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This study evaluated the influence of organic matter (OM) constituents on the potential for recovery of P from wastewaters when FeCl3 treatment is employed for P removal. The presence of OM constituents did not influence P release from Fe‐P sludges when alkaline and ascorbic acid treatments were employed. However, the overall recovery of P from wastewater was impacted by the presence of selected OM constituents through the reduction of P uptake during coagulation. The presence of protein and humic matter showed remarkably low P removal values (3.0 ± 0.4% and 23 ± 1% respectively) when compared to an inorganic control recipe (62 ± 2%). Elevated soluble Fe (SFe) residuals in the presence of proteins (87 ± 5%) and humics (51 ± 1%) indicated interactions between Fe(III) cations and negatively charged functional groups like hydroxyl, carboxyl, and phenolic groups available in these organics. Significant negative correlations between P removal and residual SFe were observed suggesting Fe solubilization by OM constituents was the mechanism responsible for reduced P removal. The findings of this study identify, for the first time, the impact of OM constituents on overall P recovery when Fe(III) salts are employed and provide insights into recoveries that can be expected when Fe is added to primary, secondary treated, and industrial wastewaters. Practitioner Points: Low P removal values were observed for protein and humic dominated wastewater recipes.Iron(III) solubilization counted for P removal reduction by proteins and humic acids.There is no effect of OM on P release from Fe‐P sludge at pH 10 and ascorbic acid treatments.OM and agent employed to release P from sludges affected overall recovery of P. [ABSTRACT FROM AUTHOR]

Environmental context: Dissolved organic carbon (DOC) is ubiquitous in freshwater and concentrations are rising universally while pH is decreasing with climate change. This study demonstrates the interrelationships among DOC characterisation techniques and the pH-sensitive aspects of these techniques that were previously not well understood. As DOC regulates important processes within ecosystems, understanding DOC behaviour at altered pH and identifying techniques to effectively evaluate DOC composition are critical requirements for monitoring aquatic ecosystem health. Rationale: Dissolved organic carbon (DOC) is both ubiquitous and heterogeneous in freshwater. Freshwaters are browning universally and pH values are decreasing with climate change. DOCs influence water pH, whereas changes in water pH potentially alter the conformation and function of DOCs. The physicochemical properties of DOCs can be characterised by optical and chemical indices, but the inter-relationships among them, and the effects of low pH, are not well understood. Methodology: We characterised five naturally sourced DOCs, spanning large differences in origin and composition, at pH 7 and 4, using multiple indices: specific absorbance coefficient at 340 nm, molecular weight index, fluorescence index, octanol–water partition coefficient, molecular charge, proton binding index, size-fractionation, and percentage humic-acid-like, percentage fulvic-acid-like and percentage protein-like components by fluorescence-based parallel factor analysis. Results: Many of the indices changed between pH 7 and 4 as reflected in the corresponding absorbance and fluorescence profiles. Generally, apparent aromaticity, apparent molecular weight and molecular charge all decreased with low pH, while lipophilicity increased. Key positive correlations occurred between aromaticity and apparent molecular weight, chemical reactivity and apparent molecular weight, and aromaticity and chemical reactivity, and a negative correlation between lipophilicity and molecular charge. These relationships were pH dependent. Discussion: Our results highlight that physicochemical indices used to characterise DOCs from distinct sources should consider pH and be interpreted carefully. The pH-dependent changes in many of the indices are likely alterations in the conformation, reflected in the optical signatures, rather than changes in the composition of DOCs. In contrast, increased lipophilicity and reduced charge at lower pH are due to actual changes in DOC molecules, resulting from proton binding. The ecological functions of DOCs are dependent on source and will likely change with natural acidification events such as increasing atmospheric CO2. Environmental context. Dissolved organic carbon (DOC) is ubiquitous in freshwater and concentrations are rising universally while pH is decreasing with climate change. This study demonstrates the interrelationships among DOC characterisation techniques and the pH-sensitive aspects of these techniques that were previously not well understood. As DOC regulates important processes within ecosystems, understanding DOC behaviour at altered pH and identifying techniques to effectively evaluate DOC composition are critical requirements for monitoring aquatic ecosystem health. (Image credit: Carolyn Morris.) [ABSTRACT FROM AUTHOR]

Leptospirosis is a reemerging infectious disease in California. Leptospirosis is the most widespread zoonosis throughout the world, though it is infrequently diagnosed in the continental United States. From 1982 to [...]

The objectives of this study are to compare the chemical properties of organic matter (OM) in alkaline extracts of turkey litter compost, source‐separated organic compost, and biosolid pellets, and to validate the use of humic acids (HAs) for analyzing the functionality (i.e., the ability to complex with nutrients) of OM. The humic fractions, including (HAs), fulvic acids (FAs), and alkaline nondissolved fraction (humin), were isolated either with NaOH or Na4P2O7 (PyroP) and the chemical properties were analyzed by solid‐state 13C NMR spectroscopy. The study showed that the proportions of each functional group of the combination of HAs, FAs, and humin were essentially identical to that of their HCl‐treated original materials, except for a lower recovery of O‐alkyl groups. Although the yield of HAs extracted with PyroP was lower than that with NaOH, their spectral characteristics were not significantly different. The functionality of the OM, assuming a correlation with the sum of the proportions of carboxyl and phenolic groups, was higher in both HAs and FAs than that in humin. Based on the proportion and functionality of the HAs in the OM, we conclude that the use of HAs extracted with either NaOH or PyroP is valid for studies of OM functionality. The study also shows that the functionality and stability of OM are highly source dependent. We predict that amendments of the more humified turkey litter compost would have higher potential to increase SOM levels and retain nutrients compared with the source‐separated organic compost and biosolid pellets. [ABSTRACT FROM AUTHOR]