Water is a very valuable natural resource to human beings. The water covers about 71% of the earth’s surface (Perlman, 2016) but only about 0.03% of this water is usable by humans (Mullen, 2012). The water is also vulnerable to numerous sources of contamination, both natural and manmade. This has resulted to global water crisis (Harhay, 2011) because millions of people across the world do not have access to safe potable water. Today, inadequate or limited supply of fresh water has become one of the most pressing global issues (Srinivasan, et al., 2012). Each year, about half a billion people across the world are affected by severe water scarcity (Mekonnen & Hoekstra, 2016). Some of these people end up using contaminated water, which is unsafe for drinking. Contaminated water is very hazardous to human life as it can transmit diseases like cholera, diarrhea, typhoid, dysentery, etc. It is estimated that contaminated potable water causes more than half a million diarrheal deaths every year (World Health Organization, 2017). This number is expected to rise with the rapidly growing global population that is estimated to reach 9.8 billion by 2050 (United Nations, 2017). Lead is one of the major toxic inorganic chemicals that contaminate water in many parts of the world. This compound is dangerous both to the ecosystem and human health (Verstraeten, et al., 2008). The problem of lead contamination in potable water is not new as this heavy metal started being used in making water supply pipes and plumbing fixtures many years ago (Payne, 2008). Lead is a corrosion-resistant soft material that is mainly used to making pipe lines, brass fixtures and lead solders. The metal can also be added other metal alloys like bronze and brass, hence it is used for making water fixtures, fittings and faucets. Lead is a harmful metal to health of both children and adults, with children being the most affected. This makes lead contamination in potable water a major health problem across the world.
Lead contamination in potable water has been reported in different countries, including the U.S., Canada, Australia, Europe, United Kingdom and China, among others. Different countries have formulated varied approaches of reducing lead contamination in potable water. Some of these include prohibiting use of lead pipes in water supply systems and lead-based solders, plumbing fixtures, fittings or faucets and setting maximum acceptable concentration of lead in potable water. The maximum acceptable concentration of lead in potable water that has been set by the World Health Organization (WHO) is 0.01 mg/L or 10 μg/L (Lead Free Water, 2015). This is the water quality standard that is used in many countries including Australia, Canada, China, European Union and United Kingdom. The U.S. Environmental Protection Agency has set the maximum acceptable concentration of lead in potable water to 15 μg/L or 0.015 mg/L (U.S. Environmental Protection Agency, 2017). In these countries, water supply companies or other relevant utilities are required to test water and ensure that the lead levels do not exceed the maximum acceptable concentration. Cumulative exposure of lead can result to permanent damage of important body organs such as the kidney, brain, heart, lungs and nervous system, or even death.
The main reason why lead contamination is of great concern worldwide is because lead is one the most toxic heavy metals. Lead exposure beyond recommended limits has several health problems. For this reason, it is always important to ensure that potable water supplied to people is free from lead. This report aims at investing sources of lead contamination in potable water, health impacts of lead-contaminated water and various methods of removing lead from potable water.
There are various ways in which lead gets into potable water. One of these ways is corrosion of water faucets and fixtures (Zietz, et al., 2010), especially older ones that were mainly made of lead. Most of water fixtures contain lead and when they get old, they can be easily corroded (Torrice, 2016). When this happens, lead compound mixes with water thus contaminating it. Solder and fittings used for connecting water supply pipes are other sources of lead in potable water. With time, the solder and fittings may start corroding and the deposits get released into potable water thus causing contamination. Lead water pipes are another source of lead contamination in potable water. This was a major source of potable water contamination many years back because most of the water pipes and other plumbing fixtures were made from lead (Rabin, 2008). This metal was preferred because it is easily malleable and stable. Today, use of lead water pipes has been prohibited in many parts of the world thus reducing potable water contamination resulting from lead plumbing pipes. Therefore it is apparent that potable water is usually contaminated after leaving the treatment plant (Renner, 2010). This makes it quite challenging to deal with lead contamination in potable water especially in areas that are still using water supply systems built many years ago, which contain lead plumbing components.
