**2.1. History of lead use**

**1. Introduction**

248 Advances in Bioremediation of Wastewater and Polluted Soil

the risk of disease.

from lead are crucial.

Pollution by heavy metals has gradually worsened in Asian, African, and South American countries, partly due to the excessive use of pesticides for growing crops which may in turn lead to the pollution of groundwater and well water. An investigation by the Food and Agriculture Organization (FAO)/United Nations Environment Programme (UNEP)/World Health Organization (WHO) suggests that the number of patients with pesticide poisoning is approximately 1–5 million annually, and several thousand cases are fatal. In some Asian countries, wells reserved for drinking water were dug below the acceptable levels to avoid pesticide pollution, and consequently, many inhabitants developed arsenic poisoning [1, 2]. Rivers and soils are also polluted by industrial wastes in those countries. In particular, wastes from metallurgy and mining industries contain various heavy metal ions, and wastes from leather industries contain cadmium and chromium. These wastes are typically exhausted and discarded in nearby rivers and in the air due to the lack of posttreatment equipment or strictly

controlled landfill sites, resulting in detrimental groundwater and soil pollution.

Additionally, environmental pollution by heavy metals has resulted in serious disease. In Japan, four historic cases of metal pollution occurring predominately in the 1950s have been reported, which include "ouch-ouch" disease and Minamata disease. In 1910, a mining company eliminated cadmium waste into a nearby river. The inhabitants who drank directly from the river or ingested food grown along the riverbanks developed cadmium poisoning and exhibited symptoms such as spine and leg pain and fragile bones. In another case of heavy metal poisoning, the improper elimination of methylmercury waste into a nearby river resulted in neuroparalysis (Minamata disease) among the locals. Recent problems due to heavy metal pollution in some countries may be more serious than the previous incidences in Japan. Therefore, it is critical to remediate polluted areas as quickly as possible in order to decrease

Lead is an important heavy metal because it is widely used to produce electronics, crystal glasses, and batteries. The annual consumption of lead has been increasing at a high rate in China due to the increased demand for cars and power-assisted bicycles according to the rapid economic growth. Recently, a relationship between high blood lead levels and lead pollution in lead mining areas has been proclaimed as a serious problem [3]. Some reports have suggested that many children living in the areas near mining industries developed symptoms of lead poisoning [4]. Therefore, the control of lead emissions and remediation of soil polluted

The purpose of this chapter is to assess both the causes of lead pollution and the efficiency of bioremediation by plants and microorganisms. First, the author investigated the causes of lead contamination, and the results suggest that soil pollution from lead occurred particularly in the areas where metallurgy and mining industries were present. Then, the author determined whether phytoextraction is a practical method for lead remediation in these areas. Finally, the author proposed a novel lead remediation process which employs microorganisms. The proposed process, the LIM method, combines immobilization with landfarming. As the

Lead has been utilized in the production of many products, such as tableware, tubes, and pipes, since the age of Ancient Rome [5] because it can be easily manipulated due to its low melting point and malleability. However, lead poisoning has gradually increased since the 1970s. One major source of lead poisoning has been gasoline. Gasoline containing tetraethyl lead or tetramethyl lead (lead gasoline) was widely utilized to protect car engines. A significant amount of volatile organic lead exhausted by cars triggered air and soil pollution, resulting in the symptoms of lead poisoning. In Japan, the soil near the roads in large cities contained 10– 30 g/kg of lead. To remedy this problem, alkylate gasoline was developed and regular and high-octane gasolines were changed to lead-free gasoline in 1975 and 1987, respectively, in Japan. The United States banned lead gasoline sales in 1995 in accordance with the Clean Air Act, and EU banned lead gasoline in 2000. Many other countries (more than 50) have banned or decreased the amount of lead in gasoline [6]. Another major source of lead poisoning was water contamination due to lead pipes. Lead pipes have been used to transport tap water in many countries and were used as service pipes for tap water until the 1970s in Japan. In Uruguay, for example, the inhabitants of old houses had elevated blood lead levels, because most of the old houses used lead pipes for tap water [7]. The dangers of lead poisoning from lead pipes are well recognized, and the use of lead is being reconsidered.

