Graphene oxide-induced variations in the processing performance, microbial community dynamics and heavy metal speciation during pig manure composting

Graphene oxide (GO) addition is a simple, cost effective, and efficient way to accelerate compost maturation, however, little research focused on the mechanism of GO-based aerobic composting. The present study aimed to determine the effects of GO on the physicochemical and biological characteristics during pig manure composting. Four treatments were conducted with the addition of GO (0, 0.1 %, 0.25 % and 0.5 % dry weight of the composting mass, respectively). Results showed that the GO addition effectively promoted physicochemical parameters and compost maturity, and particularly improved the seed germination index (GI), with 0.25 % GO addition had the highest GI of 112% at the end of composting. The GO addition also significantly improved the organic matter degradation and reduced nitrogen loss. Beneficial properties of GO optimized composting environment, accelerated the process of composting and facilitated microbial growth during the composting process. The contents of exchangeable Cu and Zn significantly were reduced by GO addition after composting, and the 0.5 % GO respectively contributed 74.86 % and 43.05 % of the Cu and Zn passivation. Generally, 0.25 % GO addition was beneficial for microbial growth and compost maturity, while 0.5 % GO addition effectively reduced nitrogen loss and the heavy metals mobility during the composting process.