The US annually produces 79 million dry tons of liquid organic waste including sewage sludge.Anaerobic digestion can only reduce the sludge volume by 50% in mass, leaving the other half as a growing waste management and hygienic problem. Hydrothermal Processing (HTP), a set of several chemical digestion processes, could be employed to convert sewage sludge into valuable products and minimize potential environmental pollution risks. Specifically, hydrothermal carbonization and hydrothermal liquefaction have been extensively studied to sustainably manage sludge. Two of the main reasons for this are the high upscaleability of HTP for public waste management and that it is estimated that HTP can recover eleven times more energy from waste products than landfilling. An integration of HTP with anaerobic digestion or recycling the soluble organics (in the HTP aqueous products) into the HTP process could lead to a higher overall rate of energy recovery for municipal sewage sludge.

Microplastic pollution represents a side-effect stemming from a global plastic waste mismanagement problem and includes degraded particles or mass produced plastic particles less than 5 mm in largest dimension. The small nature of microplastics gives this area of pollution different environmental concerns than general plastic waste in the environment. The biological toxicity of particles, their internal components, and their surface level changes all present opportunities for these particles to adversely affect the environment around them. Thus, it is necessary to review the current literature surrounding this topic and identify areas where the study of microplastic can be pushed forward. Here we present current methods in studying microplastics, some of the ways by which microplastics affect the environment and attempt to shed light on how this research can continue. In addition, we review current recycling methods developing for the processing of mixed-plastic waste. These methods, including hydrothermal processing and solvent extraction, provide a unique opportunity to separate plastic waste and improve the viability of the plastics recycling industry.

Conformal coating is typically composed of polymeric film and is used to protect delicate electronic components such as printed-circuit boards. Without removing conformal coating, it would be difficult to repair these complicated electronics. Methylene chloride, also called dichloromethane (DCM), has a widespread usage in conformal coating stripper products. The high toxicity of DCM increases human health risk when workers are exposed to DCM during the conformal coating removal processes. Therefore, the replacement of DCM would be beneficial to greatly improve the overall safety profile for workers in the electronics and coating industries. This research identified and evaluated alternative chemicals for replacing DCM used in acrylic conformal coating stripping operations. The solubility of an acrylic conformal coating was measured and characterized using Hansen solubility parameters (HSP) theory. Coating dwell time tests using various solvent blends verified the accuracy of the created HSP solubility sphere. A data processing method was also developed to identify and screen potential alternative solvent blends in terms of safety, toxicity, and cost-effectiveness. The identified safer solvent blends were demonstrated to provide equivalent stripping performance as compared to DCM based coating strippers within an acceptable cost range. The results of this research will be of value to other types of conformal coatings, such as silicone and polyurethane, where DCM is commonly used in similar coating stripping operations. By safely removing conformal coating, delicate electronics would be available for re-manufacturing, enabling a circular economy.

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