The use of lead in 1996 and 2009 in Japan is depicted in Figure 1A [8]. More than 80 % of lead is utilized for the production of lead-acid batteries for cars and industries. The second most common use is in inorganic chemicals, such as a polyvinyl chloride stabilizer, crystal glass, and paint. A polyvinyl chloride stabilizer containing lead was widely used due to its protective effects in the elimination reaction of vinyl chloride by oxygen. Crystal glass, which contains a high concentration of lead(II) oxide (PbO), is also widely used due to its high degree of transparency and refractive index, similar to crystal. Other common uses for lead include solder for electronic materials, tubes for draining and exhausting, and plates for medical equipment and lagging materials of underground cable. Moreover, lead production is rapidly increasing in some countries due to an increase in the production of lead-acid batteries, especially in China (Fig. 1B) [9].

#### **2.2. Emission control of lead in Japan and other countries**

Heavy metal pollution has become an increasing concern in the EU [10]. The amount of waste of electrical and electronic equipment (WEEE) in 2005 was approximately 9 million tons and is steadily increasing at a rate of 5 % annually. The wastes are generally burned or buried without any treatment. If the total amount is calculated based on the assumption that WEEE contains approximately 5 % solder, 22, 500 tons of lead is lost as waste every year. In addition, Running Title

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The use of lead in 1996 and 2009 in Japan is depicted in Figure 1A [8]. More than 80 % of lead is utilized for the production of lead-acid batteries for cars and industries. The second most common use is in inorganic chemicals, such as a polyvinyl chloride stabilizer, crystal glass, and paint. A polyvinyl chloride stabilizer containing lead was widely used due to its protective effects in the elimination reaction of vinyl chloride by oxygen. Crystal glass, which contains a high concentration of lead(II) oxide (PbO), is also widely used due to its high degree of transparency and refractive index, similar to crystal. Other common uses for lead include solder for electronic materials, tubes for draining and exhausting, and plates for medical equipment and lagging materials of underground cable. Moreover, lead production is rapidly increasing in some countries due to an increase in the production of lead-

**Figure 1.** Lead use and lead production. **Figure 1.** Lead use and lead production. A. The amount of lead used in various products in 1996 and 2009 in Japan. B. Worldwide lead production in leading countries.

it has been reported that lead may leak from WEEE and battery waste by the effect of acid rain. In 2000, the EU developed the "Directive of End-of-Life Vehicle (ELV)" to solve the problem of waste. The directive necessitated the recycling of end-of-life vehicles, and the ratio of lead recycling to collecting lead-acid batteries was improved. A similar recycling system has been constructed in Japan, and lead-acid battery recycling is additionally mandated by law. A. The amount of lead used in various products in 1996 and 2009 in Japan. B. Worldwide lead production in leading countries. **2.2. Emission Control of Lead in Japan and Other Countries**  Heavy metal pollution has become an increasing concern in the EU [10]. The amount of waste of

The EU also issued a strict directive in 2003 on the restrictive use of certain hazardous substances in electrical and electronic equipment (referred to as the "Restriction of Hazardous Substances (RoHS) Directive"). The directive forbids the use of hazardous heavy metals (e.g., Pb, Hg, Cd, and Cr(VI)) in newly produced products of electrical and electric equipment. The United States also issued a similar law, the "Electric Waste Recycling Act of 2003." In compli‐ ance with these directives, lead-free products (solder, glass, and paint) have been developed, and the use of lead-free solder and lead-free paint is now the standard practice in Japan. electrical and electronic equipment (WEEE) in 2005 was approximately 9 million tons and is steadily increasing at a rate of 5 % annually. The wastes are generally burned or buried without any treatment. If the total amount is calculated based on the assumption that WEEE contains approximately 5 % solder, 22,500 tons of lead is lost as waste every year. In addition, it has been reported that lead may

Another factor related to lead consumption is polyvinyl chloride consumption. In 2012, global polyvinyl chloride consumption was approximately 36 million tons. Polyvinyl chloride contains approximately 4, 500 ppm of lead stabilizer; thus, 162, 000 tons of lead stabilizer was exhausted as burned ash. The EU issued a strict directive on the management of packaging waste (Directive 94/62/EC), which banned the use of lead stabilizers in vinyl chloride produc‐ tion. To reach the target value of this directive, lead-free stabilizers, such as those containing Ca and Zn, have been developed. Furthermore, old pipes and electrical codes made of polyvinyl chloride are gradually being changed to lead-free ones in homes and industries.

A schematic illustration of lead recycling is shown in Figure 2. Recycled lead currently occupies 75 % of the total lead produced by metallurgy in the EU, and this ratio is increasing. In Japan, over 90 % of used lead in batteries was collected and reused in 2009. If a 100 % recycling ratio can be obtained and solder, polyvinyl chloride, paint, and glass can be converted to lead-free products as shown in Figure 2, lead emissions should theoretically become negligible.

**Figure 2.** Schematic illustration of lead production and recycling.
