To achieve a sustainable supply and effectively manage water, energy and food (WEF) demand, interactions between WEF need to be understood. This study developed an integrated model, capturing the interactions between WEF at end-use level at a household scale. The model is based on a survey of 419 households conducted to investigate WEF over winter and summer for the city of Duhok, Iraq. A bottom-up approach was used to develop this system dynamics-based model. The model estimates WEF demand and the generated organic waste and wastewater quantities. It also investigates the impact of change in user behaviour, diet, income, family size and climate.The simulation results show a good agreement with the historical data. Using the model, the impact of Global Scenario Group (GSG) scenarios was investigated. The results suggest that the ‘fortress world’ scenario (an authoritarian response to the threat of breakdown) had the highest impact on WEF.

The circular economy concept can enhance sustainability through restructuring consumption and production patterns using innovative designs and business models. This core premise is highly relevant for the interlinked water and food supply sectors in arid regions, which are threatened by natural scarcity and resource overuse. This paper transfers the idea of the circular economy into the practice of the water and food sectors using the example of the region of the Gulf Cooperation Council (GCC). It develops a framework for identifying circular economy strategies and issues applicable to basic supply sectors. In analyzing the value chain and circular strategies of the water and food sectors, the circular economy idea has resulted in numerous industrial applications. The range of applications is illustrated in the key industries of wastewater and local food production. Expanding the reuse options for municipal wastewater and valorizing organic waste represent important circular economy directions for the basic supply sector of the GCC. Incorporating these ideas is positive, but a more comprehensive set of measures is needed to generate low-carbon and low-metabolism economic development in the region. In addition to the current sporadic supply-side initiatives, there is a need for non-technical circular economy strategies related to demand management and waste reduction.

Biogas, generated from anaerobic digester (AD), has been one of the promising sources of renewable energy. To manage the organic waste from small cassava industry in Brazil, a waste-water-energy-food nexus (WWEF) system is proposed, combining AD and co-generation or combined heat and power (CHP) plants. However, the environmental impacts and benefits of this system are yet not known. By using Life Cycle Assessment (LCA) method, environmental impacts of three scenarios are assessed, i.e. business-as-usual (base), improved business-as-usual and WWEF closed-loop. Functional unit (FU) in this study is defined as generating 1 kg cassava starch/flour. Global warming potential (GWP), cumulative energy demand (CED), freshwater eutrophication potential (FEP), terrestrial acidification potential (TAP) and water depletion potential (WDP) are selected. Landfilling cassava waste, power use for cassava starch and flour production, and emissions from fertilizer application are identified as environmental hotspots for business-as-usual case, suggesting making decisions on these aspects when dealing with environmental impacts. By using cassava waste to recover energy and nutrients for Brazilian rural family farming, the WWEF system is identified as the best environment-friendly scenario with lowest environmental impacts for the selected impact categories. The impact savings of the closed-loop scenario for GWP are over 90%, while over 50% of emissions for other selected impact categories, except FEP (lower than 10%), are saved compared to the business-as-usual and improved scenarios. Sensitivity analysis reinforces the results. Overall, this study provides a view on the potential of using cassava waste for the WWEF closed-loop system in Brazil, suggesting that the proposed WWEF closed-loop system is feasible and beneficial for small industries from the environmental perspective.

Aims of this experiment, to examined the effects of food density and water salinity on filtration rate of oyster (Crassostrea belcheri) for fundamental data on assessing the suitable use of oyster as an alternative of biofilter in wastewater from an intensive shrimp pond. From the experimentation showed that an average of filtration rate within 24 hours of both size of oysters at different food density were significantly different (p0.01). The Filtration rate of oysters were decreased with increasing the food density. The average of filtration rate of oysters when exposed to different water salinity were significantly different (p0.01). The decrease in filtration rate of oyster was correlated with water salinity. The average filtration rate of oyster was high at water salinity range 15-25 ppt for small size and 10-25 ppt for large size.