Search

The review discusses the advancements in vermifiltration research over the last decade, focusing on pollution removal mechanisms, system performance, the fate of filter components, and by-products. Vermifiltration has demonstrated remarkable capabilities, particularly in treating highly contaminated wastewater with Chemical Oxygen Demand (COD) levels exceeding 92,000 mg/L and Biochemical Oxygen Demand (BOD5) levels over 25,000 mg/L, achieving removal rates of approximately 89% and 91%, respectively. Importantly, vermifiltration maintains its effectiveness even with fluctuating organic loads at the inlet, thanks to optimization of parameters like Hydraulic Loading Rate, biodegradable organic strength, earthworm density and active layer depth. Clogging issues can be minimized through parameters optimization. The review also highlights vermifiltrations’ potential in co-treating the organic fraction of municipal solid waste while significantly reducing heavy metal concentrations, including Cd, Ni, Pb, Cu, Cr, and Zn, during the treatment process. Earthworms play a pivotal role in the removal of various components, with impressive removal percentages, such as 75% for Total Organic Carbon (TOC), 86% for Total COD, 87% for BOD5, 59% for ammonia nitrogen, and 99.9% for coliforms. Furthermore, vermifiltration-treated effluents can be readily utilized in agriculture, with the added benefit of producing vermicompost, a nutrient-rich biofertilizer. The technology contributes to environmental sustainability, as it helps reduce greenhouse gas emissions (GHG), thanks to earthworm activity creating an aerobic environment, minimizing GHG production compared to other wastewater treatment methods. In terms of pollutant degradation modeling, the Stover-Kincannon model outperforms the first-order and Grau second-order models, with higher regression coefficients (R2 = 0.9961 for COD and R2 = 0.9353 for TN). Overall, vermifiltration emerges as an effective and sustainable wastewater treatment solution, capable of handling challenging wastewater sources, while also producing valuable by-products and minimizing environmental impacts.

Obtaining accurate values of saturated hydraulic conductivity (Ksat) is very important for managing all natural or artificial processes involving water flow into soils. Double-ring infiltration (DRI) is one of the easiest-to-work-with techniques commonly used for Ksat determination. Unfortunately, when improperly used, it leads to important variations and inaccurate results. This study was designed to investigate the necessary conditions to reach the true-value or real-world saturated hydraulic conductivity (Ksat-real-world) in the field. For this purpose, the effects of two factors—namely, the measured infiltration data type (cumulative, instant rate, and average rate) and the related non-linear regression equation type—were analyzed. Measurements with DRI were performed with samples from 106 locations in three West African countries, namely, Burkina Faso, Mali, and Cote d’Ivoire. The soils were composed of loam, sandy loam, and sandy clay loam. The results show that when infiltration rates are used rather than cumulative infiltration non-linear regression curves, the variability between the measured Ksat and the real-world saturated hydraulic conductivity (Ksat-real-world) could reach from 2.2% to 58.8%. This variability was caused by the approximate amplification—according to the procedure used—of time-increment measurement errors. Extending the test duration to more than 4 h, especially when clay soils were involved, and using the exponential one-phase decay non-linear regression of the cumulative infiltration data based on a clear measurement protocol provided the Ksat values that were closest to Ksat-real-world.

Since the droughts of the 1970s–1980s, populations in the Sahel region have opted for a mass exodus to more humid urban or rural centers. Migrations or exoduses have accelerated in recent decades due to environmental degradation and unfavorable climatic conditions. Insufficient harvests are the main reason for migration for the majority of migrants in the Sahelian areas. Migration is a major adaptation strategy to cope with extreme climatic conditions, thus requiring quantification in the destination area. The aim of this paper is to propose a metapopulation model to approximate reality by identifying the transition from one socioeconomic vulnerability group to another, from a less favorable area to favorable area in terms of natural resources, depending on the strategies, policies, and climate variability. The model was used to analyze the dynamics of socioeconomic vulnerability to study the impact of migration on the dynamics of socioeconomic vulnerability. The developed mathematical model was analyzed. Up to 2050, simulations applied to the Tougou village in northern Burkina Faso show that migration has a positive impact on the socioeconomic vulnerability of the destination area, thereby reducing the vulnerability of the population by 10% when resources are increased by up to 30%.

The dry spells are severe obstacles to rainfed agriculture in Sahelian countries. The farmers believe supplemental irrigation is an excellent way to adapt rainfed agriculture to dry spells. In this study, we analyzed the contribution of supplemental irrigation to food security and compared the profitability of different types of ponds constructed by farmers in northern Burkina Faso. Human cereal requirement was used as indicators to analyze the contribution of supplemental irrigation to food security. The criteria for analyzing the profitability of the selected ponds were gross margin (GM), net present value (NPV), internal rate of return (IRR) and payback period (PBP). The results show that the additional yield of corn obtained with supplemental irrigation makes it possible to meet the monthly cereal needs of at least 17 people and generates an additional GM of FCFA 178,483 (US$ 309.26) compared to no irrigation. The estimate of the NPV, from IRR and PBP showed that the profitability of supplemental irrigation in 15 agricultural seasons varies between type of ponds constructed. Given the up-front cost and the farmers’ lack of resources, the ponds require a subsidy or a credit policy to facilitate the adoption of supplemental irrigation in Sahelian countries.

This study analyzes farmers' practices and willingness to adopt supplemental irrigation on rainfed crops in the Sahelian and Sudano-Sahelian areas of Burkina Faso. A survey of 629 farmers revealed a diversity of farming practices within and between two agro-climatic zones. Over 65% of farmers believe that supplemental irrigation is a good way to mitigate the adverse effects of dry spells on crop yields. Determining factors of farmers’ willingness to adopt supplemental irrigation were identified using a logistic model. Lack of information is the major obstacle to promoting this innovation. Farmers’ training and information dissemination are the best ways to increase the acceptance of this promising technology.