Phosphorus Recovery by Struvite Crystallization from Livestock Wastewater and Reuse as Fertilizer: A Review

In China, the intensive livestock farming produces massive livestock wastewater with high concentration of phosphorus. Discharge of these compounds to surface water not only causes water eutrophication but also wastes phosphorus resources for plant growth. Therefore, it’s necessary combining the removal of phosphorus from livestock wastewater with its recovery and reuse as fertilizer. As a valuable slow-release mineral fertilizer, struvite crystallization has become a focus in phosphorus recovery. In this chapter, struvite crystallization mechanism, reaction factors, crystallizers, and the applications of struvite as fertilizer are discussed. Two steps of nucleation and crystal growth for struvite crystallization from generation to growth are introduced. The reaction factors, including molar ratio of magnesium and phosphate, solution pH, coexisting substances, and seeding assist, of struvite crystallization are summarized. Several innovate types of crystallizer, which relate to the shape and size of harvest struvite to realize the phosphorus recycling, are demonstrated. Due to the influence of toxic or harmful impurities in struvite on its reuse as fertilizer, the environmental risk evaluation of struvite application is introduced. In conclusion, struvite crystallization is a promising tool for recovering phosphorus from livestock wastewater

Cereal production trends, nutrient use efficiency and its management practices in agriculture: A review

Boosting global food production to meet the escalating demand without distressing the environment is a major challenge of our time. In the present review study, a-59 years global cereal production and fertilizer use trends, nutrients use efficiency (NUE) and some of its management approaches in agriculture were evaluated. Accordingly, the world cereal production increased by 3.4-fold (876.9 to 2979 Mt) from 1961 to 2019, whereas the area of production increased moderately by 1.11 folds. The chemical N, P2O5, and K2O fertilizer consumption in cereal crop production were increased by 9.45 folds (from 6.9 to 65.2 Mt), 4-fold (from 6.6 to 26.3 Mt), and 4.34-fold (from 5.2 to 22.6 Mt), respectively. The estimated world cereal N, P, and K use efficiency is 33%, 16%, and 19%, respectively. The unaccounted 65% of N, 84% of P and 81% of K fertilizer was either remained in the soil or lost to the environment through volatilization, leaching, and run-offs leading to higher environmental and economic costs. Therefore, improving NUE is a crucial step to enhance crop yields, tackle environmental pollution, reduce production costs. Several NUE management approaches were identified such as soil management (use of organic inputs, 4R nutrient stewardship, adoption of modified fertilizer, root-zone nutrient management, etc.), plant management (growing nutrient use efficient cultivars, crop rotation, and so on), integrated soil-crop system management (ISSM), and application of precision agriculture. However, no single management approach solely resulted in higher NUE but rather the combination. Hence this could be applied in agricultural production to improve yield and NUE while minimizing environmental degradation

Recovery of Phosphorus From Swine Manure by Ultrasound/H2O2 Digestion, Struvite Crystallization, and Ferric Oxide Hydrate/Biochar Adsorption

Swine manure is potentially harmful to the environment but is also a readily accessible local source of phosphorus (P) for agricultural use. Decreasing the environmental impact of swine manure and recovering P from swine manure have been a challenge for a long time. In this study, an integrated process involving ultrasound/H2O2 digestion, struvite crystallization, and ferric oxide hydrate (HFO)/biochar adsorption was used to recover P from swine manure. The ultrasound/H2O2 treatment effectively solubilized the swine manure and converted organic P and other sparingly soluble P species into soluble phosphate. The struvite crystallization process allowed 85% of the available P to be recovered at pH 10.0 using a Mg:P molar ratio of 1.4 and a stirring rate of 150 rpm. HFO was loaded onto biochar synthesized by pyrolyzing ground corncob. The mechanism through which P was adsorbed was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The adsorption of P by the HFO/biochar followed pseudo-second-order kinetics and was primarily controlled by chemical processes. The maximum amounts of P adsorbed were 225.08–242.21 mg/g. Thermodynamic calculations indicated that the adsorption of P was endothermic and spontaneous and increased the degree of disorder in the overall system. P mass balance calculations indicated that 90.4% of the total P was recovered as struvite and P-saturated HFO/biochar

Geminin is partially localized to the centrosome and plays a role in proper centrosome duplication

Background information. Centrosome duplication normally parallels with DNA replication and is responsible for correct segregation of replicated DNA into the daughter cells. Although geminin interacts with Cdt1 to prevent loading of MCMs (minichromosome maintenance proteins) on to the replication origins, inactivation of geminin nevertheless causes centrosome over-duplication in addition to the re-replication of the genome, suggesting that geminin may play a role in centrosome duplication. However, the exact mechanism by which loss of geminin affects centrosomal duplication remains unclear and the possible direct interaction of geminin with centrosomal-localized proteins is still unidentified

Reactivation of Epstein–Barr virus by a dual-responsive fluorescent EBNA1-targeting agent with Zn2+-chelating function

EBNA1 is the only Epstein–Barr virus (EBV) latent protein responsible for viral genome maintenance and is expressed in all EBV-infected cells. Zn2+ is essential for oligomerization of the functional EBNA1. We constructed an EBNA1 binding peptide with a Zn2+ chelator to create an EBNA1-specific inhibitor (ZRL5P4). ZRL5P4 by itself is sufficient to reactivate EBV from its latent infection. ZRL5P4 is able to emit unique responsive fluorescent signals once it binds with EBNA1 and a Zn2+ ion. ZRL5P4 can selectively disrupt the EBNA1 oligomerization and cause nasopharyngeal carcinoma (NPC) tumor shrinkage, possibly due to EBV lytic induction. Dicer1 seems essential for this lytic reactivation. As can been seen, EBNA1 is likely to maintain NPC cell survival by suppressing viral reactivation

An empirical analysis on performance evaluation, performance persistence and discount of closed-end funds in China

This article examines performance evaluation, performance persistence and discount of a sample of 33 closed-end funds in China. The results show that fund managers on average do not exhibit abilities to outperform the market. The performance of balanced funds is in generally better than that of growth funds. We also find some evidence on the performance persistence of market price returns but no evidence on the performance persistence of net asset value returns. The patterns of discount are similar to U.S. empirical results: most of the closed-end funds are initially traded at premiums, and traded at discounts after months. But we cannot isolate factors behind these patterns