Total Phosphorus Rates Research Articles

Modelling Phosphorus Removal in Horizontal Subsurface Flow Constructed Wetlands

In this paper a mathematical model for prediction of phosphorus removal with total phosphorus (TP) as the check index in horizontal subsurface flow constructed wetlands was developed. The model considered the water flow and transportation, diffusion, dispersion and biochemical reaction of phosphorus. The physical and biochemical parameters of the model were calibrated by one set of the experimental data. Then the model was valided by another set of the experimental data. The predicted effluent TP concentrations were well agreed with the actual effluent TP concentrations. The model can be used to simulate the phosphorus removal effect in horizontal subsurface flow constructed wetlands. The average removal rate of TP for domestic sewage in planted and unplanted constructed wetland with high concentration of influent were 88.22% and 85.06% respectively, while their removal rates were 94.23% and 90.77% respectively with low concentration of influent. So vegetation had improvement effect on TP removal.

Process Research of Ethanol Wastewater Treatment

The ethanol wastewater from one certain chemical plant in Hebei province was treated by the combined process, up-flow anaerobic sludge blanket (UASB) + anoxic/oxic (AN/O) + membrane bioreactor (MBR) + reverse osmosis (RO). The results showed that COD removal rate was 70% when the UASB residence time (HRT) was 48h; and COD removal rate reach 85%, the removal rate of NH3-N was 70%. the removal rate of total phosphorus was 95% when the AN/O residence time (HRT) was 72h; the following COD removal rate was up to 90% when the MBR residence time (HRT) was 12h. The COD of the output water after treatment was lower than 30mg/L, and met the requirement of reused water.

Reduction of Nitrogen and Phosphorus Content in Piggery Water with Algal Culture

Animal waste causes environmental problems like eutrophication of ground and water. The objective of this study was to fix the total nitrogen (TN) and total phosphorus (TP) in swine waste into biomass by investigating the performance of sole and mixed algae species culture with fast growth algae Scenedesmus obliquus and wild algae Chlorella sp. Wastewater concentrations varied from 25 to 100% and initial pH varied from 6 to 9 were conducted. The results indicated that the initial wastewater concentration and pH are crucial to biomass growth and the removing rate of TN and TP. It was found out that the maximum biomass growth rate of 73 mg/l/d was achieved with mixed species culture in 75% piggery wastewater (with TN and TP of 54 and 12 mg/l) with pH 7, meanwhile, the removing rate of TN and TP reached 87.3% and 64.3% with 10 days culture, respectively.

Efficacy of a large-scale constructed wetland to remove phosphorus and suspended solids from Lake Apopka, Florida

Constructed wetlands treat various types of waters. We examined the efficacy of a large-scale constructed wetland (the marsh flow-way), which was designed to treat lake water by maximizing the removal rate of total phosphorus (TP), and total suspended solids (TSS) from Lake Apopka. The flow-way was constructed on former agricultural land and has four independently operated wetland cells (treatment area is ∼276ha). During the operating period (November 2003–March 2007), hydraulic loading rate (HLR) was high, with annual median values between 32 and 49myr−1. On average, 87% of the treated water returned to the lake, and the remainder flowed downstream. The wetland released soluble P (mostly soluble reactive P [SRP]), which was probably caused by P release from soils and/or senescing vegetation. This release was high initially and high during summers, but declined overall with time. Despite SRP release, the system removed TP over annual periods, with maximum net TP removal in 2007 (1.8gm−2yr−1). Most of the incoming and retained P was particulate. Median percent mass removal was 58% for particulate P (PP) and about 30% for TP. Total suspended solids were always removed (median removal rate=1.4kgm−2yr−1) and the percent mass removal was high (93%). Median first-order rate constants (P-k-C* model) were 43myr−1 for TP and 228myr−1 for TSS. Removal rates of TP and PP appeared to increase linearly up to the highest loading (5–6gm−2yr−1), whereas removal rate of TSS may have approached an asymptote at loading >3kgm−2yr−1. We found that C* declined from 0.070 in the previous pilot project to 0.045mgL−1 in the current flow-way system. Continued reduction in C* as TP declines in inflow lake water would assist P removal. Otherwise, selective wetland operation during periods of high lakewater TP concentrations may be required in the future to maintain net P removal.

