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 (TiO2) 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 (Na2SO4), calcium hydroxide (Ca(OH)2), and magnesium chloride (MgCl2) 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% TiO2, 0.1 wt% ZnO, 2 wt% dimethyl carbonate, 10 wt% sludge-based biological carbon, 7.5 wt% Ca(OH)2, 0.5 wt% MgCl2, and 6 wt% Na2SO4 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.
Highlights
With the rapid development of construction in urban sewage treatment facilities, the rate of sewage concentrated disposal increased resulting in a sharp increase in dewatered sludge quantity [1,2]
The sludge be rapidly heated promoting theweights, hydrolysis of facilitating the hydrolysis of proteins into polypeptides, dipeptides, amino acids, and other carbohydrates into polysaccharides and monosaccharides with low molecular weights, and facilitating substances thatofare furtherinto hydrolyzed into dipeptides, low molecular organic ammonia, and that carbon the hydrolysis proteins polypeptides, amino acids, acids, and other substances are dioxide
Fat would be hydrolyzed into stearic acid, palmitic acid, and so on
Summary
With the rapid development of construction in urban sewage treatment facilities, the rate of sewage concentrated disposal increased resulting in a sharp increase in dewatered sludge quantity [1,2]. There are a large number of organic matters in the sludge, which usually exhibit different contents and compositions due to the variety of the source of sewage, treatment process, the living standard, and dietary habits of urban residents. Common sludge organic matter with high molecular weight and boiling point often contains twigs, sawdust, small cloth, bacteria, insect eggs, and other components [3]. The high content of organic matter in municipal dewatered sludge is corruptible if the disposition of organic matters is inappropriate, which causes environmental pollution, and brings resource waste.
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