Phosphorus Discharge Research Articles

Phytase can reduce theneedfor monocalcium phosphate supplementation in soybean and rapeseed meal-based diets of black sea bream, Acanthopagrus schlegelii (Bleeker, 1854)

A feeding trial was conducted to study the effect of partial replacement of dietary monocalcium phosphate (MCP) with phytase on growth performance, feed utilization and phosphorus discharge in black sea bream, Acanthopagrus schlegelii. In the feeding trial, the control diet (designated as P1.5) was prepared with 1.5% MCP but without phytase, and the three other diets (designated as PP1.0, PP0.5 and PP0, respectively) were supplemented with 1.0%, 0.5% and 0% MCP, respectively, along with 200 mg (400 U) phytase/kg diet in each. Each diet was tested in triplicate tanks and fish were fed twice daily to satiation. After an 8-week feeding trial in indoor flow-through cylindrical fibreglass tanks (25 fish per tank, initial body weight: 11.5 ± 0.12 g), fish fed with PP1.0 and PP0.5 had no significant change in weight gain (WG), specific growth rate (SGR), protein efficiency rate (PER) or feed conversion ratio (FCR) compared to the control (p > .05), whereas fish fed with PP0 showed a significantly lower growth performance in the above parameters (p < .05). The addition of phytase did not affect the body composition or muscle composition. The apparent digestibility coefficients (ADCs) of crude protein and phosphorus increased when fish were fed diets in which MCP was replaced by phytase. Phosphorus discharge was also significantly reduced in fish fed diets in which MCP was replaced by phytase (10.2 ± 0.50 to 8.01 ± 0.47 g/kg weight gain). The present study suggests that dietary MCP can be reduced when phytase is added to the black sea bream diet, with a maximum MCP reduction level of up to 1% when phytase is supplemented at 200 mg (400 U)/kg diet. Thus, phytase in the diet of black sea bream is economically and ecologically beneficial.

The coagulation–ultrafiltration process from pilot testing to full-scale design for the achievement of ultra-low phosphorus limit

Lake water from a Shanghai theme park faces restrictive phosphorus discharge limits (≤0.02 mg/L) that are technically challenging. Laboratory bench top and pilot plant testing were conducted. The results show that a coagulation–ultrafiltration (UF) hybrid process is able to reliably achieve the objective, while a coagulation–sand filter process cannot meet the requirement. Therefore, mature technologies such as Veolia Actiflo® and GE Zeeweed® are preferred for full-scale design. In addition, alum performs better than poly alum chloride on phosphorus removal. It was also suggested the efficiency of anion polyacrylamide for the filtered samples was reduced compared with non-filtered samples. Simultaneously, soluble PO4-P was also eliminated by UF resulting from the flocs and precipitates with greater surface area and the agglomeration of residual aluminum ions and orthophosphate. Membrane filtration helps reduce chemical dosage and 6 mg/L Al3+ (alum) concentration was enough to meet the requirement for the influent TP around 0.3 mg/L. Finally, several considerations were given to future scale-up design, such as treatment target of coagulation precipitation system, species of coagulant aid, flocculants, and online analyzers.

Evaluation of executable best management practices in Haean highland agricultural catchment of South Korea using SWAT

