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Hydrothermal carbonization converts organics in aqueous suspension to a mixture of liquid components and carbon-rich solids (hydrochars), which in turn can be processed into activated carbons. We investigated whether milk could be used as a medium for hydrothermal carbonization, and found that hydrochars prepared from milk, with or without an added fibrous biomass, contained more carbon (particularly aliphatic carbon), less oxygen, and more mineral components than those prepared from fibrous biomass in water. Activated carbons produced from hydrochars generated in milk had lower specific surface areas and CO2 capacities than those from hydrochars formed in water; however, these differences disappeared upon normalizing to the combustible mass of the solid. Thus, in the context of N2 and CO2 uptake on activated carbons, the primary effect of using milk rather than water to form the hydrochar precursor was to contribute inorganic mass that adsorbed little CO2. Nevertheless, some of the activated carbons generated from hydrochars formed in milk had specific CO2 uptake capacities in the normal range for activated carbons prepared by activation in CO2 (here, up to 1.6 mmol g−1 CO2 at 15 kPa and 0 °C). Thus, hydrothermal carbonization could be used to convert waste milk to hydrochars and activated carbons.

This paper aims to design of an active fault-tolerant control AFTC of switched systems in the presence of sensor fault and periodic disturbances. AFTC requires sensor fault estimation. Thus, a databased projection approach is proposed based on performance measures that allow fault estimation without relying on mathematical models and fault assumptions. A new switching control strategy is proposed for fault compensation and recovering the desired performances. These techniques integrate a bank of controllers, corresponding to a set of partial models to design a set of switching control laws, compensating for the fault effect and attenuating the disturbance. A new linear matrix inequality based on Lyapunov stability analysis is proposed to compute control gains. This technique allows finding the optimal values of the control gains matrices, which ensure both sensor fault compensation and disturbance attenuation. A comparative study of the proposed strategy with existing work is carried out to show the effectiveness of the designed fault-tolerant control.