The present paper aims to introduce a novel and environment-friendly sludge dewatering method based on the osmotic technique, and to examine the efficiency of this method from macro- and micro-points of view. Intact sample, taken from the primary settler of a local wastewater treatment plant in Guangzhou (China), was firstly dewatered by mechanical methods (i.e. vacuum filtration and centrifugation), then by the osmotic technique. Macroscopic experimental results show that: the vacuum filtration and centrifugation can only dewater the sludge from 94.5 to 78.3% and to 78.8%, respectively, whereas, using the osmotic technique, water content of the sludge can be decreased to 44.2% in 12 h and to 35.9% in about two days. The micro-structure, obtained by scanning electron microscope (SEM), shows that: the sludge samples after vacuum filtration and centrifugation have a porous structure and water can be drained either through the cracks that have been developed under the vacuum pressure or by the micro-pores of several micrometers that have been created under the disturbance of the centrifugal force; on the other hand, in the case of the osmotic technique, the samples show a much denser structure, where both the macro- and micro-pores are significantly decreased or even closed at high concentration of the polyethylene glycol (PEG) solution. At last, the future application of the osmotic technique in practice is discussed from the viewpoints of deep dewatering and energy consumption.

The southern tropical coastal areas of China are high-temperature and high-humidity salt environments, which hinder the durability and service life of ordinary asphalt pavement. To enhance the durability of asphalt pavement in these areas, modified bagasse fiber combined with nano-TiO₂ was used to improve the corrosion resistance of asphalt pavement in high-temperature and high-humidity salt environments. The micro-morphology, high-temperature oil absorption, high-temperature heat resistance, and hygroscopicity of bagasse fiber modified using three silane coupling agents combined with NaOH were compared, and the best silane coupling agent/NaOH modification scheme for bagasse fiber was found. Based on conventional physical tests (penetration, softening point, ductility), rheological property tests (rotational viscosity, dynamic shear rheological test, multi-stress creep recovery test, linear amplitude scanning test), and a four-point bending fatigue test of the asphalt mixture, the properties of modified bagasse fiber asphalt binder and mixture after cyclic dry–wet erosion under pure water and salt solution (NaCl, Na₂SO₄) were determined, and the effects of the erosion environment and fiber ratio on the basic physical and rheological properties of the asphalt were clarified. Compared with the silane coupling agents KH550 and KH590, the bagasse fiber modified with KH570/NaOH had a better high-temperature oil absorption capacity, heat stability capacity, and matrix asphalt compatibility. The worst erosion environment was Na₂SO₄, but the increase in test temperature and fiber content weakened the sensitivity of the asphalt binder performance in different erosion environments. The erosion capacity order was as follows: Na₂SO₄ > NaCl > pure water. In the worst erosion environment, 0.5% modified bagasse fiber/Nano-TiO₂ asphalt binder (B_{n−570−0.5}) had the best corrosion resistance in a high-temperature and high-humidity salt environment. The penetration, softening point, creep recovery rate R_3.2, non-recoverable creep compliance J_nr3.2, and fatigue life after long-term aging (with 5% strain) of B_n-570-0.5 were, respectively, increased by −16.9%, 37.5%, 37.95%, −27.86%, and 38.30% compared with unblended base asphalt binder (B). In addition, the four-point flexural fatigue life of B_n-570-0.5 was 169.2% higher than that of the unblended base mixture.