Phosphorus Release Research Articles

Isolation of the inorganic phosphorus-solubilizing bacteria Lysinibacillus sphaericus and assessing its role in promoting rice growth.

Soluble phosphorus scarcity severely limits plant growth and crop yield. In this study, a strain of inorganic phosphorus-solubilizing bacteria, Lysinibacillus sphaericus, was isolated from rice rhizosphere soil. The available phosphorus content in liquid inorganic phosphorus identification medium and in L. sphaericus-inoculated soil increased from 204.28mg/L to 1124.68mg/L and from 4.75mg/kg to 7.04mg/kg, respectively. The pH decreased significantly from 6.87 to 6.14. Incubation with L. sphaericus significantly increased malic and succinic acid content in the liquid inorganic phosphorus identification medium and increased acid phosphatase and alkaline phosphatase activity in the soil. Inoculation with L. sphaericus significantly increased rice growth, chlorophyll a/b content, and photosynthesis by increasing the soluble phosphorus content in the rice rhizosphere soil under phosphorus-deficient conditions. Further analysis revealed that L. sphaericus improved soil phosphorus release by decreasing soil pH and promoting acid phosphatase and alkaline phosphatase activity. This study supports the production of microbial fertilizers to improve rice yield in phosphorus-deficient conditions.

The efficiency of enhanced nitrogen and phosphorus removal in a vertical flow constructed wetland using alkaline modified corn cobs as a carbon source

Adding carbon sources to constructed wetlands can improve nitrogen removal efficiency. Modifying plant biomass can solve problems such as excessive release of nitrogen, phosphorus, and organic matter in the initial stage and insufficient carbon supply in the later stage. This article utilized alkali-modified corn cob as a carbon source to construct vertical flow constructed wetlands and to study the carbon release characteristics of alkali-modified corn cob, as well as its removal effect on organic matter in wastewater. The results indicated that the solid-to-liquid ratio in the alkali modification process of corn cob was 1:10, and it was found that the best treatment method for alkali modified corn cob was to use a sodium hydroxide concentration of 2%, a treatment time of 12 h, and a temperature of 20 °C. Its surface roughness increases, which is beneficial for releasing carbon sources and promoting the growth of microbial attachment. Furthermore, the porosity also increases and. Intermittent aeration could significantly enhance the removal of NH4+-N, and TP in constructed wetlands. The average removal rates of NH4+-N and TP were 60.93% and 89.50%, respectively, and the average removal rates of COD, NO3--N and TN were 60.67%, 98.38% and 83.73%, respectively. At the same time, alkali-modified corn cobs were used as carbon sources. It can effectively remove NO3--N and promote denitrification in constructed wetlands.

Phosphorus release and distribution in sediment resuspension systems under disturbing conditions

The resuspension of phosphorus (P) in sediments has the most significant contribution to the overlying water. The PP release characterization during resuspension was investigated. The results indicated that the P in suspensions had more release risk compared to the sediments. The particulate P (PP) concentration (0.54 mg L−1) under high-intensity rotational speed (250 rad min−1) was about five times higher than others (0.11 mg L−1). The sorption parameters of zero equilibrium P concentration (EPC0F) and soluble reactive P (SRP) were significantly correlated with each other (p < 0.01, r = 0.73). Suspended solids expressed stronger P source than sediments. The values of EPC0F was highly significantly correlated with the sorption coefficient (KF) and native adsorbed P (NAP) (p < 0.01). The mean values of NAP were 0.0612 mg g−1 and 0.0604 mg g−1 in the Prophase and Metaphase, respectively, and 0.0586 mg g−1 at Anaphase. The values of P sorption index (PSI) ranged from 0.4359 to 0.6862 L g−1, with mean values of 0.5350 L g−1 (Prophase), 0.6061 L g−1 (Metaphase), and 0.4967 L g−1 (Anaphase). The degree of P saturation (DPS) decreased in the order of Anaphase (2.73%) > Prophase (2.53%) > Metaphase (2.12%). The release risk index of P (ERI) decreased in the order of Anaphase (5.47%) > Prophase (4.72%) > Metaphase (3.59%), with a range of 2.12%–8.56%. To fast and slow scale, the results of NaOH–P (V1<0, V2>0) contribution indicated that the persistent disturbance promoted the release of adsorbed dissolved PP from NaOH–P in suspended sediment to the overlying water. The contribution of HCl–P (V2 > 0) was positive in the Anaphase of the slow scale, and HCl–P was a PP source in the frequently disturbing conditions.

