Municipal Solid Waste Management and the Inland Water Bodies: Nigerian Perspectives

Municipal solid waste (MSW) composition, natural transformation, dynamics and impacts on inland water bodies in Nigeria were examined, using dumpsites and landfills as the common markers. Nigeria is estimated to have over 178.5 million people and kg/capita/day of 0.26–1.02 MSW, projected to increase with the expan-sion of the economy which is in need of better articulated MSW management strategies. The enormous natural inland surface and groundwater resources are daily challenged directly and indirectly, through decline in physical, chemical and biological quality. Solid waste disposal along the waterways and leachates from natural activities on materials at dumpsites and landfills was strongly identified and recognized as the source of pollutant inputs. The immediate and projected public health consequences in changes in inland waters were provided for resident aquatic organisms, some of which serves as food for resident human populations that are largely dependent on these water bodies for their daily water requirements.


Introduction
Municipal solid wastes (MSW) refer to all wastes generated, collected, transported and disposed of within the jurisdiction of a municipal authority. In most cases, it comprises mainly food waste, discarded materials from residential areas, street sweepings, commercial and institutional nonhazardous wastes as well as (in some countries) construction and demolition waste.
MSW has been variously described as aggregation of unwanted materials generated from a range of human-related activities denominated from domestic to production. The origin of what is regarded as MSW can be closely associated with the earliest attempts by humans to transit from migrant to settler modes of living, which imposed the need to modify or change the character of raw or primary materials available to support or sustain the new modes of living and originating human activity.
Nigeria is the dominant country in West Africa, accounting for 47% of West Africa's population, with gross domestic product (GDP) growth at an average rate of 5.7% per year between 2006 and 2016, facilitated by volatile oil prices to a highest of 8% in 2006 and lowest of −1.5% in 2016; Human Development Index value also increased by 13.1% between 2005 and 2015 [1]. However, the country continues to face massive developmental challenges including, but not limited to, human development indicators and

Municipal solid waste generation in Nigeria
Generation of MSW in Nigeria is a daily occurrence, arising from diverse and varied human activities; hence the character of solid waste generated is never homogenous (Plate 1a-k). The differences can be a function of several indicators which include but not limited to originating tasks, income bracket, location, population density, population characteristics, culture, consumption pattern and seasons [6]. The quantity of MSW generated across cities in Nigeria is closely associated with population, economic, political and commercial activities. All these variables are however tied to the human element, as the driver of these changes. Changes in population pattern have been closely associated with changes in waste generation, even in the presence of optimally articulated management approaches. Table 1 presented the close relationship between population and waste generation for the world's regions. It is noteworthy that regions with increasing or high per capita for MSW are the regions with high income. Nigeria had a population increase of between 2.6 and 2.7% annually between 2010 and 2018 and oscillated around 2% since 1965 [7]. The per capita income also increases steadily [1] which translated to increased purchasing power and consumptions of more products, with attendant waste generation. However, apart from Lagos State, waste generation data are not readily available or limited in coverage. The MSW per capita per day for different Nigerian cities is presented in Table 2, while Figure 2 showed MSW per capita for low-(Agric), middle-(Bariga and Ojodu) and high-income (Lagos Island) locations in Lagos State over a period of 30 days. These values are comparable to the suggested per capita for the African region ( Table 1).The data presented further extended the suggestion of a direct relationship between economic success and waste generation.
Accordingly, solid waste can be classified into four different types [13] depending on their source, which include: a. Household waste, generally classified as municipal waste.
b. Industrial waste, as hazardous waste. It is important to mention that until recently in Nigeria, MSW disposal methods ( Table 3) received very little attention because wastes were considered an entity with homogenous properties [26,27] or largely dominated by organic/decomposable wastes. Previous reports [28,29] clearly supported this position and also suggested that study of wastes in Nigeria started in the 1970s. The components of MSW from different parts of Nigeria are presented in Tables 4-8, which showed that MSW are still largely dominated by organic/decomposable components. Shift in waste characteristics is however gradually becoming apparent reflecting changes from previously ignored traditional household electronic wastes to high-profile ubiquitous wastes of a technology-driven economy, in the form of heterogeneous components, popularly referred to as electronic wastes (e-wastes) and related components. The wastes from traditional household electronics have also increased with better purchasing power over time.
E-wastes were largely unacknowledged in Nigeria and considered part of MSW until the Koko waste incidence of 1988. This led to the separation of discarded household, ICT and personal electronic devices as e-wastes [48,49]. The availability of cheaper versions of everyday ICT and personal electronic devices now provides additional source of consistent waste volume arising from short life cycle of substandard products. The volume and characteristics of MSW showing Daily per capita waste generation of different incomes and densities from Lagos State, Nigeria. Modified from [12]. X X X X X X X Modified from [8][9][10][14][15][16][17][18][19][20][21][22][23][24][25].      e-waste proportion from dumpsites or landfills were absent from available studies. The isolation of e-waste as a unique recent component, activities of scavengers or pickers, electronic market dumpsites and dedicated studies to e-wastes probably contributed to the lack of such data.

