Investigation of disposal processes by manufacturing companies in Gaborone

Gaborone, the capital city of Botswana has experienced rapid growth in its economy and in its population. With the rapid industrial development and expansion of cities comes the increased challenge of waste generation and hence waste management. Therefore, appropriate waste handling, storage, collection and disposal practices become necessary in order to minimise environmental and public health risks. Improperly managed waste usually results in downstream costs being higher than what it would have cost to manage waste properly in the first place [1]. In Africa data on waste management is not readily available and in Botswana a few studies have focused on waste management [2,3] and none of these have exclusively concentrated on waste generated by industries. There is however a rational agreement as evidenced by waste management strategy and policy development by Botswana government that, inefficient waste management in the country threatens public health. With industries being the fundamental waste generators, it is of critical importance to determine ways in which they manage their waste particularly in the city in order to analyze industry trends and implement appropriate policy mechanisms. A report by Botswana central statistics office [4] has indicated that the greatest waste generators are urban areas and this is associated with rising demands for goods in urban areas. The city of Gaborone alone generates 85 tonnes of waste per day [5]. Waste generation is estimated to increase at a rate of 7 % per annum [6].

Industrial waste is a cause for concern as it is a common cause of pollution. Common contaminants which are either organic or inorganic include petroleum hydrocarbons, polychlorobiphenyls, polycyclic aromatic hydrocarbons, [7] heavy metals [8], surfactants, toxins and salts [9] which can be introduced into the essential elements of the ecosystem including soil, water and biodiversity causing severe degradation in the ecosystem. A wide variety of unsafe inorganic contaminants which may be produced include heavy metals, such as arsenic, lead, cadmium, and mercury. These metals can accumulate in agricultural soils; become available for plant uptake and runoff into water ways. As crops and plants extract these toxic metals from the soil and enter the food supply chain, the chance of impacts on human health increases. These metals are known to be potentially toxic to humans contributing to cancer, developmental effects, birth defects, reproductive problems and liver and kidney damage [10]. Industrial waste of organic composition on the other hand can result in the presence of excess nutrients in water which consequently lead to algal blooms, oxygen deficits and increase in color and turbidity in water sources [11]. The understanding of waste management process in companies is therefore an important step in ensuring human and environmental health. The goal is to minimize the pollution introduced into natural waterways and into the environment. Scarcity of water is another major problem in Botswana [12]. The industrial processes utilize a lot of water as raw material and consumption often exceed capacity to replenish water. Thus industries playa major role and are hence significant from the water consumption and effluent discharge point of view. Amongst other types of waste produced by industries, industrial effluent is one of the main important ones. If the effluents are discharged into natural watercourses, surface and groundwater pollution will result. This will be a huge problem in Botswana as the country is largely dependent on groundwater sources for their livelihood, particularly the farming community and rural populations in Botswana. The introduction of toxic substances from industrial effluents to agricultural environments will only add to their concentrations in underground water and cause damage to aquifers which the country is working so hard to protect. To overcome challenges associated with waste management and raw materials depletion, many industries are following the hierarchy of waste management; that is reducing the waste quantity, reusing or recycling and often recovering their waste as well treating their waste before disposal. If these strategies are implemented, Botswana will maintain its pristine and healthy environment to be enjoyed by future generations. Therefore from this viewpoint a study was carried out to investigate industrial waste management practices in selected industries in Gaborone and assess whether industries are knowledgeable in waste management practices.