A Unique Historical Case to Understand the Present Sustainable Development.

Every innovation seeks to become a profitable business, with this considered to be the engine for economic prosperity. When an innovation is revolutionary, its long-term consequences can be revolutionary too. The Haber-Bosh process for ammonia synthesis is arguably the twentieth century's most significant innovation, and its importance to global food production and its impact on the environment are not expected to diminish over the coming decades. The historical case of the ammonia synthesis process invented by Fritz Haber and the ensuing innovation provides an incomparable opportunity to illustrate the interactions across contemporary needs, prominent scientists, political concerns, moral dilemmas, ethics, governance and environmental implications at a time when the concept of sustainability was still in its infancy. Despite its high economic and environmental costs, no cleaner or more efficient sustainable alternative has so far been found, and so replacing this "old" innovation that still "feeds" a large part of the world's population does not appear to be on the cards in the near future.

Biomachining: metal etching via microorganisms.

The use of microorganisms to remove metal from a workpiece is known as biological machining or biomachining, and it has gained in both importance and scientific relevance over the past decade. Conversely to mechanical methods, the use of readily available microorganisms is low-energy consuming, and no thermal damage is caused during biomachining. The performance of this sustainable process is assessed by the material removal rate, and certain parameters have to be controlled for manufacturing the machined part with the desired surface finish. Although the variety of microorganisms is scarce, cell concentration or density plays an important role in the process. There is a need to control the temperature to maintain microorganism activity at its optimum, and a suitable shaking rate provides an efficient contact between the workpiece and the biological medium. The system's tolerance to the sharp changes in pH is quite limited, and in many cases, an acid medium has to be maintained for effective performance. This process is highly dependent on the type of metal being removed. Consequently, the operating parameters need to be determined on a case-by-case basis. The biomachining time is another variable with a direct impact on the removal rate. This biological technique can be used for machining simple and complex shapes, such as series of linear, circular, and square micropatterns on different metal surfaces. The optimal biomachining process should be fast enough to ensure high production, a smooth and homogenous surface finish and, in sum, a high-quality piece. As a result of the high global demand for micro-components, biomachining provides an effective and sustainable alternative. However, its industrial-scale implementation is still pending.

Biomachining: Preservation of Acidithiobacillus ferrooxidans and treatment of the liquid residue.

Biomachining has become a promising alternative to micromachining metal pieces, as it is considered more environmentally friendly than their physical and chemical machining counterparts. In this research work, two strategies that contribute to the development of this innovative technology and could promote its industrial implementation were investigated: preservation of biomachining microorganisms (Acidithiobacillus ferrooxidans) for their further use, and making valuable use of the liquid residue obtained following the biomachining process. Regarding the preservation method, freeze-drying, freezing, and drying were tested to preserve biomachining bacteria, and the effect of different cryoprotectants, storage times, and temperatures was studied. Freezing at -80°C in Eppendorf cryovials using betaine as a cryoprotective agent reported the highest bacteria survival rate (40% of cell recovery) among the studied processes. The treatment of the liquid residue in two successive stages led to the precipitation of most of the total dissolved iron and divalent copper (99.9%). The by-products obtained (iron and copper hydroxide) could be reused in several industrial applications, thereby enhancing the environmentally friendly nature of the biomachining process.