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At least 883 records · Page 49Linked to original sources
PubMed2003

Phosphorus removal from municipal wastewater in an experimental two-stage vertical flow constructed wetland system equipped with a calcite filter.

Laboratory studies have indicated that calcite may be used in separate, exchangeable filter units in constructed wetland systems to remove phosphorus. Based on these studies we built a full-scale experimental constructed wetland with a calcite-based filter unit to study its performance, under real-life conditions. The system consists of a 2-m3 sedimentation tank and two vertical flow constructed wetlands. The system has three 0.09 m3 calcite filter-units to study phosphorus removal. The hydraulic loading rate varied between 1.7 and 6.2 m3/d. The residence time in filters ranged from 28 to 99 minutes. Overall the system removed 62 +/- 18% of phosphorus. The removal in the calcite filter was initially good, but after three months all P-filters were saturated. The calcite increased pH by approximately half a unit and released calcium. A total of about 2.2 kg P/m3 calcite was removed by the filter. The first-stage bed receiving effluent from the sedimentation tank consistently removed phosphorus, whereas the second bed sometimes released phosphorus. The first order area-based removal rate constant for total-P in the vertical bed averaged 0.24 +/- 0.20 m/d and was highly dependent on the loading rate. This shows that first order removal kinetics do not satisfactorily describe removal of phosphorus in vertical flow constructed wetland systems with unsaturated flow.

Adsorption↗
PubMed2004

Determination of operational parameters of anaerobic phase for enhanced phosphorus removal in MBR.

Two runs of experiments were carried out to obtain an understanding of phosphorus release and uptake under the anaerobic condition and then the aerobic condition respectively. Under anaerobic condition, it was found that the extent of phosphorus release appeared to increase with the increase of the initial organic loading rate when the initial organic loading rate was up to 0.1 gSCOD/gMLSS. When the initial organic loading rate was higher than 0.1 gSCOD/gMLSS, the amount of phosphorus release per unit mass of MLSS reached nearly a same stationary value, and it seemed this is not affected by organic loading rate when there is external available substrate remained. In addition, the effect of NOx-N on the phosphorus release and uptake was also investigated, it was proved that the denitrifiers has an advantage over polyphosphate accumulating bacteria in competition for organic substrate under anoxic condition. Therefore, the existence of NOx-N is disadvantageous to the phosphorus release. Based upon the above investigations, the process configuration of membrane bioreactor(MBR) in combination with anaerobic phase was proposed to enhance the removal of phosphorus in treating domestic wastewater. During the experimental period of four months, average removals of 92.50%, 84.25%, 100%, 94.09% and 85.33% were achieved for COD, TP, SS, NH3-N and TN respectively.

Bacteria, Anaerobic↗
PubMed2004

Effect of carbon source and nitrate concentration on denitrifying phosphorus removal by DPB sludge.

Effect of added carbon source and nitrate concentration on the denitrifying phosphorus removal by DPB sludge was systematically studied using batch experiments, at the same time the variation of ORP was investigated. Results showed that the denitrifying and phosphorus uptake rate in anoxic phase increased with the high initial anaerobic carbon source addition. However once the initial COD concentration reached a certain level, which was in excess to the PHB saturation of poly-P bacteria, residual COD carried over to anoxic phase inhibited the subsequent denitrifying phosphorus uptake. Simultaneously, phosphate uptake continued until all nitrate was removed, following a slow endogenous release of phosphate. High nitrate concentration in anoxic phase increased the initial denitrifying phosphorus rate. Once the nitrate was exhausted, phosphate uptake changed to release. Moreover, the time of this turning point occurred later with the higher nitrate addition. On the other hand, through on-line monitoring the variation of the ORP with different initial COD concentration, it was found ORP could be used as a control parameter for phosphorus release, but it is impossible to utilize ORP for controlling the denitrificaion and anoxic phosphorus uptake operations.

Bacteria, Anaerobic↗
PubMed2004

A novel wastewater treatment process: simultaneous nitrification, denitrification and phosphorus removal.

