Effluent Total Phosphorus Research Articles

Removing phosphorus from aqueous solutions by using iron-modified corn straw biochar

Iron-modified corn straw biochar was used as an adsorbent to remove phosphorus from agricultural runoff. When agricultural runoffs with a total phosphorus (TP) concentration of 1.86 mg·L−1 to 2.47 mg·L−1 were filtered at a hydraulic retention time of 2 h through a filtration column packed with the modified biochar, a TP removal efficiency of over 99% and an effluent TP concentration of less than 0.02 mg·L−1 were achieved. The isotherms of the phosphorus adsorption by the modified biochar fitted the Freundlich equation better than the Langmuir equation. The mechanism of the phosphorus adsorbed by the modified biochar was analyzed by using various technologies, i.e. scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The results indicated that the surface of the modified biochar was covered by small iron granules, which were identified as Fe3O4. The results also showed that new iron oxides were formed on the surface of the modified biochar after the adsorption of phosphorus. Moreover, new bonds of Fe-O-P and P-C were found, which suggested that the new iron oxides tend to be Fe5(PO4)4(OH)3. Aside from removing phosphorus, adding the modified biochar into soil also improved soil productivity. When the modified biochar-to-soil rate was 5%, the stem, root, and bean of broad bean plants demonstrated increased growth rates of 91%, 64%, and 165%, respectively.

Practice of integrated system of biofilter and constructed wetland in highly polluted surface water treatment

To find an appropriate process for highly polluted surface water, an integrated system with a double-layer biofilter and a constructed wetland was developed. In the biofilter packed with carbon-rich ceramic granules, alternation of nitrification and denitrification was realized resulting in prominent TN (total nitrogen) removal. The constructed wetland was designed in subsurface flow mode with 0.15m depth filled with calcium-rich ceramic granules, which improved phosphorus removal greatly. COD (chemical oxygen demand), TN, NH4+-N and TP (total phosphorus) in the final effluent were mostly below 30, 15, 5 and 0.5mg/L, respectively. The overall phosphorus removal rate in the constructed wetland reached 158.9g/m2year, in which granules’ interception and plants’ uptake respectively contributed 74.7% and 25.3%. After one year’s operation, the calcium content on the surface of the granules in the constructed wetland decreased obviously, whereas phosphorus content increased greatly.

Bioavailability and Characteristics of Dissolved Organic Nutrients in Wastewater Effluents

