The three Rs hierarchy is a principle employed in waste management as a guidance for creating a sustainable environment.
The Rs are reduce, reuse and recycle and they transform waste disposal to waste management, where waste becomes a valuable resource.
Effective utilisation of the three Rs can highly supplement the country’s fertiliser requirements.
Wastes from processing plants
Coffee: It comes from harvesting the cherries, which are mainly processed by wet fermentation to obtain the parchment coffee (dried beans covered by paper-like coating).
In 2016, the country exported 46,254 tonnes of coffee and for each tonne of parchment, about 2.15 tonnes of pulp and 80m3 of wastewater were generated.
Sisal: Large amounts of residues are generated during processing because the exploitable fibres represent only 5 per cent of the total leaf weight.
During the decortications process, about 100m3 of wastewater and 25 tonnes of solid residues (pulp) are generated for each tonne of sisal fibres.
Horticulture: Of interest here are cut flowers, which are produced for export. Kenya produces tonnes of flowers and the amount of waste generated is huge.
Organic oil refining: Plant materials are used to produce oil products for body care, edible oils and drinks, detergents and industrial products.
Raw materials that produce oil include palm fruit, sunflower, soya and corn seeds. Processing from the oil refining factories produce enormous amounts of waste and waste water.
Sugar cane: Kenya has more than six sugar factories with an annual production capacity of 550,000 to 600,000 tonnes per annum. Waste from a sugar factory include bagasse, filter cake and wastewater.
Pineapples: Horticulture Crops Directorate notes that the country produced at least 429,065 metric tonnes of pineapples in 2007.
Waste from pineapple processing include fresh peels and waste water.
Slaughterhouses: Meat production stands at an average of 320,000 metric tonnes (MT) of beef, 35,000MT of mutton, 187,988MT of pork, 200,750MT of poultry meat and 7,000MT of camel meat.
In beef for example, slaughter of a 300kg animal generates 60kg of waste that include dung, stomach and intestinal contents, blood, condemned organs and others.
Municipal solid waste: Food preparation at the household level and in commercial institutions such as hotels and markets contribute to the organic waste found in dumpsites.
A survey in Nairobi showed a 2,500—3,100 tonnes per day flow of waste is generated, with 51 per cent of it being organic.
Animal waste include the faecal materials and beddings from the livestock industry. The country has a high population of animals under intensive production thus capable of producing organic fertiliser.
This include the over three million exotic cattle majority of which are under zero-grazing system, 334,689 pigs and over six million commercial chickens. Organic fertiliser value of droppings is approximately five times that of inorganic.
Taking dairy cattle for example, they produce an estimated 67.1 million MT of dung per day (an average of 20kg per animal). This translates to over 24.5 million MT of waste per year, excluding bedding material.
Sludge from waste water treatment
Sludge contains treated human waste, among others. Although many people are fearful about using the resource as a fertiliser, the fact is that sewage waste treatment end product is highly sought for fertiliser use in commercial tree plantations and tree crops.
Who should manage the waste and how
It is the responsibility of every waste producer to manage it. Practices of reducing agricultural waste include feeding it to animals, humans consuming most of the edible materials such as potato, carrot, and mango peels and practising zero food waste by serving just enough per meal.
For reuse and recycling of nutrients into the soil, composting and biogas production technologies are used.
To produce safe compost from dumpsite materials, separation of organic matter should be done at the production source to avoid contamination of the resulting fertiliser with hazardous waste such as chromium and lead.
Money to facilitate the above activities can come from the clean development mechanism’s funds.