Lead may also find its way into potable water through pollution of natural water sources such as rivers, lakes, oceans, etc. This can be through direct disposal of wastes containing lead into the water source, infiltration from a landfill or weathering of rocks containing lead into groundwater (Federal-Provincial-Territorial Committee on Drinking Water, 2016). In general, lead contamination is potable water is primarily caused by wearing away or corrosion of lead-containing materials in plumbing and water distribution systems. These materials comprise of lead pipes, lead-based solders (Nguyen, et al., 2010) that are used for joining copper pipes, and chrome plated and brass faucets, valves and fittings (Department of Public Health, (n.d.)). A very small percentage of lead contamination in potable water is caused by pollution of natural sources (World Health Organization, 2011).
There are also several factors that determine the extent to which potable water gets contaminated with lead. These factors include: water chemistry (i.e. alkalinity and acidity) and amount and types of minerals present in the water; water temperature; amount of lead coming in contact with potable water; amount of water pipe corrosion or wear; the time the water stays in supply pipes; water corrosivity (Swistock, 2017); and the presence of coatings or protective scales in plumbing pipes, fixtures, fittings and faucets (United States Environmental Protection Agency, 2017).
Lean contamination in potable water causes a wide range of health problems in infants, children and adults. Lead, which is a toxic metal, affects several body systems, including cardiovascular, hematologic, neurologic, renal and gastrointestinal systems. The most common problems in infants and children are delayed neurologic, mental or physical development (Renner, 2009), anemia, hearing problems, slowed growth, brain damage, headaches, mood disorders, hyperactivity, pica (easting strange stuffs such as paint chips, dirt, etc.) and lower IQ (reduced intelligence) and learning and behavior problems. Affected children usually show deficits in learning and attention span abilities. In adults, common health problems resulting from lead contamination in potable water include: kidney problems, heart diseases (Navas-Acien, et al., 2007), high blood pressure, hypertension, cancer, reproductive problems (infertility) (Woodruff, et al., 2008) joint and muscle pain, digestive problems, loss of appetite, (infertility) (Brown & Margolis, 2012), mood disorders, blood disorders (Iqbal, et al., 2008), Alzheimer disease, and autoimmune diseases such as multiple sclerosis, lupus, fibromyalgia, chronic fatigue syndrome, rheumatoid arthritis, type 1 diabetes, etc. (Hayward, 2017). It also affects pregnant women and their unborn babies. These effects include: premature birth, low birth weight, gestational hypertension, miscarriage or abortion and reduced fetus growth. Lactating mothers can also transmit lead to their babies through breast milk (United States Environmental Protection Agency, 2017). Pregnant women, fetuses, infants and children are more vulnerable to potable water contamination by lead because they have sensitive tissues capable of absorbing lead more easily. When exposed to same level of lead, children and adults will absorb 30-75% and 11% of the lead respectively (Water Quality Association, 2016). Therefore lead is a major threat to public health and there is need for more people to have access to information so that they can establish ways of preventing these effects. If not treated properly or managed on time, lead exposure through potable water can lead to death.
There are different methods of removing lead from potable water. Some of these methods are discussed below.
Distillation is a conventional and effective method of treating water for domestic and commercial use. This method has been in use for millennia. The method removes a wide range of impurities from water, including bacteria, dissolved solids, nitrates, hardness, lead, sodium, etc. The principle of water distillation has remained the same over the years, only the type and layout of equipment used keeps on changing. The process starts with boiling water in a container. The steam produced is then directed into cooling tubes where it is condensed then collected in a second container as purified water. In this process, almost all impurities present in water are left in the first container.