This study is to evaluate the reduction of high level nonpoint source (NPS) pollution discharges in Haean highland agricultural catchment (62.8km2) by applying best management practices (BMPs) of vegetation filter strip installation (VFS), fertilizer control (FC), and rice straw mulching (RSM) in uplands above 600m of elevation using SWAT (Soil and Water Assessment Tool). From the modeling results, the VFS BMP showed the best performance to reduce sediment (SS) of 16.0% for 1m strip width up to 34.8% for 5m strip width and total phosphorus (T-P) discharge loads of 5.1% to 21.3% from highland crop areas. The FC BMP showed the discharge loads reduction of 4.9% for 10% fertilizer reduction up to 16.4% for 30% fertilizer reduction. The RSM BMP results showed the sediment reduction of 3.0% for 6.0% runoff reduction up to 14.1% for 17.0% runoff reduction and T-P reduction of 1.3% for 6.0% runoff reduction up to 6.8% for 17.0% runoff reduction by showing negative effect of total nitrogen (T-N) up to −3.7% for 12.0% runoff reduction. However, because of the difficulties to install vegetation filter strip by farmers unwillingness in South Korea, the BMPs combination of fertilizer reduction and rice straw mulching (FC+RSM) was suggested as an executable BMP to obtain positive removal efficiency for all nutrient discharge loads. The FC+RSM BMP showed sediment, T-P, and T-N reductions up to 9.7%, 8.1%, and 9.2% respectively.

The research of the variation of seasonal nutrients loading on Sapanca Lake

In this study, the variation of seasonaJ - nutrient loading to be caused pollution and trophic state of the Sapanca Lake wliich is the only source of drinking and usage water for the city of Adapazari and its environs was investigated. Samples were taken every three inontlis through one year from fifteen different points on the streains feeding and draining off the lake. Parainetcrs of temperature, pH., N03-N, N02-N .. NH3-N., TKN, P04-P. BOI5 and KOI on the different tweJve streains feeding and three draining off points were Froni these values.. loading, discharge and accuinulation amounts of nitrogen and phosphorus causing eutrophication were calculated and trophic state of the lake was deterinined. According to the results and analyses using the Vollenweider method., indicated that the lake had passed to the mesotrophic state. In addition .. to avoid further pollution., possible subsequent eutrophic state and find soine solutions in order to protect lake were discussed.

The modeled and observed response of Lake Spokane hypolimnetic dissolved oxygen concentrations to phosphorus inputs

ABSTRACTBrett MT, Ahopelto SK, Brown HK, Brynestad BE, Butcher TW, Coba EE, Curtis CA, Dara JT, Doeden KB, Evans KR, Fan L, Finley JD, Garguilo NJ, Gebreeyesus SM, Goodman MK, Gray KW, Grinnell C, Gross KL, Hite BRE, Jones AJ, Kenyon PT, Klock AM, Koshy RE, Lawler AM, Lu M, Martinkosky L, Miller-Schulze JR, Nguyen QTN, Runde ER, Stultz JM, Wang S, White FP, Wilson CH, Wong AS, Wu SY, Wurden PG, Young TR, Arhonditsis GB. 2016. The modeled and observed response of Lake Spokane hypolimnetic dissolved oxygen concentrations to phosphorus inputs. Lake Reserv Manage. 32:246–258.Lake Spokane, a reservoir in eastern Washington State, was previously hypereutrophic due to phosphorus discharges from the City of Spokane wastewater treatment plant (WWTP). This reservoir subsequently recovered to a meso-oligotrophic state after implementation of advanced phosphorus removal. The present study tested whether the mechanistic Lake Spokane water quality (WQ) model realistically represents the sensitivity of this reservoir's hypolimnetic oxygen concentrations to phosphorus inputs. We compared the observed relationship between the mean summer input total phosphorus concentration (TPIN) and the minimum volume weighted hypolimnetic dissolved oxygen concentration (DOMIN) to model values for conditions ranging from hypereutrophic to oligotrophic. Prior to advanced phosphorus removal, TPIN and DOMIN averaged 86 ± 37 (SD) µg/L and 1.4 ± 1.3 mg/L, respectively. Currently (2010–2014), these values average 14 ± 3 µg/L and 6.5 ± 0.8 mg/L, respectively. By contrast, the model's DOMIN response for similar TPIN concentrations was much less pronounced, with hypereutrophic and contemporary DOMIN averaging 3.8 ± 0.4 and 4.7 ± 0.04 mg/L, respectively. The model also has a structural DO deficit (saturated DO − DOMIN) of 5.3 mg/L that was evident when all TP inputs to the reservoir were set to zero. Similarly, when all WWTP effluent sources were set to TPEFF = 0 µg/L, the reservoir epilimnetic TP concentrations were ≈8 µg/L higher than the Spokane River inputs. The water quality model indicates that even if effluent phosphorus concentrations are reduced to zero, the dissolved oxygen goals for Lake Spokane cannot be met.

