Shoubin Zhang

The Effect of Salinity on Membrane Fouling Characteristics in an Intermittently Aerated Membrane Bioreactor

The effect of salinity on the membrane fouling characteristics was investigated in the intermittently aerated membrane bioreactor (IAMBR). Five different salinity loadings were set from 0 to 35 g·L−1 (referring to NaCl), respectively. The removal of total organic carbon (TOC) and ammonia-nitrogen (-N) was gradually decreased with increasing salinity. The variation of membrane filtration resistance, particle size distribution (PSD), extracellular polymeric substances (EPS), soluble microbial products (SMP), and relative hydrophobicity (RH) analysis revealed that salinity has a significant effect on sludge characteristics in IAMBR. The results also indicated that the membrane fouling is often caused by the integration of sludge characteristics in saline wastewater.

Effect of power ultrasound on crystallization characteristics of magnesium ammonium phosphate

Magnesium ammonium phosphate (MAP) crystallization could be utilized for the recovery of phosphorus from wastewater. However, the effectiveness of the recovery is largely determined by the crystallization process, which is very hard to be directly observed. As a result, a specific ultrasonic device was designed to investigate the crystallization characteristics of MAP under various ultrasonic conditions. The results demonstrated that the metastable zone width (MZW) narrowed along with the rising of the ultrasonic power. Similarly, for the 6mM MAP solution, with the ultrasonic power gradually enhanced from 0W to 400W, the induction time was shortened from 340s to 38s. Meanwhile, the crystallization rate was accelerated till the power reached 350W, and then remained a constant value. It can be observed from the scanning electron microscopy (SEM), the MAP crystal became bigger in size as well as the crystal size distribution (CSD) became broad and uneven, with the increase of ultrasonic power. The results indicate that the crystallization process enhanced by power ultrasound could be used as an effective method to eliminate and recover the phosphorus from wastewater.

The development and challenges of draw solutions for forward osmosis processes

The development of draw solution is of great importance to the industrial application of forward osmosis technology. At present, the draw solutions are defined as two main types. In this study, we summarized the common draw solutions used in FO process after 2000, and detailed the two types draw solutions, responding to commercially available compounds (including volatile compounds, nutrient compounds, inorganic salts and organic salts) and synthetic materials. Introduction Forward osmosis (FO) which is known as osmosis, is a widespread physical phenomenon. It is an osmotically driven membrane separation process without additional pressure [1]. In 1748, French scientist Nollet discovered the phenomenon of osmosis, marking the beginning of the application of forward osmosis technology. Because the forward osmosis process is spontaneous process, it has the advantages of equipment simple, operation easy, energy saving and environmental protection. Since 1860s, reverse osmosis technology has undergone a long time of development, from membrane materials, engineering technology, market development, and eventually become one of the most successful membrane technology. Compared to reverse osmosis, the forward osmosis process application is still in the initial stage of development[2]. Forward osmosis has the advantages of low energy consumption, low pollution, high recovery and so on. Its application range is very extensive, involving industrial production and all aspects of daily life. Forward osmosis technology in seawater desalination, power generation, industrial wastewater treatment, food industry, aerospace industry and the pharmaceutical industry has achieved a certain degree of development[3]. It also has advantages in avellating fouling and low energy consumption, which integration with other technologies can form process of technological innovation. Copyright