Excessive phosphorus (P) is considered to be the primary cause for eutrophication in fresh waterbodies and, the increasingly stringent discharge limits have pushed wastewater facilities to achieve extremely low effluent total phosphorus (TP) levels (e.g., 10-50 μg/L). Pushing the P removal to the level of limit of technology has drawn significant attention from both regulatory agencies and wastewater utilities to the removal and bioavailability of various wastewater derived phosphorus fractions such as non-reactive phosphorus (NRP) and dissolved organic phosphorus (DOP). As more advanced treatment processes have been applied to nearly completely eliminate the soluble reactive P (sRP, i.e., ortho-P), these P fractions (NRP and DOP) contribute an increasingly larger percentage and often become the dominant P fractions in the final effluents. For utilities, the concern arises from the substantial capital cost that is required to research and implement more advanced treatment technologies beyond the current practices in order to remove these P fractions. On the regulatory side, current watershed protection plans (e.g., total maximum daily loads (TMDLs)) use TP for setting limits without considering the possibility that those different P fractions may differ in their bioavailability and therefore their potential to cause eutrophication. Bioavailable P (BAP) is defined as the sum of immediately available P and the P that can transform into an available form by naturally occurring physical, chemical, and biological processes. Although rarely analyzed in routine monitoring, effluents from municipal treatment plants contain various P forms, all of which may have different availabilities to algae and other primary producers. In addition, the bioavailability of different P fraction depends on the different sources of wastewater as well as the method and incubation length of the bioassay used. Currently, little information is available about the bioavailability of various P fractions in various wastewater effluents. Particularly, there is limited information on the bioavailability of wastewater derived DOP to eutrophying phytoplankton in receiving waters. Therefore, it is critical to further identify DOP components and their bioavailability. This study investigated and assessed: • The bioavailability of various P fractions, particularly dissolved P fractions (DOP), in advanced wastewater effluents. • The nature and composition of effluent DOP and its association with effluent dissolved organic nitrogen (DON). • The link and correlation of wastewater characteristics and treatment process with bioavailable effluent DOP. Tertiary effluents from the selected representative wastewater treatment plants were collected and subjected to a detailed and comprehensive analysis for wastewater characterization, phosphorus fractions analysis, and bioavailability assays. Standard methods were employed for the phosphorus fractionation and speciation analysis. Wastewater effluent fingerprinting was performed using fluorescence spectrum and parallel factor (PARAFAC) analysis to gain insights into the nature and characteristics of the effluent organic nitrogen and phosphorus. The bioavailability of P fractions in effluents were assessed using both chemical enzymatic assays and algal bioassays. For selected effluents, simultaneous DOP and DON bioavailability assays were performed to elucidate the differential availability of wastewater effluent-derived organic nitrogen and phosphorus and their association with hydrophilic versus hydrophobic fractions. The results provided: • Information on the bioavailability of different P fractions, particularly the dissolved P fractions, in effluents from a range of advanced treatment processes/technologies. • Revealed the nature of dissolved organic phosphorus in highly treated wastewater effluents via fluorescence spectrum analysis and C/N and C/P ratio evaluations. • Elucidated the correlation between bioavailable effluent DOP and DON with different water fractions (hydrophilic versus hydrophobic), as well as with wastewater sources (humic substances versus proteinaceous matters). • Identified the potentially bioavailable P fractions in effluent and suggested possible mechanisms for their effective removal. This title belongs to WERF Research Report Series ISBN: 9781780405568 (eBook)

Numerical simulation of phosphorus removal in horizontal subsurface flow constructed wetlands

The removal of total phosphorus (TP) in horizontal subsurface flow constructed wetlands (HSF CW) is numerically investigated using the Freundlich linear isotherm for adsorption. For the numerical simulation, the Visual MODFLOW code family, based on the finite difference method, was used. This model is applied in the simulation of five pilot-scale HSF CWs. Influent–effluent TP concentration experimental data from these facilities were used to first calibrate this model and derive appropriate values of the distribution coefficient Kd and the first-order removal coefficient λ. Then, the model was verified using the values of λ and Kd from calibration and independent experimental data from these facilities. The calibrated model was applied to comparatively simulate differences in removal efficiency under various design and operational parameters.

Phosphorus Fractionation and Removal in Wastewater Treatment - Implications for Minimizing Effluent Phosphorus

To address increasing water quality problems associated with eutrophication, state environmental agencies and the United States Environmental Protection Agency (EPA) are requiring more stringent WWTP effluent total phosphorus concentrations that are below 0.10 mg/L and more recently values as low as 0.01 to 0.06 mg/L have been considered. These represent a large decrease in effluent phosphorus permit concentration, which has challenged the POTWs to investigate and evaluate treatment alternatives to achieve additional phosphorus removal by tertiary treatment and to determine the most minimum concentrations possible. Previous studies indicated that as more advanced tertiary treatment processes are applied to eliminate nearly all the soluble reactive P in order to meet the extremely low TP limits, other non-reactive phosphorus species – such as organic P and acid-hydrolysable P – become a larger fraction of the effluent P and their behavior under different treatment methods needs to be understood. The fractional composition of effluent phosphorus and its variations between different WWTP processes have previously received little attention. Therefore, an urgent need exists to gain further fundamental understanding of effluent P chemical species in order to interpret and improve technologies for phosphorus removal to very low limits. The objective of this study is to conduct a survey of P fractions and their fate and susceptibility to a range of different P removal processes, especially tertiary P removal processes. This will help us gain insights into the removal efficiency and mechanism of different P fractions through various treatment technologies. This title belongs to WERF Research Report Series . ISBN: 9781780406893 (eBook)

Cost-effectiveness of membrane bioreactors treatment system for low-level phosphorus reduction from municipal wastewater

