Waste Disposal Methods: Perspectives for Africa

Waste disposal methods vary from city to city, state to state and region to region. It equally depends on the kind and type of waste generated. In determining the disposal method that a city or nation should adopt, some factors like type, kind, quantity, frequency, and forms of waste need to be considered.

For the purpose of this article, we will look at the three common waste disposal methods and the kind of waste they accept.

Open Dumping/Burning

This is the crudest means of disposing of waste and it is mostly practiced in rural areas, semi-urban settlements, and undeveloped urban areas. For open dumping or open burning, every type and form of waste (including household waste, hazardous wastes, tires, batteries, chemicals) is dumped in an open area within a community or outside different homes in a community and same being set on fire after a number of days or when the waste generator or community feels it should be burnt.

There is no gainsaying that the negative health and environmental impact of such practice are huge only if the propagators know better.

Controlled Dumping

This is apparent in most States in Nigeria, if not all and some cities in Africa like Mozambique, Ghana, Kenya, Cameroon, to mention but a few. It is a method of disposing of all kinds of waste in a designated area of land by waste collectors and it is usually controlled by the State or City Government.

Opening burning of trash is a common practice across Africa

Controlled dumps are commonly found in urban areas and because they are managed by the government, some dumps do have certain features of a landfill like tenure of usage, basic record keeping, waste covering, etc. Many cities in Nigeria confuse the practice of controlled dumping as landfilling but this not so because a landfill involves engineering design, planning, and operation.

Sanitary Landfill

A sanitary landfill is arguably the most desired waste management option in reducing or eliminating public health hazards and environmental pollution. The landfill is the final disposal site for all forms and types of waste after the recyclable materials must have been separated for other usages and other biodegradables have been extracted from the waste for use as compost, heat, or energy; or after incineration. These extractions can be done at household level or Material Recovery Facilities (MRFs) operated by the government or private individuals.

As desirable as a landfill is, so many factors need to be put into consideration in its siting and operation plus it requires a huge investment in construction and operation. Some of these factors include but not limited to distance from the residential area, proximity to water bodies, water-table level of the area the landfill is to be sited, earth material availability, and access road.

Note: The original version of the article was published on Waste Watch Africa website at this link.

Sugarcane Trash as Biomass Resource

cane-trashSugarcane trash (or cane trash) is an excellent biomass resource in sugar-producing countries worldwide. The amount of cane trash produced depends on the plant variety, age of the crop at harvest and soil and weather conditions. Typically it represents about 15% of the total above ground biomass at harvest which is equivalent to about 10-15 tons per hectare of dry matter. During the harvesting operation around 70-80% of the cane trash is left in the field with 20-30% taken to the mill together with the sugarcane stalks as extraneous matter.

Cane trash’s calorific value is similar to that of bagasse but has an advantage of having lower moisture content, and hence dries more quickly. Nowadays only a small quantity of this biomass is used as fuel, mixed with bagasse or by itself, at the sugar mill. The rest is burned in the vicinity of the dry cleaning installation, creating a pollution problem in sugar-producing nations.

Cane trash and bagasse are produced during the harvesting and milling process of sugarcane which normally lasts between 6 to 7 months. Cane trash can potentially be converted into heat and electrical energy. However, most of the trash is burned in the field due to its bulky nature and high cost incurred in collection and transportation.

Cane trash could be used as an off-season fuel for year-round power generation at sugar mills. There is also a high demand for biomass as a boiler fuel during the sugar-milling season. Sugarcane trash can also converted in biomass pellets and used in dedicated biomass power stations or co-fired with coal in power plants and cement kilns.

Burning of cane trash creates pollution in sugar-producing countries

Burning of cane trash creates pollution in sugar-producing countries

Currently, a significant percentage of energy used for boilers in sugarcane processing is provided by imported bunker oil. Overall, the economic, environmental, and social implications of utilizing cane trash in the final crop year as a substitute for bunker oil appears promising. It represents an opportunity for developing biomass energy use in the Sugarcane industry as well as for industries / communities in the vicinity.

Positive socio-economic impacts include the provision of large-scale rural employment and the minimization of oil imports. It can also develop the expertise necessary to create a reliable biomass supply for year-round power generation.

Recovery of Cane Trash

Recovery of cane trash implies a change from traditional harvesting methods; which normally consists of destroying the trash by setting huge areas of sugarcane fields ablaze prior to the harvest.  There are a number of major technical and economic issues that need to be overcome to utilize cane trash as a renewable energy resource. For example, its recovery from the field and transportation to the mill, are major issues.