Distillation is suitable for removing chemicals or contaminants whose boiling point is greater than that of water. The boiling point of water and lead is 100 °C and 1,749 °C respectively. When lead-contaminated water is heated, the water starts evaporating when temperature reaches 100 °C. At this point, the lead is still very away from reaching its boiling point. Therefore the water evaporates and the escaping steam is collected and directed into the cooling tubes, leaving lead and other impurities in the original boiling container. The cooling tubes deposit the steam into a condenser where the steam condenses back to liquid form. This liquid is very pure and suitable for drinking.
Advantages
Pure water: distillation is a very efficient method of removing contaminants with boiling point greater than that of water. This makes it most suitable for removing lead from drinking water. Besides heavy metals, distillation also removes all pathogens.
Reliability: the quality and purity of water obtained from distillation process always remains high as long as the distillation unit is working properly and kept clean.
Reusability: distillation method can be reused over and over again without replacing any component.
Disadvantages
Wasteful: this process wastes a lot of water as only about 20% of the water gets purified while the remaining 80% is discarded with other contaminants.
Mineral-free water: the water obtained from distillation process is mineral-free and tasteless because all minerals, including beneficial minerals, are removed. The mineral-free water is also more acidic making it dangerous to the human body.
Not suitable for contaminants with low boiling point: any contaminants whose boiling point is lower than that of water will find its way in the water collected in the final container. Therefore distilled water will still contain all contaminants with boiling point lower than that of water.
Energy: this method requires substantial amount of power for heating the water. Some water distillation units have been designed to use renewable energy such as solar power so as to reduce energy bills (Gugulothu, et al., 2015).
Slow: distillation method is relatively slow because the water output is very low.
This is one of the most common and effective methods used to remove lead from potable water for domestic, commercial and industrial uses because its efficiency is about 98%. Besides lead, reverse osmosis method also removes other organic chemicals, microorganisms and inorganic contaminants from water. The process entails passing contaminated water through a reverse osmosis membrane that sieves lead out of water. This process starts with pre-filtration where water is passed through a sediment filter to remove larger sediments. The water is then forced through the reverse osmosis membrane, which is semi-permeable, under pressure (Bakalar, et al., 2009), as shown in Figure 1 below. The size of reverse osmosis membrane pores is usually 0.0001 micron. This membrane only allows water molecules to pass through it but blocks passage of sodium, calcium, chlorine and other larger molecules including viruses, bacteria, urea and glucose. After this, the water is again passed through another carbon filter to remove any remaining contaminants that may have passed through the reverse osmosis membrane. The water is then finally passed through an in-line activated carbon filter so as to eliminate any flavors or odor.
Figure 1: Schematic diagram showing reverse osmosis process (Water Right Group, 2016)
Advantages
Reverse osmosis treatment method has numerous advantage. Some of these are discussed below
Removes contaminants: reverse osmosis methods removes almost 100% of contaminants from water. This includes lead, arsenic, copper, sodium, nitrates, organic chemicals, viruses, protozoa, bacteria, etc.
Cost-effective: this method produces very clean potable water for about $0.25 per day (Linton, 2016), making it affordable even for domestic uses.
Environmental friendly: the method does not require uses of large amount of energy that could otherwise result to emission of greenhouse gases to the environment and it does not use or produce any toxic chemicals. Additionally, it eliminates the need of buying water bottles that could end up being disposed in landfills because it provides clean potable water at all times.
Reduces odor and improves taste: reverse osmosis not only removes lead but numerous other contaminants including arsenic, nitrates, nickel, chlorine and total dissolved solids. Removal of these impurities leaves clean water that tastes better and has no odor.
Small size: reverse osmosis systems are usually small in size thus suitable for home uses.
By removing most of the metals and dissolved minerals from water, reverse osmosis helps in preventing corrosion of plumbing systems.
Disadvantages
This method removes all chemical materials and minerals from water, including beneficial and/or healthy minerals such as manganese and iron.
By removing most of the minerals, this method leaves the water more acidic.
