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Shrimp, a most consumed seafood, when processed, results in an enormous generation of wastes. Current ways of shrimp waste utilization are uneconomical and far from being environmentally friendly. Alternative sustainable technologies to utilize shrimp wastes completely are essential. Hydrothermal carbonization (HTC) that converts moisture-rich biomass into hydrochar is mostly employed for pure lignocellulosic biowaste. However, the suitability of HTC to produce good quality hydrochar from pure non-lignocellulosic wastes such as shrimp waste is unknown. Here, for the first time, a response surface design guided optimization of microwave hydrothermal carbonization (MHTC) process parameters, holding temperature (150− 210 °C) and time (60−120 min), showed that a temperature of ∼184 °C and a time of ∼112 min yielded maximal hydrochar (∼42%). The atomic carbon and ash content, and calorific value of hydrochar were ∼39−49%, ∼21−25%, and 18.26−23.22 MJ/ kg, respectively, depending on the MHTC operating conditions. Taken together, these results confirm that MHTC produces hydrochar from shrimp waste of quality comparable to one produced from low-grade lignocellulosic, sewage, and municipal wastes.

Abstract-Eggs are one of the most nutritious foods available in nature. This rich nutritive environment attracts microbes to invade, feed and multiply. Salmonella enteritidis is one such microbe that is highly pathogenic and is the causative agent for the disease salmonellosis. To ensure safety of eggs, processing them without affecting their unique physical properties is essential. In this study, the impact of radiofrequency (RF) heating on the dielectric properties (dielectric constant and dielectric loss factor) of the egg at varying temperatures (5 • C-56 • C) and frequency (10 MHz-3 GHz) is evaluated. This study on the dielectric parameters is essential to devise a better heating paradigm wherein there is minimal detrimental effect to the egg components. Based on the dielectric study, the heating process parameters were determined. The effect of such heat treatment on the physical properties viz. Viscosity, foam density, foam stability and turbidity of the egg white were also studied. This study was conducted to provide sufficient literature and experimental background for employing RF in pasteurization of in-shell eggs. This study showed that if careful process parameter optimization and meticulous equipment design is done, RF heating can be successfully employed to pasteurize in-shell eggs.

Hydrothermal carbonization (HTC) is a promising technique that converts wet biomass into a coal-like material and has a wide application to the fields of energy, material science, and nanotechnology. HTC has been primarily used to treat a limited number of feedstocks, mainly lignocellulosic biomass such as wood. Recently, the HTC process has been utilized to treat high-moisture-containing complex waste streams, a mixture of lignocellulosic and nonlignocellulosic biomass, such as sewage and municipal waste. However, there is limited knowledge on the effectiveness of HTC on purely nonlignocellulosic industrial waste like seafood waste. Processing of seafood generates enormous amounts of waste in the form of solid residues and liquid effluents. Currently there is a demand for attractive seafood waste utilization strategies that minimize environmental pollution while recovering products that are of commercial interest to the industry. In this study, we have devised one such strategy where seafood waste is pretreated by enzymatic hydrolysis for subsequent HTC to produce hydrochar and biocrude liquor. Enzyme hydrolysis conditions including enzyme concentration, incubation time, and enzyme ratios were carefully optimized for maximal hydrolysis of seafood waste. By using an enzyme cocktail of Viscozyme, Lipase, and Protease, it was found that an enzyme ratio of 1:1:1 (w/w/w), and an enzyme concentration of 10−20% with a treatment time of 16 h, resulted in maximal hydrolysis of fish and shrimp waste. Subsequently, hydrochar and biocrude liquor were generated from hydrolyzed fish and shrimp waste by microwave hydrothermal carbonization (MHTC) using a high-pressure Mini WAVE Digestion Module (SCP Science, Canada) with quartz vessels at conditions of 150 °C for a 1 h reaction time. The results of this study show for the first time that MHTC can be successfully employed to produce valuable products from pure nonlignocellulosic waste like seafood waste. This would pave the way for effective utilization of other moisture-rich nonlignocellulosic industrial wastes.

Shrimp is among the most consumed seafood across the world. Shrimp-processing operations generate enormous quantities of waste. Current strategies of shrimp waste management and the current utilization strategies suffer from several disadvantages, especially from being not environmentally friendly. This warrants alternate methods to completely utilize shrimp waste. Previously, we have shown that microwave hydrothermal carbonization (MHTC) can be used to treat shrimp waste to produce hydrochar. In this study, conventional hydrothermal carbonization (CHTC) using a customized autoclave reactor was performed to treat shrimp waste. Upon using response surface design, it was found that at a holding temperature of 186 °C and a time of 120 min, a maximal hydrochar yield of ∼29% was achieved. Furthermore, characterization results of elemental, proximate, energy, and surface properties of CHTC shrimp waste hydrochar were found to be comparable to that of the MHTC hydrochar from shrimp waste. In addition, the hydrochar properties were comparable to those produced from other wastes such as low-grade lignocellulosic waste and mixed wastes. This study further confirms that nonlignocellulosic wastes such as shrimp waste could be used as a biomass to produce hydrochar by HTC irrespective of the heating medium used.