###### Abstract  
This study aimed to utilize a microwave technology to degrade active organic matters of the municipal dewatered sludge in a high-temperature environment. The effects of extraction agent, nanomaterial assistants, and microwave-absorbing agents and activating agents on the degradation efficiency were investigated. Dimethyl carbonate was used as the extraction agent. Nanostructured titanium oxide (TiO\({}_{2}\)) and zinc oxide (ZnO) exhibited effective assistance in the process of microwave treatment. We also developed a kind of microwave-absorbing agent, which was the sludge-based biological carbon. The sodium sulfate (Na\({}_{2}\)SO\({}_{4}\)), calcium hydroxide (Ca(OH)\({}_{2}\)), and magnesium chloride (MgCl\({}_{2}\)) were selected as activating agents to facilitate the organic matter discharging from the sludge. Through optimizing the experimental factors, it was confirmed that 0.1 wt% TiO\({}_{2}\), 0.1 wt% ZnO, 2 wt% dimethyl carbonate, 10 wt% sludge-based biological carbon, 7.5 wt% Ca(OH)\({}_{2}\), 0.5 wt% MgCl\({}_{2}\), and 6 wt% Na\({}_{2}\)SO\({}_{4}\) were the most appropriate addition amounts in the municipal dewatered sludge to make the organic matter decrease from 42.17% to 22.45%, and the moisture content reduce from 82.98% to 0.48% after the microwave treatment. By comparison, the organic matter degradation is almost zero, and the moisture content decreases to 8.69% without any additives. Moreover, the residual inert organic matter and sludge can be further solidified to lightweight construction materials by using liquid sodium silicate as the curing agent. The research provides a significant reference for the effective, fast, and low-cost treatment of the organic matter in the municipal sludge. municipal dewatered sludge; microwave; organic matter +
Footnote †: journal: Applied  
dewatered sludge by degrading the organic matters and explore an effective route to improve the degradation efficiency. Usually, traditional sludge treatment strategies include concentration, dehydration and deweighting, dewatering, anaerobic and aerobic nitrification, pyrolysis, and drying [4; 5; 6; 7]. As is well known, microwave irradiation is a new type of green energy, which contains both electric field and magnetic field. There are thermal effects and nonthermal effects under microwave irradiation, both of which conduct highly efficient treatments for the organic matter, heavy metal, and water in sludge [8; 9]. When the nanostructured materials were irradiated by microwave, the dipole of organic matters surrounded by the nanostructured materials would generate turning-direction polarization. When the direction of the electric field with a high frequency is changed, the polarization direction of the dipole will accordingly alter. In the change process, a lot of heat is produced due to friction among the molecules, resulting in the temperature increase of the municipal dewatered sludge. Thus, the thermal effect of microwave treatment can promote the degradation of the organic matters [10; 11; 12]. At the same time, the nonthermal effect of microwave treatment is more significant. The microwave electric field increases the absorption efficiency and carrier separation of the nanostructured materials, and promotes water removal and formation of free groups. More importantly, the high-frequency electromagnetic waves of microwave radiation can penetrate the extraction medium and reach the vascular bundle and adenocyte system [13]. The temperature inside the cell rises quickly ascribes due to the absorption of microwave energy, leading to cell lysis. Consequently, the active components in the cells flow out freely, which can be captured and dissolved by the extraction medium at a low temperature. Therefore, microwave heating causes greater heating of materials compared with conventional heating methods. Furthermore, microwaves can penetrate inside materials, providing heat from inside to outside, which is advantageous to the volatilization of the water and organic matters.