Bioenergy derived from PABR sludge through hydrothermal liquefaction: effects of temperature

Presently, clean and renewable energy sources, that don't have any adverse impacts on the environment, are the basic requirement for sustainable development. In this context, bioenergy generation from sludge through hydrothermal liquefaction (HTL) has been recognized as a promising approach since it reduces the waste volume, effectively utilizes the resources, recovers energy, and eliminates pathogens. In addition, this approach can solve both energy crisis and sludge management problems by introducing a sustainable pathway of bioenergy generation. The present work investigated the effect of temperatures on HTL products (biochar and biocrude) of sludge derived from a photo anoxic baffled reactor (PABR). The FTIR analysis indicated the biochar samples contain aliphatic amine, aromatic nitrile, and n-methyl amino compounds, which may be used to make fertilizers. On the other hand, biocrude consisted of hydrocarbon, esters, aldehydes, and ketone compounds. Additionally, the peaks for biocrude sample at 280 ° is similar to biocrude samples heated at 260°C with long-chain alkyl hydrocarbons (at wavenumber ranges from 2916-2936 cm-1, 2845-2975 cm-1, 1360-1390 cm-1, 1415-1475 cm-1), but the peak intensity for the biochar sample increased around 10 to 25% for all the functional groups due to the increases of temperature. So, the optimum thermal condition for producing high-quality biochar and biocrude could be achieved at 280 ° temperature. Thus, the sludge-to-energy approach would be a sustainable pathway for achieving the UN's sustainable development goal (SDG 7).