Integrative microbial community analysis reveals full-scale enhanced biological phosphorus removal under tropical conditions

Management of phosphorus discharge from human waste is essential for the control of eutrophication in surface waters. Enhanced biological phosphorus removal (EBPR) is a sustainable, efficient way of removing phosphorus from waste water without employing chemical precipitation, but is assumed unachievable in tropical temperatures due to conditions that favour glycogen accumulating organisms (GAOs) over polyphosphate accumulating organisms (PAOs). Here, we show these assumptions are unfounded by studying comparative community dynamics in a full-scale plant following systematic perturbation of operational conditions, which modified community abundance, function and physicochemical state. A statistically significant increase in the relative abundance of the PAO Accumulibacter was associated with improved EBPR activity. GAO relative abundance also increased, challenging the assumption of competition. An Accumulibacter bin-genome was identified from a whole community metagenomic survey, and comparative analysis against extant Accumulibacter genomes suggests a close relationship to Type II. Analysis of the associated metatranscriptome data revealed that genes encoding proteins involved in the tricarboxylic acid cycle and glycolysis pathways were highly expressed, consistent with metabolic modelling results. Our findings show that tropical EBPR is indeed possible, highlight the translational potential of studying competition dynamics in full-scale waste water communities and carry implications for plant design in tropical regions.

Furrow Cover Effects of Black Non-woven Fabric on Reduction of Nitrogen and Phosphorus Discharge from Upland Soil Used for Red Pepper Cultivation

Control of surface runoff from upland soil is essential to reduce nonpoint source pollution. The use of non-woven fabric as a soil cover can be helpful to control surface runoff. The field experiment was conducted to evaluate the furrow cover effects of black non-woven fabric on the nutrient discharge from upland soil used for red pepper cultivation. The experimental plots consisted of chemical fertilizer (CF), cow manure compost (CMC), and pig manure compost (PMC) treatment. Each nutrient material treatment plot has control (no furrow cover (NFC)) and black non-woven fabric cover treatment, respectively. The amount of nutrient application was chemical fertilizer of <TEX>$190-112-149(N-P_2O_5-K_2O)kgha^{-1}$</TEX>, cow manure compost of <TEX>$29.5tonha^{-1}$</TEX>, and pig manure compost of <TEX>$7.9tonha^{-1}$</TEX> as recommended amount after soil test for red pepper cultivation. Compared to control (NFC), furrow cover treatment with black non-woven fabric reduced the amount of T-N discharge by 50% at CF treatment, 36.9% at CMC treatment, and 44.8% at PMC treatment. Furrow cover treatment with black non-woven fabric reduced the amount of T-P discharge by 37.1% at CF treatment, 49.9% at CMC treatment, and 63.4% at PMC treatment compared to control (NFC). The production of red pepper did not show significant difference. There was no weed occurring in furrow cover treatment plots with black non-woven fabric. Results from this study showed that the furrow cover with black non-woven fabric could play a significant role in reduce nutrient discharge from upland soil used for red pepper cultivation.