Effect of Phosphate Rock Powder, Active Minerals, and Phosphorus Solubilizing Microorganisms on the Phosphorus Release Characteristics of Soils in Coal Mining Subsidence Areas

Effect of Phosphate Rock Powder, Active Minerals, and Phosphorus Solubilizing Microorganisms on the Phosphorus Release Characteristics of Soils in Coal Mining Subsidence Areas

Deciphering the crop-soil-enzyme C:N:P stoichiometry nexus: A 5-year study on manure-induced changes in soil phosphorus transformation and release risk

Carbon:nitrogen:phosphorus (C:N:P) stoichiometry plays a vital role in regulating P transformation in agriculture ecosystems. However, the impact of balanced C:N:P stoichiometry in paddy soil, particularly regarding relative soil P transformation, remains unknown. This study explores the response of C:N:P stoichiometry to manure substitution and its regulatory role in soil P transformation, along with the associated release risk to the environment. Based on a 5-year field study, our findings reveal that replacing 30 % of chemical P fertilizer with pig manure (equal total NPK amounts with chemical P fertilizer treatment, named CFM) increased soil total C without altering soil total P, resulting in an elevated soil C:P ratio, despite the homeostasis of crop stoichiometry. This increase promoted microbial diversity and the accumulation of organic P in the soil. The Proteobacteria and Actinobacteria produced lower C:PEEA metabolism together, and enhanced in vivo turnover of P. Additionally, by integrating high-resolution dialysis (HR-Peeper), diffusive gradients in thin films (DGT), DGT-induced fluxes in the soil (DIFS), and sediment P release risk index (SPRRI) models, we observed that, in addition to organic P, CFM simultaneously increased soil Al-P, thereby weakening the diffusion and resupply capacity of P from soil solids to the solution. Consequently, this decrease in P release risk to the environment was demonstrated. Overall, this study establishes a connection between crop-soil-enzyme C:N:P stoichiometry, soil microorganisms, and soil P biogeochemical processes. The study further evaluates the P release risk to the environment, providing a novel perspective on both the direct and indirect effects of manure substitution on soil P cycling.

Seasonal hypoxia enhances sediment iron-bound phosphorus release in a subtropical river reservoir

Dams worldwide commonly accelerate the eutrophication of reservoirs. While the seasonal hypoxia in deep reservoirs is widely acknowledged, there is limited research on its impact on benthic phosphorus (P) cycling and P fraction release from the reservoir sediments. Here we show that seasonal hypoxia enhances sediment P release and P fluxes at the sediment-water interface (SWI) which might alter P dynamics in deep reservoirs. We conducted a detailed measurement of sediment P fractions through the SEDEX approach, combined with a labile P gradient analysis using the diffusive gradients in thin films (DGT) technique to understand P cycling patterns in sediments during the transition period from spring (oxic) to late summer (hypoxic) conditions. The sediment P pool was predominantly composed of iron-bound phosphorus (Fe−P, 76–80 %), primarily due to the widespread occurrence of lateritic red soil (rich in Fe2O3/MnO2) in subtropical areas. More organic-P was observed in summer compared to spring. A significant increase in labile P occurred at the depth of 0–4 cm and 0–1 cm in spring and summer, respectively, where sediment P release was primarily governed by the reduction of Fe−P and the generation of S2−. A higher apparent fluxes of phosphate across the SWI were observed in summer characterized by higher temperature and lower oxygen levels. The current results suggest that seasonal hypoxia was a crucial factor affecting P cycling and diffusion in deep reservoirs. These findings present important implications for the ecology and management of the watershed-coast ecosystem.

