A review of struvite crystallization for nutrient source recovery from wastewater.

Nutrient recovery from wastewater not only reduces the nutrient load on water resources but also alleviates the environmental problems in aquatic ecosystems, which is a solution to achieve a sustainable society. Besides, struvite crystallization technology is considered a potential nutrient recovery technology because the precipitate obtained can be reused as a slow-release fertilizer. This review presents the basic properties of struvite and the theory of the basic crystallization process. In addition, the possible influencing variables of the struvite crystallization process on the recovery efficiency and product purity are also examined in detail. Then, the advanced auxiliary technologies for facilitating the struvite crystallization process are systematically discussed. Moreover, the economic and environmental benefits of the struvite crystallization process for nutrient recovery are introduced. Finally, the shortcomings and inadequacies of struvite crystallization technology are presented, and future research prospects are provided. This work serves as the foundation for the future use of struvite crystallization technology to recover nutrients in response to the increasingly serious environmental problems and resource depletion.

Ultrasonic power combined with seed materials for recovery of phosphorus from swine wastewater via struvite crystallization process.

Recovering P via struvite crystallization is an effective way to utilize the resources in swine wastewater. At present, the main challenges of traditional struvite crystallization process are the long reaction time and insufficient removal efficiency. In this study, a novel method to promote struvite crystallization process through ultrasound (US) combined with seed materials is proposed to overcome these defects. We systematically study the effects of US, seed materials, and ultrasonic power on nutrient recovery. The experimental results show that under the conditions of pH 9.5 and MgCl2:P molar ratio1.4:1, the addition of 2 g/L pre-synthesized struvite as the seed materials can increase the P removal rate to 91.56%, whereas, the addition of 80 W ultrasonic power for 15 min can make the P removal rate reach 94.18%. Meanwhile, the combination of US and struvite seed crystals can achieve a maximum P removal efficiency value of 97.66% in which 10 min for the reaction time is enough. The products are characterized using XRD, SEM, and FTIR to determine the phosphorus removal mechanism of ultrasonic power combined with seed induction. The shearing effect of US is found beneficial to affect the surface morphology of the seed crystals, which provides more nucleation sites to enhance crystal nucleation and growth. The removal efficiency comparison reveals that this combined technology performs an excellent removal effect.

Use of Haploid Model of Candida albicans to Uncover Mechanism of Action of a Novel Antifungal Agent.

Antifungal agents for the treatment of Candida albicans infections are limited. We recently discovered a novel antifungal small molecule, SM21, with promising in vivo activity. Herein, we employed the newly developed C. albicans haploid toolbox to uncover the mechanism of action of SM21. Comprehensive RNA-Seq analyses of the haploid susceptible GZY803 strain revealed significant gene expression changes related to mitochondria when exposed to SM21. Mitochondrial structure visualization and measurement of ATP generation, reactive oxygen species (ROS) levels, and the antioxidant potential of SM21-treated and untreated GZY803, mitochondrial structure defective haploid mutant (dnm1Δ), and wild-type diploid SC5314 strains confirmed defects in mitochondria. Exploiting the advantage of C. albicans haploids as a single ploidy model, we further exposed GZY803 to repetitive treatments of SM21 in order to generate resistant mutants. Three colonies designated S3, S5 and S6, which displayed resistance to SM21, were isolated. All resistant strains exhibited enhanced transcriptomic responses for peptide and protein metabolism and secreted aspartate proteases (SAPs) activity under SM21 treatment compared to the parent strain GZY803. Consistently, supplementing the resistant strains, GZY803, and SC5314 with peptone, a form of digested peptides, decreased susceptibility to SM21. The present study demonstrates the usefulness of haploid C. albicans model in antifungal drug discovery. The findings will be invaluable to develop SM21 as a novel antifungal agent, which will benefit millions of patients suffering from Candida infections.