Simultaneous nitrification and denitrification (SND) via the nitrite pathway and anaerobic-anoxic enhanced biological phosphorus removal (EBPR) are two processes that can significantly reduce the COD demand for nitrogen and phosphorus removal. The combination of these two processes has the potential of achieving simultaneous nitrogen and phosphorus removal with a minimal requirement for COD. A lab-scale sequencing batch reactor (SBR) was operated in alternating anaerobic-aerobic mode with a low dissolved oxygen concentration (DO, 0.5 mg/L) during the aerobic period, and was demonstrated to accomplish nitrification, denitrification and phosphorus removal. Under anaerobic conditions, COD was taken up and converted to polyhydroxyalkanoates (PHA), accompanied with phosphorus release. In the subsequent aerobic stage, PHA was oxidized and phosphorus was taken up to less than 0.5 mg/L at the end of the cycle. Ammonia was also oxidised during the aerobic period, but without accumulation of nitrite or nitrate in the system, indicating the occurrence of simultaneous nitrification and denitrification. However, off-gas analysis found that the final denitrification product was mainly nitrous oxide (N2O) not N2. Further experimental results demonstrated that nitrogen removal was via nitrite, not nitrate. These experiments also showed that denitrifying glycogen-accumulating organisms rather than denitrifying polyphosphate-accumulating organisms were responsible for the denitrification activity.

Acetates↗
PubMed2005

Enhancing phosphorus removal in constructed wetlands with ochre from mine drainage treatment.

No single end-use has yet been identified that is capable of consuming the projected production of ochre (mainly iron (III) oxides) from mine drainage treatment. However, the high sorption capacity of ochre for phosphorus (up to 26 mg kg(-1)) means that it could be used in constructed wetlands to enhance phosphorus removal. Laboratory batch experiments showed that coarse-grained ochre removes 90% of all phosphorus forms from sewage effluent after 15 minutes of shaking. From a larger-scale experiment, it is estimated that constructed wetlands with an ochre substrate should remove phosphorus from sewage effluent for up to 200-300 years. The suitability of ochre for phosphorus removal is being investigated at the field scale in a wastewater constructed wetland (175 m2 area) in Berwickshire, UK. The hydraulic and treatment performance of the wetland were monitored for 15 months prior to installation at the inlet in November 2003 of a tank containing approximately 1200 kg ochre. Results so far show that improved hydraulic design is required for ochre to increase the mean phosphorus removal efficiency of the system (27 +/- 28%), but potentially toxic metals (Al, Cd, Cr, Cu, Fe, Ni, Pb, Zn) have not been released from the ochre into the wetland outflow.

Biodegradation, Environmental↗
PubMed2005

Considerations on the influence of extreme events on the phosphorus transport from river catchments to the sea.

In this paper, results from rivers of different sizes in Romania, Hungary and Austria are presented. The paper shows the dynamics of extreme events and their contribution to the total P and suspended solids transported in these rivers. Special attention is paid to the influence of the size of the catchment and the event probability on the relative contribution of a single event to the total loads transported in the river. Further, the development of phosphorus loads along the Danube River at a flood event is shown. From the results it can be concluded that there is no immediate influence of high flow and flood events in upstream parts of the Basin on the transport of phosphorus from the catchment to the receiving Sea. Particle-bound phosphorus is mobilised from the catchment (through erosion) and the river bottom to a high extent at high flow events and transported at peak discharges to downstream, where retention by sedimentation of particles takes place. On the one hand this retention is a transport to flooded areas. In this case it can be considered as more or less long term retention. On the other hand sedimentation takes place in the riverbed, in case the tractive effort of the river is reduced. In this second case the P-pool in the sediments of the sedimentation area will be increased. If anaerobic conditions in the sediment appear, part of the phosphorus will be transformed to soluble ortho-phosphate and will continuously contribute to the phosphorus transport to the receiving sea. Part of the P-retained in the river sediment will be mobilised by resuspension at the next biggest high flow event. Altogether, these alternating processes of suspension, transport, export to flooded areas or sedimentation in the river bed with partly solution and partly resuspension at the next event decrease the share of the phosphorus transport during high flow events on the total loads transported in the more downstream parts of a catchments as compared to the more upstream parts. In the year of occurrence of an extreme flood event the P-transport of this year is dominated by the flood event. As an average over many years the contribution of high flow events to the total P-transport still may be between 7 and 20% in smaller catchments (around 1,000 km2). In a big catchment (e.g. river Danube) much smaller contributions of flood events on the total P-transport can be expected as an average over many years.

Austria↗
PubMed2005

[Effect of environment and nutrient factors on the content of nitrogen and phosphorus in two duckweeds species: Spirodela polyrrhiza and Lemna aequinoctialis].

