Influence of palygorskite addition on biosolids composting process enhancement

Abstract

Mineral addition is considered to be one of the effective methods for the organic waste composting management. The aim of this study was to investigate the potential effect of palygorskite addition on the composting treatment of biosolids. Four dosages of palygorskite (0, 2, 5, and 10%, by dry weight) were added to a mixture of biosolids and sawdust and aerobically composted for 52 days on a pilot scale. The results showed that the addition of palygorskite extended the duration of the thermophilic phase, reduced salinity, and promoted detoxification of the compost. Moreover, the addition of palygorskite accelerated the decomposition of organic matter, reduced the volatilization of ammonia, and increased the total Kjeldahl nitrogen content. Treatment with 2, 5, and 10% palygorskite had a positive effect, reducing peak gaseous emissions by 51.24%, 67.54%, and 73.76% for CH4, and by 34.50%, 47.34%, and 53.32% for N2O, respectively. Additionally, the addition of palygorskite reduced the contents of DTPA-extractable Cu, Zn, Pb, and Cd in the compost, and enhanced the degradation of estrogen during composting. The results suggest that a proportion of 2% palygorskite is recommended for biosolids composting, and employing the palygorskite additive in biosolids composting has great potential on resource and nutrient recycling.