Assessment of three different approaches for integrating phosphorus recovery from sewage sludge and derived products in existing wastewater treatment plants

Three different technological solutions, namely acidogenic fermentation and chemical extraction (alkaline or acidic), followed by precipitation with 1% Ca(OH)2, were investigated in the view of integrating phosphorus recovery into existing wastewater treatment plants. Experiments were conducted at the lab-scale using (i) sludge taken from biologically and chemically promoted phosphorus removal activated sludge processes and (ii) ashes obtained from sludge muffle incineration. Results highlighted the benefits of enhanced biological phosphorus removal (EBPR) systems rather than chemically promoted phosphorus removal in not only phosphorus extraction (up to 40% with EBPR) and recovery directly from secondary sludge (P precipitation between 66 and 92%), but after sludge incineration as well (P extraction up to 96% and precipitation above 96%). Acidogenic fermentation ensured the highest phosphorus release from EBPR sludge (equal to a concentration in solution of 122 mg/L P-PO43−), while the derived ashes had a lower level of metal contamination (particularly Fe and Al content < 2%). The phosphorus-rich product obtained by means of the recovery process showed relevant metal contamination (Cu, Zn, and Ni) under some operating conditions, suggesting the need for further treatments.

Effects of pH-varying thermal modification on sewage sludge: A focus on releasing nitrogen- and phosphorus-containing substances

Sewage sludge is promising for the recovery and utilisation of nutrient components, but its complex nature hinders the release of these components. The combination of pH and thermal modifications shows promise for the release of nutrient components from sludge. However, comprehensive studies on the full spectrum of pH levels and corresponding mechanisms of pH-varying thermal modification are lacking. In this study, the main nutrient components, physicochemical properties, molecular structure, and noncovalent interactions of sludge were comprehensively investigated through pH-varying thermal modification (within a pH range of 2.0 to 12.0 under the same thermal condition). The experimental results showed that the release of main organics, particularly nitrogen (N)-containing organics, was well-fitted, with a tick-like function (R2: 0.74–0.96). The thermal protons exhibited a notable accumulative mutagenic effect on the N-containing organics release, while the thermal hydroxyl ions had a more direct effect, as revealed by the changes in multivalent metals and molecular structures with the protonation–deprotonation of carboxyl groups. The driving force for the release of N-containing organics was identified as the fluctuation of electrostatic interactions at the solid–liquid interface of the sludge. However, the release of phosphorus (P)-containing substances exhibited a contrasting response to that of N-containing substances with varying pH, likely because the reaction sites of thermal protons and thermal hydroxyl ions for P-containing substances were different. Moreover, high concentrations of thermal protons and hydroxyl ions collapsed the Lifshitz–van der Waals interactions of sludge, resulting in a decrease in viscoelasticity and binding strength. These propositions were further confirmed through statistical analyses of the main indicators of the main nutrient components, physicochemical properties, and noncovalent interactions of sludge. These findings can provide a basis for optimising characteristic-specific methods to recovery nutrient components (N/P) from sludge.

An Air-Stable Storage Compound for White Phosphorus: Reversible Addition to a Stannylene and Chemical Release of P4.

Controlled insertion into a single P-P bond of white phosphorus (P4) was achieved by employing a diaryl stabilized stannylene, Ar*2Sn (Ar*=2,6-bis(benzhydryl)-4-iPr-phenyl). Conversions of the stannylene with P4 gave a non-pyrophoric, air-stable storage compound, which releases P4 quantitively upon irradiation with light (354 or 455 nm). Alternatively, the phosphorus cage is detached by reacting the storage compound with PhChChPh (Ch=Se, Te). Despite the recent advances in the directed conversion of P4 using main group element compounds, Ar*2Sn constitutes only the second structurally characterized example of a stannylene capable of performing controlled, reversible addition and release of white phosphorus.

