INVESTIGATION ON THE ENVIROMENTAL EFFECT OF LOCAL PRODUCTION METHOD OF ALUMINIUM

This research investigated the environmental effect of local production methods of aluminium utensils in Bachirawa, Ungogo local government Kano. Three soil samples and two samples of water were collected from sites A, B,C, D and E. The samples were then taken to faculty of agriculture for analysis. Atomic absorption spectrophotometer (A A S model No 240 FSAA) was used to determine the concentration levels of heavy metals in the samples. The results show that, the concentration levels of heavy metals in the soil samples A, B and C are: Zn ranges between (1158.13 11,117.80) mg/kg; Mn between (285.719 – 1809.672) mg/kg; Cd between (0.026 – 0.540) mg/kg; Cr (0.498 – 0.832) mg/kg and Pb between (42.54 285.53) mg/kg. The observed concentration levels in water samples for Zn ranges between (0.2411 – 0.4435)mg/l; Cd between (0.091 – 0.123) mg/l; Cr between (0.015 – 0.022) mg/l; Mn between (0.284 – 0.728) mg/l and Pb between (0.00-0.08) mg/l. Zinc and Manganese have higher concentration levels than the recommended permissible limit set by European Union (EU) and United Kingdom(UK) while Cd, Cr and Pb have lower concentration levels than the recommended permissible limit set by EU and UK in soil samples A, B and C. The concentration levels of Mn, Cd and Pb in water samples were higher than the permissible limit set by World Healh Organization (WHO) whereas Zn and Cr have concentrations lower than the recommended permissible limit set by WHO. Generally, the values of Zn, Mn, Cd, Pb and Cr obtained from the sites were higher than the control sites. The contamination/pollution index revealed that the soil was in a state of moderate to excessive pollution. Drinking water directly from the sites can be deleterious to the people.


INTRODUCTION
The third most abundant element in the earth's crust a part from oxygen and silica is aluminum (Patricia, 2000). Bauxite is a rock that consists of one or more aluminum hydroxide minerals and is the principle raw material used in the production of alumina by the aluminum industries. Gibbsite{Al(OH)3}, boehmite {AlO(OH)} and mixed bauxite (gibbsite and boehmite) are the bauxites used in the production of aluminum metals (Patricia, 2000). Some of the properties that attract many industries in using aluminum are light weight, corrosion resistance, formability and high strength-toweight ratio (Tan and Khoo, 2004). Metal casting technique was known to have been practiced in the middle belt of Nigeria through iron melting during the NOK culture. Iron smelting was also known to be in practice in Kano City over 1000 years ago. Bronze castings were made on the South-West of Benin, Ife and Egboukwu for over 1000 years in the city of Benin (Khan, 2005). Basic tools were locally manufactured by artisans; iron ore was mined and smelted around Ajaokuta, Kogi State and Ojirtami in Edo State before colonization. These include basic agricultural tools, surgical tools, domestic tools and military tools. Foundry technology is one of the vital bases for industrial development of any nation (Shuaib-Babata et. al., 2017). Sand is used in making moulds for casting metals of different sizes and is found to be relatively cheap and adequate for use in foundry industry (Shuaib-Babata et. al., 2017). Researchers had discovered through their studies that most Nigerian moulding sands were suitable for foundry application (Abolarin, 2004;Tokan, 2004 andShuaib-Babata, 2014). Solid state or direct recycling of aluminium reduces the amount of fund spend on environmental protection and energy consumption than the conventional recycling by smelting (Shazarel et. al., 2016). The energy spend in secondary aluminium production is about 10 GJ/tons of the material which is 5-10% of the energy in the primary aluminum output (Güley et. al., 2010). Land is polluted with both solid and liquid materials, these include: agricultural wastes, metals, rubbers, plastics, woods, grease, oil, etc. Such pollutants cause serious problems to the environment and to human beings. Heavy metal contamination in soil is a major concern because of their toxicity and threat to human life and environment (Begum et.al., 2009). Toxic heavy metals entering ecosystem may lead to geo-accumulation, bio-accumulation and magnification (Suciu, et. al, 2008). Researchers have asserted that due to the absorptive properties of the soil, some pollutants such as Cd, Pb, Fe, Cr, and Zn have long lives in soils and food grown on such polluted soils (Lickens, 2004). These environmental problems are influenced by industries such as foundries. The objective of this research is to access the environmental effect associated with the local production method of aluminium utensils in Bachira, Ungogo local Area of Kano State.

