Slow pyrolysis as a measure for rapidly treating cow manure and the biochar characteristics

Abstract

It is imperative to develop an innovative method for quickly treating the large volume of cow manure produced in intensive cow farms in China, particularly in Inner Mongolia. In this study, cow manure was slowly pyrolyzed at different temperatures (300°C, 400°C, 500°C, and 700°C for 2h) and with retention times (0.5h, 1h, and 2h at 400°C). The results showed that pH, electrical conductivity (EC), basic functional groups, and aromaticity enhanced, but both carboxyl functional groups and aliphaticity decreased when temperature increased from 300°C to 500°C and retention time increased from 0.5 to 1h at 400°C. However, most of these parameters of the collected biochars changed little when temperature increased from 500°C to 700°C and retention time increased from 1h to 2h at 400°C, implying that the pyrolysis reached to relative stable status. These results suggested that the slow pyrolysis might be as a rapid measure for treating cow manure and producing biochar. The proper pyrolysis conditions could be 500°C for 1–2h, considering the relative high and stable characters of the harvested biochar. Further work is necessary to determine the impacts of the biochar on soil quality while used as a soil conditioner.