Display of phytase on the cell surface of Saccharomyces cerevisiae to degrade phytate phosphorus and improve bioethanol production

Currently, development of biofuels as an alternative fuel has gained much attention due to resource and environmental challenges. Bioethanol is one of most important and dominant biofuels, and production using corn or cassava as raw materials has become a prominent technology. However, phytate contained in the raw material not only decreases the efficiency of ethanol production, but also leads to an increase in the discharge of phosphorus, thus impacting on the environment. In this study, to decrease phytate and its phosphorus content in an ethanol fermentation process, Saccharomyces cerevisiae was engineered through a surface-displaying system utilizing the C-terminal half of the yeast α-agglutinin protein. The recombinant yeast strain, PHY, was constructed by successfully displaying phytase on the surface of cells, and enzyme activity reached 6.4 U/g wet biomass weight. Ethanol productions using various strains were compared, and the results demonstrated that the specific growth rate and average fermentation rate of the PHY strain were higher 20 and 18 %, respectively, compared to the control strain S. cerevisiae CICIMY0086, in a 5-L bioreactor process by simultaneous saccharification and fermentation. More importantly, the phytate phosphorus concentration decreased by 89.8 % and free phosphorus concentration increased by 142.9 % in dry vinasse compared to the control in a 5-L bioreactor. In summary, we constructed a recombinant S. cerevisiae strain displaying phytase on the cell surface, which could improve ethanol production performance and effectively reduce the discharge of phosphorus. The strain reported here represents a useful novel engineering platform for developing an environment-friendly system for bioethanol production from a corn substrate.

A bioenergetic approach to manage production and control phosphorus discharges from a salmonid hatchery

The environmental effects of fish culture operations are important issues in Michigan as well as many other parts of the world. The State of Michigan Department of Natural Resources operates the Platte River State Fish Hatchery (PRSFH) located near Honor, Michigan (USA). This facility has a restrictive discharge permit that limits the input of phosphorus into the Platte River that subsequently drains into a downstream oligotrophic lake (Platte Lake). The permit has been violated on occasion in recent years. Hatchery managers and operators need to understand the cause of these violations and prevent them in the future; and at the same time meet production goals to satisfy fishery management objectives. This paper describes the development and application of models designed to quantitatively analyze these issues. First, a bioenergetic growth and consumption model is developed for juvenile coho (Oncorhynchus kisutch) and Chinook (Oncorhynchus tshawytscha) salmon to quantify the relationship between fish production and by-product phosphorus loads. Next, phosphorus mass balance equations are used to calculate the phosphorus discharge from the facility as a function of the by-product phosphorus load and the efficiency of various phosphorus removal equipment and processes. The accuracy and consistency of the energy and mass balance equations are verified using extensive measurements. The ability of the model to successfully match various aspects of system performance supports the contention that the bioenergetic modeling approach developed here can provide reliable estimates of salmonid growth and feed requirements for a variety of food compositions, rations, and temperatures. This capability, along with knowledge of the effectiveness of phosphorus removal equipment, forms the basis of a practical operational and management tool. An example of model utility is presented that analyzes the PRSFH phosphorus discharge and provides insights into why permit violations occurred in 2009 but not in 2010. The model demonstrates how to avoid food waste caused by over feeding, lower the food conversion ratio, and evaluate the effectiveness of phosphorus removal treatment processes. A steady-state version of the model can be used by managers to establish production goals that avoid future violations of the phosphorus discharge limits. Statement of relevanceThe environmental effects of fish culture operations are important issues in many parts of the world. This paper describes the development and application of models designed to quantitatively analyze the relationships among fish production, by-product phosphorus loads, and the phosphorus concentration of the discharge following treatment. The ability of the model to successfully match various aspects of system performance supports the contention that the bioenergetic modeling approach developed here can provide reliable estimates of salmonid growth and feed requirements for a variety of food compositions, rations, and temperatures. This capability, along with knowledge of the effectiveness of phosphorus removal equipment, forms the basis of a practical operational and management tool. The model demonstrates how to avoid food waste caused by over feeding, lower the food conversion ratio, and evaluate the effectiveness of phosphorus removal treatment processes. A steady-state version of the model can be used by managers to establish production goals that avoid future violations of the phosphorus discharge limits.