Control of phosphorus release from sediment by the combined use of Elodea nuttallii, hydrous ferric oxide, zeolite and calcite: Efficiency, mechanism and response of bacterial communities

The effectiveness of Elodea nuttallii combined with a mixture of hydrous ferric oxide, zeolite and calcite (HZC) to reduce the internal loading of phosphorus (P) from sediment and its mechanism were studied, and the effect of Elodea nuttallii combined with HZC on the composition and function of the microbial communities in the surface sediment was also investigated. The results showed that the combination utilization of Elodea nuttallii and HZC can decrease the risk of phosphorus liberation from sediment to the overlying water, and the controlling efficiency of Elodea nuttallii combined with HZC was higher than that of Elodea nuttallii or HZC alone. The passivation of labile P measured by diffusive gradient in thin film device and mobile P played a crucial role in the control of internal P loading from sediment by the combined Elodea nuttallii + HZC treatment. HZC capping had a promoting effect on the growth of Elodea nuttallii. This was beneficial to the absorption of phosphorus from sediment by Elodea nuttallii. The combined application of Elodea nuttallii and HZC not only had a certain negative effect on the diversity of bacteria in the surface sediment, but also changed the microbial compositions of the surface sediment at the levels of phylum and genus. However, the microbial communities in the surface sediment still can perform good ecological function. The above results suggest that the combined application of Elodea nuttallii and HZC has a high potential in the management of internal P loading from sediment.

PSIII-17 Comparative assessment of New Generation Phytase (HiPhorius vs. Ronozyme HiPhos in growing-finishing pigs

Abstract The aim of the present study was to evaluate the effect of HiPhorius (DSM-Firmenich), a new generation of phytase with improved temperature and pH stability, as a replacement of Ronozyme HiPhos (DSM-Firmenich) on performance of growing-finishing pigs fed corn and soybean meal-based diet. A total of 1,200 growing pigs [PIC genetics, with average initial body weight (BW) = 26.8 ± 0.6 kg] were divided into 60 pens, with each pen consisting of 20 pigs and equal number of gilts and barrows. Each pen within a location block was randomly assigned to one of 4 dietary treatments consisting of 2 sources of phytase (Ronozyme HiPhos and HiPhorius) at a low or a high level of available Phosphorus release (AvP, 0.15 and 0.19% respectively). To achieve a low (0.15%) or high (0.19%) AvP, 1,000 or 2,000 FYT/kg of Ronozyme HiPhos was used respectively. To achieve the same levels of AvP, a decreased inclusion of HiPhorius was used (600 and 1,000 FYT/kg for the low and high AvP, respectively). A five-phase feeding program was utilized until pigs reached market weights. All performance data were analyzed using GLIMMIX procedure in SAS (SAS 9.4, SAS Institute Inc., Cary, NC) in a randomized complete block design with initial body weight as covariate. Least squares means were compared using Fisher’s LSD (P &amp;lt; 0.05). Overall (d 0 to d 92), there were no differences observed in any of the performance parameters [final BW, average daily gain (ADG), average daily feed intake (ADFI), gain to feed ratio (G:F] regardless of the dietary treatments provided (P &amp;gt; 0.20). There were also no differences in mortality and removals (P &amp;gt; 0.20) and in final weight variation (P &amp;gt; 0.20). In summary, using a reduced inclusion rate of HiPhorius (600 and 1,000 FYT/kg) resulted in similar overall growth performance as growing-finishing pigs fed Ronozyme HiPhos at 1,000 and 2,000 FYT/kg, respectively. The present study confirms the improved efficacy of the new generation phytase (HiPhorius) compared with Ronozyme HiPhos.

