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management in
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Environmental Management and Health, Vol. 11 No. 1, 2000, pp. 39-46.#MCB University Press, 0956-6163
Hazardous wastes
Assessing the efficacy of structures and
approaches to management in Nigeria
Abimbola Y. Sangodoyin
Department of Agricultural Engineering, University of Ibadan, Nigeria, and
Stephen F. Ipadeola
Civscon Consult, Ibadan, Nigeria
Keywords Waste, Management, Hazard, Nigeria
Abstract In this study, characterization of hazardous wastes components, treatment and disposal systems were examined for Southwestern Nigeria. The data were used to assess the effectiveness of monitoring systems and existing regulations on the subject and to proffer solutions for efficient management. Three sources of hazardous wastes were examined, namely: household units, commercial enterprises and industrial outfits. The household units, which were further classified into high, medium and low income earner groups, produced wastes with hazardous components of 5.6 per cent, 4.4 per cent and 4.2 per cent respectively. Typical results also show that the Pb component of wastes from a hairdressing salon, and that from a local aluminium pot making industry, were 0.026ppm and 0.046ppm respectively. Most of the other parameters examined were far higher than limits recommended by the World Health Organisation (WHO) for safe disposal. The trace elements, however, fall within the recommended limit of WHO. The current investigation has stressed the need to: properly monitor industrial wastes discharge as well as environmental protection officials to conduct the test themselves; enforce regulations that might require the installation of treatment plants appropriate for the type of wastes generated; encourage waste reuse and recycling; intensify public education; remediate land already polluted by hazardous waste; divert some profit generated by industries to waste management research; and establish standard laboratories all over the study area for unhindered waste monitoring.
Introduction
The simple nature and relatively small volume that characterized waste in the past have since been changing with the advent of industrialization and urbanisation. Continuing advancement in science and technology is contributing significantly to the increasing volume and toxicity of waste generated. Accidents associated with the release of hazardous wastes span both the developed and developing countries. (UNEP, 1994; FEPA, 1991; Shaw, 1992). A typical example of the deleterious effect of hazardous waste on the environment was recorded in 1991 during the Gulf War. The approximately 2.5 million barrels of crude oil and 35 million cubic meters of associated gases that were at one time burning in the Kuwait oil fields emitted considerable tonnes of SO2, CO, nitrogen oxides and particulates on a daily basis (Dabbagh, 1993).
After the burning of the oil wells, chromium and copper toxicities also pose a
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threat to the terrestrial and aquatic environments (Sadiq and Mian, 1993). The introduction of toxic and hazardous materials from utilization of industrial products was also illustrated with the accidental contamination of a local public well in Rowley, Massachusetts, USA with trichloroethane (TCE) from a nearby machine shop (Anderson, 1987). The 1998 Koko waste episode in Nigeria also opened up the behind-the-scene deals on hazardous wastes involving many African countries. Ignorance and poverty were recognized as being responsible for acceptance of toxic/hazardous wastes from industrialized countries. One estimate (West Africa Magazine, 1988) put the revenue from the acceptance of hazardous material by the countries concerned as being equivalent to twice their national income.
A battery of professionals among whom are environmentalists, meteorologists, ecologists, chemists, environmental engineers and oceanographers have demonstrated interest in issues of hazardous wastes and proposed theories and solutions to minimize pollution (Halawaniet al., 1993). Reduction in waste toxicity has, for example, been proposed (Levenson, 1990) along the lines of provision of alternatives to the use of some elements specifically, Pb, Hg, Cd and benzene in industrial processes. Success in the use of treatment systems such as wet oxidation process (Force, 1992), remediation (Opie, 1992), biodegradation (Stroo, 1992; Borchert 1994) and incineration (WARMER, 1994) are also well documented.
In Nigeria, household, commercial and industrial units generate hazardous wastes with no organized management system. Unlike in developed countries where scientific approaches are continuously harnessed to combat pollution issues, researchers are not motivated towards this direction in developing countries. The present economic atmosphere in Nigeria encourages the flight of highly qualified personnel to other countries. Soon, they return with sophisticated equipment acquired to start some commercial or industrial enterprises. Due cognisance has to be taken of the resulting waste products. The present study, aimed at examining the existing hazardous waste management facilities and their adequacy, is therefore necessary to gear all parties concerned into action .
Materials and methods
The study area, located in the southwestern part of Nigeria, spans the Guinea Savannah and forest zones. The annual mean temperature ranges from 298C to 358C. The alternate effects of the tropical maritime and continental air mass produce two distinct seasons namely: wet and dry.
The humid and hot tropical climate promotes bio-degradation of wastes. The negative effect of such climate on leachate production was also noted. The study and appraisal was thus conducted at the inception of the rains (April) and lasted through September, 1995.