Daily mass balance of phosphorus and nitrogen in effluents of production sectors of trout farming system

Abstract Aim: The mass balance has recently been applied in Brazilian aquaculture. In relation to trout farming, few studies have used this methodology as environmental indicator, especially when considering each development stage of fish. The daily mass balance allows an estimate of nutrients discharge, because the sampling effort over 24 hours enables to monitor the variations throughout the day. This study aimed to identify the breeding sector (fingerlings, juveniles and adults) in trout farming contributes with the great discharge of phosphorus and nitrogen in the effluent. Methods The concentrations of total phosphorus (TP), orthophosphate (PO4-P), total nitrogen (TN) and ammonium (NH4-N) were determined in affluent and effluents of the production system. The environmental indicators were calculated based on the values of nutrients loads and by quantifying the daily discharge of nutrients from the mass balance method. Results Over the 24 hours, the trout farming exported an average of 0.26 kg TP, 0.11 kg PO4-P, 3.11 kg TN and 0.18 kg NH4-N. The discharge of phosphorus and nitrogen in the effluent was higher at night associated to feeding management (hours and feeding frequency) and the nocturnal habits of trout. The juvenile and adult sectors accounted for the greatest contribution of these nutrients, related the largest fish biomass and metabolism, supported by the feed conversion ratio of 1.95:1 and 2.01:1, respectively. Conclusion In order to reduce exports of phosphorus and nitrogen there is a need to adequate the feeding management (feeding frequency from two to four times per day according to the trout development stage; carry out feeding in times close at twilight due to the nocturnal habits of this specie; reduce excess of ration offered and use good quality ration considering the distinct nutritional requirements of each trout stage of development). Besides the mass balance, the feed conversion ratio is also an efficient tool to detect the efficiency of feed utilization; therefore, it is proposed its use as environmental indicator, aiming the aquaculture environmental sustainability.

Risiko des Eintrags von Phosphor in den Hallwilersee durch Bodenerosion

Abstract. An important factor in the release of phosphorus by soil erosion, with corresponding consequences on the quality of surface waters, is the formation of aggregates and their stability. Around the eutrophic Lake Hallwil six arable lands were examined in five repetitions regarding aggregate and particle size distribution, P-contents of the different fractions and aggregate stability. Central to this was the use of the setting column for fractionation of soil samples. In the case of Lake Hallwil the risk of phosphorus discharges by soil erosion seems low since the phosphorus is mainly bound in aggregates which are transported over short distances only. Thus other pathways (runoff from grassland, leaching via drains) may be more important.

Calculating discharge of phosphorus and nitrogen with groundwater base flow to a small urban stream reach

Summary Elevated levels of nutrients, especially phosphorus, in urban streams can lead to eutrophication and general degradation of stream water quality. Contributions of phosphorus from groundwater have typically been assumed minor, though elevated concentrations have been associated with riparian areas and urban settings. The objective of this study was to investigate the importance of groundwater as a pathway for phosphorus and nitrogen input to a gaining urban stream. The stream at the 28-m study reach was 3–5 m wide and straight, flowing generally eastward, with a relatively smooth bottom of predominantly sand, with some areas of finer sediments and a few boulders. Temperature-based methods were used to estimate the groundwater flux distribution. Detailed concentration distributions in discharging groundwater were mapped using in-stream piezometers and diffusion-based peepers, and showed elevated levels of soluble reactive phosphorus (SRP) and ammonium compared to the stream (while nitrate levels were lower), especially along the south bank, where groundwater fluxes were lower and geochemically reducing conditions dominated. Field evidence suggests the ammonium may originate from nearby landfills, but that local sediments likely contribute the SRP. Ammonium and SRP mass discharges with groundwater were then estimated as the product of the respective concentration distributions and the groundwater flux distribution. These were determined as approximately 9 and 200 g d−1 for SRP and ammonium, respectively, which compares to stream mass discharges over the observed range of base flows of 20–1100 and 270–7600 g d−1, respectively. This suggests that groundwater from this small reach, and any similar areas along Dyment’s Creek, has the potential to contribute substantially to the stream nutrient concentrations.