Alternatives include the current situation where the cane is separated from the trash by the harvester and the two are transported to the mill separately, to the harvesting of the whole crop with separation of the cane and the trash carried out at the mill. Where the trash is collected from the field it maybe baled incurring a range of costs associated with bale handling, transportation and storage. Baling also leaves about 10-20% (1-2 tons per hectare) of the recoverable trash in the field.

A second alternative is for the cane trash to be shredded and collected separately from the cane during the harvesting process. The development of such a harvester-mounted cane trash shredder and collection system has been achieved but the economics of this approach require evaluation. A third alternative is to harvest the sugarcane crop completely which would require an adequate collection, transport and storage system in addition to a mill based cleaning plant to separate the cane from the trash .

A widespread method for cane trash recovery is to cut the cane, chop into pieces and then it is blown in two stages in the harvester to remove the trash. The amount of trash that goes along with the cane is a function of the cleaning efficiency of the harvester. The blowers are adjusted to get adequate cleaning with a bearable cane loss.

On the average 68 % of the trash is blown out of the harvester, and stays on the ground, and 32 % is taken to the mill together with the cane as extraneous matter. The technique used to recover the trash staying on the ground is baling. Several baling machines have been tested with small, large, round and square bales. Cane trash can be considered as a viable fuel supplementary to bagasse to permit year-round power generation in sugar mills.

Thus, recovery of cane trash in developing nations of Asia, Africa and Latin America implies a change from traditional harvesting methods, which normally consists of destroying the trash by setting huge areas of cane fields ablaze prior to the harvest. To recover the trash, a new so-called “green mechanical harvesting” scheme will have to be introduced. By recovering the trash in this manner, the production of local air pollutants, as well as greenhouse gases contributing to adverse climatic change, from the fires are avoided and cane trash could be used as a means of regional sustainable development.

Cane Trash Recovery in Cuba

The sugarcane harvesting system in Cuba is unique among cane-producing countries in two important respects. First, an estimated 70 % of the sugarcane crop is harvested by machine without prior burning, which is far higher than for any other country. The second unique feature of Cuban harvesting practice is the long-standing commercial use of “dry cleaning stations” to remove trash from the cane stalks before the stalks are transported to the crushing mills.

Cuba has over 900 cleaning stations to serve its 156 sugar mills. The cleaning stations are generally not adjacent to the mills, but are connected to mills by a low-cost cane delivery system – a dedicated rail network with more than 7000 km of track. The cleaning stations take in green machine-cut or manually cut cane. Trash is removed from the stalk and blown out into a storage area. The stalks travel along a conveyor to waiting rail cars. The predominant practice today is to incinerate the trash at the cleaning station to reduce the “waste” volume.

Waste Management Outlook for Nigeria

waste-nigeriaNigeria, the most populous country in Africa with population exceeding 182 million people, is grappling with waste management issues. The country generates around 43.2 million tonnes of waste annually. By 2025 with a population of 233.5 million, Nigeria will be generating an estimated 72.46 million tonnes of waste annually at a projected rate of 0.85 kg of waste/capita/day. This means that Nigeria annual waste generation will almost equal its crude oil production which currently stands at approximately 89.63 million tonnes per year.

Also, at an estimated annual waste generation figure of 72.46 million tonnes, Nigeria will be generating about one-fourth of the total waste that will be produced in the whole of Africa. This is scary and if proper attention is not paid to this enormous challenge, Nigeria might become the “Waste Capital of Africa”.

Waste is a Resource for Nigeria

Nonetheless, this challenge can be turned into a blessing because waste is a resource in disguise. If its potential is properly tapped, waste management can create employment, enable power generation, create a waste-based economy and contribute to economic diversification which Nigeria. There is no doubt that this is achievable because we have examples of countries already utilizing their waste judiciously.

Some good examples of sustainable waste management systems that can be implemented in Nigeria includes (1) Shanghai (China) which turn 50% of the waste generated into power generation electrifying 100,000 homes; (2) Incheon (South Korea) where its Sudokwon landfill receives about 20,000 tons of waste daily which is converted into electric power, has a water recycling and desalination facility, and has created more than 200 jobs; (3) Los Angeles (USA) which produces electric power enough for 70,000 homes in its Puente Hills landfill; (4) Germany whose sophisticated waste processing systems through recycling, composting, and energy generation has already saved the country 20% of the cost of metals and 3% of the cost of energy imports; (5) Austria, though a small country, is doing big things in waste management especially through recycling; (6) Sweden, whose recycling is so revolutionary that the country had to import waste; and (7) Flanders, Belgium which possesses the best waste diversion rate in Europe with 75% of their waste being reused, recycled or composted. An interesting fact is that per capita waste generation rate in Flanders is more than twice that of Nigeria at 1.5 kg/day.