Effects of temperature, light density, nitrogen level and phosphorus level of medium to the content of two species Spirodela polyrrhiza and Lemna aequinoctialis were researched. The results showed that the content of nitrogen in two species kept constant when the concentration of nitrogen was higher than 3 mg x L(-1) and temperature higher than 25 degrees C. It decreased under lower concentrations of nitrogen and lower temperature. Photon flux density had no effect on it. But weak photon flux density and low temperature led to reduce the content of phosphorus of duckweed. The content of phosphorus in two duckweed species kept constant when photon flux density was higher than 8 000 1x and temperature higher than 25 degrees C. The relationship between the content of phosphorus and concentrations of phosphorus in medium could be described by Monod model. The saturated phosphorus content of Spirodela polyrrhiza was higher than Lemna aequinoctialis.

Araceae↗
PubMed2005

Influence of phosphorus on Microcystis growth and the changes of other environmental factors.

The growth processes of Microcystis aeruginosa (FACHB-41) in simulated Taihu Lake water with different phosphorus concentrations were investigated using laboratory microcosms. The algal biomass increased with the increase of phosphorus concentration when it was lower than 0.445 mg/L, while the dissolved oxygen (DO) and pH increased, dissolved inorganic nitrogen(DIN) and light intensity underwater (I) decreased. Responding to the changes of the "environmental factors", the cellular carbohydrate and its ratio to cellular protein decreased generally as phosphorus increased. However, when phosphorus concentration was higher than 1.645 mg/L, the biomass, the "environmental factors", the cellular carbohydrate and its ratio to cellular protein did not change likewise. Since the environmental factors and the physiological and biochemical responses are important factors, the change of environmental factors and cell physiology and biochemistry induced by phosphorus may become the key factors that steer the growth and dominance of Microcystis under certain conditions. To sum up, phosphorus not only stimulate the growth of Microcystis directly by supplying nutrient element, but also has complex interactions with other "environmental factors" and play important roles in the growth processes of Microcystis.

Algal Proteins↗
PubMed2006

[Influencing factor of natural zeolite barrier for controlling nitrogen and phosphorus release from sediments].

Influencing factor of natural zeolite barrier for controlling nitrogen and phosphorus release from sediments was researched. The results show that: (1) Zeolite barrier can effectively control the ammonia release from sediment under anaerobic conditions. (2) The ammonia release in a short term was not influenced by temperature, grain size of zeolite, thickness of barrier and aeration; However, long-term effectiveness of zeolite barrier was greatly influenced by grain size of zeolite and barrier thickness, and the little the grain size or the more thick the width, the better the effectiveness of controlling release of ammonia from sediment. (3) The release rate of total phosphorus from sediments increases as temperature heightening; the release rate of total phosphorus from sediments decreases with grain size of zeolite smaller or width thicker. (4) For barriers with zeolite's grain size 3-5 mm and width 1 cm, the rate of release of total phosphorus from sediments was decreased by aeration; For barriers with zeolite's grain size <2 mm and width 1 cm, efficiency of controlling release total phosphorus was decreased by aeration during prior period, and its efficiency was increased by aeration in the late stage; For barriers with zeolite's grain size 3-5 mm and width 3 cm, efficiency of controlling release total phosphorus was decreased by aeration.

Geologic Sediments↗
PubMed1991

The influence of dietary lactose on phosphorus-induced nephrocalcinosis in female rats.

The effect of dietary lactose, when compared with glucose, on phosphorus-induced nephrocalcinosis was studied in young, female rats. Nephrocalcinogenic diets containing either 0.4 or 0.6% (w/w) phosphorus were used, and lactose was added up to concentrations of 30%. The diets were fed for 28 days. The 0.4 and 0.6% phosphorus diets, when compared with a diet containing 0.2% phosphorus, caused mild and severe kidney calcification, respectively; kidney calcification was demonstrated chemically by the analysis of kidney calcium, and histologically by staining kidney slides for calcium deposits. Dietary lactose caused calciuria, decreased urinary pH and increased cecum weights. The addition of lactose to the diet partly counteracted nephrocalcinogenesis induced by diets containing 0.4% phosphorus, but it did not influence the severity of nephrocalcinosis seen in rats fed diets containing 0.6% phosphorus. It is suggested that high amounts of lactose in the diet have only weak anti-nephrocalcinogenic activity.

