Pollution Situation And Water Desalination In Saudi Arabia
Saudi Arabia is a petrostate and one of the world’s most arid countries. It has a growing population of about 34 million and an estimated total land area of about 2,149,690 Km2 (830,000 sq. miles) (Worldometers). Until the discovery of oil, the economy of Saudi Arabia was based on and driven by nomadic pastoralism and oasis agriculture.
Since the ‘50s and particularly after the Second World War, the Saudis have benefitted from the exportation and rapid rise in oil revenues, which has allowed the country to undertake audacious economic development programmes over the past 50 or so years. A large and growing problem with the rising population and increasing urbanization has been the provision of usable water for the burgeoning cities.
A parallel problem is the per capita increase in water demands as the quality of life and standards of living rise. While in rural communities the daily water requirement (average consumption) of an individual may be as little as 20-40 liters, in the fashionable billets of the larger and comparatively affluent cities, per capita water demand may exceed 500 liters per day (Beaumont). For these and other reasons such as poor water management and perennial water scarcity, Saudi Arabia has decided upon desalination as a solution to the problem.
Desalination has, however, come with significant environmental implications. The process creates huge volumes of chemical-laced brine that threatens marine life and risks contaminating food chains. What follows is a discussion of the downsides of desalination – the dangers of toxic brine and chemical pollution to the affected coastal environments and human health.
Saudi Arabia suffers from acute water shortage. Growing population and rapid urbanization have pushed the demands for potable water to uncharted limits. Burdened by limited access to natural sources of water – renewable or not – the growing demand for water has pushed the country towards desalination to meet the deficit. Complexes such as Marafiq’s desalination plant in Jubail have therefore been constructed to satisfy the country’s growing need for water (Ferzly).
The desalination of seawater is, however, creating huge volumes of brine and chemical-laced effluents that are polluting the marine environment and contaminating food chains thereby imperiling not only human health but also the wellbeing of other organisms. According to Tirone, Saudi Arabia emits about 31.5 million cubic meters of brine and contaminated effluents every day. For every liter of clean (potable) water produced, Tirone estimates that close to 1.5 liters of liquid polluted with chlorine (Cl) and copper (Cu) are generated. When released back into the ocean, the effluent depletes dissolved oxygen (DO) amounts and impacts marine organisms along the entire food chain.
At present, the Arabian Gulf is the global ‘hotspot’ of intense seawater desalination activities. As of 2012, there were 199 plants in the region with a plan of adding 38 more with a desalination capacity of approximately 5,000 million m3/year, which translates to slightly less than half (45%) of the overall global production of desalinized portable water (Dawoud and Al Mulla). The leading producers in the region are UAE (United Arab Emirates) (35% of the overall worldwide seawater desalination capacity), Saudi Arabia (at 34%), and Kuwait (14%). These countries are followed by Qatar, Bahrain, and Oman at 8%, 5%, and 4% respectively.
Between 2000 and 2012, the total desalination capacity in the GCC region increased from 3,000 million m3/year in 2000 to approximately 5,000 million m3/year by 2012 (Dawoud and Al Mulla). The increase occurred primarily to meet the region’s growing water demand. In Saudi Arabia, desalination began in 1907 and the first MSF (multistage flash) plant constructed in Duba and Al-Wajf in 1928 (Al-Mutaz). Since then, several plants have been built across the country. The majority of the plants are situated along the Gulf Coast and the Red Sea with a combined capacity of 4,615,552 m3/year as of 2012 (Dawoud and Al Mulla).
Although the Kingdom can treat the brine to remove toxic chemicals and heavy metals contained in the effluents, the required processes are both expensive and energy-intensive. While brine can be used to grow forage shrubs and cultivate an assortment of dietary supplements, such application, however, comes with adverse impacts on land salinization, which can have prolonged and irredeemable impacts (Tirone). The list of potential environmental impacts is protracted; however, the information available about the impacts of desalination on marine discharges alone shows that there is a need for remedial actions to be taken to avert a potential ecological crisis.
