Thermal Chemistry Characteristics Analysis Of Sewage Sludge And Products Of Low Temperature Pyrolysis Experiment

In urban China, the wastewater generation rates in major Chinese city are increasing by speed of 15% per year.The main component of which is organic matter, thus making them a predominantly renewable energy source. During the exploration for many years, low temperature pyrolysis is considered as more advantages and a huge potential.In this work, it studied the sewage sludges from treatment factory that deal with wasterwater with biological processes. Its objective is to evaluate the characteristics of sewage sludge through proximate analysis, elements analysis, and thermogravimetric analysis by thermal gravitational analysis apparatus, metal content analysis by ICP-AES. Then, Pyrolysis of sewage sludge was investigated under inert conditions in a tube furnace to study the effects of temperature and diameter of sludge particle on the product yield distribution and composition. As the results show:From the results from the proximate analysis and elements analysis, the results show a high concentration of organic oxygen for the sewage sludge studied, with 47.52% values and carbon content with values around of 35.66% and the calorific value is 16.61MJ/kg. The large amount of oxygen suggests a high number of polar compounds were present in the sludge. The high value obtained for the H/C ratio indicates a high content of aliphatic hydrogen in these wastes, suggesting the presence of long chains with CH2 groups. All of these characteristics account for that sewage sludge is a very important pyrolysis material. The thermogravimetric analysis show, with the increase of temperature, the mass percentage is fall down and the highest decreasing range is about 40%. The higher the last temperature is, the more decreasing range is and the lower the last temperature is, the less decreasing range is. As to three kinds of sweage sludges with different diameter, chars after pyrolysis are 58%,56%,52%, separaterly. These data from ICP-AES appears that 5 of 11 mentals in sample are beyond the normal range compared to sludge from other areas. Pyrolysis technology can fix the mentals into the char to prevent second pollution.Pyrolysis of sewage sludge was investigated under inert conditions in a tube furnace to study the effects of temperature and diameter of sludge particle on the product yield distribution and composition. The temperature ranged from 250 to 700℃and the sludges was divided into three group according to diameter: 1-0.5mm, 0.5-0.2mm and≤0.2mm. A maximum of 32% oil yield was achieved at a pyrolysis temperature of 450℃and particle diameter of 0.5-0.2mm. The oil composition was analyzed using GC-MS to determine the main components under different condition. The compounds identified in three oils can be grouped into the following classes: Monoaromatic compounds, Aliphatic compounds, Aliphatic compounds, Oxygenated hydrocarbons, Nitrongenated compounds, Steroid, halide, Heterocyclic compound with nitrogen, PAHs. The paper studies the characteristics of pyrolysis products for the probability of these products as fuel and application in industry.Through these analysises and experiments, the data from this article can contrubite for the utilization of sweage sludge in this area and making policies for treating sweage sludge.