Phosphorus removal from municipal wastewater is primarily accomplished through a combination of biological uptake and chemical precipitation. This study examines the capital and operating costs of four strategies for phosphorus removal: conventional activated sludge (CAS), CAS followed by sand filtration, CAS followed by membrane filtration, and membrane bioreactors (MBR). The cost-effectiveness of these four strategies to achieve three target levels of effluent total phosphorus is contrasted: 2.0, 0.3, and 0.1 mg/L. The impact of simultaneously achieving biological nitrogen removal in the system to achieve 10 mg/L total nitrogen is also considered. This study, which is balanced carefully to try to ensure a ‘level playing field’, reveals that MBR facilities are cost-competitive with CAS facilities when tertiary media filtration or tertiary membrane filtration is required for achieving moderate to high levels of phosphorus removal, particularly when simultaneous nitrogen removal is required.

Mixed sulfur-iron particles packed reactor for simultaneous advanced removal of nitrogen and phosphorus from secondary effluent.

A mixed sulfur-iron particles packed reactor (SFe reactor) was developed to simultaneously remove total nitrogen (TN) and total phosphorus (TP) of the secondary effluent from municipal wastewater treatment plants. Low effluent TN (<1.5mg/L) and TP (<0.3mg/L) concentrations were simultaneously obtained, and high TN removal rate [1.03gN/(L·d)] and TP removal rate [0.29g P/(L·d)] were achieved at the hydraulic retention time (HRT) of 0.13h. Kinetic models describing denitrification were experimentally obtained, which predicted a higher denitrification rate [1.98gN/(L·d)] of SFe reactor than that [1.58gN/(L·d)] of sulfur alone packed reactor due to the mutual enhancement between sulfur-based autotrophic denitrification and iron-based chemical denitrification. A high TP removal obtained in SFe reactor was attributed to chemical precipitation of iron particles. Microbial community analysis based on 16S rRNA revealed that autotrophic denitrifying bacteria Thiobacillus and Sulfuricella were the dominant genus, indicating that autotrophic denitrification played important role in nitrate removal. These results indicate that sulfur and iron particles can be packed together in a single reactor to effectively remove nitrate and phosphorus.

A case study for upgrading existing carousel process to achieve low effluent phosphorus discharges

In this study, Al-Qateef wastewater treatment plant was selected as a case representing the upgrade of carrousel technology with tertiary treatment. This technology is applied in many cities in the Eastern province, Kingdom of Saudi Arabia. The use of chemical treatment alternative for phosphorous removal was evaluated versus the newly implemented tertiary treatment unit. The study showed that chemical phosphorous removal has an additional advantage of reducing the final effluent total phosphorus concentration to less than 1 mg/L at an alum dose of 50 mg/L without any significant alteration of the expected final effluent quality that could be achieved by the newly installed sand filters. Furthermore, the study showed that the use of chemical treatment for phosphorous removal could reduce the chlorine dose required for the treated effluent disinfection.

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.

Controls of phosphorus loading and transport in the Cuyahoga River of northeastern Ohio, USA

An urban stream differs from a natural stream in that it commonly contains anthropogenic nutrients from a variety of diffuse and point sources (e.g., urban runoff, industrial and municipal effluents). The Cuyahoga River as one of such stream systems receives on average 30% of water from over a dozen wastewater treatment plants (WWTPs) and exports over 300Mg/yr of total phosphorus (TP) into Lake Erie. Municipal effluents account for at least two thirds of the TP loading and 90% of the effluent TP is in the form of soluble reactive phosphorus (SRP), i.e., the highly bioavailable form in aquatic ecosystems. Owing to its dominance of the effluent P, the Cuyahoga River may pose a disproportionately greater ecological risk to Lake Erie. Here we report results of TP and SRP as measured on water samples collected from 12 locations along the Cuyahoga River and its major tributary – Tinkers Creek under three different flow conditions in July 2007 through May 2008. Our results show that the loadings of SRP and TP increased progressively with the effluent inputs increasing from the upper basin downstream. We found the loadings of SRP and TP are not only affected by the amount of effluent P input but also regulated by stream flow regimes. Effluent P is more likely to be transformed during storm runoff events, whereas TP is more likely to be retained under low flow conditions. As a result, most of the TP loading was exported during the storm and intermediate flow conditions, whereas most of the SRP loading was delivered during the low and intermediate flow conditions. These results suggest that stream hydrology has played an important role in the loading and transport of P across the Cuyahoga River as it dictated the amount, form, and timing of P exported to Lake Erie.

