Timothy O. Williams, 'Managing water for food and agricultural transformation in Africa: key issues and priorities', pp.pp.470-487, 2020

Urbanisation will be one of the 21st century's most transformative trends. By 2050, it will increase from 55% to 68%, more than doubling the urban population in South Asia and Sub-Saharan Africa. Urbanisation has multifarious (positive as well as negative) impacts on the wellbeing of humans and the environment. The 17 UN Sustainable Development Goals (SDGs) form the blueprint to achieve a sustainable future for all. Clean Water and Sanitation is a specific goal (SDG 6) within the suite of 17 interconnected goals. Here we provide an overview of some of the challenges that urbanisation poses in relation to SDG 6, especially in developing economies. Worldwide, several cities are on the verge of water crisis. Water distribution to informal settlements or slums in megacities (e.g. N50% population in the megacities of India) is essentially non-existent and limits access to adequate safe water supply. Besides due to poor sewer connectivity in the emerging economies, there is a heavy reliance on septic tanks, and other on-site sanitation (OSS) system and by 2030, 4.9 billion people are expected to rely on OSS. About 62–93% of the urban population in Vietnam, Sri Lanka, the Philippines and Indonesia rely on septic tanks, where septage treatment is rare. Globally, over 80% of wastewater is released to the environment without adequate treatment. About 11% of all irrigated croplands is irrigated with such untreated or poorly treated wastewater. In addition to acute and chronic health effects, this also results in significant pollution of often-limited surface and groundwater resources in Sub-Saharan Africa and Asia. Direct and indirect water reuse plays a key role in global water and food security. Here we offer several suggestions to mitigate water and food insecurity in emerging economies.

Realizaram-se dois estudos, e primeiro deles objetivou verificar a influência do comportamento próximo ao comedouro e bebedouro sobre o consumo de água (CA) e avaliar a adequação das equações de predição para estimar o CA em bovinos Brangus no subtrópico. Os dados foram coletados em dois experimentos realizados no Rio Grande do Sul, na EEA-UFRGS, o primeiro em 2017, com 60 novilhas da raça Brangus e o segundo em 2018 com 30 bezerros da mesma raça. Os valores preditos foram calculados utilizando 6 equações previamente publicadas na literatura científica e comparados com os valores de CA medidos nos bebedouros automáticos. As análises de regressão linear entre CA medido e os valores preditos mostraram que todas as equações superestimaram o CA medido, devido a diferenças ambientais e genotípicas e fatores não considerados nas equações. Com as informações geradas nos experimentos, foram propostas equações de predição: CA= - 2,44 + (0,009 x PC) + (0,84 x CMS) – (0,10 x UR) + (0,64 x TMAX) e CA= - 2,52 + (0,96 x CMS) – (0,09 x UR) + (0,45 x TMAX) + (0,76 x NVCB) + (0,18 x TCB) - (0,02 x NVCC) + (1,81 x TI) para novilhas; e CA1= - 4,23 + (0,98 x CMS) + (0,50 x TMAX) - (0,98 x PP) e CA2 = 13,07 + (0,61 x CMS) - (0,14 x UR) + (0,34 x TMAX) – (0,91 x VV) - (0,09 x RS) + (0,99 x NVCB) para bezerros. As equações propostas para os bezerros foram validadas com dados coletados em outro período, com novilhos Brangus. Entre os dois modelos propostos no estudo, o modelo comportamental (CA2) apresentou maior coeficiente de determinação, com média estimada de CA de 9,49 kg para um CA medido de 19,55 kg/d. O segundo estudo objetivou avaliar a influência do temperamento sobre o consumo de água e alimentos de bezerros de corte confinados e analisar o efeito do temperamento sobre as características produtivas dos animais. Os dados foram coletados de 30 bezerros da raça Brangus no ano de 2018 em três avaliações. O temperamento foi avaliado como o escore composto de balança (escores de 1 a 5, de calmos a muito reativos) e, posteriormente, os animais foram categorizados em calmos, intermediários e reativos. O temperamento não influenciou o consumo de água e alimentar dos animais. Animais calmos ganharam menos peso no primeiro período de avaliação que os demais. Animais calmos permaneceram menos tempo no cocho que os demais. O presente estudo confirmou o baixo coeficiente de determinação dos modelos de predição de consumo de água e a superestimação do consumo. O consumo de água e alimentos e a maior parte dos atributos comportamentais ligados à ingestão não foram influenciado pelo temperamento dos bovinos. | Two studies were carried out, the first one aimed to verify the influence of the behavior close to the feeder and drinker on water intake (WI) and to evaluate the adequacy of the prediction equations to estimate the WI in Brangus cattle in the subtropical region. Data were collected in two experiments carried out in Rio Grande do Sul, at EEA- UFRGS. The first was in 2017 studying 60 Brangus heifers and the second was in 2018 studying 30 calves of the same breed. The predicted values were calculated using six previously published equations and compared with the WI values measured in the automatic drinkers. Linear regression analyzes between WI and predicted values demonstrated that all equations overestimated WI, due to both environmental and genotypic differences as well as to factors not considered in the equations. From the information generated in the experiments, new prediction equations were proposed: WI = - 2,44 + (0,009 x BW) + (0,84 x DMI) – (0,10 x HU) + (0,64 x MT) e WI = - 2,52 + (0,96 x DMI) – (0,09 x HU) + (0,45 x MT) + (0,76 x NVCB) + (0,18 x TCB) - (0,02 x NVCC) + (1,81 x TI) for heifers; and WI1 = - 4,23 + (0,98 x DMI) + (0,50 x MT) - (0,98 x PP) e WI2 = 13,07 + (0,61 x DMI) - (0,14 x HU) + (0,34 x MT) – (0,91 x WS) - (0,09 x SR) + (0,99 x NVCB) for calves. The proposed equations for the calves were validated with data collected in other period with Brangus steers. Among the two models proposed in the study, the behavioral model (WI2) presented the highest coefficient of determination, with an estimated mean of 9.49 kg of WI for an observed overall WI of 19.55 kg/d. The second article aimed to evaluate the influence of temperament on the consumption of water and feed of beef calves and to analyze the effect of temperament on the productive characteristics of animals. Data were collected from 30 Brangus calves in 2018 in three evaluations. The temperament was evaluated as the balance composed score (scores from 1 to 5 from calm to very reactive) and, later, the animals were categorized into calm, intermediate and reactive. The temperament did not influence the water and food consumption of the animals. Calm animals gained less weight in the first evaluation period than the rest of them. Calm animals spent less time in the feeder than the others. The present study confirmed the low coefficient of determination of the water intake prediction models and the overestimation of water consumption. The intake of water and food and most of the behavioral attributes linked to ingestion were not influenced by temperament in beef cattle raised in the subtropics.