Casting
Metal casting process begins by creating a mould and is made from a refractory material, for example, sand. The metal is heated in an oven until it melts and the molten metal is poured into the mould cavity. After the molten metal solidifies in the cavity, the part is then remove from the mould and finally clean. (Ekundayo, 2003). In sand casting process, moulds are formed by ramming sand onto a pattern. The pattern is then removed which leaves a cavity in the sand and the cavities are made with sand cores. Molten metal is poured into the mould and after it has solidified the mould is broken to remove the casting. Sand casting is a versatile and low cost process using a wide range of alloys. Sand castings do not give accurate dimensions compared to other casting processes and have a relatively poor surface finish (Lenka, 2010). Die casting is commonly used for permanent mould casting process. It is used for producing components of home appliances such as; rice cookers, stoves, fans, washing and drying machines, etc. The surface finish and tolerance of die cast parts is good and does not require any post-processing. Die casting moulds are expensive and require significant time to fabricate.

Local Production of Aluminum Utensils in Bachirawa:
Alhaji Sunusi and Sons Company, Bachirawa Ungoggo local government, Kano state, Nigeria involved in the production of local cooking pots, frying pans and spoons of various sizes using Aluminum scraps. Melting of the Aluminum scrap is carried out in a local melting furnace. The local furnace consists of a cast iron crucible which is placed in the combustion chamber and then heated by charcoal (source of fuel). The combustion chamber is lined with red clay which serves as the refractory material. Heat is supplied to the furnace from the bottom by a combination of an electric motor, a fan and a duct system. The sources of aluminium scraps are vehicles, metal products for construction, cables and wires, electrical and electronic equipment and packaging (Lenka 2010). Figure 1 shows an example of the products from Alhaji Sunusi and Sons Company Bachirawa Ungoggo local government, Kano state, Nigeria.

Study area:
Ungogo local government Area is one of the forty-four local government areas of Kano state Nigeria with an estimated population of 367,657 people and land mass of 204 km 2 . It is located between latitude 12 o 05՛ 26՛՛ N and longitudes 8 o 29՛ 48՛՛ E. It's headquarter is located at the north of an ancient city of Kano. The indigenes are (Hausa and Fulani) and their main occupation is farming, trading, and rearing of animals. The main crops grown in the local government are guinea corn, millet, maize and beans. Ungoggo local government area is shearing border with six local governments namely; Kumbotso, Dawakin Tofa, Dala, Nassarawa, and Minjibir.

Samples collection Soil samples
Three sampling sites for soil were selected. 1kg of sample was collected at each sampling site and the control site at a depth of 18cm each using a spade. The samples were taken from 50, 100 and 150 m away from production site and then labeled as samples A, B & C. The soil samples were grounded using pestle and mortar, dried and sieved through 2 mm size. They were then taken to Faculty of Agriculture Laboratory, Bayero University Kano for heavy metal content analysis.

Water samples
Two samples of water labeled D and E were collected in 75cl bottles from boreholes 50 m away from the project site and then taken to Faculty of Agriculture Laboratory, Bayero University Kano for heavy metal content analysis.

Determination of heavy metal in the soil samples
One gramme(1g) of dried and sieved soil sample form site A, site B, site C and control site was collected at each site. The samples and a blank were digested with 5ml of concentrated nitric acid (HNO3) and 2 ml of 70% Perchloric acid (HCIO4). Each beaker was covered with a watch glass and the digestion was carried out on a hot plate in a fume chamber until it's colour turned white. The digestion continued until the entire volume was reduced to about 15 ml. The digestion was allowed to cool to room temperature and then filtered. The mixture was diluted with 5ml of 20% Nitric acid. Atomic absorption spectrophotometer Model No 240FSAA was used to analyze the samples extract (ASTM, 1981).
Determination of heavy metals in the water samples 50 ml of each sample was acidified with 20 ml of nitric, hydrochloric and perchloric acid. The mixture was digested on a hot plate in a fume chamber for one hour at 100 o C until clear solution was seen and the volume reduces to 20 ml with presence of white fumes. The mixture was filtered with filter paper after cooling and transferred to100 ml plastic bottle.
Deionized water was added into the bottle up to 50 ml mark. Atomic Absorption Spectrophotometer (AAS) was used to analyze samples (Dauda, 2011).