Adaptability of wastewater wetland models in estimating nutrient removal in a stormwater wetland on dry days

ABSTRACT Several types of nutrient removal models, which were developed for wastewater wetlands, were applied to the data collected from a wetland treating stormwater runoff from extensive cow feeding area. First-order and regression equations were used and calibrated to estimate the removal of total phosphorus (TP), ammonium (NH4–N), total kjeldahl nitrogen (TKN), and total nitrogen (TN). To evaluate the performance of the models, the coefficient of determination (R 2), relative root mean square error (RRMSE), and model efficiency (ME), were determined. The first-order models developed produced a good prediction of the effluent TP concentration with R 2 = 0.79, RRMSE = 0.23, and ME = 0.66. On the other hand, the regression models produced very good predictions of effluent NH4–N, TKN, and TN concentrations with R 2 > 0.70, RRMSE 0.70. Therefore, the models for wastewater wetlands can be used to estimate the nutrient removal in stormwater wetlands during dry days. The removal of nutrients ...

Advanced phosphorus removal for secondary effluent using a natural treatment system

Mechanisms for low concentrations phosphorus removal in secondary effluent were studied, and a process was developed using limestone filters (LF), submerged macrophyte oxidation ponds (SMOPs) and a subsurface vertical flow wetland (SVFW). Pilot scale experimental models were applied in series to investigate the advanced purification of total phosphorus (TP) in secondary effluent at the Chengjiang sewage treatment plant. With a total hydraulic residence time (HRT) of 82.52 h, the average effluent TP dropped to 0.17 mg L(-1), meeting the standard for Class III surface waters. The major functions of the LF were adsorption and forced precipitation, with a particulate phosphorus (PP) removal of 82.93% and a total dissolved phosphorus (TDP) removal of 41.07%. Oxygen-releasing submerged macrophytes in the SMOPs resulted in maximum dissolved oxygen (DO) and pH values of 11.55 mg L(-1) and 8.10, respectively. This regime provided suitable conditions for chemical precipitation of TDP, which was reduced by a further 39.29%. In the SVFW, TDP was further reduced, and the TP removal in the final effluent reached 85.08%.

WEF/WERF study of BNR plants achieving very low N and P limits: evaluation of technology performance and process reliability

The Water Environment Research Foundation (WERF) funded a two-year comprehensive study of nutrient removal plants designed and operated to meet very low effluent total nitrogen (TN) and total phosphorus (TP) concentrations. WERF worked with the Water Environment Federation (WEF) to solicit participation of volunteers and provide a forum for information exchange at workshops at its annual conferences. Both existing and new technologies are being adapted to meet requirements that are as low as 3.0 mg/L TN and 0.1 mg/L TP, and there is a need to define their capabilities and reliabilities in the real world situation of wastewater treatment plants. A concern over very low daily permits for ammonia caused the work to be extended to include nitrification reliability. This effort focused on maximizing what can be learned from existing technologies in order to provide a database that will inform key decision makers about proper choices for both technologies and rationale bases for statistical permit writing. To this end, managers of 22 plants, 10 achieving low effluent TP, nine achieving low effluent TN, and three achieving low effluent NH(3)-N, provided three years of operational data that were analyzed using a consistent statistical approach. Technology Performance Statistics (TPSs) were developed as three separate values representing the ideal, median, and reliably achievable performance. Technological conclusions can be drawn from the study in terms of what can be learned by comparing the different nutrient removal and nitrification processes employed at these 22 plants.