Improvement of Nutritive Value of Sesame Oil Cake in Formulated Diets for Rohu, Labeo rohita (Hamilton) After Bio-Processing Through Solid State Fermentation by a Phytase-Producing Fish Gut Bacterium

Sesame oil cake (SSC) was bio-processed through solid state fermentation (SSF) under optimized conditions by a phytase-producing fish gut bacterium, Bacillus subtilis subsp. subtilis (JX292128). SSF significantly reduced anti-nutritional factors (e.g., phytic acid, tannins and trypsin inhibitor) and crude fibre, while enhanced free amino acids, fatty acids and different minerals. Phytase production (39.72 ± 1.06 U/g) during SSF was also recorded. Along with a fish meal based reference diet (RD), 8 isonitrogenous (36% crude protein) and isocaloric (4.60 kcal g -1 ) experimental diets incorporating raw (R1-R4) and SSF processed (F1-F4) SSC(20%, 30%, 40% and 50%, w/w) were fed to rohu, Labeo rohita fingerlings (mean weight 3.28 ± 0.15 g) in triplicate treatments for 70 days. In general, growth and feed utilization efficiencies in fish fed diets containing SSF-processed SSC were superior to the groups fed diets containing raw SSC. The diet F3 (40% fermented SSC) showed significantly ( P <0.05) better result in terms of weight gain, feed conversion ratio, protein efficiency ratio, apparent net protein utilization, activities of digestive enzymes, carcass composition and apparent digestibility of protein, lipid and phosphorus. Faecal phosphorus discharge reduced significantly ( P <0.05) in fish fed fermented diets. The results indicated that incorporation of SSF-processed SSC might be practiced as a function to replace fish meal in the diets of L. rohita fingerlings.

Biotechnology in Environmental Monitoring and Pollution Abatement 2015.

Rapid industrial growth has led to elevated discharges of toxic chemicals and nutrients in water bodies. The level of a particular pollutant discharged into water bodies depends on industrial activities in the vicinity. Industries such as textiles, mining, tanneries, metal plating, fertilizer and agroindustries, batteries, pesticides, ore refineries, petrochemicals, and paper manufacturing are amongst others that contribute greatly to soil, sediment, air, and water pollution problems. Some of the chemicals are not biodegradable and therefore tend to accumulate in tissues and bioaccumulate in the food chain. This results in health problems in human beings and death of aquatic organisms. In water bodies, the presence of nitrogen and phosphorus increases the production of biomass in aquatic systems, thereby impairing the water quality and threatening the natural balance of these ecosystems. Although stringent nitrogen and phosphorus discharge standards from wastewater have been set in many countries, industries often face problems in meeting these requirements. From the regulatory perspective of a particular country, it is necessary to develop new or optimize the existing wastewater treatment technologies for compliance with the latest discharge standards. The demand for the use of sustainable and ecofriendly environmental processes is rapidly growing subjected to economic, public, and legislation pressure. Biotechnology provides a plethora of opportunities for effectively addressing issues pertaining to the monitoring, assessment, modeling, and treatment of contaminated soil, sediment, air, and water streams. The different biotechnologies available nowadays represent both well-established and novel (bio)technologies, although several aspects of their performance remain to be tested, for instance, the use of novel biocatalysts and reactor designs, a fundamental understanding of microbial community dynamics and mechanisms occurring within a (bio)reactor, the assessment of the performance of (bio)reactors during long-term operation, and its modeling [1–6]. If these mechanisms are understood and the knowledge gap is bridged, novel biotechniques will potentially change the way users rebuild technologies for the sustainable use of different biological processes for soil, sediment, air, and wastewater treatment.