Current studies on the food-energy-water nexus do not capture effects on human health. This study presents a new methodology for assessing the environmental sustainability in the food-energy-water-health nexus on a life cycle basis. The environmental impacts, estimated through life cycle assessment, are used to determine a total impact on the nexus by assigning each life cycle impact to one of the four nexus aspects. These are then normalised, weighted and aggregated to rank the options for each aspect and determine an overall nexus impact. The outputs of the assessment are visualised in a “nexus quadrilateral” to enable structured and transparent interpretation of results. The methodology is illustrated by considering resource recovery from household food waste within the context of a circular economy. The impact on the nexus of four treatment options is quantified: anaerobic digestion, in-vessel composting, incineration and landfilling. Anaerobic digestion is environmentally the most sustainable option with the lowest overall impact on the nexus. Incineration is the second best option but has a greater impact on the health aspect than landfilling. Landfilling has the greatest influence on the water aspect and the second highest overall impact on the nexus. In-vessel composting is the worst option overall, despite being favoured over incineration and landfilling in circular-economy waste hierarchies. This demonstrates that “circular” does not necessarily mean “environmentally sustainable.” The proposed methodology can be used to guide businesses and policy makers in interpreting a wide range of environmental impacts of products, technologies and human activities within the food-energy-water-health nexus.

The gasification of biomass in supercritical water is a promising technology for hydrogen production and the paper reports a thermodynamic analysis, based on minimization of Gibbs free energy, of the gasification with supercritical water of different biomass and agro-food residues: almond shells, digestate from wastewater treatment, algae and manure sludge. Numerical simulations were performed in order to assess the effect of temperature, pressure and biomass-to-water ratio on gas-phase yield and composition.A partial energy integration was also discussed, by considering the energy recovery from a turbine expansion of the gas-phase stream leaving the gasifier. The proposed thermodynamic approach allows predicting not only gasification efficiency of gasifier but also energy balance on the entire gasification process. Results showed that the dry substrates (almond shells and algae more than digestate and sludge) tend to form more carbon monoxide. Besides, data comparison revealed that the produced hydrogen comes from biomass and water for high process temperature, while when temperature decreases, the thermodynamic path tends to promote water formation from the hydrogen of the dry biomass.

