Summary
In this paper, authors present a design case study of integrating the phosphate recovery as an example of applied environmental technology into chemistry education via a nonformal learning experience for high school students in Germany. Along with a short overview on phosphate in chemistry education literature, a description of the intervention, the details of a series of experiments, and their introductions via an interdisciplinary teaching approach are explained.
The topic of recycling phosphate out of wastewater and sewage sludge offers a holistic view that is relevant to many fields such as chemistry as it deals with recycling processes, biology or agriculture that influence the world’s food supply, or geographical and political issues in the use and locations of the world’s phosphate reserves. In this paper, an approach is suggested to adapt recycling processes of phosphate for high school and college classes.
A series of experiments was developed following four technical innovative procedures from environmental technology: (a) leaching (resolve the phosphate out of the sewage sludge/sewage sludge ash); (b) filtration (separating the solution from solid sewage sludge); (c) crystallization and filtration (crystallizing the phosphates by a precipitant); (d) quantification (measuring the chemical yield using a colorimetric test). A model sewage sludge is recommended in the experiments because working with real sewage sludge has a high risk of contamination. Students were asked to explore learning materials, which provides information on the nature of phosphates and their biological and agricultural importance. Learning materials also explain the use of phosphates in daily life and the economic, societal, and geographical dimensions of the topic. Students were also informed about the importance of phosphates for all the countries around the world by highlighting the cases of Morocco and the island of Nauru. Laboratory experiments were designed to be operated by guided inquiry approach using a model for differentiated learning environments in nonformal education. According to this model, graded learning aids on the content and laboratory procedures are provided in case students need more structure.
The proposed approach provide learners with a rich context and helps them construct meaningful learning experiences in the laboratory with practical and interdisciplinary information. It illustrates how new developments in environmental technology can be adapted to make chemistry learning relevant to students and embrace an interdisciplinary curriculum approach. It brings a sustainability-related socioscientific issue, which has great importance to the future of the world, into secondary chemistry teaching.
Relevance for Complex Systems Knowledge
The paper deals with interdisciplinarity, systems thinking, and sustainable development.
Authors claim that key challenges for the global society such as poverty, hunger, climate change, and ocean acidification that need to be approached in an interdisciplinary way. A chemistry curriculum that goes beyond “pure chemical” content and incorporates interdisciplinary learning, reflects chemistry’s impact on society, the environment, and the economy. The use of chemistry experiments in combination with digital pre- and post-laboratory learning materials incorporating perspectives from biology, agriculture, economics, politics, and geography into chemistry education is proposed to overcome disciplinary boundaries.
Conducting a review of relative literature, authors present systems thinking in various disciplines. In Earth System Education, systems thinking is described by various characteristics starting with the identification of individual components leading up to an investigation of interconnectedness between those components, so that cyclicity in systems and their potential to provide solutions about today’s complex issues can be better understood. In geography education, a model for systems competence that includes systems organization, systems behavior, and systems-adequate intentions is suggested as a guide for those who design the curriculum. The dimensions of the model start with the ability to identify a few elements and relations of a system (mainly isolated), study them individually, and understand the relationship between them. Such a geographical systems perspective was adopted by the authors to enrich chemistry teaching by allowing more holistic views toward major challenges such as phosphate sustainability.
“sustainable development”
Authors believe that the needs for clean water, food, improved health, and enhanced energy security are global challenges that could be addressed as parts of the Sustainable Development Goals (SDGs) defined by the United Nations. The intense use of phosphates in agriculture is described as one of the most demanding challenges for a sustainable development of the world, because phosphates are needed as fertilizers to provide the world with enough food but too much phosphate in the environment can cause eutrophication. Processes for recovering phosphate from wastewater and sewage sludge help to close the phosphate cycle and reduce potential risks, including eutrophication’s influence on the environment.
