Isolation and Assessment of Cyanide Biodegradation Potential of Indigenous Bacteria from Contaminated Soil

Eight effective bacterial strains were isolated from cyanide-contaminated soil, from which, two (S11 and S13) were tested to determine their minimum inhibitory concentration using potassium cyanide (KCN) and potassium tetracyano nickelate (K2Ni(CN) 4). The isolates were tested for their KCN biodegradation potential (by measuring ammonia production) at neutral and alkaline pHs (7.0 and 9.0). Furthermore, the effect of the initial KCN concentration on biodegradation was evaluated at the optimal pH using nitrogen free M9 medium, supplemented with KCN as nitrogen source. The results showed that both strains tolerated cyanide concentrations of up to 10 × 10-3 mol⋅l-1 (0.651 g⋅l-1 KCN;2.409 g⋅l-1 K2Ni(CN)4) which makes them good candidates for cyanide bioremediation. For both strains, a change of initial pH from 7.0 to 9.0 significantly enhanced KCN degradation. S13 grown at pH 9.0 and S11 cultivated at pH 7.0 released the highest and lowest amounts of ammonia, respectively. For both strains, the release of ammonia increased when the initial KCN concentration increased from 10-3 to 5 × 10-3 mol⋅l-1. These findings open prospects for the application of these bacteria for remediation of cyanide-contaminated soils and wastewater at alkaline pH, alkaline pH being conditions that prevent cyanide volatilization.

More than Target 6.3： A Systems Approach to Rethinking Sustainable Development Goals in a Resource-Scarce World

《2030年可持续发展议程》概述了17个独立的可持续发展目标(SDGs),用于指导世界范围内包括工程、科研、政策和发展在内的大量专业学科的实践。SDGs致力于减少贫困、饥饿和疾病,同时致力于改善性别歧视、环境恶化以及水和卫生设施匮乏的现状。但是,如果我们采取传统的简化方法研究和优化其中的单一目标,很可能由于在实现其他目标时带来的意外后果,而导致在技术、政策或管理层面的失败。本研究采用系统分析方法研究SDGs之间的动态机理,识别个体目标之间的协同或拮抗作用,构建了一个概念系统模型来说明SDGs之间的因果联系,利用了通用系统基模来检验系统结构,确定了杠杆节点来有效控制系统中的预期变化并最小化非预期变化。SDGs之间相互作用的结构反映了系统行为的三种基模:强化成长、成长上限和成长与投资不足。由概念模型确定的杠杆节点包括:性别平等、水和卫生设施的可持续管理、可替代资源、可持续生活标准和全球伙伴关系。这种对SDGs的概念系统分析能够加深发展社区对资源管理、环境可持续发展和气候变化相关项目带来的潜在协同效应的理解。通过把项目间的影响和反馈与经济收益、妇女平权和教育平等联系起来,利益相关者可以意识到可从整体上改善全球众多贫困群体的生活质量。