Synergic management of the local crop-biomass coproduction system is the potential to increase resource efficiency and promote sustainable development. In this paper, an interval fuzzy linear fractional programming (IFLFP) model is developed for planning regional food production with the consideration of ecological protection, water resource conservation, biomass energy supply, and food-energy-water (FEW) nexus. The main advantages of the proposed IFLFP model are the abilities to reflect uncertainties with different characters as interval values and fuzzy sets and to provide system efficiency measurement by the ratio form of conflict objective functions. The IFLFP model is then tailored for the application of the crop-biomass coproduction management with FEW nexus in Jiangsu Province, China. The influences of different optimization goals (i.e. economic benefits and environmental benefits per unit irrigation water consumption) and multiple water resource scenarios under climate change are examined and discussed to provide more managerial insights. The results reveal that wheat, barley, and tuber crops would be more easily affected by water resource availability and optimization goals. Besides, recycle water would be considered as an important source for irrigation under scare water scenario, and gain the priority for the economic purpose. The results also imply that it is impossible to realize “double-win” of environmental and economic goals simultaneously, and decision makers should make compromises among different strategies.

A hybrid inexact optimization model is developed for food-water-energy nexus system management with the consideration of complex uncertainties and decision makers’ risk tolerance. A multi-stage stochastic fuzzy random programming (MSFRP) model is tailored to tackle variables with deeper uncertainties, a mixture of fuzzy and random fuzzy characteristics. Allowing to reflect decision makers’ subjective opinion and risk preference, it can provide decision makers the tradeoff information between system benefit and risk attitude. The proposed model was applied to an agricultural area Shandong Province, China with the aim of maximum total system benefits. The valuable managerial insights on optimal cultivated land distribution, water resource allocation, and energy supply strategies are provided for decision makers under uncertainties. Meanwhile, the pesticide and fertilizer consumption for crop planting, and the carbon emission embodied in per unit crop supply are also quantitatively estimated. Moreover, by setting different water resource availability scenarios, the impacts of future water resource conditions on optimal management strategies under climate change are evaluated and discussed. The results suggested that rice would be the critical crop with the largest planting area for food security during the planning horizon. Under scarcer water resource conditions, the system benefits would reduce due to more desalination water consumption and planting strategy adjustment. However, it would lead to less carbon emission embodied in per unit crop supply and relieve local carbon emission control pressure. Compared to the conventional multi-stage stochastic programming, the developed MSFRP can be more effective to reflect the optimistic and pessimistic attitude of decision makers and deal with future scenario information with deeper uncertainties.

In China, waste sorting practice is not strictly followed, plastics, especially food packaging, are commonly mixed in food waste. Supercritical water gasification (SCWG) of unsorted food waste was conducted in this study, using model unsorted food waste by mixture of pure food waste and plastic. Different operating parameters including reaction temperature, residence time, and feedstock concentration were investigated. Moreover, the effect of three representative food additives namely NaCl, NaHCO₃ and Na₂CO₃ were tested in this work. Finally, comparative analysis about SCWG of unsorted food waste, pure food waste, and plastic was studied. It was found that higher reaction temperature, longer residence time and lower feedstock concentration were advantageous for SCWG of unsorted food waste. Within the range of operating parameters in this study, when the feedstock concentration was 5 wt%, the highest H₂ yield (7.69 mol/kg), H₂ selectivity (82.11%), total gas yield (17.05 mol/kg), and efficiencies of SCWG (cold gas efficiency, gasification efficiency, carbon gasification efficiency, and hydrogen gasification efficiency) were obtained at 480 °C for 75 min. Also, the addition of food additives with Na⁺ promoted the SCWG of unsorted food waste. The Na₂CO₃ showed the best catalytic performance on enhancement of H₂ and syngas production. This research demonstrated the positive effect of waste sorting on the SCWG of food waste, and provided novel results and information that help to overcome the problems in the process of food waste treatment and accelerate the industrial application of SCWG technology in the future.

Waste fractions of food processing are promising sources of polyphenols, which are of high demand because of their favourable bioactivities. More recently, also wastewater and process water fractions are in focus of research and technologies for downstream processing, which is reviewed here. Adsorption as well as membrane technologies are widely used to achieve selective recovery of polyphenols from waste water. For technical implementation the processing of waste fractions must be separated from the primary food production process. Therefore, the key step is the efficient transfer of the waste fractions into a storable and transportable form of polyphenol-enriched fractions. This strategy is shown exemplarily for the marzipan production. Almond skin and blanch water are waste fractions containing catechin and procyanidins, for which a recycling concept has been developed. The polyphenolic ingredients of the blanch water can be specifically adsorbed by means of Amberlite resins or zeolites with high yield followed by ultrafiltration.