Municipal solid waste and inland water bodies in Nigeria
The magnitude of changes experienced by inland water bodies as a result of MSW in Nigeria could be attributed to inappropriate siting, design, operation and maintenance of dumps and landfills. The history of the association between changes in quality of inland waters and MSW generation in Nigeria has not been adequately documented. However, classical reports [50,51] provided a different trajectory to the narratives, where low-level perturbations reported for both the Ona River and Ogunpa River were associated with generation and disposal of MSW in Ibadan, Southwest Nigeria. Inland waters in Nigeria have been on the receiving end of MSW, but the details have been patchy. Inland surface and groundwaters in the vicinity of dumpsites in Nigeria have been reported to be generally compromised, and leachates have been the most cited reason.
Dumpsites usually undergo modification of wastes [52] in the following five basic steps: • Phase I (lag phase/initial adjustment).
The products of these processes include volatilized chemicals as gas, leachate and changing community of organisms, all of which have profound influence on the physical, chemical and biological conditions in the immediate surroundings.
Leachates from dumpsites and landfills have been characterized ( Table 9) and associated with contamination of inland surface water ( Table 10) and groundwater ( Table 11) resources from different parts of Nigeria with profound physical, chemical and biological consequences. Aquatic life and recreational criteria [53] suggested compromise in physical and chemical qualities, due largely to the presence of dumpsites close to these water bodies. Also age and the unique composition or characteristics of wastes deposited at dumpsites will greatly influence the resultant water quality. The biotic or biological responses of resident organisms to changes as elicited by activities associated with dumpsites have not attracted deserved attention or investigation considering the ecological and public health consequences. However, limited laboratory studies on aquatic organisms, Chironomus sp. Culex pipiens, Bufo regularis tadpoles and Clarias gariepinus, using products from dumpsites in the form of leachates from Oyo [57,58,77] and Lagos [77,78] States showed pronounced aberrant behavioral responses and gross morphological and genetic damages. In spite of the limited studies from Nigeria, the reports agreed with comparable reports from other parts of the world on the negative influence of products of dumpsites on surface inland waters.
Groundwater in Nigeria provides water supply for 40.1% of Nigerians [79] and is considered to be the preferred source of water for different sectors providing about 40% of water public water supply [80] underlying the importance of groundwater sources. The integrity of such groundwater is therefore of importance because of direct consequences on human health. The quality of groundwater showed the presence of substances considered dangerous to human health at concentrations above standards [53,68]  [56] [57,58] All in mg/l except pH and colour. Table 9.
Leachate characteristics from dumpsites and landfills from Southwest Nigeria.    chromium, copper, lead, arsenic and aluminum and cobalt in groundwater from most locations should be a cause for concern and perhaps necessitates detailed nationwide surveillance, considering the proportion of population dependent on groundwater. The intake of these metals has been implicated in a variety of human ailments leading to severe problems via disruption of metabolic functions in two ways [81]:

