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Protracted and prolonged droughts lead to famine and substantial decline in agricultural productivity that contribute to food insecurity and hunger in sub-Saharan Africa which needs to explore the risk coping strategies to better target risk mitigation. The main research question of this paper was to analyze ex-post coping strategies and their determinants in rural Ethiopia. We use a cross-section data collected in 2013 from vulnerable rural households in Rayitu district, Bale Zone of Oromia Regional State. Using population-proportionate to size (PPS) sampling technique, a total number of 1,402 households in the district participated in this study. The data were analyzed using a three-stage least squares (3SLS) method. Our analysis confirms that rural households in Rayitu district experience drought and are vulnerable to the consequences of shocks. As a response, rural households adopt interdependent risk coping strategies. This supports the notion of addressing the problem of risk through integrated rural development strategies (and policies) to help the poor to improve the vulnerability to shock and help to escape out of poverty. In addition, we found that the risk coping strategies that households adopt are influenced by the resource holdings and income levels of the rural households, their access to product and financial market, and their socio-demographic characteristics. Hence, we argue that strategies and interventions to improve the livelihood of the poor and to support the vulnerable ones should be targeted to fit to the needs and priorities of households.

Currently, the depletion of natural resources and contamination of the surrounding environment demand a paradigm shift to resource recycling and reuse. In this regard, phosphorus (P) is a model nutrient that possesses the negative traits of depletion (will be exhausted in the next 100 years) and environmental degradation (causes eutrophication and climate change), and this has prompted the scientific community to search for options to solve P-related problems. To date, P recovery in the form of struvite from wastewater is one viable solution suggested by many scholars. Struvite can be recovered either in the form of NH 4 -struvite (MgNH 4 PO 4 •6H 2 O) or K-struvite (MgKPO 4 •6H 2 O). From struvite, K (MgKPO 4 •6H 2 O) and N (MgNH 4 PO 4 •6H 2 O) are important nutrients for plant growth, but N is more abundant in the environment than K (the soil's most limited nutrient), which requires a systematic approach during P recovery. Although K-struvite recovery is a promising approach, information related to its crystallization is deficient. Here, we present the general concept of P recovery as struvite and details about K-struvite, such as the source of nutrients, factors (pH, molar ratio, supersaturation, temperature, and seeding), advantages (environmental, economic, and social), disadvantages (heavy metals, pathogenic organisms, and antibiotic resistance genes), and challenges (scale-up and acceptance). Overall, this study provides insights into state-of-the-art K-struvite recovery from wastewater as a potential slow-release fertilizer that can be used as a macronutrient (P-K-Mg) source for plants as commercial grade-fertilizers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Available freshwater scarcity significantly affects sustainable food production for the rapidly growing population. This problem has forced people in most parts of the world to use wastewater as a viable solution. However, wastewater reuse has some deleterious effects on human and environmental health. This study was designed to investigate the health risks (HRs) of heavy metals (HMs) from vegetables irrigated with untreated and treated wastewater. The composite wastewater was collected at various sites in Arba Minch town and subjected to aerobic-anoxic treatment. Treated and untreated wastewater (UTW) was used to irrigate vegetables (lettuce, cabbage and tomato), and HM results were compared with the control (tap water) and standards. Water, soil and vegetables were investigated for various physical and chemical properties. Human health effects due to vegetable consumption were analyzed using HR- index (HRI), target hazard quotient (THQ) and hazard index (HI). The results revealed that most of the water quality indexes were significantly enhanced after aerobic-anoxic treatment, suggesting that wastewater collected from different sites was suitable for biodegradation. Soil physicochemical analyses also showed that pH, cation exchange capacity, organic carbon and organic matter were higher for UTW irrigated soil. Heavy metal concentrations were relatively greater in soils than water used for irrigation purposes and vegetables. The HM concentration in vegetables was higher for UTW than for treated and tap water irrigated vegetables. In vegetables, the order of HM content was Fe > Mn > Zn > Pb > Cu > Cd. Tomato followed by cabbage and lettuce accumulated significant amount of HMs (Fe > Mn > Zn > Pb > Cu > Cd) in their different organs (fruit/leaf>root>stem). The individual and combined health indexes (HRI, THQ and HI) showed that Pb and Cd have values greater than unity for wastewater irrigated vegetables, which could result in non-carcinogenic disease for short/lifetime exposure in adults and children. Overall, consumption of vegetables can be safer when grown with treated effluent than with UTW., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Phosphorus recovery from urine is a sustainable approach. However, the challenge of this process is the accessibility of economically feasible magnesium sources. This study aimed to investigate the potential of low-cost Rift Valley Lake magnesium (RVL-Mg) source for phosphorus recovery from urine, where data is deficient in the source area. The effect of various operational conditions such as storage, Mg:P ratio (0.8-2.0), pH (5.5-10.5), mixing speed (30-180 rpm), urease enzyme addition (50-700 μL), urine dilution (0.11-9.0) and Ca:Mg ratio (0.3-2.5) was investigated. Under optimum operating conditions (M:P = 1.6, pH = 9, urease enzyme = 500 μL, mixing speed = 120 rpm, 60 min precipitation), the phosphorus removal efficiencies were >96% for actual and >98% for synthetic urine. During storage, spontaneous phosphorus losses were observed from synthetic (24.0%) and actual (32.0%) hydrolyzed urine due to precipitation with calcium and magnesium. The phosphorus recovery efficiency was reduced at higher (0.11:1) and lower (9:1) urine to RVL-Mg dilution, which is related to lower supersaturation of phosphorus and magnesium ions, respectively. Addition of calcium did not affect phosphorus removal efficiency, but the effect was significant on crystal product. With low (<1.0) Ca:Mg ratio, the crystal chemical analysis showed that the product has to be pure struvite (>99%), which was further identified by scanning electron microscope and X-ray diffraction to be quality struvite that might be used for agricultural purpose. Overall, low-cost magnesium ion collected from Rift Valley Lake can be a potentially candidate for sustainable phosphorus recovery from urine and any other phosphorus containing waste stream., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)