Animals↗
PubMed1987

[Supplementation of maternal milk with calcium and phosphorus for the feeding of premature neonates weighing 1500 g or less. How long should it be continued?].

Feeding four preterm infants weighing less than or equal to 1,500 g with human milk supplemented with calcium (160-200 mg/kg/day) and phosphorus (80-200 mg/kg/day) until term postmenstrual age was reached, and suitable levels of plasma calcium, phosphorus and alkaline phosphatase and urinary excretion index of calcium and phosphorus were attained. When such a supplementation was suppressed at 38-40 weeks of postmenstrual age a rapid onset of biochemical disturbances was observed: a rise of plasma calcium (p less than 0.025) and alkaline phosphatase (p less than 0.0025) with a decrease of plasma phosphorus (p less than 0.005) and of urinary phosphate excretion (p less than 0.002). Reincorporation to former supplemented regime results in quick recovery of these parameters. Authors can assert that the necessity of calcium and phosphorus supplementation of human milk for less than or equal to 1.500 g preterm infant feeding exceeds the term postmenstrual age if suitable calcium and phosphorus levels are to be obtained.

Alkaline Phosphatase↗
PubMed1986

Calcium and phosphorus metabolism in chronically vitamin D-deficient laboratory rabbits.

Calcium and phosphorus metabolism were investigated in chronically vitamin D-deficient adult albino rabbits that were consuming a diet containing 1% calcium and 0.5% phosphorus. Mineral balances, net intestinal and renal handling of calcium and phosphorus, and serum concentrations of calcium, phosphorus, parathyroid hormone, 25-hydroxycholecalciferol, and calcitriol were measured during metabolic balance studies. Chronic vitamin D deficiency (with undetectable serum concentrations of 25-hydroxycholecalciferol or calcitriol) was associated with mild hypocalcemia, moderate hypophosphatemia, and generally elevated serum parathyroid hormone concentrations. Net intestinal absorption of calcium or phosphorus was equal in chronically vitamin D-deficient adult rabbits and nutritionally matched, vitamin D-supplemented controls. In contrast, urinary excretion rates of both minerals were reduced significantly in the vitamin D-deficient group, indicating the action of homeostatic mechanisms within the kidneys. As a result of the decreased urinary excretions of calcium and phosphorus, the net external balance for each mineral during the metabolic balance studies was significantly more positive in the chronically vitamin D-deficient rabbits than in the vitamin D-supplemented controls. These observations demonstrate the importance of the renal conservation of Ca and P to mineral homeostasis in the chronically vitamin D-deficient adult rabbit.

Animals↗
PubMed1985

Phosphorus in the British household food supply.

The intake of phosphorus in Britain was calculated for 1975 by applying the values for phosphorus in foods from the 4th edition of McCance and Widdowson's 'The composition of foods' to the average household food purchases recorded in the National Food Survey (NFS). A similar exercise was carried out for 1982, but using many updated values for the phosphorus content of foods. In 1975 the average household intake of phosphorus was 1310 mg per person per day while by 1982 it had declined to 1223 mg per person per day. The calcium: phosphorus ratio was 1 : 1.3 in both years. These intakes are above the US recommendation for adults but well below the maximum tolerable daily intakes for phosphorus.

Diet↗
PubMed1978

[Disorder in the circladian rhythms of calcium, magnesium and phosphorus excretion in hypertension (use of the "cosinor" method)].

The daily rhythms of calcium, magnesium, and phosphorus excretion were studied in 10 healthy individuals and in 43 patients with hypertensive disease. All the subjects under study followed the standard regimen of wakefulness, sleep, and meals. The transverse "cosinor" method of rhythm study was used. Statistically significant daily rhythms of calcium, magnesium, and phosphorus excretion were revealed in healthy individuals, in which case the phenomena of internal synchronization were encountered. Daily rhythms of phosphorus and calcium excretion were revealed in patients with stage IB hypertensive disease, while the rhythm of magnesium excretion was statistically insignificant. In stage IIA the rhythms of calcium, magnesium, and phosphorus excretion are demonstrated, but desyncronization as compared to the findings in healthy individuals is observed. There are no statistically significant daily rhythms of calcium, magnesium, and phosphorus excretion in patients with stages IIB and III hypertensive disease. The change in the rhythm of magnesium excretion in patients suffering from IB stage hypertensive disease points to the early inclusion of the disturbance of its homeostasis in the development of this disease. The control mechanisms of the daily rhythms of calcium, magnesium, and phosphorus excretion are not clear to date. The study of the daily rhythms of these elements is nevertheless of definite importance in revealing disturbances in their homeostasis.