Spatiotemporal patterns in nutrient loads, nutrient concentrations, and algal biomass in Lake Taihu, China

Lake Taihu, China's third largest freshwater lake, exemplifies the severity of eutrophication problems in rapidly developing regions. We used long term land use, water quality, and hydrologic data from 26 in-lake and 32 tributary locations to describe the spatiotemporal patterns in nutrient loads, nutrient concentration, algal biomass, measured as chlorophyll a (Chl-a), in Lake Taihu. Point and nonpoint sources, as determined by chemical oxygen demand, contributed approximately 75 and 25% of the total nutrient loads to the lake, respectively. Spatial patterns in total phosphorus (TP) and total nitrogen (TN) concentrations in Lake Taihu strongly corresponded with observed loads from adjoining rivers with high concentrations proximate to densely populated areas. Chl-a concentrations exhibited spatial patterns similar to TP and TN concentrations. Generally, nutrient and Chl-a concentrations were highest in the northwestern region of the lake and lowest in the southeastern region of the lake. Seasonally, the largest nutrient loads occurred during summer. The annual net retention rate of TP and TN in Lake Taihu was approximately 30% of the total load. This study identifies regions of the lake and the watershed that are producing more nutrients to develop targeted management strategies. Reducing external P and N input from both point and nonpoint sources is obviously critical to address water quality issues in the lake. In addition, atmospheric deposition and resuspension of existing lake sediments also likely play a role in eutrophication processes and harmful algal blooms occurrence.

Productive Experiment of Combined Process Treating Sewage of Three Gorges Reservoir Region

To investigate the domestic sewage treatment processes fitting for small mountain towns in Three Gorges Reservoir Region, a demonstration project was built to treat domestic sewage which combined with anaerobic hydrolysis, natural water-dropping aeration and improved artificial soil rapid infiltration and was based on the features of large terrain elevation and many barren ravines. Changes of major pollutants were analyzed in the combined process. The impact of temperature and influent loadings on removal rates of pollutants was investigated. The results showed that, the treatment system had a strong resistance to the influent loadings with good removal rates of pollutants. There was a relationship between temperature and the removal rates of chemical oxygen demand, ammonia and total nitrogen in the system, where the removal rate of total phosphorus was not associated with temperature. There was a clear linear relationship between effluent concentration and influent loadings, effluent concentration increased with influent loadings. There were approximate logarithmic relationships between removal loadings per unit area and influent loadings.

Remediation of Eutrophic Water Body by Zoobenthos

To study the temperature factor affecting nutrient release of Cipangopludina Chinensis, laboratory simulation experiments were carried out, and other traits of Cipangopludina Chinensis, such as the effects of nitrogen cycling, phosphorus cycling, suspended substance in water column. Results showed that temperature had great influence on nutrient release of Cipangopaludina Chinensis. The release rate of total nitrogen and dissolved nitrogen increased, but not clear. The release rate of total phosphorus and dissolved Phosphorus increased greatly. When the temperature rose from 8 °Cto15 °C and 35 °C, the release rate of total nitrogen was increased by 5.71% and 23.43%;The release rate of dissolved nitrogen was increased by 6.76% and 17.57%. While the release rate of total phosphorus was increased by 92.60% and 208.35%,the release rate of dissolved phosphorus was increased by 2.25% and 110.17%. At the same situation, the release rate of ammonia nitrogen was increased by 1.89% and 26.55%, The release rate of phosphate was increased by14.27% and 225.96%, but temperature had little influence on nitrate nitrogen. In addition, temperature had little influence on suspended substance(P>0.05). In a word, zoobenthos play a significant role on eutrophic purification, which provide reference for lake eutrophication control.

Accelerated testing of nutrient release rates from fertiliser granules

A method is developed for estimation of accelerated nutrient release rates into a soil from particulate fertiliser formulations, by carrying out release studies at elevated temperatures. This can provide time-saving targetting of samples to be subsequently used in field trials. The rate of total phosphorus leaching into water from a standard commercial fertiliser product embedded in grey, deep, sandy duplex soil was monitored using inductively coupled plasma-optical emission spectroscopy. The time dependence of phosphate concentration at a given temperature was found to obey simple first-order kinetics. These data fitted an Arrhenius relation within acceptable limits, enabling release rates at ambient field temperatures to be estimated significantly faster than by field experiment. A release rate calculated for the accelerated test, i.e. (1.2 ± 0.1) × 10−3/min, when compared with a more standard-type pot-trial leaching rate for the corresponding temperature of 2.3 × 10−4/min, gives a direct correlation of ~1 : 1 when corrected for concentration differences.