70 Determination of phosphorus release of Microtech phytase in nursery pig diets

Abstract A total of 320 barrows (DNA 241 × 600; initially 10.7 ± 0.21 kg) were used in a 21-d growth trial to determine the available P (aP) release curve for Microtech phytase (Guangdong VTR Bio-Tech Co, Ltd. Zhuhai, Guangdong, China). At approximately 21 d of age, pigs were weaned and randomly allocated to pens and fed a common diet for 18 d and then fed a P depletion diet (0.11% aP) for 3 d. On d 21 post-weaning, considered d 0 of the study, pigs were blocked by average pen body weight (BW) and randomly allotted to 1 of 8 dietary treatments with 5 pigs per pen and 8 pens per treatment. Dietary treatments were derived from a single basal diet and ingredients including phytase, monocalcium P, limestone, and sand were added to create the treatment diets. Treatments include 3 diets with increasing aP (0.11, 0.19 and 0.27%) using monocalcium phosphate that were used to develop the standard curve and 5 diets with 0.11% aP and increasing phytase (250, 500, 1,000, 1,500 and 2,000 FTU/kg) that were used to develop the aP release curve. Pigs were weighed weekly and feed disappearance was recorded per pen for the calculation of average daily gain (ADG), average daily feed intake (ADFI) and gain to feed ratio (G:F). At the conclusion of the experiment, 1 pig, closest to the mean weight of each pen, was euthanized for bone analysis. The right fibula, rib, and metacarpal were collected for the determination of bone density, bone ash weight, and bone ash percentage. Pigs fed diets with increasing aP from inorganic P had improved (quadratic, P ≤ 0.05) final BW, ADG, and G:F (Table). Pigs fed diets with increasing phytase had linearly increased (P &amp;lt; 0.01) final BW and ADFI and quadratically increased (P ≤ 0.04) ADG and G:F. Bone density, bone ash weight, and bone ash percentage increased linearly (P &amp;lt; 0.01) with increasing aP from inorganic P and increasing phytase. Results were used to determine release values for Microtech phytase for each response criteria as shown in the table. The aP release quadratically increased (P ≤ 0.02) with increasing phytase when growth performance was used as response criteria and linearly increased (P &amp;lt; 0.01) when bone characteristics were used as response criteria. The available P release curve developed for Microtech phytase for percentage bone ash using combined data generated from all three bones is: aP = (0.868 × FTU/kg) ÷ (9,599.511 + FTU/kg).

Spatial and Temporal Changes in Nutrient Source Contribution in a Lowland Catchment Within the Baltic Sea Region Under Climate Change Scenarios

AbstractCurrently, climate change is considered as an important factor affecting nutrient loads introduced through riverine systems into the Baltic Sea. Although the prospect of a large increase in pollution has long seemed very real, it still does not translate into planning of effective remedial actions. One of the factors limiting the development of such activities is the scale of simulations, focusing generally on catchment outlet profiles. To fill this gap and enable a step forward in understanding responses toward future predictions in a higher resolution scale (subcatchment), we assessed nutrient load contribution using calculation profiles localized along a main watercourse and its tributaries. To track spatial and seasonal changes of total nitrogen and phosphorus for the Wełna River (central Poland), we used climate change data and the SWAT model. Having at our disposal a catchment model with a good performance we could follow not only total load changes in particular subcatchments, but also track localization of the pollution sources and their direct impact on load estimations. Our results showed an increase of the loads, especially from the agricultural land use type, up to 34% for TN and 85% for TP, in the most extreme scenario. Moreover, forest areas have been noted as highly reactive to climate change, and through their localisation are able to distinctly alter nutrient outflow. Finally, the contribution of urban areas should be further investigated since the dynamics of nitrogen and phosphorus release from impervious surfaces is noticeably different here than from the other diffuse sources.

Environmental dynamics of nitrogen and phosphorus release from river sediments of arid areas

Environmental dynamics of nitrogen and phosphorus release from river sediments of arid areas

Control of phosphorus release from sediment by iron/aluminum co-modified zeolite: efficiency, mechanism, and response of microbial communities in sediment.

