Treating industrial drainage for Petrochemical Projects

The importance of Treating industrial drainage for petrochemical projects stems from their dependence on the use of large quantities of water in industrial processes, especially in the production of olefins and aromatics. Wastewater is also an important source for the production of hydrogen, which is one of the most important inputs for the petrochemical industry. Water is also used in cooling processes and for temperature control in polymerization and monomerization processes, as well as for cooling equipment such as compressors and pumps, among other uses.

The concept of treating and reusing domestic and industrial wastewater has become more widespread in recent times. Wastewater treatment and reuse technologies have contributed to the conservation of freshwater resources, especially in the face of water scarcity and supply shortages in many regions, and have helped reduce the cost of water production, meet strict environmental standards, and protect the environment.

The petrochemical industry is one of the industries most suitable for reusing treated industrial wastewater. Industrial wastewater is defined as the water discharged from factories or plants, resulting from the use of water in some or all stages of manufacturing, cleaning, cooling, or other processes, whether treated within the plant or untreated.

The quantity and characteristics of industrial wastewater generated from petrochemical production depend heavily on the type of processes carried out in the production units and auxiliary facilities.

Water Quality and the Impact of Contaminants on treating industrial drainage

The properties of water and the proportions and quantities of contaminants present in it affect its quality. The following outlines the implications of the presence of pollutants and contaminants, the most important metals and non-metals, and their impact on the properties and quality of water used in industry.

Implications of the Presence of Pollutants, Contaminants, and their Impact on the Properties and Quality of treating industrial drainage

Turbidity:

Fine suspended particles, unstable, not settling. Causes a muddy, cloudy appearance of the water.

Color:

The presence of color in natural waters is attributed to the presence of organic plant residues and metals, causing a change in color from colorless to dark brown.

Electrical Conductivity:

Pure water has no ability to conduct electric current.
The solubility of salts in water causes the water’s electrical conductivity property.
Electrical conductivity is a measure of the amount of dissolved salts in the water.

Suspended Solids

The insoluble solids in water are usually referred to as suspended solids.

Suspended solids consist of silt, clay, organic matter, algae, bacteria, fungi, and minerals.

They contain a large amount of organic matter, which can cause putrefaction leading to a decrease in the amount of dissolved oxygen.

It can cause foaming in boilers and form scales on equipment.

They cause turbidity and can clog water transmission pipelines and internal components of equipment.

They can settle in heat exchangers and boilers.

Such materials do not pose serious problems if they are treated and disposed of by filtration.

Dissolved Solids

The concentration of dissolved solids is one of the most important criteria in determining the suitability of water for industrial uses.

Dissolved solids are primarily composed of bicarbonates, carbonates, sulfates, chlorides, and nitrates of calcium, magnesium, sodium, and potassium, with traces of iron and manganese.

Silica is an important constituent of dissolved solids.

Fluoride is present in very low concentrations.

Phosphate is a component of dissolved solids in boilers.

Dissolved solids in water are undesirable for industrial uses, as they are a major factor in the formation of scales and deposits.

High concentrations of them can accelerate corrosion processes and cause foaming in boilers.

Total Suspended Solids (TSS)

It is the sum of the amounts of suspended, and dissolved solids.

Water Hardness

Water hardness is a term used to describe the condition of water when the mineral salt content is high.

Calcium and magnesium salts are among the most important mineral salts that cause water hardness.

Water hardness should be monitored, as it is one of the main causes of scale formation.

Alkalinity

There may be confusion between the definition of pH and the definition of alkalinity.

The pH concept measures the acidity or basicity of the liquid. At the same time, alkalinity is the measure of the water’s “liquid” capacity to absorb acid without changing the pH.

Precipitates form in the case of high alkalinity.

Low alkalinity values help corrosion occur.

Alkaline materials can turn into carbon dioxide (CO2) in steam, causing corrosion.

Bicarbonates (HCO3), carbonates (CO2), and hydroxides (OH) can be determined by titration.

pH

Water is characterized by its ability to behave as an acid or a base in chemical reactions.

pH is used to measure the degree of acidity or basicity of the liquid.

There are certain uses where the water needs to be within a specific pH range.

Acidity

Acidity is not a single major component, it is a measure of the effects of a group of substances and conditions in the water. It can be defined as the water’s ability to neutralize hydroxide ions, and it is expressed in terms of calcium carbonate. Acidity usually results from the presence of free carbon dioxide, mineral acids such as sulfuric acid, and weak dissociating acids, as well as from the decomposition of iron and aluminum salts. Most natural waters contain no mineral acidity and only carbon dioxide acidity.

There is no definite limit for acidity, but it is controlled indirectly by setting limits for the pH.

Excessive acidity causes damage to metal structures.

It needs to be neutralized to reduce corrosion.

Most industrial processes require water free of acidity, even from carbon dioxide acidity.

Free Mineral Acidity

The presence of free mineral acidity is attributed to the presence of sulfuric acid and hydrochloric acid.

Dissolved Gases

These are gases that may be dissolved in water, such as oxygen gas and carbon dioxide gas.

The presence of such dissolved gases helps facilitate the phenomenon of corrosion.

Cations

Positively charged ions, such as calcium, potassium, sodium, and magnesium.

Anions

Negatively charged ions, such as carbonates, sulfates (SO4), chlorides, and nitrates (NO3).