimize oil spills and exclude oil spills that contaminate the soil. This includes among other things: implementing a plan to exclude leakage from pipe work and tanks. This plan may include inspection, corrosion monitoring, leak detection instruments and double bottoms among others.
It also includes performing a risk analysis to rank in order of significance cases where an accidental leak may occur (elements to consider are the product in the tanks/pipes, the age of the equipment, the nature of the soil and groundwater that would be affected). It as well includes prioritizing areas where impermeable floors are needed most and design installations with the minimum of underground piping and tanks.
Apart from the waste, it is also expected that noise generated from the project transport facilities and activities such as vessel, automobile, engine, pipping and mechanical activities will affect the surrounding residents and workers in the working site.
The clearance for site will destroy the habitat of biological species living in/ surrounding the project area. Noise and Vibration generated from construction activities and traffic would impact on terrestrial biological species that are sensitive with those elements. The wild life in this area is significant and therefore the impact is negligible. In this phase, flora fauna may get affected. The actual impact of flora and fauna of the region will be assessed after performing baseline surveys and detailed impact assessment to be conducted during the FEED stage.
Compiled from the FOSTERWHEELER Report on Uganda’s oil refinery