• Energy Research

This communication is motivated by recent publications discussing the affordability of appropriate decentralized solutions for safe drinking water provision in low-income communities. There is a huge contrast between the costs of presented technologies, which vary by a factor of up to 12. For example, for the production of 2000 L/d of treated drinking water, the costs vary between about 1500 and 12,000 Euro. A closer look at the technologies reveals that expensive technologies use imported manufactured components or devices that cannot yet be locally produced. In the battle to achieve the United Nations Sustainable Development Goal for safe drinking water (SDG 6.1), such technologies should be, at best, considered as bridging solutions. For a sustainable self-reliance in safe drinking water supply, do-it-yourself (DIY) systems should be popularized. These DIY technologies include biochar and metallic iron (Fe0) based systems. These relevant technologies should then be further improved through internal processes.

This communication is motivated by recent publications discussing the affordability of appropriate decentralized solutions for safe drinking water provision in low-income communities. There is a huge contrast between the costs of presented technologies, which vary by a factor of up to 12. For example, for the production of 2000 L/d of treated drinking water, the costs vary between about 1500 and 12,000 Euro. A closer look at the technologies reveals that expensive technologies use imported manufactured components or devices that cannot yet be locally produced. In the battle to achieve the United Nations Sustainable Development Goal for safe drinking water (SDG 6.1), such technologies should be, at best, considered as bridging solutions. For a sustainable self-reliance in safe drinking water supply, do-it-yourself (DIY) systems should be popularized. These DIY technologies include biochar and metallic iron (Fe0) based systems. These relevant technologies should then be further improved through internal processes.

The energy demands in Zimbabwe have drastically increased due to the improvement of the country`s economy. To supply the electricity, Zimbabwe imports most of its energy but the demands are yet to be fulfilled. Bio-waste provide an alternative energy source, however, it has not been fully explored and their quantities are currently unknown. Therefore, this study assessed the bio-wastes availability for bioenergy generation in Zimbabwe. Yield data on biomasses were obtained from the international databases of Food and Agricultural Organization which was validated by the data obtained from Zimbabwean Ministry of Lands and Agriculture as well as from research institutes. The information compiled included biomass from agriculture, municipal solid waste, livestock's dung and municipal sewage sludge. Forests were not considered due to the government prohibition of forests exploitations. The results showed that a total of 49 Gtons of bio-wastes are sustainably available producing a total of 539 PJ of energy which constitute ∼42.3% of the total energy required in Zimbabwe. Among the available bio-wastes, crop residues with ∼48 Gtons produce the largest amount of energy ∼502 PJ followed by animal dung ∼36.2 PJ, then MSW ∼9.1 TJ and lastly by MSS ∼0.8 TJ. Assessment of the bio-waste availability is vital for bio-energy technology to be used sustainably implemented in Zimbabwe.

The energy demands in Zimbabwe have drastically increased due to the improvement of the country`s economy. To supply the electricity, Zimbabwe imports most of its energy but the demands are yet to be fulfilled. Bio-waste provide an alternative energy source, however, it has not been fully explored and their quantities are currently unknown. Therefore, this study assessed the bio-wastes availability for bioenergy generation in Zimbabwe. Yield data on biomasses were obtained from the international databases of Food and Agricultural Organization which was validated by the data obtained from Zimbabwean Ministry of Lands and Agriculture as well as from research institutes. The information compiled included biomass from agriculture, municipal solid waste, livestock's dung and municipal sewage sludge. Forests were not considered due to the government prohibition of forests exploitations. The results showed that a total of 49 Gtons of bio-wastes are sustainably available producing a total of 539 PJ of energy which constitute ∼42.3% of the total energy required in Zimbabwe. Among the available bio-wastes, crop residues with ∼48 Gtons produce the largest amount of energy ∼502 PJ followed by animal dung ∼36.2 PJ, then MSW ∼9.1 TJ and lastly by MSS ∼0.8 TJ. Assessment of the bio-waste availability is vital for bio-energy technology to be used sustainably implemented in Zimbabwe.

Rainwater is conventionally perceived as an alternative drinking water source, mostly needed to meet water demand under particular circumstances, including under semi-arid conditions and on small islands. More recently, rainwater has been identified as a potential source of clean drinking water in cases where groundwater sources contain high concentrations of toxic geogenic contaminants. Specifically, this approach motivated the introduction of the Kilimanjaro Concept (KC) to supply fluoride-free water to the population of the East African Rift Valley (EARV). Clean harvested rainwater can either be used directly as a source of drinking water or blended with polluted natural water to meet drinking water guidelines. Current efforts towards the implementation of the KC in the EARV are demonstrating that harvesting rainwater is a potential universal solution to cover ever-increasing water demands while limiting adverse environmental impacts such as groundwater depletion and flooding. Indeed, all surface and subsurface water resources are replenished by precipitation (dew, hail, rain, and snow), with rainfall being the main source and major component of the hydrological cycle. Thus, rainwater harvesting systems entailing carefully harvesting, storing, and transporting rainwater are suitable solutions for water supply as long as rain falls on earth. Besides its direct use, rainwater can be infiltrating into the subsurface when and where it falls, thereby increasing aquifer recharge while minimizing soil erosion and limiting floods. The present paper presents an extension of the original KC by incorporating Chinese experience to demonstrate the universal applicability of the KC for water management, including the provision of clean water for decentralized communities.

Rainwater is conventionally perceived as an alternative drinking water source, mostly needed to meet water demand under particular circumstances, including under semi-arid conditions and on small islands. More recently, rainwater has been identified as a potential source of clean drinking water in cases where groundwater sources contain high concentrations of toxic geogenic contaminants. Specifically, this approach motivated the introduction of the Kilimanjaro Concept (KC) to supply fluoride-free water to the population of the East African Rift Valley (EARV). Clean harvested rainwater can either be used directly as a source of drinking water or blended with polluted natural water to meet drinking water guidelines. Current efforts towards the implementation of the KC in the EARV are demonstrating that harvesting rainwater is a potential universal solution to cover ever-increasing water demands while limiting adverse environmental impacts such as groundwater depletion and flooding. Indeed, all surface and subsurface water resources are replenished by precipitation (dew, hail, rain, and snow), with rainfall being the main source and major component of the hydrological cycle. Thus, rainwater harvesting systems entailing carefully harvesting, storing, and transporting rainwater are suitable solutions for water supply as long as rain falls on earth. Besides its direct use, rainwater can be infiltrating into the subsurface when and where it falls, thereby increasing aquifer recharge while minimizing soil erosion and limiting floods. The present paper presents an extension of the original KC by incorporating Chinese experience to demonstrate the universal applicability of the KC for water management, including the provision of clean water for decentralized communities.