Properties of Soil Organic Layer of Three Shrub Communities in Karst Area, Northwest Guangxi, China*

This paper presents the investigation on the physical and chemical properties of organic layer(OL)and topsoil(TS)in three shrub communities in the karst area of northwest Guangxi,China.The three communities in the process of natural restoration represent three different succession stages.The results showed that the reserve of litter was in the order of tree-shrub(5 478.96kg hm-2)vine-shrub(4 538.99kg hm-2)shrub(3 665.37kg hm-2),and the water contents of OL and TS followed the orders of tree-shrubvine-shrubshrub,and tree-shrubshrubvine-shrub,respectively.There were higher total organic carbon(TOC)and total nitrogen(TN),but lower total phosphorus(TP)and total potassium(TK)in litter layer(LL)compared with those in fragmented litter layer(FL).The returning rates of TN and TP were affected more seriously by the quality of litter than by the habitats;P needed the longest time to return to soil there,so it was the limiting factor of nutrient returning.In OL the stocks of TN decreased from shrub to tree-shrub,and TP,TK did not vary signif icantly among the three communities.However,the stocks of nutrients in TS were in different patterns:Almost the TN,TP and TK stored the most in tree-shrub,indicating that nutrient accumulation in soil increased as the succession proceeded on.Fig 1,Tab 3,Ref 25

Characteristics and mechanisms of the hydroponic bio-filter method for purification of eutrophic surface water

The hydroponic bio-filter method (HBFM) was adopted to purify eutrophic surface water. The average removal efficiency of total nitrogen (TN) and total phosphorus (TP) was 16.8% and 30.8%, respectively, at the hydraulic loading rate (HLR) of 3.0 m 3 (m 2 d) −1. The mass removal rate of TN and TP accordingly reached 1.0 and 0.1 g (m 2 d) −1 separately. The sedimentation of particulate nitrogen and phosphorus played a major role in removal of nitrogen and phosphorus, which contribute 62.2% and 75.9%, respectively. The optimal HLR of HBFM ranged from 3.0 to 4.0 m 3 (m 2 d) −1. The sediment in midstream reached a maximum nitrification potential of 4.76 × 10 −6 g (g h) −1, while upstream it reached a maximum denitrification potential of 8.1 × 10 −7 g (g h) −1. The distribution of nitrification potential corresponded to the ammonium-oxidizing bacteria density. The key for improving nitrogen removal efficacy of HBFM system consisted of changing the nitrification/denitrification region distribution and accordingly enhancing the denitrification process. The sum of dissolved nitrogen removed by denitrification and plant assimilation was nearly equal to the amount released by sediment. Secateur length of Nasturtium officinale had some effect on its uptake rate. The length of cut should be less than 10 cm at a time. The harvesting frequency of once a month for N. officinale had no influence on nitrogen and phosphorus removal.

Removal of Nutrients, Organic Matter and Heavy Metals from Paddy Field Drainage by Charcoal

This study examined the ability of charcoal to remove organic matter, nutrients and heavy metals from agricultural drainage. Water treatment equipment containing wood charcoal was installed in a test paddy field. Concentrations of total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and heavy metals (Cr, Fe, Zn and Pb) in water samples taken before and after passing through the equipment were analyzed. The equipment was installed simply at the outlet in the test field and removed environmental load substances during a contact time of more than one hour. The reduction rates of TOC and TN ranged from 20 % to 40 %. The reduction rate of TP ranged from 20 % to 90 %. The reduction rates of metals (Cr, Fe, Pb) ranged from 23 % to 62 %. These results suggest that charcoal can be used in water treatment equipment to treat paddy field drainage water.