Hazardous waste
management in
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analysis formed the bedrock of information acquisition on the subject. Household units were divided into low, medium and high-income groups. Five households were selected for waste collection and composition analysis in each of the identified income groups. In order to ensure unhindered waste collection, the hazardous wastes were sorted from the general collection bin. Other important factors taken into consideration include the management system such as sorting, storage, treatment and disposal techniques.
The appreciable quantity of toxic waste from commercial outfits made their consideration imperative. This outlet or contact point could cause severe problems because of high patronage. Ten commercial centres were investigated on problems of hazardous wastes while questionnaires were administered on over 50 other outfits. The investigation cut across photographic development centres, plan printing shops, laundries, hair dressing salons, department stores; X-ray centres gave valuable information on the variety of chemicals being used as well as concentrations of hazardous components.
Industrial units are undoubtedly the primary source of hazardous wastes. Greater attention accorded the industrial sector is, therefore, not misplaced. Modification of industrial processing system can reduce the amount of toxic waste generated as well as potency of products to generate hazardous wastes. The industrial concerns investigated include food, drinks and beverages, battery manufacture, electrical, and electronic factories, chemical and pharmaceutical industries, electroplating and metal finishing industries, traditional industries and textile, plastic and cement manufacturing companies. Waste samples collected from six industrial ventures and one commercial outfit were analyzed for the presence and concentration of toxic materials using procedures outlined in Hanson (1973).
Results and discussion
Household wastes
The result of waste composition analysis (Table I) shows that garbage constitutes the major component of waste from the high and medium-income earner groups.
Conversely the low-income earners group generate waste with over 40 per cent of leaves by weight. The results detailed in Table I give an indication of consumption pattern in the different households. While food waste such as remnants, maize husks, fruits and other assorted materials are commonly found with high and medium-income earners (because they utilize their waste collection bins properly) their low-income counterparts litter surroundings with such waste materials. A focus on hazardous constituents of the wastes such as insecticide cans, empty drug containers, old batteries, electric bulbs and fluorescent tubes, etc. indicate an average of 5.6 per cent, 4.4 per cent and 4.2 per cent by weight for the high, medium and low-income groups respectively.
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tanks. Effluents such as detergents, strain removal, bleaching agents and petroleum oils are discharged indiscriminately. The effects of these wastes are not usually noticeable in the dry season, but waste effluent interaction with groundwater has been confirmed in an earlier study (Sangodoyin, 1993). Leachate effects on water courses are pronounced with waste discharge near a well and in places where the water table is very high.
Mercury and lead have been identified as active pollutants and could have profound effects on children especially when paints have not matured for at least ten years (Purves, 1977). Children's exposure to environmental hazards in painted houses appears to be high in the medium and high income groups. Gaseous pollution from automobile exhausts appears to be high for household at distances less than 100m from major streets. Incomplete combustion could expose the household concerned to Co and Pb the latter being used extensively as antiknock agent in petrol. Better control of vehicles' roadworthiness is desirable, the dwindling economy in the study area notwithstanding.
Commercial venture wastes
Most respondents were ignorant of the waste from their processes. However, they attested to the fact that some chemicals used are corrosive. The return rate of questionnaires was discouragingly low but informal interviews revealed that wastes are rarely reused and are often disposed of indiscriminately. Wastewaters are thrown on to open spaces in front of shops or salons. At best, such systems are linked with the open drain system. Chemical constituents of hair care salon waste include Pb, Cr, Hg and Se. Plan printing offices generate solid wastes which, in most cases, are contaminated with ammonia. Photo development centres generate waste with appreciable quantity of CN, Cr, Pb, Hg and Cd. All these wastes mixed with other components are disposed of in open dumps or landfills. Expectedly, no co-operation was received from offices, departmental stores, X-ray centres and medical laboratories. X-ray centres particularly did not allow inspection of their facilities though heaps of wasted
Table I.
Solid waste composition (percentage by weight) in households classified on the basis of income (Southwest Nigeria)
Income earner group
Component High Medium Low
Leaves 5.1 23.3 42.2
Garbage 29.5 24.0 15.4
Paper 23.0 15.8 13.7
Rags 2.7 8.0 6.2
Polythene and plastics 7.5 5.7 3.5
Tins and metals 15.8 11.2 10.5
Bottles and glasses 11.3 6.7 3.2
Bones 2.8 2.0 2.3
Ashes 2.3 3.2 2.7
Faecal matters 0.0 0.1 0.3
Sum total 100 100 100
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films and papers are in their waste bins. Results of laboratory analysis of liquid waste from a hair care salon are shown along with those from some industrial establishments (Figure 1 and Table II).
The recommended values of the World Health Organization which has been adopted by the Nigerian Federal Environmental Protection Agency is also shown. The foregoing thus indicate that accumulation of waste from this source can constitute serious harm to the environment especially through soil and water pollution.
