Characterization And Comparison Study On Energy And Fertilizer Related Properties Of Animal Manure In China

Animal manure is an important biomass resource. Effective utilization of animal manure has attracted much attention at the global and national scales, as it could not only reduce the waste disposal costs, alleviate pressures on the environment, but also provide clean energy and help realize the sustainable development of agriculture. Animal manure properties are important for their efficient and safety utilization. This study investigated the difference, variability and correlation of the chemical composition, proximate analysis, ultimate analysis, mineral elements, energy and energy potentials of pig manure, dairy manure, beef manure, layer manure and broiler manure. Near Infrared Spectroscopy technology was used for rapid analysis of the proximate analysis and higher heating value of different animal manures. The characteristics and products of the pyrolysis and combustion of the various types of animal manure were also studied. The main contents and results of this thesis are listed as follows:The energy related properties of the different types of animal manure were highly variable. The enrichment trends obtained for the compositional characteristics between the different animal manures were the following:volatile matter, phosphorus, magnesium, copper and zinc for pig manure; ash and iron for dairy manure; volatile matter and fixed carbon for beef manure; ash, nitrogen, sulfer, potassium, sodium, and calcium for layer manure; and ash, nitrogen, sulfer, potassium and sodium for broiler manure. Principal component analysis results demonstrated that the closest compositional characteristics were between dairy manure and beef manure. The calculated outputs of total potential annual thermal energy, syngas and methane yields from the five types of animal manure in China were 4400.63 TJ,983.40×109 m3 and 188.89×109 m3, respectively.The fertilizer related properties of the various types of animal manure present a wide variation. The enrichment trends obtained for the related fertilizer properties between the various animal manures were the following:phosphorus, available phosphorus, magnesium, copper and zinc for pig manure; kjeldahl nitrogen, ammonium nitrogen, calcium and magnesium for layer manure; dry matter, organic matter, total organic carbon, kjeldahl nitrogen, organic nitrogen, potassium and sodium for broiler manure. Pig, layer and broiler manures exhibited higher fertilizer values than other types of animal manures, with the sum of nitrogen, phosphorus and potassium contents of these manures at approximately 3%. Principal component analysis results showed that similar fertilizer properties were found between dairy and beef manures, and between layer and broiler manures.Near infrared reflectance (NIR) spectroscopy could accurately predict the moisture, volatile matter and higher heating value of pig manure, dairy manure, beef manure and layer manure. One single broad based model could be developed for the prediction of moisture and higher heating value of the various types of animal manure, their separate characterization may be avoided. The fixed carbon prediction models of pig and beef manure had moderate accuracy. The ash prediction models of the various types of animal manure should be improved in the further study.The pyrolysis characteristics parameters and kinetic parameters of the various types of animal manure exhibited wide variations. There were significant differences in the pyrolysis characteristics among the various types of animal manure.Beef manure exhibited better pyrolysis characteristic than the other types of animal manures. The activation energy of the various types of animal manure is in the range of 61.53-100.06 kJ/mol. The pyrolysis characteristics parameters and kinetic parameters of animal manure were significantly correlated with their composition contents. The yield of biochar derived from animal manure at 400℃、550℃ and 700℃ range from 36.78 to 51.42%.The porous texture and nutrient-rich properties of biochars produced from the various types of animal manure could be used as a soil amendment, or as an adsorbent for the removal heavy metal ions from wastewater.The combustion characteristics parameters and kinetic parameters of the various types of animal manure exhibited wide variations. There were significant differences in the combustion characteristics among the various types of animal manure. The combustion characteristics of beef manure were the best. The activation energy of volatile matter and fixed carbon combustion stages is in the range of 61.71-111.72 kJ/mol and 89.53-625.45 kJ/mol, respectively. The combustion characteristics parameters and kinetic parameters of animal manure were significantly correlated with their composition contents. The alkaline index of animal manure was higher than 0.34. The main mineral compounds include Ca9Fe(PO4)7, Ca9MgK(PO4)7, SiO2, KCl, K2SO4, CaCO3 and Ca5(PO4)3(OH).