Quantification of Heavy Metal Contamination/Pollution Index
The level of contamination in the soil samples was determined using the quantification of contamination/pollution index (MPI) of metals in soil adopted by Lacatusu (2000).
MPI gives the ranges between soil contamination and soil pollution. This index represents the ratio between the concentration of heavy metal content measured in soil by chemical analysis and reference value obtained from the control soil. The values of contamination/pollution index of soil greater than 1(> 1) gives the pollution range and those less than 1 (< 1) gives the contamination range. The two ranges were divided into interval of <0.1 as very slight contamination, 0  (Lacatusu, 2000).

RESULTS AND DISCUSSION Results
Tables 1-3 present the contamination/pollution levels caused by heavy metals in the soil samples. Table 4 presents concentration levels of heavy metals in water when compared with the permissible limits set by World Health Organization (WHO). Table 5 presents the Maximum permissible limits for heavy metals in soil. Figure 3 presents the graph of concentration levels of heavy metals in the soil samples while figure 4 presents the concentration levels of heavy metals in water samples.      Cr recorded from the sites are lower than the maximum permissible limit of 180 mg/kg and 6.4 mg/kg set by E.U. and U.K. standards respectively. The contamination/pollution Index shows that, there was moderate to severe pollution of Cr in the sites.

Table1: Contamination/pollution index for heavy metals in site A at 18 cm depth
Lead: The concentrations of Pb are 285.59 mg/kg, 42.54 mg/kg and 148.19 mg/kg for sites A, B and C respectively while the control sites recorded lower concentrations of 1.863 mg/kg, 4.24 mg/kg and 13.061 mg/kg. The concentrations of Pb observed in all the sites are higher than the concentration recorded in the control sites. The concentrations of Pb in the sites are lower than the standard permissible limit of 300 mg/kg set by E.U but higher than U.K standard with 70 mg/kg. The contamination/pollution Index shows that, there was very severe pollution to excessive pollution of Pb in the study area.

Concentrations of heavy metals in water
The concentration of zinc obtained from water samples was higher in site D with 0.4435 mg/l and lower in site E with 0.2411mg/l. The concentrations of Zn in all the samples were observed to be below the maximum permissible limit of 3.0 mg/l set by WHO for drinking water.
The concentration of cadmium obtained from the sampling sites D and E are shown in figure 4. The results have shown that, the highest concentration of Cd was recorded in site E with 0.123mg/l and the lowest in site D with 0.091 mg/l. The concentration of Cd in all the sites were higher than the maximum permissible limit of 0.003 mg/l set by the world health organization(WHO) for drinking water. Cadmium causes fibrosis, respiratory diseases, hypertension and also affects the nerves system. sampling sites are presented in figure 4. The concentration of Mn recorded was higher in site E with 0.728 mg/l and lower in site D with 0.284 mg/l. The concentrations of Mn were higher than the maximum permissible limit of 0.1mg/l set by the world health organization (WHO) for drinking water. The concentrations of chromium in the sites are presented in figure  4. Site E has the highest concentration of chromium with 0.022 mg/l and site D has the lowest with 0.015 mg/l. The concentration of chromium in all the sites were observed to be below the maximum permissible limit of 0.1 mg/l set by the world health organization (WHO) for drinking water. The concentrations of Pb obtained from the sampling sites D and E are presented in figure 4. The highest concentration of Pb was recorded in site E with 0.08 mg/l while the lowest was recorded in site D with 0.00 mg/l. The results show that, there was Pb in site E and site D has no Pb. The concentration of Pb in site E was higher than the maximum permissible limit of 0.05 mg/l set by WHO (2008) for drinking water. Therefore, drinking water from site E may cause toxicity to the central and peripheral nervous system, cancer, and can affect mental development in infant WHO (2008).

CONCLUSION
The study revealed that foundry activities are also sources of environmental pollution in Bachirawa foundry market. It was found that, the concentrations of heavy metals in decreasing order are as follows: Zn>Mn>Pb>Cd> Cr. Zinc, Manganese, lead and Cadmium were the major soil pollutants in the study area. The results obtained from water samples have showed that, the concentrations of Cd and Mn in all the sites and Pb in site E were above the permissible limit set by WHO (2008), therefore, drinking water directly from the sites can be deleterious to the people.