Hydrochar derived from green waste by microwave hydrothermal carbonization

Microwave-assisted hydrothermal treatments for biomass valorisation: a critical review

“…For example, Nizamuddin et al 64 concluded that the hydrochar yield decreased continuously (from 58.6 to 49.5%) with rising temperature from 160 to 220 ºC during the MA-HTC of rice husk, which is in line with the trends reported in the literature. 56,[65][66][67][68][69][70][71] On the contrary, Gao et al 72,73 demonstrated that the hydrochar yield produced during the MA-HTC of fish waste firstly increased with increased the temperate. It then reached a point after which decreased with further temperature increments.…”

“…The influence of the MA-HTC processing conditions on the HHV of the hydrochar has been assessed by several authors, who concluded that both the reaction conditions and the biomass type significantly influence the HHV of hydrochars. Shao et al 67 revealed that an increase in the MA-HTC process severity (temperature and time) facilitated the production of a hydrochar with a higher HHV. In particular, increasing the temperature (from 160 to 190 o C) rose the HHV of the hydrochar from 17.91 to 23.01 MJ kg −1 with 1 h holding time and 1:8 m/m biomass loading.…”

Green Waste Disposal

“…Processing of green waste would reduce the quantity of green waste reaching dumping sites or burned. Developing sustainable technologies to utilize green waste is attracting attention [8]. Education on proper disposal of waste is essential to raise awareness.…”

A Comprehensive Review on Hydrothermal Carbonization of Biomass and its Applications

“…The vessel is then closed and the reaction mixture is heated at 200-300 °C, 4-6 MPa pressure for 4-12 h. The vessel is then opened and black watery carbon-rich fluid can be obtained inside it, which undergoes further processing steps prior to being used as hydrochar. Recently investigators are using microwave HTC (MHTC) over traditional HTC because of fast processing time and high calorific value (HHV) of hydrochar on similar conditions [141,142]. Several studies have been reported where scientist are using natural microalgae with a high ash content, sewage sludge, dairy manure, Chinese fan palm etc.…”

“…Hydrochar also possesses higher atomic O/C and H/C ratios and reduced carbon recovery, produced at the same operating process temperature [38]. Also, hydrochar prepared by HTC is found to be environment-friendly, and thus it does not generate any hazardous chemical or by-product as other char can [141,142,178]).…”