Waste Management Outlook for Nigeria

Below are some of the major things the government need to do to judiciously utilize the free and abundant resource available in the form of trash in Nigeria:

Firstly, attention needs to be paid to building the human resource potential of the country to build the required capacity in conceptualizing fit-for-purpose innovative solution to be deployed in tackling and solving the waste challenge.

While knowledge exchange/transfer through international public private partnership is a possible way in providing waste management solution, it is not sustainable for the country especially because there is already an unemployment problem in Nigeria. Hence, funding the training of interested and passionate individuals and entrepreneurs in waste management is a better way of tackling the waste crisis in Nigeria.

Olusosun is the largest dumpsite in Nigeria

The Federal Government through the Petroleum Trust Development Fund (PTDF) and National Information Technology Development Agency (NITDA) of the Ministry of Communication currently sponsor students to study oil and gas as well as information technology related subjects in foreign countries in the hope of boosting manpower in both sectors of the economy. The same approach should be used in the waste management sector and this can be handled through the Federal Ministry of Environment.

Interestingly, waste generation is almost at par with crude oil production in Nigeria. Therefore, equal attention should be paid to waste-to-wealth sector. Needless to say, this is important as there is no university in Nigeria currently offering waste management as a stand-alone course either at undergraduate or postgraduate level.

Secondly, there is an urgent need for a strong National Waste Management Strategy to checkmate the different types of waste that enters the country’s waste stream as well as the quantity of waste being produced. To develop an effective national waste strategy, a study should be carried out to understand the country’s current stream of waste, generation pattern, and existing management approach. This should be championed by the Federal Ministry of Environment in conjunction with State and Local Government waste management authorities.

Once this is done, each State of the Federation will now integrate their own individual State Waste Management Plan into that of the Federal Government to achieve a holistic waste management development in Nigeria. By so doing, the government would also contribute to climate change mitigation because the methane produced when waste degrades is 25 times more potent than carbon dioxide (a major greenhouse gas known to many and contributor to global warming).

Finally, the government needs to support existing waste management initiatives either through tax-holiday on major equipment that need to be imported for their work and/or on their operation for a certain period of time. Also, if workable, the government can float a grant for innovative ideas and provide liberal subsidies in waste management to jumpstart the growth of the sector.

Lastly, the Government of Nigeria can raise a delegation of experts, entrepreneurs, industry professionals, academia, and youngsters to visit countries with sound waste management strategy for knowledge sharing, capacity-building, technology transfer and first-hand experience.

Note: The unedited version of the article can be found at this link

Energy Potential of Palm Kernel Shells

palm-kernel-shellsThe Palm Oil industry in Southeast Asia and Africa generates large quantity of biomass wastes whose disposal is a challenging task. Palm kernel shells (or PKS) are the shell fractions left after the nut has been removed after crushing in the Palm Oil mill. Kernel shells are a fibrous material and can be easily handled in bulk directly from the product line to the end use. Large and small shell fractions are mixed with dust-like fractions and small fibres. Moisture content in kernel shells is low compared to other biomass residues with different sources suggesting values between 11% and 13%.

Palm kernel shells contain residues of Palm Oil, which accounts for its slightly higher heating value than average lignocellulosic biomass. Compared to other residues from the industry, it is a good quality biomass fuel with uniform size distribution, easy handling, easy crushing, and limited biological activity due to low moisture content. PKS can be readily co-fired with coal in grate fired -and fluidized bed boilers as well as cement kilns in order to diversify the fuel mix.

The primary use of palm kernel shells is as a boiler fuel supplementing the fibre which is used as primary fuel. In recent years kernel shells are sold as alternative fuel around the world. Besides selling shells in bulk, there are companies that produce fuel briquettes from shells which may include partial carbonisation of the material to improve the combustion characteristics. As a raw material for fuel briquettes, palm shells are reported to have the same calorific characteristics as coconut shells. The relatively smaller size makes it easier to carbonise for mass production, and its resulting palm shell charcoal can be pressed into a heat efficient biomass briquette.