The efficiency of iron/aluminum co-modified zeolite (FeAl-Z) covering and amendment for controlling the internal loading of phosphorus (P) from sediment to the overlying water (OW) and its controlling mechanism were explored. The response of the composition of sedimentary microbial communities in sediment and their function to the FeAl-Z capping and amendment was also examined. FeAl-Z showed good removal performance for phosphate in aqueous solution. The maximum phosphate adsorption quantity for FeAl-Z at pH 7 attained 11.2mg P/g. The release of sediment endogenous phosphorus to OW can be successfully restrained by the FeAl-Z covering and amendment, and the suppression ability of FeAl-Z covering was stronger than that of FeAl-Z amendment. Under the capping or amendment condition, FeAl-Z can effectively inactivate the labile phosphorus measured by diffusion gradient in thin film (DGT-LP) in the overlying water and surface sediment. The added FeAl-Z transformed redox-sensitive phosphorus (BD-P) to metal oxide-bound phosphorus (NaOH-IP) and residual phosphorus (Res-P) in sediment, which increased the stability of inorganic phosphorus in the sediment. The passivation of soluble reactive phosphorus (SRP) and DGT-LP in the surface sediment by FeAl-Z significantly contributed to the inhibition of sediment endogenous phosphorus release to OW by the FeAl-Z capping, and the passivation of SRP, DGT-LP and mobile phosphorus in the surface sediment played a pivotal role in the control of sediment internal phosphorus release by the FeAl-Z amendment. The FeAl-Z amendment and capping did not increase the liberation risk of Fe from sediment, and the microorganisms in the sediments under the conditions of FeAl-Z amendment and covering still can perform good ecological functions. Results of this research demonstrate that FeAl-Z capping has high application potential in the control of phosphorus transfer from sediment to OW.

Release of phosphorus and metal(loid)s from manured soils to floodwater during a laboratory simulation of snowmelt flooding.

Phosphorus (P) and metal accumulation in manured agricultural soils and subsequent losses to waterways have been extensively studied; however, the magnitudes and the factors governing their losses during spring snowmelt flooding are less known. We examined the P and metal release from long-term manured soil to floodwater under simulated snowmelt flooding with recent manure additions. Intact soil columns collected from field plots located in Randolph, Southern Manitoba, 2 weeks after liquid swine manure treatments (surface-applied, injected, or control with no recent manure addition) were flooded and incubated for 8 weeks at 4± 1°C to simulate snowmelt conditions. Floodwater (syringe filtered through 0.45µm) and soil porewater (extracted using Rhizon-Mom samplers) samples were periodically extracted and analyzed for dissolved reactive phosphorus (DRP), pH, zinc (Zn), manganese (Mn), iron (Fe), magnesium (Mg), calcium (Ca), and arsenic (As). Mean floodwater DRP concentrations (mg L-1) for manure injected (2.0±0.26), surface-applied (2.6±0.26), and control (2.2±0.26) treatments did not differ significantly. Despite manure application, DRP loss to floodwater did not significantly increase compared to the control, possibly due to the elevated residual soil P at this site from the long-term manure use. At the end of simulated flooding, the DRP concentrations increased by 1.5-fold and 5-fold in porewater and floodwater, respectively. Metal(loid) concentrations were not affected by manure treatments in general, except for Zn and Mg on certain days. Unlike DRP, where porewater and floodwater concentrations increased with time, metalloid concentration in porewater and floodwater did not show consistent trends with flooding time.

Management of eutrophication using combined the “flock &amp; sink” mitigation technique and submerged plants restoration: a mesocosm study

Abstract Currently, the issue of eutrophication and cyanobacterial blooms persists in water bodies worldwide, prompting the exploration of various treatment methods. This study conducted a comparative analysis of eutrophic water bodies using ferric chloride-modified zeolite (FMZ) and calcium hydroxide-modified zeolite (CMZ) combined with Elodeanuttallii (E. nuttallii) for removal and purification effects. The results revealed that the addition of E. nuttallii had a sustained inhibitory effect on phosphorus release, maintaining stability with lower Turbidity(Tur) and stabilized pH within the range of 8.5-9. FMZ demonstrated rapid reduction in dissolved phosphorus concentration, achieving a removal rate of 96% within 3 days. The combined plant group of CMZ and FMZ exhibited synergistic effects with E. nuttallii, achieving an impressive total phosphorus (TP) removal rate of 80.13% and a total nitrogen (TN) removal rate of 48.77%. Additionally, chlorophyll a (Chl a) concentration decreased from 100.74 ± 24.72 μg/L to 49.96 ± 2.08 μg/L. The phytoplankton community composition indicated that diatoms thrived in low temperatures and high NH4 conditions. Under the same low Total Nitrogen to Total Phosphorus (TN:TP) ratio, high TP concentrations were associated with cyanobacteria dominance, while green algae dominated in other scenarios. This comprehensive approach demonstrates the potential efficacy of CMZ and FMZ combined with E. nuttallii in addressing eutrophic water bodies and mitigating cyanobacterial blooms.

