Oladele Osibanjo

The challenge of electronic waste (e-waste) management in developing countries

Information and telecommunications technology (ICT) and computer Internet networking has penetrated nearly every aspect of modern life, and is positively affecting human life even in the most remote areas of the developing countries. The rapid growth in ICT has led to an improvement in the capacity of computers but simultaneously to a decrease in the products lifetime as a result of which increasingly large quantities of waste electrical and electronic equipment (e-waste) are generated annually. ICT development in most developing countries, particularly in Africa, depends more on secondhand or refurbished EEEs most of which are imported without confirmatory testing for functionality. As a result large quantities of e-waste are presently being managed in these countries. The challenges facing the developing countries in e-waste management include: an absence of infrastructure for appropriate waste management, an absence of legislation dealing specifically with e-waste, an absence of any framework for end-of-life (EoL) product take-back or implementation of extended producer responsibility (EPR). This study examines these issues as they relate to practices in developing countries with emphasis on the prevailing situation in Nigeria. Effective management of e-waste in the developing countries demands the implementation of EPR, the establishment of product reuse through remanufacturing and the introduction of efficient recycling facilities. The implementation of a global system for the standardization and certification/labelling of secondhand appliances intended for export to developing countries will be required to control the export of electronic recyclables (e-scarp) in the name of secondhand appliances.

TOXICITY CHARACTERIZATION OF WASTE MOBILE PHONE PLASTICS

Waste plastic housing units (N=60) of mobile phones (of different models, and brands), were collected and analyzed for lead, cadmium, nickel and silver using atomic absorption spectrophotometry after acid digestion using a 1:1 mixture of H2SO4 and HNO3. The mean (+/-S.D.) and range of the results are 58.3+/-50.4mg/kg (5.0-340mg/kg) for Pb, 69.9+/-145mg/kg (4.6-1005mg/kg) for Cd, 432+/-1905mg/kg (5.0-11,000mg/kg) for Ni, and 403+/-1888mg/kg (5.0-12,500mg/kg) for Ag. Approximately 90% of the results for the various metals were < or =100mg/kg. Results greater than 300mg/kg were generally less than 7% for each metal and could be attributed to exogenous contamination of the samples. These results suggest that there may not be any immediate danger from end-of-life (EoL) mobile phone plastic housing if appropriately treated/managed. However, considering the large quantities generated and the present low-end management practices in most developing countries, such as open burning, there appears a genuine concern over the potential for environmental pollution and toxicity to man and the ecology.

Residues of organochlorine pesticides in fruits, vegetables and tubers from Nigerian markets

Residue levels of organochlorine pesticides have been determined in raw fruits, vegetables and tubers from markets in Nigeria. In the fruits, total HCH, aldrin and total DDT were detected in 77, 38 and 30% of all samples, respectively. In the vegetables, total HCH, HCB, total DDT and aldrin were detected from 95, 53, 50 and 30%, respectively, of all samples. Aldrin + dieldrin, total HCH, and total DDT were detected from 98, 79 and 49%, respectively, of all tuber samples. Other pesticides were below their detection limits. The average levels were generally low and none were above the FAOs maximum residue limits.

Trace metal levels in tree barks as indicators of atmospheric pollution

Abstract Barks of six species of trees were sampled at thirty-nine different locations in Ibadan, Nigeria and were analysed for the trace metals lead, cadmium, cobalt, copper, zinc, manganese, and iron. Lead levels in barks from areas with relatively high traffic density were generally higher than lead levels in barks from areas with low traffic density. The lead level recorded in the high traffic density areas, 40–140 μg/g, is low compared to values reported for barks of trees along busy roads in developed countries. For the other metals, no correlation with traffic density was observed.

The impact of industries on surface water quality of River Ona and River Alaro in Oluyole Industrial Estate, Ibadan, Nigeria

Samples of water from two rivers (River Ona and River Alaro) in Oluyole Industrial Estate, Ibadan, Nigeria were analysed to evaluate the impact of industrial discharges on the surface water quality. The results obtained indicated that most of the parameters analysed (pH, total hardness, sulphate, chloride, nitrate and dissolved solids) were lower than the World Health Organisation (WHO) maximum permissible limit for drinking water. However, the levels of nitrate, chloride, total phosphorus, total solids and oil and grease were higher in the industrial zones than those found in the upstream of both rivers. These ranged between 3.00 – 8.55, 7.48 – 11.78, 2.14 – 3.57, 260 – 520 mg/l and 381.20 – 430.80 mg/l, respectively. Nitrate and total phosphorus which are essential nutrients for plants were the most accumulated in both rivers. The gross organic pollution indicators monitored (chemical oxygen demand and oil and grease) revealed that River Alaro was more polluted than River Ona. It was established from the results of this study that industrial discharges had negative impact on the surface water qualities of both rivers. Hence, extraction of water from both rivers for domestic and agricultural purposes requires some forms of physical and chemical treatment.

