Comparison and Optimization of Pyrolysis Bio-Oil Composition from Sewage Sludge and Spirulina Microalgae

The abundant presence of spirulina microalgae and sewage sludge led to the researchers pay attention to recycling and economical conversion into valuable materials. This study investigated the simultaneous pyrolysis composition of two materials, spirulina microalgae and sewage sludge and also the factors affecting of the production of bio-oil from them. The effect of temperature, weight ratio of spirulina to SS, and the heating rate was investigated with the help of Design Expert software. Optimal conditions for pyrolysis was obtained at 519.3 °C, the weight ratio of 0.73 and heating rate of 17.9 °C/min and bio-oil production yield also was obtained 69.35%. The heat value of bio-oil was obtained at 25.52 MJ/kg and its energy efficiency was 66.3%. The results showed that with increasing in the temperature, aromatic content that enhance the heat value were increased. Also, by directing the reaction to optimal conditions, the oxygenated and nitrogenous compounds in the bio-oil were reduced. The simultaneous combination of spirulina and SS increases the number of aromatic substances and decreases oxygenated and nitrogenous group spirulina in bio-oils. It is expected to obtain suitable liquid fuel and chemical substances by pyrolysis of various biomasses.