The method requires large amount of water because only about 5-15% of the water that gets pushed through the reverse osmosis system returns (Craig, (n.d.)). The remaining water leaves the system as wastewater.
The method is consuming meaning it requires a lot of time in order to treat a substantial amount of water. For example, filtering one gallon of water using reverse osmosis system may take between 3 and 4 hours.
Reverse osmosis systems usually require frequent maintenance so as to maintain high level of effectiveness in removing lead from the water.
This is one of the oldest and common methods of water treatment (Bhatnagar, et al., 2013). The method is also known as adsorption. Most of the activated carbon filters used today have been improved and therefore are more effective in water treatment than those used several years back (Egbon, et al., 2013). Activated carbon filtration method removes lead from potable water using a special type of carbon filter. The lead and other contaminants get removed from water through a process known as adsorption. Activated carbon filtration system uses reactive or adsorptive filters. These filters contain a medium that reacts with or adsorbs the lead present in water. The medium can be made from petroleum coke, wood products, lignite, peanut shells, bituminous coal or coconut shell. When the water is passed through the activated carbon filter, it gets attracted and adsorbed or held on the carbon particles surface. The adsorption process efficiency depends on carbon characteristics (pore size, particle size, hardness, density and surface area) and contaminant characteristics (solubility, attraction to carbon surface and concentration) (Dvorak & Skipton, 2013).
Before the start of water treatment process, the carbon medium has to be activated first. This is done by subjecting it to high temperature of up to 1260 °C and steam in absence of oxygen. Sometimes the carbon medium may be coated with a specific compound or processed using acid wash so as to improve its capability of removing particular contaminants from water. This activation process generates carbon that has numerous small pores thus its surface area is also very high. After that, the carbon medium is crushed to create a pulverized or granular carbon product creating smaller particles whose outside surface area is more available for adsorption of contaminants.
Once the carbon medium or activated carbon filter has been prepared, water is passed through it. Since the filter is made from carbon that is more effective in removing lead, the lead particles present in water will get strongly and easily adsorbed onto the surface of the carbon filter. The efficiency of lead adsorption is also directly proportional to the length of contact time between carbon and water. When the same activated carbon filter is used for a long period of time, it gets saturated. This basically means that its pores become filled with lead contaminant and therefore further adsorption cannot take place. In such cases, the filters have to be cleaned or replaced.
Advantages
Installation and maintenance: it is very easy to install an activated carbon filtration system and maintain it. These processes require less tools and equipment.
Low operating costs: the operation costs of activated carbon filtration method are relatively low because they usually require less energy and maintenance needs are also low.
Efficiency: this method is very efficient in removing lead from water as long as the activated carbon filter is made from carbon medium that has high affinity for lead.
Flexibility: the method can also be used to remove lead from water at point-of-use (such as community or household filters) or at point-of-entry (such as wastewater treatment facilities or semi-centralized potable water treatment facilities) (Mazille & Spuhler, 2011).
Availability: this method can be used anywhere because activated carbon filters can be made in any part of the world. The required raw materials for making activated carbon are abundant.
Reliability: this method is very reliable in removing lea from water as long as the activated carbon filter is made or selected by considering the characteristics of the contaminant (composition, solubility, quantity and affinity).
Disadvantages
Maintenance: activated carbon filters require regular regeneration or replacement. This is because the filters, after adsorbing lead for some time, get clogged or saturated making them ineffective in removing lead from the water. The filters can be replaced based on the manufacturer’s recommendations or the user can calculate replacement intervals based on the amount of lead being removed and quantity of water being purified by the system on daily basis.
Limited lifetime: activated carbon filters’ lifetime is limited. After these filters have been used for a long time, their surfaces get saturated with lead or other water contaminants and they stop purifying water. Sometimes backwashing the filter may not be enough leaving replacement as the only best solution.