Reasons causing the problem: Pollutants from desalination plants
A desalination process can employ either one (or a combination) of the following two main methods: (1) thermal (distillation) and (2) membrane (Al-Mutaz). These techniques differ not only in terms of cost but also in terms of energy consumed. The selection of which technology to use also depends on such variables as salt content of the feedwater, overall water capacity requirements, site location, and end-use consideration amongst others (ESCWA). Of the thermal processes, MSF is the principal process.
Other processes include reverse osmosis (RO) (hyperfiltration), multi-effect distillation (MED), and electrodialysis (ED) (See Figure 2). As a process, desalination refers to the removal of dissolved salts and other mineral elements from seawater (or brackish water) thereby producing two streams of water: (1) with low salt concentration (the end product stream) and (2) the high salt concentration stream (brine) (ESCWA).
The product stream is used to provide potable water for domestic, municipal, as well as irrigation purposes. The desalination process, especially the most common distillation approach is based on the principle of extensively heating the feedwater and evaporating it in order to separate the dissolved minerals from the water, hence creating the desired separation of freshwater and salts.
Regarding pollution, the impacts of desalination plants depend on the type of process and location of the plant. In coastal plants, for example, water (marine) pollution is the primary concern while in inland plants the disposal of the effluents – concentrated brine plus chemicals – is the leading problem. Air pollution problems arise when the desalinization plants are of the MSF variant (Al-Mutaz).
This is because, in MSF plants, significantly large amounts of petroleum are burned to generate sufficient energy for desalting. The resulting pollutants are therefore of fuel combustion types and include nitrogen oxides, sulfur oxides, carbon oxides, and unburned hydrocarbons. According to Tirone, Saudi Arabia burns nearly 1.5 million barrels of oil every day in order to power its desalination plants, meaning that desalination consumes about 15% of the country’s local oil production.
Water pollution of desalination plants is caused by two factors, namely brine, and chemical discharge. The options for brine management are limited and include (1) land disposal, (2) discharge to surface water or channeling to wastewater treatment plants, (3) release to evaporation ponds, (4) deep well injection, and (5) mechanical or thermal evaporation (Dawoud and Al Mulla). The reject brine contains several and variable concentrations of different chemicals including anti-scale additives like Sodium hexametaphosphate (NaPO3)6 and an array of inorganic salts (H2SO4, HCO3, HCL, Mg, Ca, Langlier SI, and SiO2) that can adversely affect soil and groundwater. Other common chemicals found in brine include NaOCl (sodium hypochlorite), FeCl3 (ferric chloride), and AlCl3 (aluminum chloride) (Dawoud and Al Mulla).
Factors affecting the problem
Due to the presence of numerous and different types of chemicals, reject brine discharged in the ground or to the sea can alter the salinity, temperature, and alkalinity averages of the seawater thereby causing significant changes to the marine environment to the detriment of aquatic organisms. However, the level of impact depends on the characteristics of the brine, which in turn is determined by the type of feedwater used and the type of desalination process employed.
For example, distillation processes are energy-intensive and therefore add the problem of air pollution into the mix. The characteristic and impact of the brine also depend on the percent recovery as well as the type and concentration of the chemical additives used in the pre and post-treatment processes (Dawoud and Al Mulla).
The effects of rejected brine on the environment and human health are manifold. The desalination plants, which are powered by oil contributes to not just to the release of air pollutants but also impact marine ecosystems with the release and offload of harmful byproducts. These products can bioaccumulate in the food chain and end up in human systems with detrimental outcomes. Al-Hammad and Abd El-Salam evaluated the levels of metals in the fish caught from the basin of Wadi Hanifa to determine the fitness of the fish for human consumption. The investigators tested the physical and chemical parameters from 192 water samples and analyzed the 48 fish samples for heavy metal concentrations.