Removal of Nitrogen, Phosphorus, and Organic Pollutants From Water Using Seeding Type Immobilized Microorganisms

To study the possibility of removing nitrogen, phosphorus, and organic pollutants using seeding type immobilized microorganisms. Lakes P and M in Wuhan were chosen as the objects to study the removal of nitrogen, phosphorus, and organic pollutants with the seeding type immobilized microorganisms. Correlations between the quantity of heterotrophic bacteria and the total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in the two lakes were studied. The dominant bacteria were detected, inoculated to the sludge and acclimated by increasing nitrogen, phosphorus and decreasing carbon source in an intermittent, time-controlled and fixed-quantity way. The bacteria were then used to prepare the seeding type immobilized microorganisms, selecting diatomite as the adsorbent carrier. The ability and influence factors of removing nitrogen, phosphorus, and organic pollutant from water samples by the seeding type immobilized microorganisms were studied. The coefficients of the heterotrophic bacterial quantity correlated with TOC, TP, and TN were 0.9143, 0.8229, 0.7954 in Lake P and 0.9168, 0.7187, 0.6022 in Lake M. Ten strains of dominant heterotrophic bacteria belonging to Pseudomonas, Coccus, Aeromonas, Bacillus, and Enterobateriaceae, separately, were isolated. The appropriate conditions for the seeding type immobilized microorgansims in purifying the water sample were exposure time=24 h, pH=7.0-8.0, and quantity of the immobilized microorganisms=0.75-1 g/50 mL. The removal rates of TOC, TP, and TN under the above conditions were 80.2%, 81.6%, and 86.8%, respectively. The amount of heterotrophic bacteria in the two lakes was correlated with TOC, TP, and TN. These bacteria could be acclimatized and prepared for the immobilized microorganisms which could effectively remove nitrogen, phosphorus, and mixed organic pollutants in the water sample.

Nutrients removing by arrowheads in different growing periods in the transition zone between lands and rivers

Riparian macrophytes are very effective for nutrients purification in surface water through absorption, precipitation enhancement and the biochemical functions of microbes around plants’ rods and roots. In river networks of Taihu watershed in China, arrowheads distribute widely in the river riparian macrophyte buffers. Experiments were performed following three months of different growing periods including July, October and November, which indicate the blooming period, the fruit bearing period and the withered beginning period. Contents of Total Nitrogen (TN) and Total Phosphorus (TP) in water body were tested. Results show that the concentrations of these nutrients were decreased with arrowheads growing, and the degradation degree are larger while arrowhead thriving in July with the TN and TP average degradation rate of 80.5% and 87.1% after 15 days’ duration. The biomass of arrowheads per square meter show logarithmic relativity to nutrient removing rates in the three periods. In addition, comparative experiments were performed to separate the contribution to the degradation of nutrients between soil absorption and the arrowhead action. Results indicate that the contents of Total Nitrogen decreased larger with plants than that of without, the difference is about 20% or so. However, arrowheads impact little on TP remove, the contents of total phosphorus decreased mainly by soil adsorption and precipitation, as a result, the final degradation rates of TP are about at the same in the two systems with or without plants.

Characteristics of simultaneous organic and nutrient removal in a pilot-scale vertical submerged membrane bioreactor (VSMBR) treating municipal wastewater at various temperatures

A pilot-scale vertical submerged membrane bioreactor (VSMBR) with anoxic and oxic zones in one reactor was operated in an attempt to reduce the problems concerning effective removal of organic matter and nutrients from municipal wastewater. Source water with total chemical oxygen demand (TCOD)/total nitrogen (TN) ratio of 5.5 was treated at various temperatures (13–25 °C) over an interval of about 1 year. As a result, total suspended solid (TSS) and TCOD were removed by 100% and higher than 98%, respectively. Moreover, the average removal efficiencies of TN and total phosphorus (TP) were found to be 74% and 78% at 8 h-hydraulic retention time (HRT) and 60-days sludge retention time (SRT). Under these conditions, the specific removal rates (SRR) of TN and TP were found to be 0.093 kg N m −3 day −1 and 0.008 kg P m −3 day −1, and the daily production of excess sludge (DPES), 0.058 kg TSS day −1.