Palm kernel shells have been traditionally used as solid fuels for steam boilers in palm oil mills across Southeast Asia. The steam generated is used to run turbines for electricity production. These two solid fuels alone are able to generate more than enough energy to meet the energy demands of a palm oil mill. Most palm oil mills in the region are self-sufficient in terms of energy by making use of kernel shells and mesocarp fibers in cogeneration. In recent years, the demand for palm kernel shells has increased considerably in Europe, Asia-Pacific, China etc resulting in price close to that of coal. Nowadays, cement industries and power producers are increasingly using palm kernel shells to replace coal. In grate-fired boiler systems, fluidized-bed boiler systems and cement kilns, palm kernel shells are an excellent fuel.

Cofiring of PKS yields added value for power plants and cement kilns, because the fuel significantly reduces carbon emissions – this added value can be expressed in the form of renewable energy certificates, carbon credits, etc. However, there is a great scope for introduction of high-efficiency cogeneration systems in the industry which will result in substantial supply of excess power to the public grid and supply of surplus PKS to other nations. Palm kernel shell is already extensively in demand domestically by local industries for meeting process heating requirements, thus creating supply shortages in the market.

Palm oil mills around the world may seize an opportunity to supply electricity for its surrounding plantation areas using palm kernel shells, empty fruit branches and palm oil mill effluent which have not been fully exploited yet. This new business will be beneficial for all parties, increase the profitability for palm oil industry, reduce greenhouse gas emissions and increase the electrification ratio in surrounding plantation regions.

Is Aquaculture the Answer to World Hunger?

aquaculture-fish-farmsFeeding a growing world population could become problematic, but aquaculture might hold the key. If humans are anything, we are resourceful. We see a problem with the world, and we do what we can to fix it.  When being nomadic and following food sources was no longer sustainable, we solved the problem by developing agriculture.  Currently, as the population continues to grow and our taste for seafood increases, we’re trying to find ways to meet demand and, at the same time, sustain wild populations of fishes.

Aquaculture is the answer to this current dilemma. Farming fish for food has been around since about 2000 B.C. Since then, technology has helped it advanced and developed better techniques to raise fish for food.

Benefits of Aquaculture

Fish is a great source of protein, and it also contains essential minerals including potassium, zinc, iodine and magnesium. Fish are also rich in phosphorus and calcium. For a healthy heart, the American Heart Association recommends eating fish twice a week.

The health benefits of fish are more than enough reason to eat them, but they are also a delicious meal. There is a large variety of fish to choose from, including freshwater and saltwater varieties. However, the increased amount of people eating fish has had an impact on wild populations. To prevent certain species from being overfished, it is important to find an alternative to providing fish to people, and that includes aquaculture.

Different types of aquaculture must be used to raise different species of fish. Large companies can engage in aquaculture on an industrial scale with fish held in tanks or in pens in lakes, ponds or even the ocean. Families can even perform aquaculture in their backyard.  The variety of fish that you can raise for food includes catfish, bait minnow, trout, carp and tilapia, among others.  It’s also possible to raise shellfish, including oysters and shrimp. Want to try your hand at growing water plants?  You can also use aquaculture principles for water chestnuts and red and brown algae.

Studies have shown that marine aquaculture has the potential to produce 16.5 billion tons of fish per year, which is more than enough to feed the growing population and meet nutritional needs.

Different types of aquaculture must be used to raise different species of fish.

Different types of aquaculture must be used to raise different species of fish.

In some areas, such as parts of Africa, aquaculture has made an enormous impact on the local community’s economy and employment as well. The food produced helps to sustain Africa’s growing population and provides local jobs with steady income.

The Downside of Aquaculture

While it has the potential to feed hungry communities and contribute to local economies, there are some problems associated with aquaculture. Having too many fish in a tank can lead to the spread of disease.  Also, the type of feed the fish eat can impact how healthy they are for humans. Keeping fish in pens in lakes, ponds or the ocean might cause the spread of parasites to wild populations.  Farmed fish could also escape their enclosure and, as a result, alter the natural ecosystem.

Recognizing the shortcomings of aquaculture is the first step to remedying its problems. As technology and farming practices advance and techniques improve, it’s possible that we will resolve many of these issues. This will lead to greater benefits for the human population that depends on fish for food.