Full-scale operating experience of deep bed denitrification filter achieving &amp;lt;3 mg/l total nitrogen and &amp;lt;0.18 mg/l total phosphorus

The Arlington County Wastewater Pollution Control Plant (ACWPCP) is located in the southern part of Arlington County, Virginia, USA and discharges to the Potomac River via the Four Mile Run. The ACWPCP was originally constructed in 1937. In 2001, Arlington County, Virginia (USA) committed to expanding their 113,500 m³/d, (300,000 pe) secondary treatment plant to a 151,400 m³/d (400,000 pe) to achieve effluent total nitrogen (TN) to <3 mg/l and total phosphorus (TP) < 0.18 mg/l. Key to this conversion was the implementation of deep bed denitrification filters to simultaneously achieve both low effluent TN and TP concentrations. A challenge with implementing this technology is maintaining a health denitrifying biomass within the denitrification filters while reducing an essential nutrient, phosphorus, to very low concentrations. This paper will review the steps from concept to the first year of operation, including pilot and full-scale operating data and the capital cost for the denitrification filters.

Pilot Scale Study on Biological Nutrient Removal and Membrane Fouling Alleviation in Combined Membrane Bioreactor for Municipal Wastewater Treatment

To solve the problem of eutrophication in receiving water, a novel Membrane Bioreactor (MBR) with combined configuration was designed for municipal wastewater treatment and reclamation. By dividing bioreactor into three zones, the combined MBR operated under anoxic, anaerobic and aerobic conditions. It provided optimum conditions for nitrification, denitrifying and phosphate accumulating bacterial growth which resulted in high biological nutrient removal rate directly. The operational performance of combined MBR pilot plant showed that it exhibited high nutrient removal rate on Chemical oxygen demand (CODcr), total nitrogen (TN) and total phosphorus (TP). The mean value of effluent CODcr, TN and TP removal rate was 90.63%, 63.05% and 60.51% respectively during 180 days of operation. In order to obtain stable membrane flux, the combined MBR packed with fibrous bio-film carrier and added diatomite. Furthermore, it could alleviate membrane fouling effectively. As a result, the combined MBR improved effluent water quality significantly and alleviated membrane fouling remarkably.

Enhanced nutrient removal MBR system with chemical addition for low effluent TP

A pilot study was conducted to test an membrane bioreactor (MBR) process for combined biological and chemical P removal to achieve a very low effluent total phosphorus (TP) concentration of 0.025 mg P/L. With the data from the pilot test, a simulation study was performed to demonstrate that: (1) the pilot system behaviour (effluent quality, MLSS, etc.) can be modelled accurately with an activated sludge model combined with a chemical precipitation model; and (2) with the calibrated model, simulation scenarios can be performed to further understand the pilot MBR process, and provide information for optimizing design and operation when applied at full-scale. Results from the pilot test indicated that the system could achieve very low effluent TP concentration through biological P removal with a limited chemical addition, and chemical addition to remove P to very low level did not affect other biological processes, i.e., organic and nitrogen removal. Simulation studies indicate that the process behaviour can be modelled accurately with an activated sludge model combined with a chemical precipitation model, and the calibrated model can be used to provide information to optimize system design and operation, e.g., chemical addition control under dynamic loading conditions is important for maintaining biological P removal.

Investigation of a sewage-integrated technology combining an expanded granular sludge bed (EGSB) and an electrochemical reactor in a pilot-scale plant

A sewage-integrated treatment system (SITS) for the treatment of municipal wastewater, consisting of an expanded granular sludge bed (EGSB) reactor to remove soluble organic matter and an electrochemical (EC) reactor to oxidize the NH 3–N, was evaluated. The performance of the EGSB reactor was monitored for 12 months in a pilot-scale plant. Iron shavings were added to the EGSB reactor on the sixtieth day to improve the removal efficiency of the chemical oxygen demand (COD), suspended solids (SS) and total phosphorus (TP). After the iron shavings were added, the effluent COD, SS and TP decreased from 104 to 46 mg L −1, 21 to 8.6 mg L −1 and 3.62 to 1.36 mg L −1, respectively. Moreover, in the EC reactor, which was equipped with IrO 2/Ti anodes, the NH 3–N and total nitrogen (TN) concentrations decreased from 25 to 12 mg L −1 and 29 to 15 mg L −1, respectively. The NH 3–N was directly oxidized to N 2, resulting in no secondary pollution. The results demonstrated the possibility of removing carbon and nutrients in a SITS with high efficiency. The system runs efficiently and with a flexible operation, making it suitable for low-strength wastewater. The results and parameters presented here can provide references for the practical project.

