Kinetics and capacities of non-reactive phosphorus (NRP) sorption to crushed autoclaved aerated concrete (CAAC).

With growing interest in resource recovery and/or reuse, waste materials have been considered a promising alternative for phosphorus (P) adsorption because they are low-cost and easily accessible. Crushed autoclaved aerated concrete (CAAC), as representative construction waste, has been extensively studied for P removal in ecological technologies such as treatment wetlands. However, most of the previous studies focused on the adsorption of orthophosphate, namely reactive phosphorus, and lacked attention to non-reactive phosphorus (NRP) which is widely present in sewage. This study presents the first investigation on the potential and mechanism of CAAC removing four model NRP compounds. Adsorption isotherm and kinetics of NRP onto CAAC indicate that the removal of NRP was a chemisorption process and also involved a two-step pore diffusion process. The desorption experiment shows that different NRP species showed varying degrees of desorption. Most NRP was irreversibly adsorbed on CAAC. Among the model compounds considered in this study, the adsorption capacity and hydrolysis rate of organophosphorus were much less than that of inorganic phosphorus. Moreover, the adsorption of different NRP species by CAAC in the mesocosm study was different from the results of laboratory adsorption experiments, and the possible biodegradation was essential for the conversion and removal of NRP. The findings confirmed the validity of CAAC for NRP removal and the potential advantages of CAAC in terms of costs and environmental impact. This study will contribute to a better understanding of NRP conversion and environmental fate and that can be the basis for a refined risk assessment.

Evaluation of phosphorus removal in floating treatment wetlands: New insights in non-reactive phosphorus.

Excess phosphorus (P) in surface runoff has significant deleterious impacts on water quality through eutrophication. Commonly, P is transported via non-point pollution and the proportion of easily plant-available reactive P (RP) among other P forms may vary significantly. Non-reactive P (NRP) can potentially contribute to the eutrophication of waterbodies, however the cleavage into bio-available P forms and eventually their biological uptake remains uncertain. This holds also true for floating treatment wetlands (FTWs) which became established as nutrient mitigation measures for surface waters in recent years. However, little information is available about the conversion and removal of NRP in FTWs. In this study, the conversion and removal of different forms of P in FTWs were investigated. Experiments were operated in batch mode and treatments consisted of (1) two concentration levels: a high P concentration of 3.0 mg/L and a low P concentration of 1.0 mg/L, and (2) four mesocosm treatments: (a) artificial roots only, (b) substrates only, (c) plants only, (d) plants and substrates. The results showed that RP removal mainly depended on sedimentation, substrate sorption, and biological assimilation. The removal of NRP mainly depended on hydrolysis, microbial-mediated conversion, and biological absorption. The combination of plant and substrate provided stable and efficient phosphorus removal performance in high P conditions, while plants were important for P removal in low P conditions. Living plants were indispensable and greatly affected the performance of FTWs. The specific enrichment and culling of microorganisms by plants resulted in the formation of specific rhizosphere microbial communities and promoted the removal of NRP. Pseudomonas, Enterobacter, Acidovorax might be responsible for P mineralization in the FTWs. Comprehensive analysis indicated that the conversion and removal pathways of P in the FTWs were not mutually independent, and the plant-microbe-substrate interactions cannot be underestimated.

A long-wavelength ultrasensitive colorimetric fluorescent probe for carbon monoxide detection in living cells.

Exploring techniques for monitoring the intracellular signaling molecule carbon monoxide (CO) in biosystems is important to help understand its various cellular functions. Therefore, a simple long-wavelength colorimetric fluorescent probe LW-CO was designed for selectively and sensitively detecting intracellular CO in living systems. Probe LW-CO is ultrasensitive and can track CO levels in the range of 0-1 µM, with a detection limit of about 3.2 nM. Additionally, the obvious color changes of probe LW-CO with CO (yellow to pink) provide a convenient way for on-site detection of CO with the naked eye. Probe LW-CO was applied to track the exogenous levels of CO in RAW264.7 cells. Probe LW-CO proved to be an efficient method for investigating various cellular functions of CO.