Pollution is the presence of matter (gas, liquid, solid) or energy (heat, noise, radiation) whose nature, location or quantity directly or indirectly alters characteristics or processes of any part of the environment and causes (or has potential to cause) damage to the condition, health, safety, or welfare of animals, humans, plant or property.1 Business dictionary.

POLLUTION IN KENYA

Industrial waste, sewage and domestic waste have been flowing into rivers and other water masses polluting and making it unsuitable for use. Particulate matter emission from manufacturing sites, automobile exhaust, smokes or fugitive dust emissions have been a major air pollutant.  Domestic waste has been the largest contributor to the urban centres Landfill menace in the country.

Pharmaceuticals and agricultural chemicals have had their pollution impact, either while undergoing processing or in use.

All these streams of pollution do pose serious health risks on human, animals, plants and more operating systems key in supporting our ecosystems. This lead to specific negative effects of; reduced visibility, machinery fouling, environmental damage (Deposition) and Aesthetic damage.

CAUSES OF POLLUTION

Modern society is characterized by sophistication of technology and high population pressure.   The two factors go hand in hand as the latter depends directly on the success of the former for its survival.  Further to these, both factors directly contribute to the increased challenge of high pollution in our planet.  The whole scenario has led to side effects like; global warming, pollution associated diseases, pollution discomfort to mention a few.  Knowledge of pollution challenges is not sufficient without the understanding of major causes of pollution. These include;

  1. 1. Transport
  2. 2. Manufacturing/ processing
  3. 3. Municipal waste
  4. 4. Thermal energy generators
  5. 5. Natural effluent

BLUE ECONOMY IN KENYA

Blue economy refer to the sustainable use of water resources for economic growth, improved livelihoods, jobs and waters ecosystem health. It encompasses among others, the following activities:2

Fisheries

Tourism

Waste management

Marine transport

Renewable energy

Climate change

Sea extraction

Kenya has been harnessing its water resources in food harvesting, tourism and transport. However the above list show there is more to Blue Economy than what has traditionally been envisaged to encompass. To fully tap on the waters economic value sustainably, these activities have to be engaged concurrently in order to maximize on the economic benefit of each aspect.  Example; it is key to keep pollution at a low to attract marine life growth and tourism.

Studies show that over 80% of sea pollution is derived from land activities.   Further to the aforesaid Mombasa as severally received international condemnation due to its improper waste management approaches jeopardizing its tourism potential.   Therefore pollution control is a key factor in determining healthy Blue Economy spectrum and cannot be ignored.  In this regard, pollution control initiatives need to be developed and applied with impact on Blue Economy in mind.

POLLUTION SOLUTION

Critical analysis of pollution stream causes indicate two major factors; Energy sourcing and domestic/industrial processes.  The pollution control would only be overcome through efficient and effective approaches of managing the aforementioned factors.   There are numerous potential measures envisaged to mitigate on the challenge this may be categorized into;

  1. 1. Ecofriendly/ green measures
  2. 2. Technology innovations
  3. 3. Conducive legal framework
  4. 4. Community good will
  5. 5. Personal protection

These approaches are independent yet interdependent in achieving the ultimate goal of pollution control.  Example; To achieve effective pollution control levels, is key to understand prevailing pollution state.  This calls for suitable technical solution capable of measuring pollution levels necessary in setting acceptable pollution levels.   The pollution measuring exercise is further used in developing legal regulation framework. 

KDF POLLUTION SOLUTIONS

KDF has been proactive in putting in place measures designed to mitigate pollution impact.  Among Envisaged programs run by the KDF include: Environmental Soldier Program (ESP), Energy Management and Environmental Conservation Policy (EMECP) programs, Innovation stimulus projects program, collaboration initiatives with other willing organizations, to mention a few.

Positive output achieved in these initiatives include;  Enhancement of awareness within KDF community, development of award winning projects like the Defence Forces Kitchen (DEFKITCH-2012) and the Incinerator’s waste heat recovery system.

For purposes of this document focus is directed towards highlighting the basic development, application and impact of the Incinerators with Waste Heat Recovery System.  Have sited a working project of a plant stationed at Moi Air Base (MAB), Eastliegh.

MAB is located approximately 5km of Nairobi CBD and comprise of a typical residential community.  It has several buildings including offices, messes and residence.

The community registers an average annual electricity consumption and bill of 2,140,165 kWh and Kshs 32,895,481 respectively.  In addition, it consumed fuels with an annual bill of Kshs 7,142,400.00.  The location also has an incinerator used to manage Municipal Solid Waste (MSW) generated by the community.  The waste aggregate constitutes; domestic waste, office wastes among others, and is eliminated through combustion to ash and flue.

