About 1.6 billion tons of food are wasted worldwide annually, calling for advanced methods to recycle food waste into energy and materials. Anaerobic digestion of kitchen waste allows the efficient recovery of energy, and induces low-carbon emissions. Nonetheless, digestion stability and biogas production are variables, due to dietary habits and seasonal diet variations that modify the components of kitchen waste. Another challenge is the recycling of the digestate, which could be partly solved by more efficient reactors of anaerobic digestion. Here, we review the bottlenecks of anaerobic digestion treatment of kitchen waste, with focus on components inhibition, and energy recovery from biogas slurry and residue. We provide rules for the optimal treatment of the organic fraction of kitchen waste, and guidelines to upgrade the anaerobic digestion processes. We propose a strategy using an anaerobic dynamic membrane bioreactor to improve anaerobic digestion of kitchen waste, and a model for the complete transformation and recycling of kitchen waste, based on component properties.

Due to their unique characteristics, Lanthanides series (15 elements) together with scandium and yttrium are used as critical metals in numerous applications such as energy sources, catalysts, hybrid cars, medical technology, and military industry. The significance of rare earth elements has been continuously increasing because the global demand for producing high-tech devices is continuously rising. The recovery of rare earth oxide from concentrate based on eudialyte and steenstrupine was performed using a hydrometallurgical and pyrometallurgical method. Eudialyte and steenstrupine are a complex Na-Ca-zirconosilicate mineral containing rare earth elements (REEs), Zr, Hf and Nb, thus serving as a potential source of Zr. Because of the presence of silica in eudialyte, the main challenge in its processing is avoiding silica gel formation, which is an unfilterable solid residue. The influence of leaching temperature, time and solid-liquid ratio on leaching efficiency was studied in laboratory conditions. A new research strategy was developed in order to recover rare earth elements using hydrochloric acid, avoiding silica gel formation.

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China's industrial and economic development over the past 20 years has particularly affected the provinces on the east coast of China. The absolute focus of development has been the Greater Shanghai region and the Yangtze delta area. This development was accompanied by a high demand for drinking water and industrial water and a correspondingly high volume of wastewater. The inadequate treatment of wastewater from municipalities, industry and agriculture led to a significant deterioration in the quality of water resources. This applies in particular to Lake Tai, the most important regional water resource in the greater Shanghai area. In the summer of 2007, Lake Tai developed very strong eutrophication for the first time, so that the water could no longer be used for drinking water supply for a time. Due to the massive expansion of wastewater treatment with nutrient elimination that has taken place in the meantime, the conditions have improved somewhat.With the 13th Five-Year Plan of the Chinese government, water protection has gained special political significance since 2016. This included much stricter targets for the water quality of sensitive waters such as Lake Tai. As a result, Jiangsu Province, to which a large part of the lake catchment area belongs, issued new requirements for wastewater treatment. These are specified in the "Discharge Standard of Main Wastewater Pollutants for Municipal Wastewater Treatment Plant & Key Industries of Taihu Lake Area". This also applies to the nutrient elimination requirements for the treatment plants in the lake catchment area. Previously, two categories of wastewater treatment plants were considered: Category I wastewater treatment plants with less than 50% industrial wastewater and Category II wastewater treatment plants with more than 50% industrial wastewater. Since May 2018,