Pollution studies on Nigerian rivers, II: Water quality of some Nigerian rivers

Abstract Twenty-six Nigerian rivers were sampled during the dry season periods of 1977 and 1978. The samples were analysed for Biochemical Oxygen Demand (BOD5); Chemical Oxygen Demand (COD), pH, dissolved oxygen, ammonia, nitrite and phosphate. Seventeen of the river examined were found to be more or less unpolluted six of them being of high quality. The remaining nine were found to be ‘polluted naturally’.

Trace metal content of fish and shellfishes of the Niger delta area of Nigeria

The trace metal contents of various fish and shellfishes from the Niger delta area of Nigeria were determined. The levels in the shellfishes were higher than those in the fish, which could be due to their being bottom feeders. The levels of fish varied from <0.01-0.10 ..mu..g/g for Cd, < 0.05-3.69 ..mu..g/g for Cu, 0.49-16.52 ..mu..g/g for Fe, and 0.08-6.90 ..mu..g/g for Zn. 15 references, 1 figures, 2 tables.

Pollution studies on Nigerian rivers: The onset of lead pollution of surface waters in Ibadan

Abstract Lead levels in the waters and sediments of the lake of the International Institute of Tropical Agriculture, Agodi Lake, Oba Lake, at three stations on Ogunpa stream, and at three stations on Ona River were measured from October 1977 to June 1978, using the combined APDC-MIBK-flame atomic absorption spectrophotometry technique. The lead levels recorded ranged from 0.2 to 46 μg/L for the aqueous phases; however, the levels in the sediments were much higher, ranging from about 18 to 85 mg/kg (dry weight). Although there is nothing alarming about these levels, the levels of lead in water bodies located in areas with high traffic density were consistently higher than levels for comparable waters in low traffic density areas. Similarly, lead levels were significantly higher in the fresh sediments of water bodies in areas with high traffic density, clearly indicating the onset of lead pollution for those high traffic density areas.

Heavy metal characterization of waste portable rechargeable batteries used in mobile phones

Ten brands of spent portable rechargeable batteries used in mobile phones (lithium-ion and nickel metal hydride) were collected and disassembled and the battery electrode and printed wiring board prepared using the EPA Method 3050B. The metal concentrations were determined by atomic absorption spectrometry. The mean (± standard deviation) concentrations and range of cobalt, chromium, nickel and cadmium in the battery electrodes were 361284±32281mg/kg (range 20870–575330 mg/kg); 25.3 ± 4.6 mg/kg (7.9–149 mg/kg); 75272 ± 14630 mg/kg (3589–266607 mg/kg) and 2.8 ± 0.6 mg/kg (0.2–16.3 mg/kg), respectively. Similarly, the mean values of cobalt, chromium, nickel and cadmium in the PWB were 564 ± 165 mg/kg (56.1–4068 mg/kg); 28.1 ± 4.0 mg/kg (ND-97.2 mg/kg); 735 ± 188 mg/kg (22.7–2727 mg/kg) and 1.8 ± 0.3 mg/kg (ND-7.2 mg/kg), respectively. The Li-ion battery electrodes contained significantly higher levels of cobalt (p < 0.01) whereas, the NiMH battery contained significantly higher nickel (P < 0.01). All the results for the cobalt and nickel levels in the battery electrodes exceeded the toxicity threshold limit concentration used in the toxicity characterization of solid wastes (cobalt, 8000 mg/kg; nickel, 2000 mg/kg). In fact, the mean cobalt level of the battery electrode is about 45 times the toxicity threshold limit concentration limit for cobalt while the mean nickel result is about 38 times the toxicity threshold limit concentration. Spent portable rechargeable batteries should be handled as toxic materials that require special treatment. Implementation of a well-coordinated management strategy for spent batteries is urgently required to check the dissipation of large doses of toxic heavy metals and rare earth into the environment.

Mobility and speciation of heavy metals in soils impacted by hazardous waste.

Abstract This study describes the mobility and chemical fractionation of heavy metals (HMs) from a site impacted by auto battery slag that was generated from secondary lead smelting operations. Samples were collected from the waste pile and from the immediate surrounding soil at four depths to assess the migration and potential bioavailability of Pb, Cd, Cr, Ni and Zn. Total levels of the HMs and their fractionation were determined. The results indicate that highest levels of HMs are present in the uppermost layer with significant migration down the depth, thereby posing a threat to groundwater quality. In the fractions, the concentrations of the metals follow this sequence: Pb>Zn>Cd>Cr>Ni. The chemical fractions of Pb, Cd, Cr, Ni and Zn in the samples, expressed as mean concentrations of the sum of the individual chemical fractions, demonstrate that the HMs exist mainly in the non-residual fractions. For instance, the percentage of non-residual fractions of lead in the waste pile and the surrounding soil ranged from 48.9 to 95.6% and 69.4 to 98.3% respectively. The mobility factors of the heavy metals are significantly high indicating high potential mobility and bioavailable forms of these HMs. The high concentrations of the HMs particularly Pb in the non-residual fractions, as observed in this study, shows the impact of anthropogenic activities on enrichment of natural soil with bioavailable HMs. Consequently, there is a need to be cautious in the way waste that is generated from heavy metals projects is added to natural soil.