In considering the waste menace and high energy costs incurred in the community’s facilities, it was deemed necessary to tap into the waste to energy opportunity that was presenting in the incinerator with waste heat recovery system. The solution was developed through design of a waste heat recovery unit to be incorporated in the incinerator.  The unit was designed to tap the waste flue heat in warming water for domestic preheat applications like; washing, bathing, cooking to mention a few. The incinerator has a running data of burning over fifteen (15) Ton per week and burning chamber attaining temperatures of over 500oC.

Proposal document worked out a design output of 5,000ltr water supply daily at over 60oC. The preliminary work did project that the setup would result to an energy cost saving of Kshs 1,352,442.93 per year, at the prevailing ambient conditions of the project site.   On comparing the saving to the initial construction cost of Kshs 4,848,000,000.00 gives rise to a Simple Payback Period (SPP) of three (3) years seven (7) months.  Kindly note that the project was implemented in a research environment and capital cost of similar consequent works are projected to go down with reduced uncertainties.

A performance evaluation of the project is in progress, this is after completion of the pilot phase.  The current plant performance is 5,000 ltr at 53.00oC, this yield to an indicative annual energy saving of 60,063.92 kWh or Kshs 1,117,189.00 Therefore the current project performance compared to the design performance is 80.4%. This is attributed to among other reasons; increased enthusiasm and confidence for the project among beneficiaries.

The project was initiated for the following main reasons:

(1) Domestic waste management has been a challenge and expensive. Therefore raising need for designing an efficient mode of controlling waste.

(2) Contracting for waste collection has been expensive and the method is not  absolute  as  the  waste  would  be  damped  in  continuously  shrinking identified damp sites.

(3) Heat exchanger technology has been in use for many applications. This technology was customized to the incinerator in enhancing its efficiency through harnessing the waste heat and therefore making the larger incineration project more viable.

(4) It provides a technical solution in reducing the rate of breaking down of the chimney occasioned by high exhaust temperatures.  It also reduces on smoke and fly-ash problem experienced at the immediate proximity of the chimney, which is made possible by condensing the exhaust particles before reaching the chimney outlet.

(5) Create supplementary source of low-cost energy to the especially growing need for domestic heat energy applications.

(6) Meet the growing need for local innovative solutions especially in energy sourcing and waste management as a tool to accelerated development and economic enhancement in the region.

Waste incineration offers a mode for waste combustion under controlled environment.  The controlled environment is essential for among other reasons; optimize combustion efficiency, reduce on landfill emissions and now more attractive; open up opportunities for innovatively and optimally harnessing of waste heat to more useful applications.

When waste is combusted, energy is given out as heat.  Some of the energy is consumed in drying the waste (evaporate moisture content in the waste) and rest (net) is available for conversion into useful utility.

A water system is incorporated in the incinerator plant as a medium for harvesting the heat energy. The system is constructed to allow natural convection of the water and consequently secure the warm water in the insulated warm water cistern ready for consumption by the end user.

MOMBASA A CASE STUDY

In an effort to address a dire shortage or comprehensive, up to date scientific data concerning waste characteristics in Mombasa County, investigators performed a solid waste characterization study of the city.  The study was designed both to quantify waste production per capita and also to analyze the composition of waste streams in low, middle and high-income areas of Mombasa County.  The aim of the study was to inform the development of a relevant waste management policy and to highlight how changes in practice can create exciting opportunities for more efficient collection models, resource recovery and job creation.   Data yielded waste production at 850 tonnes per day.  420 tonnes of solid waste per day is dumped at one of three uncontrolled dumpsites.  An additional 23, 16 and 2 tonnes of waste is recycled or incinerated by commercial industries for export, energy or heat recovery. Average waste composition in Mombasa is dominated by organic waste streams (68%), at density/moisture content rates of 947kg/m3  and 41% respectively.  The average  proportion  of  inorganic  recyclables,  based  on  the  identification  of corresponding markets is 23%, with non-recyclable waste accounting for the remaining 9% of waste composition.3

With an assumption of organic waste at dump sites to be the available waste for energy, waste yield for incineration would be 280 Ton daily. Working on inference of the Incinerator with Waste Heat Recovery System has a potential of harvesting over 20,000kWh daily or Kshs 100M worth of energy annually.

CONCLUSION

If the project is replicated at the coastline has a potential of not only enhancing a cleaner, green environment that enhance tourism but also energy harnessing potentials.   This would be utilized to open opportunity for larger domestic community to benefit in waste heat recreation to useful applications. Note Mombasa is just one of the many towns at the coastline that stand to benefit from such a project. 

References

  1. 1. Business dictionary.
  2. 2. //www.worldbank.org/content/dam/infographics/780xany/2017/may/imageJPG

3.Mapping out waste characteristics in mombasa,                            kenya, //www.researchgate.net/publication/282815718_MAPPING_OUT_WASTE_CHARACTERISTICS_IN_ MOMBASA_KENYA , accessed Sep 05 2018.

 

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Kenya Engineer is the definitive publication of Engineers in East Africa & beyond and the official journal of the Institution of Engineers of Kenya. Kenya Engineer has been in publication since 1972.

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