Skilled labour: removing lead from potable water using active carbon filtration method requires skilled labour, at least occasionally. The skilled labour is needed for monitoring removal efficiency and/or performance of the activated carbon filtration unit.
Water analysis: for the activated carbon filtration method to remove lead effectively from the water, water analysis has to be carried out comprehensively. This helps in determining the most effective type of activated carbon for removal of lead. The water analysis process may require more resources, including time, personnel and money.
Energy: activated carbon filtration units are usually driven by power and therefore energy must be provided.
This method also only separates lead and other contaminants from the water but it does not destroy them. As a result of this, the adsorbed contaminants, including lead, may still find themselves back in water creating more health problems. Ion exchange
This is a water treatment method that uses ion exchange resins to remove contaminants from the water. Ion exchange resins are simply colored synthetic spherical micro-porous beads of size ranging between 0.5mm and 1mm and have pores on their surfaces for trapping and absorbing contaminants present in water. Ion exchangers are water-insoluble substances that exchange some of their ions with similar charged ions that are present in the media with which they come in contact with (Kumar & Jain, 2013). The method treats water through exchange of ions between the water and resin. Ion exchange resins contain loosely held positive and negative ions. The positively charged ions are known as cations while the negatively charged ions are called anions. There are two main types of ion exchange resins: cation exchange resin and anion exchange resin (New Hampshire Department of Environmental Services, 2009). A cation exchange resin is a type of resin that has a positive charge and is suitable for treating water containing a positive charge whereas an anion exchange resin is a type of resin that has a negative charge and is suitable for treating water containing a negative charge. Cation exchange resins comprise of polystyrene chains of divinylbenzene covalent bonds. A cation exchange resin is denser than an anion exchange resin thus the former has a greater exchange capacity than the latter. A cation exchange resins also needs less volume than an anion exchange resin of the same exchange capabilities. Since lead-contaminated water contains positively charged lead ions, this water is treated using cation exchange resin.
The operation of ion exchange process is very easy. The water is made to flow through the cation exchange resin. As the water passes through the resin, the positively charged lead ions from water get attracted to the cation exchange resin and they get exchanged with the cation exchangers (positive ions in the ion exchange resin). In other words, lead ions are removed from the water and get trapped in the resin while the positive ions in the resin moves from the resin to the water molecule. This means that cations in the ion exchange resin get exchanged with lead ions from the water. In this process, ions obtained from an ion exchange resin are used to exchange with lead ions that are in an aqueous solution (Arar, 2013). It is important to note that ion exchange resins used to remove lead from water are selective ion exchange resins. These resins have greater affinity for lead and they can effectively remove any dissolved lead present in water (Rohm and Haas, 2008). In most cases, i0n exchange resins are made or modified depending on the contaminants that are targeted to be removed from water (Wang, et al., 2014).
When an ion exchange resin has been used for some time, it needs to be regenerated or reactivated. This basically means rebooting the exchange capacity of the ion exchange resin. An anion exchange resin is usually regenerated using sodium hydroxide while a cation exchange resin is regenerated using sulfuric or hydrochloric acid.
Advantages
Low initial capital: the cost of installing an ion exchange resin for water treatment is relatively low. This is because the equipment used is simple thus installation does not necessarily require technical expertise.
Low operating costs: this is the major advantage of ion exchange process. The process has very low operating costs because it requires little amount of energy, the cost of chemicals used for regeneration is very low and the ion exchange resins can last for several years before replacement as long as they are maintained properly.
Low maintenance needs: if the ion exchange resin is properly designed, installed and maintained, it can be used for numerous years before any maintenance is done.
Efficiency or exchange capacity: ion exchange resins can be reformulated or modified so as to increase their affinity or exchange capacity for lead. Therefore this method is very effective in removing lead, using selective cation exchange resins.
Regeneration: instead of replacing an ion exchange resin when its exchange capacity reduces, the resin can be regenerated. This saves both time and cost.
Simplicity: this technology is very simple, which translates into easy installation and operation processes.