Humans have the ingenuity and drive to make the world a better place for themselves and others. Population growth isn’t going to slow down any time soon, and we need to make sure everyone is taken care of and has enough to eat. While aquaculture has its pros and cons, it can be a sustainable and economic way to feed hungry people.  In time, it may even be the answer to world hunger.

Solid Waste Management in Nigeria

waste-nigeriaSolid waste management is the most pressing environmental challenge faced by urban and rural areas of Nigeria. Nigeria, with population exceeding 170 million, is one of the largest producers of solid waste in Africa. Despite a host of policies and regulations, solid waste management in the country is assuming alarming proportions with each passing day.

Nigeria generates more than 32 million tons of solid waste annually, out of which only 20-30% is collected. Reckless disposal of MSW has led to blockage of sewers and drainage networks, and choking of water bodies. Most of the wastes is generated by households and in some cases, by local industries, artisans and traders which litters the immediate surroundings. Improper collection and disposal of municipal wastes is leading to an environmental catastrophe as the country currently lack adequate budgetary provisions for the implementation of integrated waste management programmes across the States.

According to the United Nations Habitat Watch, African city populations will more than triple over the next 40 years. African cities are already inundated with slums; a phenomenon that could triple urban populations and spell disaster, unless urgent actions are initiated. Out of the 36 states and a federal capital in the country, only a few have shown a considerable level of resolve to take proactive steps in fighting this scourge, while the rest have merely paid lip services to issues of waste management indicating a huge lack of interest to develop the waste sector.

Scenario in Lagos

Lagos State, the commercial hub of Nigeria, is the second fastest growing city in Africa and seventh in the world.  The latest reports estimate its population to be more than 21 million making it the largest city in entire Africa.  With per capita waste generation of 0.5 kg per day, the city generates more than 10,000 tons of urban waste every day.

Despite being a model for other states in the country, municipal waste management is a big challenge for the Lagos State Waste Management Agency (LAWMA) to manage alone, hence the need to engage the services of private waste firms and other franchisee to reduce the burden of waste collection and disposal. One fundamental issue is the delayed collection of household solid waste.  In some cases, the wastes are not collected until after a week or two, consequently, the waste bin overflows and litters the surroundings.

Improper waste disposal and lack of reliable transport infrastructure means that collected wastes are soon dispersed to other localities. Another unwelcome practice is to overload collection trucks with 5-6 tons of waste to reduce the number of trips; this has necessitated calls by environmental activist to prevail on the relevant legislature to conform to the modern waste transportation standard.

Situation in Oyo

Away from Lagos State, Oyo is another ancient town in Nigeria with an estimated population of six million people. Here, solid waste is regulated by the Oyo State Solid Waste Management Authority (OYOWMA). Unlike Lagos State, Oyo State does not have a proper waste management scheme that cuts across the nooks and crannies of the state, apart from Ibadan, the capital city, people from other towns like Ogbomoso and Iseyin resort to waste burning. In case the waste generators feels that the amount being charged by the waste franchisee is beyond their means, they dump the waste along flood paths thus compounding the waste predicament.

Burning of municipal wastes is a common practice in Nigeria

Burning of municipal wastes is a common practice in Nigeria

Kano and Rivers State with its fair share of population also suffers similar fate in controlling and managing solid waste. Generally speaking, population increase in Nigeria has led to an unprecedented growth in its economy but with a devastating effect on the environment as more wastes are generated due to the need for housing, manufacturing industries and a boost in trade volume.

Future Perspectives

The government at the federal level as a matter of urgency needs to revive its regulatory framework that will be attractive for private sectors to invest in waste collection, recycling and reusing.  The environmental health officer’s registration council of Nigeria would do well to intensify more effort to monitor and enforce sanitation laws as well as regulate the activities of the franchisees on good sustainable practices.

Taking the advocacy further on waste management, to avoid littering the environment, some manufacturing companies (e.g. chemical and paint industry) have introduced a recall process that will reward individuals who returns empty/used plastic containers. This cash incentive has been proven over time to validate the waste to wealth program embarked upon by the manufacturing companies. It is also expected that the government will build more composting and recycling plants in addition to the ones in Ekiti and Kano State to ensure good sustainable waste management.

Waste management situation in Nigeria currently requires concerted effort to sensitize the general public on the need for proper disposal of solid waste. Also, the officials should be well trained on professionalism, service delivery and ensure that other states within the country have access to quality waste managers who are within reach and can assist on the best approach to managing their waste before collection.