The findings indicated that the basic water quality parameters of total dissolved solids (TDS), alkalinity (CaCO3), phosphates (PO4- –P), Sulfates (SO4), Ammonia (NH3-), and Nitrates (N03-), exceeded the Saudi standards (Al-Hammad and Abd El-Salam). The mean metal concentrations in the fish tested also exceeded the country’s standards for Arsenic (As) and Cadmium (Cd) and FAO’s standards for Chromium (Cr), lead (Pb), Iron (Fe), Nickel (Ni), Manganese (Mn), and Zinc (Zn). This finding highlights the urgent importance of controlling and monitoring brine and wastewater discharge in the country to ensure public safety.
Heavy metals are non-biodegradable, meaning they cannot be neutralized through biological degradation processes. They, therefore, accumulate in aquatic animals, potentially having harmful effects not only on the health of the affected organisms but also on that of humans and other animals that feed on them (Al-Hammad and Abd El-Salam). The gaseous pollutants from desalination chimneys besides polluting the atmosphere and potentially driving global warming have severe effects on human health. CO2, for instance, is a highly poisonous gas that can suffocate an individual by depriving the body of essential oxygen.
It combines with hemoglobin to form a stable biocompound called carboxyhemoglobin (COHb), which reduces the oxygen carrying capacity of blood. Nitrogen oxides are irritants. Both NO2 and NO react with unburned hydrocarbon molecules in the presence of sunlight to create photochemical oxidants such as PAN (peroxyacetyl nitrate) and PBN (peroxybenzoyl) (commonly known as smog), which are harmful to humans, botanical life, and materials. Together with sulfur oxides, NO2 and NO also contribute to the formation of acid rain, which affects soil and other natural resources (Dawoud and Al Mulla).
If awareness about the negative impacts of desalination is not created, solutions will not be proposed, and the problem could get out of hand. It is likely that without adequate measures brine will continue to be discharged into the sea with serious effects as highlighted previously. Brine and the toxic chemicals contained in discharges from desalination plants can cut the levels of DO with profound impacts on aquatic organisms leading to ecological effects that impact the entire food chain.
Other adverse impacts that are likely to worsen if appropriate action is not undertaken include increased water temperatures, heavy metal concentration, and the proliferation of other chemicals such as halogenated organics, coagulants (FeCl3) and coagulant aids (polyacrylamides), antiscalants (H2SO4), and antifoaming agents (polyglycol) (Dawoud and Al Mulla).
Solutions and mitigating measures
Several measures can be adopted to address the environmental and health impacts of desalination processes. Some of this includes:
- Management and proper handling of brine discharge through pre-dilution and power plant cooling
- Negative impacts of brine can be reduced by treatment before discharge. For example, chlorine can be removed using sodium bisulfite. Brine can also be treated using the Solvay process to generate other useful materials like sodium bicarbonate (Dawoud and Al Mulla).
- The use of nuclear, freezing, and solar-or wind-driven mechanisms to power desalination plants can help reduce GHG emission and excessive energy use.
- The reclamation and sale of salt from the brine effluent emanating from the desalination process can mitigate the release of salts into the environment as well as serving as a source of revenue. The income can then be used to offset some of the costs associated with the desalination process (ESCWA).
Saudi Arabia is burdened with the scarcity of water supply. Its renewable and non-renewable sources of water are inadequate to meet the large and growing water demands of its population and industrial complexes. This shortage has pushed the kingdom towards desalination. While the process generates sufficient potable water to meet the country’s needs, it comes with serious environmental and potentially deleterious health consequences. Adverse effects, especially on marine environments, occur when high brine discharges coincide with the nation’s already sensitive ecosystems.
The overall impact, however, depends on the physic-chemical properties of the effluent and brine as well as the biological and hydrographical attributes of the affected environment. Potential impacts include air and marine pollution, biodiversity loss, decreasing physic-chemical and biological qualities of water, soil and groundwater pollution, human health impacts, and aesthetic degradation of the affected locales. To reduce the environmental damage, flue gas desulphurization and carbon capture of chimney exhaust gases can help reduce the amount of GHG that escape to the environment.
Cooling of the brine before discharge can also reduce the amount of excessive heat getting into the receiving seawaters. The pretreatment of the effluent is necessary to withdraw chemicals and heavy metals present in the discharge and which can help serious health implications to marine life and human wellbeing.
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