Chronic increasing nitrogen and endogenous phosphorus release from sediment threaten to the water quality in a semi-humid region reservoir

The water quality in the drinking water reservoir directly affects people's quality of life and health. When external pollution input is effectively controlled, endogenous release is considered the main cause of water quality deterioration. As the major nitrogen (N) and phosphorus (P) sources in reservoirs, sediment plays a vital role in affecting the water quality. To understand the spatial and temporal variation of N and P in the sediment, this study analyzed the current characteristics and cumulative effects of a semi-humid reservoir, Yuqiao Reservoir, in North China. The N and P concentrations in the reservoir sediment were decreased along the flow direction, while the minimum values were recorded at the central sediment profile. External input and algal deposition were the main factors leading to higher sediment concentrations in the east (Re-E) and west (Re-W) areas of reservoir sediment profiles. According to the long-term datasets, the peaks of both sediment total nitrogen content and deposition rate were observed in the 2010s, which has increased about three times and six times than in the1990s, respectively. Therefore, the increase in phosphorus concentration may be the main reason for eutrophication in water in recent years. The mineralization of organic matter has a significant promoting effect on releasing N and P from sediments, which will intensify eutrophication in water dominated by P and bring huge challenges to water environment management. This study highlights that the current imbalance in N and P inputs into reservoirs and the endogenous P release from sediment will have a significant impact on water quality.

Phosphorus Release Dynamics from Ashes during a Soil Incubation Study: Effect of Feedstock Characteristics and Combustion Conditions

Recovering phosphorus (P) through combustion from waste streams, like wastewater sludge and animal manure, offers a promising solution. This research explores the P release patterns in different ashes derived from secondary raw materials, using a long-term soil incubation lasting 160 days. The study evaluated the P release dynamics in five types of ashes from enhanced biological phosphorus removal (EBPR) systems and pig slurry burned at different temperatures. According to the results, a primary effect was observed on P bioavailability during the initial incubation period. All tested ashes release more than 50% of the total P applied between days 5 and 10. Ashes from EBPR exhibited higher P release than those from pig manure, indicating ash origin as a key factor in P release. Additionally, combustion temperature was crucial, with higher temperatures resulting in increased P release rates. Furthermore, the Pearson correlation revealed a strong relationship between the characteristics of the ashes and the amount of P release. Overall, these findings suggest that ashes could be a valuable P-source for agriculture avoiding the process of wet chemical P extraction, thus reducing both economic and environmental costs.

How to develop a bio-based phosphorus mining strategy for eutrophic marine sediments: Unlocking native microbial processes for anaerobic phosphorus release

This study examined the anaerobic release of phosphorus (P) from two different Baltic Sea sediments (B and F), focusing on the impact of initial concentration of externally introduced waste-derived volatile fatty acids (VFA) as the carbon source, temperature, pH, and mixing conditions. The first batch bioreactor set was operated to demonstrate the effect of VFA on anaerobic P release at different concentrations (1000–10000 mg/L as COD) at 20 °C. A notable P release of up to 15.85 mg/L PO4–P was observed for Sediment B at an initial carbon concentration of 10000 mg COD/L. However, VFA consumption in the bioreactors was minimal or no subsequent. The second batch bioreactor set was carried out to investigate the effect of temperature (20 °C-35 °C), pH (5.5, 7.0 and 8.5) and mixing conditions on P release by introducing lower initial carbon concentration (1000 mg COD/L) considering the potential risk for VFA accumulation in the bioreactors. Maximum P releases of 4.4 mg/L and 3.5 mg/L were for Sediment B and Sediment F, respectively. Two-way ANOVA tests revealed that the operation time and pH and their interactions were statistically significant (p < 0.05) for both sediments while the effect of mixing was not statistically significant. Most of the sulfate was reduced during batch bioreactor operation and Desulfomicobiaceae became dominant among other sulfate-reducing bacteria (SRB) possibly shows the importance of SRB in terms of anaerobic P release. This study gives an insight into future implementations of phosphorus mining from eutrophic environment under anaerobic conditions.