A new study led by Dr. DUO Jia from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences unveils a novel and environmentally friendly approach to remediating saline-alkali soils using cotton straw, a by-product of agricultural practices. 

The study, published in Waste Management, demonstrates the effectiveness of optimized hydrothermal carbonization (HTC) in transforming agricultural waste into resources that address environmental issues.

The study centers on the sustainable management of agricultural and livestock waste, a critical concern given the pollution and resource wastage often associated with such materials. The researchers designed an experimental process utilizing a central composite design to optimize the HTC process. This process converts readily available cotton straw into valuable hydrochar and liquid products, both with potential for substantial soil improvement.

Under optimal conditions with reaction temperatures of 180-200 °C over 3.5 hours, a liquid-solid ratio of 15 mL/g, and precise process control, they achieved a hydrochar yield of 42.6 wt% with a pH of 5.20, and a fertile liquid phase yield of 57.4 wt% with a pH of 5. This process demonstrated a high model validation accuracy of 98%, indicating robust and reliable optimization.

The researchers found that HTC offers a clear advantage over traditional pyrolysis (Py) methods. HTC generated a significantly lower carbon footprint, with a total environmental impact of -4.9E-05 kg CO2-Eq per kg of cotton straw. This translates to notable reductions across key environmental indicators: global warming potential (29%), ecotoxicity (14%), acidification (24%), and eutrophication (11%).

"Our findings demonstrate that optimized HTC of cotton straw offers a dual benefit: it both valorizes agricultural waste and provides a sustainable, environmentally friendly solution for saline-alkali soil remediation," said Dr. Collins Elendu, first author of the study.

This study not only offers a promising technique for treating and managing agricultural waste, but also paves the way for integrating waste management with sustainable agriculture.