Release Of Soluble Phosphorus Research Articles

Effects of Dissolved Organic Matter on the Release of Soluble Phosphorus and Fluoride Ion from Phosphate Ore

Unreasonable storage of phosphate ore is becoming an important pathway causing phosphate pollution in the surrounding aquatic environment. However, there is little research on the influence of dissolved organic matter (DOM) in water on the fate of phosphate ore. Here, we collected phosphate ores from two phosphate mines along the coast of Tanglang River and studied the effects of DOM concentrations and pH on the release of soluble active phosphorus (SRP) and fluoride ion (F−) from phosphate ores using humic acid (HA) as the representative of DOM. Based on the analysis of ZP, FTIR, XPS, and SEM, the influence mechanism of HA was revealed. The results showed that HA efficiently promoted the release of SRP and F− from phosphate ore. With decreasing pH, the P release increased in both water and HA solutions in general. The beneficial influence of HA on the release of SRP and F− from phosphate ore was ascribed to the introduction of oxygen-containing functional groups by HA, which altered the surface properties and enhanced the dispersion stability of phosphate ore. These findings provided new insights into the dispersion behavior of phosphate ore, which is helpful in promoting the pollution control and management strategy of phosphate ore.

An investigation of the effects of humic acid on soil erosion and loss of phosphorus from soil to runoff: Experiment and modeling

Phosphorus (P) transport from soil to runoff is affected by the chemical adsorption of P by organic matter, or clay minerals. However, little information is available on the relative effects of different clay minerals on P adsorption in the presence, or absence of humic acid (HA). To achieve this objective, a rainfall erosion experiment was carried out in a cylindrical glass container with a basal area of 45 cm2. The experiment used four soil mixtures, namely kaolinite mixed soil (KMS), montmorillonite mixed soil (MMS), kaolinite mixed soil treated with HA (KMS-HA), and montmorillonite mixed soil treated with HA (MMS-HA), to analyze the influence of HA on soil erosion and loss of P. The experimental results showed that the cumulative loss of clay was highly significantly (p < 0.01) correlated with HA. The total loss of clay from KMS-HA and MMS-HA was five times and 1.7 times that from KMS and MMS, respectively. The results of the experiments showed that the addition of HA had a significant (p < 0.05) impact on the loss of soluble phosphorus (SP), and particulate phosphorus (PP) from the KMS, respectively, but did not significantly influence the SP and PP cumulative loss from the MMS. Temporal variation and inter-relationship of clay, SP, and PP in the soil matrix and runoff, as well as total organic carbon (TOC), were simulated using an integrated P transport model. The values for the coefficient of determination (R2, all greater than 0.73) indicated that the transport model performed well. The results of the experiments and simulations showed that there was competition between P and HA for adsorption onto clay particles, especially for kaolinite, resulting in the release of more SP and PP to runoff. This highlights why more attention needs to be given to HA in nutrient loss management.

Effects of drying and rewetting on soluble phosphorus and nitrogen in forest floors: An experiment with undisturbed columns

AbstractDrying and rewetting (D/W) of soils often resulted in the release of soluble phosphorus (P) and nitrogen (N), thereby changing the availability of both nutrients. Most experiments on D/W have been conducted with disturbed mineral soil samples and with rewetting of the soil samples by abrupt change in the water potential. Here, we studied the effect of D/W on the leaching of P and N from undisturbed forest floors of a European beech and a Norway spruce site under near field conditions of desiccation and rewetting. We hypothesized that even under realistic rewetting of undisturbed forest floors, the leaching of P and N is increased after D/W and that the effects are less pronounced for spruce than for beech because of the larger hydrophobicity of the spruce forest floor. Undisturbed forest floor columns were subjected to desiccation at 20°C until a matrix potential of –100 MPa (pF 6.0) was reached, while controls were kept at moist conditions. Columns were irrigated by 22 mm day−1 from day 1–3 and by 10 mm day−1 from day 4–14 given in automated short pulses. Leachates from the soil columns were analyzed for orthophosphate, total P, NH4, NO3, and total N. In the spruce forest floor the concentrations of total P in leachates and the leachate fluxes were strongly increased after D/W. The increase of solute P was less for beech than for spruce coinciding with less actual rewetting of the beech forest floor. Leaching of total N from the spruce forest floor was not affected by D/W, however, concentrations and leaching of NH4 increased, while leaching of NO3 decreased. For beech the leaching of total N and NH4 increased after D/W, while NO3 leaching decreased. The results indicate that also under realistic conditions, D/W of forest floors increases solute P and leads to changes in the ratio of NH4/NO3 in solution, thereby altering the availability of the nutrients.