A NOVEL PROCESS FOR NUTRIENTS REMOVAL AND PHOSPHORUS RECOVERY FROM DOMESTIC WASTEWATER BY COMBINING BNR WITH INDUCED CRYSTALLIZATION

An excessive discharge of phosphorus from wastewater to water bodies may potentially contribute to eutrophication. On the other hand, mineral phosphorus resources will be depleted in the near future, because of difficulty to automatically recycle from water to land, unlike nitrogen. A new process for nutrients removal coupled with phosphorus recovery was proposed in this study by combining biological nutrients removal (BNR) with induced crystallization (IC), BNR-IC for short later, differently from conventional phosphorus recovery process. Our results showed that the BNR-IC system can maintain not only high and stable carbon, nitrogen and phosphorus removal efficiencies, all presenting above 90%, but also good phosphorus recovery performance from synthetic domestic wastewater, displaying about 70.2% of phosphorus recovery rate. When the COD, TN, NH4–N and P concentrations of 250 mg L−1, 42 mg L−1, 40 mg L−1, and 10 mg L−1, respectively were given in the influent, a stable removal efficiencies of 92.5% COD, 78.6% TN, 85.9% NH4–N and 95.2% P were obtained for the BNR-IC process and correspondingly the COD, TN, NH4–N and P concentrations of 18.75 mg L−1, 8.99 mg L−1, 5.64 mg L−1, 0.42 mg L−1 were monitored in the effluent, meeting the Chinese National Class I (grade A) Sewage Discharge Standard. Analyses of SEM and EDS, moreover, also demonstrated that the surface of seed crystal (calcite used here) was completely covered by hydroxyl calcium phosphate (HAP) produced during the induced crystallization process to recover phosphorus. Although our study involved only a small-scale trial, the proposed BNR-IC process here may be a promising technology, and can potentially aid in improvement of the effluent quality from WWTP and in recycle of mineral phosphorus resources when applied to practice.

Development of a Fuzzy-Boundary Interval Programming Method for Water Quality Management Under Uncertainty

This study develops a fuzzy-boundary interval programming (FBIP) method for tackling dual uncertainties expressed as crisp intervals and fuzzy-boundary intervals. An interactive algorithm and a vertex analysis approach are proposed for solving the FBIP model and solutions with α-cut levels have been generated. FBIP is applied to planning water quality management of Xiangxi River in the Three Gorges Reservoir Region, China. Biological oxygen demand (BOD), total nitrogen (TN), and total phosphorus (TP) are selected as water quality indicators to determine the pollution control strategies. Results reveal that the highest discharge of BOD is observed at the Baishahe chemical plant, among all point and nonpoint sources; crop farming is the main nonpoint source with the excessive nitrogen loading due to too much uses of livestock manures and chemical fertilizers; phosphorus discharge derives mainly from point sources (i.e. chemical plants and phosphorus mining companies). Abatement of pollutant discharges from industrial and agricultural activities is critical for the river pollution control; however, the implementation of management practices for pollution control can have potentials to affect the local economic income. These findings can help generate desired decisions for identifying various industrial and agricultural activities in association with both maximizing economic income and mitigating river-water pollution.

Co-removal of phosphorus and nitrogen with commercial 201 × 7 anion exchange resin during tertiary treatment of WWTP effluent and phosphate recovery

Excessive nitrogen and phosphorus discharge into natural water from wastewater treatment plants still have the potential of causing eutrophication. How to remove those excessive nitrogen and phosphorus in an appropriate way is welcome in practice. This study co-removed nitrate and phosphorus via the operation of commercial 201 × 7 exchange resin column, and recovered phosphate simultaneously. Experimental results demonstrated that the adsorption of PO43--P onto the 201 × 7 resin satisfactorily fitted to Freundlich isotherm, while NO3--N followed Langmuir model, with a maximum adsorption capacity of 12.47 mg/g for PO43--P and 107.59 mg/g for NO3--N, respectively. Up to 92% of PO43--P and 90% of NO3--N in the secondary effluent were recovered by 201 × 7 resin column under the optimal flow rate of 50 BV/h. The exhausted 201 × 7 resin could be regenerated by 5% NaCl within 1 h at a flow rate of 15 BV/h. Moreover, this regeneration would guarantee the effluent PO43--P and NO3--N are lower than the breakthrough points even when 1175 BV wastewater passed the resin column. These findings are of great significance for ensuring stricter effluent phosphorus and total nitrogen discharge criteria.