Disadvantages
Clogging: ion exchange resins may get clogged by other solid particles present in water thus reducing their efficiency in removing lead because efficiency of exchange of ions will decrease.
Bacterial contamination: this method is not effective in removing bacteria and other microorganisms from water. In fact, organic matter that accumulates at the resin beds helps in bacterial growth by acting as their source of nutrients. Therefore is has to be combined with other water treatment methods for the water to be safe for drinking.
Environmental concern: during regeneration of an ion exchange resin, minerals and salts from the system is usually dumped into the environment, which raises a major environmental concern.
Frequent regeneration: the exchange capacity of an ion exchange resin declines quickly making it necessary to regenerate the resin regularly. The decline is usually as a result of the resin trapping some organic elements present in water.
This is one of the latest and most effective methods of removing lead from potable water (Brooks, et al., 2010). AAM-PRB is an innovative material made with a filer material (coarse aggregates and sand) and fly ash alkali. The material is produced from alkali-activation process where a caustic sodium hydroxide is mixed with conc. sodium silicate then reacted with fly ash to form a material that has a unique microstructure with cementitious properties (Brooks, et al., 2010).
This is a method that removes lead from water using an electrical current (Bouguerra, et al., 2015). Lead is maintained in water by electrical charges (Arbabi, et al., 2015). The electro-coagulation system provides negative electrical charges that neutralizes the positively charged lead ions. Through this process, the lead ions get precipitated and destabilized leaving water free from lead particles (Ahluwalia & Goyal, 2007). This method has been found to be very effective in removing lead from water (Heffron, et al., 2016) and new and better electrode materials are still being developed. Efficiency of this method is also affected by factors such as temperature, co-existing ions, current density, inter-electrode distance, pH and electrode configuration (Kamaraj, et al., 2015).
This is a membrane separation method where water is passed along the surface of the membrane under pressure. As a result of this, pure water permeates through the membrane while lead and other contaminants are not allowed to pass through the membrane. A complete UF system comprises of a screening unit, filtration unit, microfiltration unit and UF unit in that order, as shown in Figure 2 below. Screening unit is used to remove large particles from water such as organic matter, hair, etc. Filtration unit usually removes sand and other particles larger than 10 microns. Microfiltration unit removes particles greater than 0.1 microns, and ultrafiltration unit removes particles greater than 0.02 microns. Alternatively, the screening, filtration and microfiltration units can be separate from the UF unit so that the water is pretreated before being discharged to the UF unit (Rojas-Serrano, et al., 2015). There are different types of UF membranes, each with a unique filtration capacity (Reyhani, et al., 2015). Several studies are still ongoing to develop more effective UF membranes using nanomaterials. More UF systems for industrial water treatment have also been developed and have become a sustainable way of treating water for industrial use (Chew, et al., 2016).
Figure 2: Schematic diagram of UF system (Aquasource, 2011)
This is a membrane technology method of water treatment (Barakat, 2011). In this method, water ions are passed through a semi-permeable membrane. The water is under effect of an electrical potential. There are two main types of semi-permeable membranes: anion-selective or cation-selective membranes. Anion-selective membranes contain positively charged matter thus they reject and allow positively and negatively charged ions respectively. On the other hand, cation-selective membranes contain negatively charged matter thus they reject and allow negatively and positively charged ions respectively. Anion-selective membranes are used for removing lead from water. These membranes do not allow the positively charged lead ions to pass through them. In this method, water is passed through a series of anion-selective membranes until all the lead has been removed. However, the membrane pores can be clogged especially if the water contains particles larger than 10 μm. This requires the water to be pre-treated before it can be treated using ED method (Lenntech, (n.d.)).
There are also several ongoing research and development projects aimed at using nanomaterials and nanotechnology to develop more efficient water treatment systems (Gehrke, et al., 2015). These nanomaterials are specially made to block flow of lead through them. The nanomaterials and nanoparticles have less energy and operating costs, discard less wastewater and produce high quality water (Tambe, 2015).