Ithaca Area Wastewater Treatment Facility (IAWWTF) Tertiary Treatment Upgrades Before/After Impact Study: Effluent and Lake Phosphorus Results

Ithaca Area Wastewater Treatment Facility (IAWWTF) Tertiary Treatment Upgrades Before/After Impact Study: Effluent and Lake Phosphorus ResultsThe results of the IAWWTF tertiary treatment upgrade were analyzed by geostatistical analysis and Before/After impact studies. In May 2006, a tertiary treatment process was added to the IAWWTF treatment process. This upgrade has had a significant and positive effect on both the performance of the plant and on the water quality of southern Cayuga Lake. The effluent total phosphorus concentration...Author(s)Jose LozanoLynn SmithSourceProceedings of the Water Environment FederationSubjectSession 43: Nutrients: A Numbers GameDocument typeConference PaperPublisherWater Environment FederationPrint publication date Jan, 2011ISSN1938-6478SICI1938-6478(20110101)2011:14L.2626;1-DOI10.2175/193864711802721271Volume / Issue2011 / 14Content sourceWEFTECFirst / last page(s)2626 - 2649Copyright2011Word count171

Domestic wastewater treatment with CEPT-wetlands process

This study aimed to develop an effective process with less construction and operation cost and with flexibility of meeting different temperature requirements, namely CEPT-construted wetland processes. To reduce the chemical cost for the CEPT process, fly ash was firstly utilised to develop an efficient compound coagulant. The lab-scale experimental results showed that with low Fly Ash Coagulant (FAC) dosage the removals of COD, Total Phosphorus (TP) and Suspended soild (SS) could achieve more than 62%, 91% and 93%, respectively. The coagulation effluent TP and SS had already met the level IB of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002). When the effluent was further treated by following wetlands system with a HRT 2?4 d, the COD could be removed up to 65-77% with the final effluent COD less than 64 mg/L.

연 재배지를 활용한 자유수면형 인공습지의 수질정화효율

In order to investigate the treatment efficiency of pollutants in free water surface constructed wetlands (FWS CWs) with lotus (Nelumbo nucifera) cultivation pond, the experiment was consisted of two sites (site I and II) in Lake Juam, Korea. The sites were configured a lotus cultivation pond (with fertilizer application) - a dropwort bed - a reed bed for site I, and a lotus cultivation pond (without fertilizer application) - a dropwort bed - a reed bed for site II. Removal rate of COD in site I and II were 13.3% and 26.0%, respectively. Removal rate of total nitrogen (TN) was 29.7% for site I, and 36.3% for site II. Removal rate of total phosphorus (TP) in site I and II were 36.0% and 36.5%, respectively. COD, TN and TP in effluent from site I (with fertilizer) was higher than that in site II (without fertilizer), showing that COD, TN and TP in effluent were strongly influenced by fertilizer addition. Therefore, in order to satisfy established water-quality standards, the amount of fertilizer used in lotus cultivation showed be evaluated. 【In order to investigate the treatment efficiency of pollutants in free water surface constructed wetlands (FWS CWs) with lotus (Nelumbo nucifera) cultivation pond, the experiment was consisted of two sites (site I and II) in Lake Juam, Korea. The sites were configured a lotus cultivation pond (with fertilizer application) - a dropwort bed - a reed bed for site I, and a lotus cultivation pond (without fertilizer application) - a dropwort bed - a reed bed for site II. Removal rate of COD in site I and II were 13.3% and 26.0%, respectively. Removal rate of total nitrogen (TN) was 29.7% for site I, and 36.3% for site II. Removal rate of total phosphorus (TP) in site I and II were 36.0% and 36.5%, respectively. COD, TN and TP in effluent from site I (with fertilizer) was higher than that in site II (without fertilizer), showing that COD, TN and TP in effluent were strongly influenced by fertilizer addition. Therefore, in order to satisfy established water-quality standards, the amount of fertilizer used in lotus cultivation showed be evaluated.】