Recent Increases in Sediment and Nutrient Accumulation in Bear Lake, Utah/Idaho, USA

This study examines historical changes in sediment and nutrient accumulation rates in Bear Lake along the northeastern Utah/Idaho border, USA. Two sediment cores were dated by measuring excess 210Pb activities and applying the constant rate of supply (CRS) dating model. Historical rates of bulk sediment accumulation were calculated based on the ages within the sediment cores. Bulk sediment accumulation rates increased throughout the last 100 years. According to the CRS model, bulk sediment accumulation rates were <25mgcm−2year−1 prior to 1935. Between 1935 and 1980, bulk sediment accumulation rates increased to approximately 40mgcm−2year−1. This increase in sediment accumulation probably resulted from the re-connection of Bear River to Bear Lake. Bulk sediment accumulation rates accelerated again after 1980. Accumulation rates of total phosphorus (TP), total nitrogen (TN), total inorganic carbon (TIC), and total organic carbon (TOC) were calculated by multiplying bulk sediment accumulation rates times the concentrations of these nutrients in the sediment. Accumulation rates of TP, TN, TIC, and TOC increased as a consequence of increased bulk sediment accumulation rates after the re-connection of Bear River with Bear Lake.

Transport and retention of phosphorus pollutants in the landscape with a traditional, multipond system

The landscape structure of a multipond system, runoff type andP-pollutant transport in an experimental watershed was studiedduring 1995 and 1998. A multipond system is a wetland system composed with many tiny ponds and ditches. In this watershed, it was found that such a system effectively controls the hydrological process through its huge storage capacity. The multipond system has a high interaction of land/water ecotones,which decreases the flow velocity systematically and results ina high sedimentation of the particulate matters.The multipond system intercepts runoff and creates either continuous or discontinuous flow. The retention efficiency of the system was very high in both cases but differed in nature. During continuous runoff on 1 May 1998, in a subwatershed Baojiatang, the retention rates of water, total phosphorus (TP),dissolved phosphorus (DP) and suspended solids (SS) by the multipond system were 83.0, 93.9, 90.9 and 94.9%, respectively.During discontinuous runoff on 29 June 1998, runoff volume generated from all lands was 1841 m3, but no surface waterwas exported and the system retention rates of TP, DP and SS were nearly complete. The removal of particulate phosphorus bythe system was more effective than removal of DP and thus DP wasthe main form of phosphorus exported from the watershed duringcontinuous flow. Because of such control, the export amount ofphosphorus was greatly reduced. The output of TP and DP was 0.013 and 0.012 kg ha-1, respectively, from Liuchahe watershed in 1995, and they were 0.037 and 0.030 kg ha-1 in 1998 correspondingly.

An integrated wastewater treatment system for land-based fish-farming

A newly developed low cost system for fish-farm wastewater treatment was evaluated. The system consisted two major parts: (1) a new type of square tank design with two separate outlets, i.e. one centrally positioned high solids concentration outlet and one corner located low solids concentration primary outlet; and (2) a stationary bowed screen for solid removal from the high solids effluent. Removal rates for the particle outlet were on average 43.2% total phosphorus (TP) and 7.3% TN. The mean TP, TN, chemical oxygen demand (COD) and TS removal rates of the bowed screen were 49.3, 42.7, 48.0, and 74.4%, respectively. TP and TN waste removal rates for the whole system were 21.3 and 3.1%, respectively. The self-cleaning in the tank was poor at the start of the trials, but improved throughout the experimental period as fish density increased, thus also increasing the removal rates for the whole system.