The rapidly increasing global population, climate change and depleting water resources have increased the necessity of developing efficient, cost effective, environmental friendly and easy water treatment methods (Amin, et al., 2014). There are various methods that can be used to remove lead from water so as to make it potable. However, there are several factors that must be considered when selecting the most suitable method. Some of these factors are discussed below
Effectiveness: the method selected should be able to remove lead from water up to the required minimum acceptable level and/or concentration
Capacity: the method selected should be able to produce the required amount of water output within the expected time.
Lead concentration: the method selected should also be based on the concentration level of lead. Some methods are only effective for low levels while others are effective for high levels of lead concentration.
Cost: each method has different initial, operating and maintenance costs. Therefore the method selected should be able to be installed, operated and maintained properly using the available resources.
Skills: the labour skills required should also be considered so as to ensure that the system is operated as recommended by the manufacturer and in compliance with relevant industry requirements. The skills required depend on simplicity and technicality of the water treatment method.
Safety: the method selected should also be safe to the operator, water users, technicians and the environment.
Renewable energy: considering the negative effects of non-renewable energy, it is always a good decision to consider selecting a method that can be effectively run using renewable energy.
Environmental impacts: the method selected should also have no or minimal impacts on the environment.
Reliability and durability: the method selected should also be reliable and durable so as to avoid frequent replacements or inconveniences.
Conclusion:
The importance of water in human life cannot be overemphasized. However, millions of people across the world do not have access to potable water. This is due to various reasons, including lead contamination. Water that is contaminated with lead is not fit for drinking. This is because lead is one of the toxic heavy metals that cause numerous health problems when exposed to human bodies either through air, food, water, etc. These health problems affect unborn babies, infants, children, pregnant women and other adults. Some of the health problems resulting from consumption of lead contaminated water include: delayed neurologic, mental or physical development, anemia, hearing problems, slowed growth, brain damage, headaches, mood disorders, hyperactivity, pica, lower IQ, learning and behavior problems, kidney problems, heart diseases, high blood pressure, hypertension, cancer, reproductive problems, joint and muscle pain, digestive problems, loss of appetite, mood disorders, blood disorders, Alzheimer disease, autoimmune diseases, premature birth, low birth weight, gestational hypertension, miscarriage or abortion and reduced fetus growth. Children are the most affected.
Lead typically gets into potable water through corrosion of water supply pipes, solders and plumbing systems, including components such as fittings, faucets and fixtures. Lead is predominantly used to make most of these components and therefore when they get corroded, lead deposits find their way into potable water. Potable water may also get contaminated with lead through pollution of natural water sources by direct disposal of lead wastes, infiltration from a landfill or weathering of rocks containing lead into groundwater. According to World Health Organization, the maximum acceptable concentration of lead in potable water is 0.01 mg/L (10 μg/L). This is the level that is applicable in many countries across the world.
However, lead contamination in potable water is a problem that can be solved. There are many conventional and contemporary methods that are used to remove lead from potable water. These methods include: distillation, reverse osmosis, activated carbon filtration, ion exchange, alkali ash material permeable reactive barrier, electrocoagulation, ultrafiltration, electrodialysis, and use of nanomaterials and nanoparticles. Each of these methods has its advantages and disadvantages. Before selecting a particular method, it is also important to consider factors such as effectiveness, capacity, cost, lead concentration, skills, safety, renewable energy, environmental impacts, reliability and durability. There are also several other ongoing research and development projects aimed at developing simpler and more reliable, cost effective, energy efficient and environmental friendly methods of removing lead from potable water. Considering the significance of potable water to human life, it is recommended that everyone should support efforts made towards creating more efficient, reliable and cost effective methods and/or processes of removing lead from potable water. This will save many lives today and in the future because lead contamination in potable water is a major public health threat.
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