Experimental Research On The Disposal Of Domestic Waste By Supercritical Water Oxidation

China's population hits almost 13 billion, annual output reached over 1 billion ton, and growth rate increase progressively at around 8% of the high speeds every year. Facing the overrun condition of waste, we must take powerful measures, treatment and comprehensive utilization of waste. But the composing of garbage is complex and hard by biodegradation. Traditional treatments to domestic waste (landfill,compost and incineration) are not efficient and clean enough and easy to cause secondary pollution. Therefore, it is necessary to seek for a new method to dispose waste.First,Supercritical water oxidation of domestic waste in a tank reactor with oxygen as an oxidant was studied under the conditions of temperature 367℃～420℃,different carbon content with adding activated carbon and excess oxygen coefficient from 2 to 7. The impacts of carbon dioxide generation rate were investigated. Results show that the carbon dioxide generation rate reaches above 80% at the temperature higher than 400℃,pressure higher than 23MPa,excess oxygen coefficient over 3,resident time longer than 1 minute. And activated carbon which changes the carbon content in domestic waste can improve the carbon dioxide generation rate over 10%.Activated carbon show good catalytic. Reaction temperature is the main factor.Second, elemental migration mechanisms of Carbon, Nitrogen and Sulfur were investigated. Results show carbonous yield increases in gas productions, decreases in solid residues and keeps stable in liquid products with improving of the temperature. Nitrous yields of NO,NO₂,NH₃ and HCN are close to zero, a part of Nitrogen generates to nitrous oxide. Sulfur is converted into sulfate with the level of 5%-30%, emissions of SO₂ and SO₃ approximate to zero. Experiments find that activate carbon enhances waste's oxidation and N₂O can be reduced by adding activated carbon. SCWO is a kind of clean and high efficiency treatment to waste.At last, based on review of relevant literatures and test data,supercritical water oxidation and incineration are compared.Result shows: Domestic waste generated less acid gas by SCWO than incineration. Dioxins can be producted by waste incineration,but dioxins will be decomposed or disappear in supercritical water oxidation(SCWO). Method of SCWO can recover more heavy metals from domestic waste . In a word, SCWO is more safe and cleaner than incineration.Carbon dioxide generation rate reaches above 80% by SCWO,activate carbon enhances waste's oxidation and N2O can be reduced by adding activated carbon. Conforming to the idea of unharming,reducing and reusing of wastes.microwave pyrolysis technology could also be used for solid wastes treatment, which indicates its promising prospect.