Release of soluble phosphorus through biodegradation of poultry litter by Bacillus

Release of soluble phosphorus through biodegradation of poultry litter by Bacillus

Long term in-line sludge storage in wastewater treatment plants: the potential for phosphorus release

Phosphorus removal in on-site wastewater treatment plants is normally obtained by chemical precipitation. Aluminium-based chemicals are the favoured coagulants as they are not affected by redox potential. On-site wastewater treatment package plants do not have separate sludge treatment facilities, and sludge is normally collected on an annual basis. This can potentially increase the risk of phosphorus release into the water phase, subsequently reducing treatment efficiency. This study aimed to detect release of phosphorus as a result of chemical and biological processes. Variables in the study were time, aluminium dosage and pH. Wastewater sludge was monitored for 46 weeks to investigate the different mechanisms of phosphorus release and the longevity of the aluminium treatment involving varying aluminium dosages. Phosphorus compounds were analysed based on a modified Psenner sequential fractionation method. Both pH and aluminium dosage affect the longevity of the phosphorus retention of chemically precipitated wastewater sludge, where sufficient longevity is obtained with pH control and increased aluminium dosages. Chemical dosages similar to what is considered normal levels are sufficient to retain the phosphorus in the sludge for annual sludge collection intervals. Release of soluble phosphorus was attributed to microbial activity and crystallization of Al-hydroxide complexes.

Factors controlling the distribution of aquatic macrophyte communities with special reference to the rapid expansion of a semi-emergent Phalaris arundinacea L. in Bibi River, Hokkaido, northern Japan

To identify the causes of the rapid expansion of the semi-emergent Phalaris arundinacea L. community in a nutrient-loaded river, we investigated the factors that determine the distribution of the Phalaris and other aquatic macrophyte communities and the shoot growth of P. arundinacea. The Phalaris community was distributed through areas with high organic nitrogen (Org-N), total phosphorus (T-P), PO4-P and suspended solids (SS) concentrations and low dissolved oxygen (DO). P. arundinacea shoots grow better in deep mud and high SS and T-P, all of which were strongly correlated with slower stream currents. Accordingly, although the concentration of total nitrogen constantly increased from 1985 to 1998, the determining nutrient for the expansion of the Phalaris community and P. arundinacea shoot growth stimulation was phosphorus rather than nitrogen. The Phalaris community increased rapidly between 1991 and 1996, when brief but prominent loadings of phosphorus were observed. We concluded that the Phalaris community was restricted due to phosphorus deficiency under nitrogen excess until 1991 and subsequently rapidly expanded over the channel due to the temporary excess phosphorus present during this period. Thereafter, the rapid expansion of the Phalaris community was maintained by the clogging effect of the floating mats formed by shoots and their remains of P. arundinacea, which results in slower currents. A slower current resulted in low DO, the sedimentation of degraded plant remains (high Org-N), and the adsorption of phosphorus by suspended matter (high SS and T-P). The anaerobic conditions caused by low oxygen and the accumulation of decomposable organic matter ensure the continuous development of the Phalaris community through the release of soluble phosphorus from the sediment.