A comparison of the effect of dietary fungal phytase and dicalcium phosphate supplementation on growth performances, feed and phosphorus utilization of tra catfish juveniles (Pangasianodon hypophthalmusSauvage, 1878)

Six isonitrogenous (320 g kg−1) and isolipidic (60 g kg−1) diets were formulated with graded levels (0, 5, 10 and 15 g kg−1) of dicalcium phosphate (DCP) and fungal phytase (750 and 1500 FTU kg−1 diet). Tra catfish (Pangasianodon hypophthalmus), 9.6 g, were fed the diets for 12 weeks. Each experimental diet was fed to eight replicates of fish to apparent satiation. At the end of the trial, fish fed the diets containing 15 g kg−1 DCP, 750 and 1500 FTU kg−1 phytase had higher growth performances, protein efficiency ratio and phosphorus retention than those fed the control diet, 5 g kg−1 DCP and 10 g kg−1 DCP diets (P < 0.05). Whole body ash and phosphorus concentration of fish fed the 10 g kg−1 DCP and 15 g kg−1 DCP diets were significantly higher than those of fish fed the control diet. Higher apparent digestibility coefficient of phosphorus was observed in fish fed the phytase supplemented diets. The present results indicate that supplementation of phytase at 750 FTU kg−1 and 1500 FTU kg−1 improves growth performances, feed and phosphorus utilization. The supplementation can completely replace dicalcium phosphate or other phosphorus sources in tra catfish feed and reduce the phosphorus discharge into environment.

Enhancing simultaneous removal of nitrogen and phosphorus from municipal wastewater by Fe–Cu shavings

AbstractTo alleviate the environmental stress and meet the increasingly strict regulation requirements for total nitrogen (TN) and total phosphorus (TP) discharge, hybrid system of Fe–Cu shavings with activated sludge was studied in a lab-scale to treat actual municipal wastewater. The results showed that Fe–Cu shavings could enhance TN and TP removal from municipal wastewater without external carbon source addition. Compared with the simple biological system, TP and TN removal efficiency raised about 30 and 10%, respectively, in the hybrid system at temperature of 3–26.5°C, while the improvement of COD removal was not obvious. Moreover, total ferrum concentration of the effluent was lower than 0.6 mg/L, no additional metal pollution appeared. Therefore, a new N&P removal technology is proposed, which provides an easy implementation and effective upgrading to the existing wastewater treatment plants.

Phosphate recovery from animal manure wastewater by struvite crystallization and CO2 degasification reactor

Abstract The problem of phosphorus discharge is related to environmental protection and food security. Struvite crystallization is a useful technology for phosphate recovery from wastewater. In the research, struvite crystallization process with CO2 degasification continuous U-shape reactor (CUSR) was application for phosphate recovery from animal manure wastewater. The result indicated PO4 3--P recovery ratio could achieve 47-53% without magnesium addition when CUSR hydraulic retention time controlled at 60 min. With extra magnesium addition, PO4 3--P recovery ratio could significant achieve 80-86% at magnesium addition amount 57.5 mg/dm3. PHREEQC modeling predictions trend of struvite crystallization was close to CUSR experimental results. The modeling calculation can provide a theoretical guide for operational parameters design. For seeding technology, high phosphate recovery efficiency was obtained and preformed struvite was the most effective seeding material. Surface characterization analysis demonstrated the dominant composition of chemical solids was struvite. Water extraction analysis indicated chemical solids recovery from animal manure wastewater could release PO4 3--P slowly and be available as slow-release fertilizer.