Adult↗
PubMed1983

Calcium and phosphorus metabolism during total parenteral nutrition.

Calcium and phosphorus metabolism and balance were studied in 151 patients receiving total parenteral nutrition (TPN). Hypercalciuria was common, with mean (+/- SD) urinary calcium excretion 17.5 +/- 3.9 meq/24 hours (n = 2610). There was a significant positive correlation between urinary calcium excretion and parenteral calcium intake (r = 0.34, p less than 0.001). There was also a positive correlation between calcium balance and parenteral calcium intake (r = 0.61, p less than 0.001) in patients without extra-renal losses. Positive calcium balance was achieved with parenteral calcium intake greater than 15 meq/24 hours. Urinary phosphorus excretion correlated positively with parenteral phosphorus intake (r = 0.50, p less than 0.001). Phosphorous balance also correlated positively with parenteral phosphorus intake (r = 0.78, p less than 0.001). Positive phosphorus balance was achieved with parenteral phosphorus intake above 15 mmol/24 hours. Fifty-three patients received 1,000 IU vitamin D once weekly and showed no significant change in serum calcium. Ninety-eight patients received 1,000 IU vitamin D twice weekly and showed a gradual but significant mean increase over time in serum calcium.

Adolescent↗
PubMed1981

Efficacy of intravenous phosphorus therapy in the severely hypophosphatemic patient.

To evaluate the efficacy and safety of a simple approach to intravenous (IV) phosphorus therapy, ten adult patients with severe hypophosphatemia (less than or equal to 1 mg/dL) and normal renal function were studied prospectively. They were treated with a solution containing 9 mmole of phosphorus as monobasic potassium phosphate (KH2PO4), infused continuously every 12 hours. Serum phosphorus, potassium, and calcium levels and urinary excretion of phosphorus were measured every 12 hours. The serum phosphorus level was significantly improved at 12 hours, more than 1 mg/dL in all patients at 36 hours, and normal in six patients at 48 hours. The serum potassium level was never above normal, and serum calcium levels declined in only one patient. Administration of 9 mmole of phosphorus as KH2PO4 every 12 hours is both safe and efficacious IV therapy for severe hypophosphatemia in the adult patient with normal renal function and without hyperkalemia or hypercalcemia.

Acute Disease↗
PubMed1980

Effect of dietary calcium, magnesium, and phosphorus on phosphate urolithiasis in rats.

Female Wistar rats were fed a basal diet containing various concentrations of calcium, phosphorus, and magnesium: calcium and phosphorus at 0.4, 0.5, 0.8, 1.0, 1.5, and 2 per cent and magnesium at 0.2, 0.4, 0.8, and 1 per cent of the diet dry matter. Two types of uroliths developed: magnesium phosphate in the renal pelves, bladders, and/or ureters of rats fed rations containing 1 per cent magnesium with either 1.0 or 0.5 per cent phosphorus and calcium phosphate uroliths in the renal tubules at the corticomedullary junction of rats fed rations containing phosphorus equal to or greater than 0.8 per cent and magnesium equal to or less than 0.8 per cent. The incidence and severity of calcium phosphate uroliths were reduced by increasing the magnesium concentration in the diet from 0.2 to 0.8 per cent and by increasing the calcium-to-phosphorus ratio to greater than 1. Results of this study indicated that the interactions among dietary calcium, magnesium, and phosphorus seemed to affect the incidence, severity, and type of uroliths in rats.

Animals↗
PubMed1993

[Intravenous drop of calcium gluconate for phosphorus burns].

20 patients with phosphor burn (TBSA 2%-75%) were cured by i.v. drop of calcium gluconate combined with other therapies including eschar conservation. Our experimental data showed that dogs with burn by spreading 85% phosphoric acid and napalm locally increased the level of plasma phosphorus and pathological damages to the heart, lung, kidney and etc were similar to those previously reported phosphorus burns. Intravenous drop of calcium gluconate after phosphate burn reduced the level of plasma phosphorus to normal rapidly and lessened the visceral damages. We consider that i.v. drop of calcium gluconate can accelerate the elimination of phosphorus, and prevent phosphorus poisoning after phosphorus burns.

Adolescent↗