Hydrolysis and acidification of waste activated sludge at different pHs

The effect of pH from 4.0 to 11.0 on the hydrolysis and acidification of waste activated sludge (WAS) was investigated. Experimental results showed that at room temperature the sludge hydrolysis was in the following order: alkaline>acidic>(neutral and blank test), and between pH 6.0 and 11.0 the sludge hydrolysis increased with pH. The three main components, soluble protein, carbohydrate and volatile fatty acids (VFAs) in the hydrolytic product were analyzed. It was observed that both the soluble protein and carbohydrate increased with pH in the pH range 7.0–11.0, but also increased to a smaller extent with pH from 7.0 to 4.0. The VFAs concentration was also affected by pH. Under alkaline conditions, the VFAs production was significantly higher than under other conditions. The concentration of VFAs on the 8th day of fermentation at pH 4.0, 7.0 and 10.0 was, respectively, 354.49, 842.00 and 2708.02 mg/L, while VFAs in the blank test was only 633.59 mg/L. The VFAs consisted of acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acids, but acetic, propionic and iso-valeric were the three main products. Also, the release of soluble phosphorus and ammonia and the production of methane was studied during WAS fermentation at different pHs.

The effect of steeping on soluble phosphorus levels in wheat, wheatfeed and soyabean meal

Much of the phosphorus in feed ingredients is unavailable to the pig because it is locked up in phytic acid and phytates, which the pig cannot digest. Raw ingredients that have not been heat-treated contain endogenous phytases which can be activated by steeping in water prior to inclusion in liquid feed for pigs. This results in an increase in soluble phosphorus due to the hydrolysis of phytic acid and phytates, and hence an increase in the phosphorus available to the pig. However, with heat-treated ingredients such as soyabean meal (SBM) endogenous enzymes are destroyed during processing. In liquid feed systems steeping combinations of raw materials may have an advantageous affect on the availability of phosphorus as the endogenous phytases of the cereal component of the diet may hyrolyse phytates present in SBM. In wheat the phytate phosphorus and phytase is concentrated in the aleurone layer of the grain (Eeckhout and De Paepe 1994). Therefore, the addition of wheatfeed to liquid feed may increase the amount of endogenous wheat phytase present and hence the amount of soluble P released during steeping. The amount of phosphorus that is available to the pig from these raw ingredients is 30%, 42% and 66% of the total phosphorus for SBM, wheat and wheatfeed respectively (Ewing 1997). The objective of this study was to determine the effect of steeping SBM with wheat, wheatfeed or a combination of the two on the release of soluble phosphorus.

Conditioning and Dewatering of Anaerobically Digested BPR Sludge

Anaerobic digestion of sludge from a full‐scale biological phosphorus removal (BPR) treatment facility resulted in significant release of soluble phosphorus. However, the increase in phosphorus and/or change in microbial population associated with the BPR conversion had no significant impact on sludge dewatering characteristics. Cationic polymer requirements (Percol 757) for effective sludge conditioning were not significantly impacted by the conversion to BPR treatment. Inorganic chemical addition using both lime and ferric chloride promoted effective sludge conditioning while concurrently promoting the reduction in filtrate phosphorus concentration. Suggestions for implementing the experimental results in full‐scale sludge treatment systems are also presented.

Soluble phosphorus release from organic soils

Soluble P release during soil organic matter decomposition was measured under fluctuating seasonal temperatures in several of Florida's organic soils. Natural soil profiles obtained from seven locations in central and south Florida were used in the study. Soil columns were leached once every 25 days, followed by applying a suction of 100 cm. Soil columns were flooded for 25 days in the months of July and August (between 14 and 21 weeks after initiation of the study for central Florida organic soils and between 11 and 18 weeks for south Florida organic soils) to simulate normal agronomic practice. The amounts of P released into effluent from Florida's organic soils were in the range of 2.9–26.2 μg P/cm 3 of soil per year (16–168 kg P ha −1 year −1). This represents 2.2–20% of the total soil P for central Florida organic soils and 0.75–1.1% of total soil P for south Florida organic soils. Soluble ortho-P accounted for about 70–89% of total effluent P for central Florida organic soils and 54–57% of effluent P for south Florida organic soils. Estimated soil P mineralization during organic matter decomposition was about 38–185 kg P ha −1 year −1 for central Florida organic soils and 16–23 kg P ha −1 year −1 for south Florida organic soils. Seasonal temperature fluctuations had minimal influence on the P release into effluent. Flooding the organic soils, however, increased P release into drainage effluent by about 4–8 times, compared with drained conditions.