Study on Effects of Hydrothermal Heat Treatment Method on Fertilizer Efficiency of Biomass Waste

Abstract

This study explores a new way of utilizing biomass waste as fertilizer based on the hydrothermal heat treatment method. Hydrothermal heat treatment was carried out on common biomass waste, including corn stalks, livestock manure, and vegetable waste. by heating them to 120°C and then to 240°C respectively, while measuring the contents of organic matter, total nutrients, and humus in hydrothermal solid products. The experimental results are as follows. With the increase in temperature, the pH of three kinds of biomass waste hydrothermal products is reduced to different degrees. The content of organic matter in the solid products of corn stalk increased with the increase of temperature, the content of organic matter in the hydrothermal products of vegetable waste was opposite to that of corn stalk, and the content of organic matter in the hydrothermal solid products of pig manure was higher than 30% at different temperatures. The total nutrient content of the hydrothermal product of corn stalk decreased first and then increased with the increase of temperature, and reached the minimum value of 10.12 g/L at 180°C. The total nutrient content of the solid product of vegetable waste showed a negative correlation with temperature, and the total nutrient content of the raw material of pig manure was 60.55 g/kg. The total nutrient content of solid products after different hydrothermal temperature treatments was 41.8–59.03 g/kg, which was lower than that of raw materials. With the increase of temperature, the humic acid content of the solid product of corn stalk first increased and then decreased, the humic acid content of hydrothermal product of pig manure continued to increase with the increase of temperature, and the humic acid content of hydrothermal product of vegetable continued to increase with the increase of temperature. At 210°C, the contents of humic acid and fulvic acid reached the maximum, and the humification rate reached the maximum of 0.856.