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Gas flotation for oily wastewater treatment is based on the attachment of gas bubbles to oil droplets to produce lighter aggregates that rise to the wastewater surface. It is a feasible, promising, and effective method for oily wastewater treatment due to its high separation efficiency with no secondary contamination, cost-effectiveness, and simple operation. This review focuses on separating oil from emulsions by gas flotation using microbubbles (MBs) and nanobubbles (NBs), which offer the advantages of small bubble size, large specific surface area, and slow rising velocity. The properties of different types of gas bubbles and their generation methods were discussed. Different gas flotation system designs and operational parameters were summarized for dissolved gas flotation, induced gas flotation, and electrolytic flotation (EF). The review illustrated that oil removal efficiency in MB- and NB-based gas flotation was affected by various factors including initial oil concentration, pH, temperature, flotation time, and oil droplet size. Key words: gas flotation, microbubble, nanobubble, oil-in-water emulsion, oily wastewater treatment La flottation gazeuse pour le traitement des eaux usées contaminées par les hydrocarbures est basée sur la fixation des bulles de gaz aux gouttelettes d'hydrocarbures pour produire des agrégats plus légers qui remontent àla surface des eaux usées. Il s'agit d'une méthode réalisable, prometteuse et efficace pour le traitement des eaux usées contaminées par les hydrocarbures en raison de sa grande efficacité de séparation sans contamination secondaire, de sa rentabilité et de sa simplicité d'utilisation. Cette synthèse se concentre sur la séparation des hydrocarbures des émulsions par flottation gazeuse en utilisant des microbulles et des nanobulles qui offrent les avantages d'une petite taille de bulle, d'une grande surface spécifique et d'une vitesse d'ascension lente. Les propriétés des différents types de bulles de gaz et leurs méthodes de génération ont été discutées. Les différentes conceptions de systèmes de flottation gazeuse et les paramètres opérationnels ont été résumés pour la flottation par gaz dissous, la flottation par gaz induit et la flottation électrolytique. La synthèse a montré que l'efficacité de l'élimination des hydrocarbures par la flottation gazeuse àbase de microbulles et de nanobulles était affectée par divers facteurs, notamment la concentration initiale d'hydrocarbures, le pH, la température, le temps de flottation et la taille des gouttelettes d'hydrocarbures. [Traduit par la Rédaction] Mots-clés : flottation gazeuse, microbulles, nanobulles, émulsion d'huile dans l'eau, traitement des eaux usées contaminées aux hydrocarbures, 1 Introduction Oily wastewater is generated from oil spill incidents and many other sources, such as food processing, oil refining, textile and leather industries, metal rolling and finishing, paper deinking, [...]

Drawing on county-level foreign trade archival documents, this article explores export production in the rural Pearl River delta during the 1960s and 1970s, focusing on the relationship between local foreign trade agencies and grassroots collectives in three counties. The study contends that, instead of the state having complete control of the entire production and procurement process, rural export production in the Pearl River delta demonstrates remarkable diversity and responsiveness to fluctuating overseas market conditions, whose adaptability, however, was significantly constrained by the grain-first policy during the Maoist era. This research further posits that the interplay between control and autonomy mechanisms shaped the institutional context in which rational, calculating Chinese peasants navigated the Maoist state. Notably, the state was not a monolithic entity, and its boundaries with the peasants were permeable and dynamic. [ABSTRACT FROM AUTHOR]

Flooded streets and homes, polluted surface waters, degraded aquatic habitats, stressed aquifers, and expensive drainage infrastructures are evidence that Canada's current approach to stormwater management requires rethinking. To address these challenges, the authors developed an integrated community-level urban stormwater decision support framework. The framework assesses low impact development infrastructure, traditional stormwater infrastructure, and community-level stormwater reuse schemes to better understand the interactions between various water resources in the context of various stormwater management strategies. The framework also incorporates stochastic variation in natural processes to predict a community's water footprint using the One Water Approach. A climate change sensitivity analysis is also incorporated to test proposed stormwater systems for resiliency to climate change. Fuzzy clustering analysis was then performed to identify the most appropriate stormwater management strategy. A case study demonstration of the framework was performed for a hypothetical 80-hectare mixed-use urban community in Kelowna, British Columbia. [ABSTRACT FROM AUTHOR]