Parameters
1. They accumulate and thereby disrupt function in vital organs and glands such as the heart, brain, kidneys, bone, liver, etc.
2. They displace the vital nutritional minerals from their original place, thereby hindering their biological function.
Residents around the dumpsites are partly or wholly dependent largely on either surface or groundwater for direct or indirect daily water requirements. Thus contact with these water bodies is inevitable, even at distances considered areas with no likely effects. Determination of the health implications of such contacts at present has not been clearly defined, from very limited reports on public health aspects of dumpsite managements. This is because it has not been possible to separate consequences of dumpsite contaminated surface and groundwater contacts from medical conditions associated with population living around dumpsites. Studies [82][83][84][85] reported the following: inhalation of odor, exposure to dust, exposure to smoke, exposure through water sources, consumption of plant materials, consumption of animal materials, exposure through organisms (vectors), noise from vehicles, exposure to fire, dermal contacts and exposure through domestic animals as possible routes of human exposure and contact with dumpsites and products of dumpsite modifications. Medical conditions reported from the population living close to dumpsites in different parts of Nigeria are presented in Table 12, which have been observed in Nigeria from areas of regular contacts with contaminated water [90] but not from dumpsites or landfills. The implication of the above is that symptoms may indicate conditions from multiple exposures or contacts. Inland waters in Nigeria have been subjected to inundations with inputs from multiple sources with resultant changes in quality. The almost hidden nature of contamination and contamination routes by dumpsites reinforces the dangers of not paying required attention to dumpsites, associated activities and value chain. This is because each step or link has an effect on inland water and hence human population making these sources of contamination very dangerous and harmful. Therefore, numerous health hazards associated with waste dump sites in major economic centres in Nigeria [27,91,92] can be said to be largely denominated by the resident and/or dominant waste components.
Radionuclides have also been reported and associated with dumpsites and landfills in Lagos State [93][94][95] [106]. These dangerous natural and artificial radiation materials from unregulated and unmanaged dumpsites and landfills released into inland water sources pose risks to resident organisms and population of humans, dependent directly on water for domestic purpose and consumption of resident aquatic organisms.
Radionuclides have been reported in leachates [102] and groundwater [102,105,107] and rivers [107,108] with identified sources being the human activities, inclusive of dumpsites [102,105] and abattoir wastes [109]. Dumpsites and landfills are therefore potential sources of radionuclide inputs into inland surface and groundwaters; the above-cited reports indicated the presence of radionuclides in soils around target dumpsites, confirming the migration of substances from dumpsites, as reported [108], using time-lapsed vertical electrical sounding (VES). This migration of materials into ground-and surface waters will facilitate exposure of resident and non-resident population to radioactive material by direct or indirect intake, respectively. Low cancer risks from chronic exposure to radiation from dumpsites in Nigeria have been suggested [97] even at the low level, thus further establishing the need for urgent management strategies for MSW in Nigeria.

Conclusion and recommendation
Nigeria's development is currently enjoying active support of multilateral agencies, with the sole aim of expanding and diversifying the economy through, but not limited to, multinational manufacturing and small-and medium-scale enterprises. These are desirable and needed to improve socioeconomic status of the populace. However, complementary in-depth consideration of the ecological consequences of expanded economy must include increased generation of MSW, which usually begin with unregulated and undocumented dumpsites associated with penetration of economic activities. The inability of agencies responsible for waste management to anticipate and plan for the increase of MSW is the major reason for the surge in MSW generation and persistence. These will eventually become sources of sometime unexplained inland water contamination and/or public health problems or outbreaks. In view of this, the following be deeply considered to minimize the negative impacts of MSW on inland waters: 1. Collection of dumpsite and landfill history and location data in each local government area (LGA) nationwide.
2. Characterize wastes associated with each dumpsite and landfill, to provide data for risk assessment of dumpsite or landfill products.  4. Information on geophysical assessment of pollutant movements in soil.
5. Regular determination of inland water quality in the vicinity. 6. Create awareness on the need to sort waste from source before disposal.
7. Encourage adoption of recycle and reuse of wastes to reduce wastes generated.
8. Undertake spatial analyses of population or residents' socioeconomic characteristics to predict waste profiles and determine appropriate management MSW strategy.

Conflict of interest
I declared no conflict of interest.