Effectiveness and Longevity of Phosphorus Inactivation with Alum

ABSTRACT Effectiveness and longevity of alum treatments were evaluated in 21 lakes (or lake basins) across the United States; 9 were polymictic and 12 were dimictic. Effectiveness was judged from reductions in lake TP (total phosphorus) and internal loading rate, as well as chlorophyll a (chl a), both initially and over periods ranging from 4 to 20 years following treatment. Internal loading rate was reduced in six of nine polymictic lakes/basins by an average of two-thirds, and lake TP was reduced by about one-half, which persisted for 5–11 years. Internal loading rate in dimictic lakes (7 of 7 with adequate data) remained reduced by an average of 80% for 4 to 21 years (average 13 yrs). For the six polymictic lakes, in which treatment was effective, chl a decreased by an average of two-thirds initially, but was about 40% less than die pre-treatment level after 5 to 11 years. Chl a decreased in seven dimictic lakes by an average of 57% initially and 42% after 5–18 years. In some cases, response was independent of alum treatment because the trophogenic zone was affected more by external than internal P loading. At West Twin Lake, OH, nutrient diversion was more important than control of P release from hypolimnetic sediments in improving surface water quality. The significance of vertical P entrainment, as well as external loading, should be considered before treating dimictic lakes. Alum was initially ineffective in two polymictic lakes and was effective only for a few years in a third, apparently due to interference from macrophytes. Dense macrophytes may have caused uneven floe distribution or sediment P was recycled from below the floe layer through plant senescence and decay. Where macrophytes did not interfere, treatments were usually effective for at least 8 years and up to 11 years in polymictic lakes; an expectation of 10 years longevity is considered reasonable for unstratified lakes. Several dimictic lakes showed effectiveness/longevity of internal loading control for at least 13 and up to 18 to 20 years; an expectation of 15 years longevity seems reasonable for dimictic lakes. The decline in treatment effectiveness could have been due to bioturbation, or to sinking and burial of the aluminum floe over time, as evidenced by a distinct Al layer located at about 20 cm after 16 years in West Twin Lake, OH. A direct relation between dose and treatment longevity, as well as an inverse relation between dose and sediment P release rate, was apparent in the dimictic lakes.

Zooplankton and bacteria contribution to phosphorus and nitrogen internal cycling in a tropical and eutrophic reservoir: Pampulha Lake, Brazil

AbstractNutrient regeneration and respiration rates of natural zooplankton from a tropical reservoir were experimentally measured. Excretion rates of ammonia (Ea), orthophosphate (Ep) and community respiration rates (R) were estimated considering the variations in the concentrations of ammonia, orthophosphate and dissolved oxygen between control and experimental units. The ranges obtained for these rates from the 2 h assays were Ea = 1.95–4.95 μg N‐NH4 · mg · DW−1 · h−1; Ep = 0.12–0.76 μg P‐PO4 mg DW−1 · h−1. Respiratory rates were quite constant (R = 0.01–0.02 mg O2 · mg DW−1 · h−1). The uptake of nutrients due to bacteria can affect the experimental determination of excretion rates of zooplankton. Orthophosphate release increased from 0.28 to 0.82 μg P‐PO4 · mg DW−1 · h−1 when bacterial activity was depleted by antibiotic addition in experimental vessels (Exp IV). This demonstrates that free living bacteria are able to consume promptly most phosphorus excreted by zooplankton. Ammonia excretion rates were lower in experimental units containing antibiotics. Lower excretion rates were also obtained with longer exposure times and higher biomass levels in the experimental units. Finally, this study also showed that zooplankton excretion can affect significantly turn over rates of total phosphorus in Pampulha Reservoir. In some periods, specially during the dry season when zooplankton biomass was very high, phosphorus release by zooplankton, during one single day, can be as high as 40% of the total phosphorus content in lake water (Turn over time = 2.5 days).

A comparison of phosphorus retention in lakes determined from mass balance and sediment core calculations

Phosphorus retention (TP acc) was determined in 7 lakes in Ontario, Canada from mass balances and from the direct measurement of phosphorus accumulation in the sediments. Phosphorus retentions determined using the mass balance technique ranged between 20 ± 4.0 and 95 ± 23 mg/m 2/yr and were slightly lower than those calculated by multiplying sediment total phosphorus (TP) concentrations by sediment accumulation rates (49 ± 14 to 148 ± 37 mg/m 2/yr). The lower TP acc values measured using the mass balance approach may result from the underestimation of external TP inputs. Alternatively, it is suggested that in the more acidic lakes, a decrease in TP concentrations in the lakewaters and/or a decrease in TP export from the catchment may have resulted in a decrease in TP acc through time. Thus, relatively higher TP acc values would be calculated using the sediment approach (since TP acc values calculated from the sediment data are averaged over a greater number of years than those calculated from the mass balance data). Provided several cores are collected from the lake, the direct measurement of sediment TP and sediment accumulation rates for estimating TP acc may be a suitable alternative to mass balances, especially in situations where it is not possible to measure all inputs of TP to the lake.