Industrial wastes
The importance of industrial waste has been stressed by the results of the investigation in this sector. The field survey and questionnaire show reticence of most industries to the collation of data for adequate evaluation of hazardous waste management facilities. The response and observation of toxic waste disposal in the various industries are as detailed below:
0.06
0.05
0.04
0.03
0.02
0.01
0
Salon Al. Pot. Ind. Paints FEPA
Type of Industry
Concentration (ppm)
Pb Cr Cd
Figure 1. Comparison of the most critical waste samples
Table II. Concentration of toxic substances in some industrial waste samples (Southwest Nigeria) Parameters concentration (mg/l)
Industry pH Cu Zn Na Pb Cr Cd
Match producing 6.1 0.14 21.01 780.01 0.02 ND ND
Paints 5.9 0.13 0.35 92.05 0.003 0.007 0.001
Blacksmith 6.0 0.10 0.14 105.8 0.01 0.008 ND
Cashew nut processing 7.7 0.01 0.02 4.8 0.008 0.003 0.003
Aluminium pot producing 7.3 0.01 0.04 45.12 0.046 0.008 ND
Milk processing 6.2 0.01 0.19 30.05 0.016 0.001 0.002
Hairdressing salon 6.3 0.01 3.20 138.06 0.026 0.05 Nil
WHO 6.5-8.5 0.5 5 NS 0.01 0.01 0.01
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Paint
Waste materials from the industry include papers, scrap plastics, cartons, liquid effluents and some gaseous emissions while burning solid wastes. No organized system of waste management is in operation. Liquid effluent is discharged into a nearby stream. While reuse of solid waste is possible there are no facilities for monitoring waste toxicity.
Food processing
Humidification, roasting, shelling, sterilization and juice extraction produce a variety of wastes. Most of the wastes are disposed in open dumps. Leachates from waste dump will definitely affect water course downstream.
Material finishing
The major waste producing processes are the foundry and heat treatment. Inert residues such as slag or silica sand are unsightly dumped near work premises. In one instance, wastewaters are collected via a close drain into a chamber where sedimentation is allowed before H202 is used in oxidizing CN and
dilution to a pHof 7 is achieved.
Wood and wood products
Major raw materials in this industry have been identified as timber, phosphate and Arabic gum among others. The associated waste comes in all the three phases of solid, liquid and gases. Wood wastes are burnt or heaped in open space. In one of the factories, liquid waste from operations are combined with restaurant and clinic waste and discharged into a nearby stream.
Traditional industries
Three industries namely, blacksmith, goldsmith, and aluminium pot producers were considered. The metal chips are reused in various ways for production of bullets. The aluminium pot producer claimed that the waste cannot be reused. An attempt to use it as fill material was reported to have failed as settlement resulted. The goldsmith indulges in open dumping of waste and feels that the practice is harmless.
Drug manufacturing
The firm, engaged in the manufacture of pads and drugs, discharges waste into a dug pit without any treatment. The company also generate an average of 10kg of paper per week and this has not attracted patronage for reuse or recycling. Most other firms that generate highly hazardous waste refuse response to enquiries.
Level of pollution
Hazardous waste
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The trace elements are generally within the stipulated limits with the exception of an occasionally high value for Zn in wastewater from the match industry. Sodium values were generally high in all the wastewater analyzed. The more acidic samples also tend to have higher concentration of Na as compared with the alkaline samples. The laboratory test results highlighted in Table II also show the metal concentrations and the WHO standard already adopted by the Nigerian Federal Environmental Protection Agency. A comparison of the most critical waste samples with current guidelines is shown in Figure 1. Despite the relatively high Pb concentrations in the waste samples, most of the industrial outfits are not inclined to the placement of a monitoring device nor facilities for appropriate waste disposal. The products of some of the industrial outfits, for example pots, are used in food preparation, thus constituting a possible contact point for people for exceptionally high levels of some metals. The limited data have demonstrated the need for careful monitoring of waste effluents and facilities for disposal before any clean bill is issued to industrial outfits in the study area.
Conclusion
The current investigation has examined the various paths through which hazardous wastes can be discharged into the environment. Reactions of the residents of the study area to hazardous waste management were also assessed. Household hazardous waste potential has not been recognized. Landfilling or open dumping of waste as currently practised will deter groundwater quality. Commercial ventures also generate hazardous waste which has not attracted attention by way of coordinated disposal and management technique. The results of laboratory analysis revealed that desirable limits of some parameters are being exceeded while the awareness of implication of indiscriminate hazardous waste disposal is yet to be realized by the residents of the study area.
The results and observations have demonstrated the need for adequate monitoring of industrial wastes discharge and sorting of hazardous components at the household level.
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