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1. Introduction
The internal phosphorus (P) loading from P-rich sediments is considered the major cause of delay in shallow lake restoration after reduction of external P loading (Simple 3 Fold Orthopedic Folding Foam Mattress,www.qj-ec.com). As a result, several chemical methods have been applied to control P internal loading worldwide (Wholesale Oil Tanker Trailer 3 Axle 42000L Trailer Fuel Tank Semi Truck Trailer;Factory Price Resin Wedding Chairs for Sale;Non-Bladder Single Tube Disposable Thigh NIBP Cuff of 45-56.5cm). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Silica Gel Aerogel Thermal Insulation Materials Felts Fireproof Acoustic). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,1215GSM Fiberglass Multiaxial Composite Zero Crimp Triaxial Fabric Roll (0/+45/-45 Degree), flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Good Electric 2 in 1 Hair Curling Straightening Iron Brush),Best Plastic Water Bottle 750ml Tritan Drinking Bottle. Among the Al-based coagulants, the aluminium sulphate (Al2(SO4)3), or alum, is the most commonly used chemical in lake restoration. Its effectiveness in removing phosphorus has been reported in several laboratory and whole-lake experiments (Linkable PIR Motion Sensor Indoor LED Linear Strip Under Cabinet Light;20W 30W 40W Solar Lighting System Solar Street Lights for Road Lighting Fittings;Round Pipe Welded Pipe Middle Size for Chemical Companies). However alum may result in high concentration of residual Al and is strongly affected by temperature (Quality Medium Stapler with Staples Remover) and pH.
In order to improve coagulation process pre-hydrolysed Al-based coagulants as polyaluminium chloride (PAC) were developed. Polyaluminium coagulants are made by the partial hydrolysis of acid aluminum chloride in controlled conditions and do not consume the alkalinity from water. Thus, PAC has a superior coagulation performance than alum due to its wider pH range, lower sensitivity to low water temperature, lower doses required and lower residual Al concentrations (China Factory Customized High Quality FDA Silicone Tea Bag Infuser). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (G02f12L Tempered Glass Shower Cabin;Cold Rolled Steel Coil Galvalume/ Hot Dipped Galvanized Steel;Tandem Axle Semi-Trailer Lift Germany Mechanical Overslung Suspension; 7050;Addressable Heat Detector for Fire Alarm System;115cm Mini Sex Doll for Man Big Breast Love Doll;Fancy Design Formal Dress Shirt Short Sleeve for Women).Recessed Colorful Solar Interaction LED Underground Lighting(Pear or Regular Shaped Screw Lock Metal Quick Link;Traffic Safety Plastic Signs/Accessible Fire Exit Emergency Signs;m.anebonmetal.com;Popular Lifejacket EPE Foam Life Vest for Water Safety Equipment) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (14G Auto Computerized Collar Flat Knitting Machine), and it has been suggested as a lake restoration measure.
Coagulation-FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body(Portable Metal and Nonmetal CNC Fiber Laser Marking Machine) and also by water chemistry (pH and alkalinity) (Long Span Galvanized Light Weight Steel Structure). PAC was developed to depress alkalinity consumption but its efficiency is pH dependent. The effectiveness of PAC coagulation is affected by aluminium speciation after its application in water which in turns is determined by pH (1688 Buying Sourcing Agent). At pH of 6.0-7.Industrial Air Cooled Heat Pump Water Chiller in Many Field(China Gingseng Extract Ginsenosides 15% 20% 80%,PVC Shoe Upper with LED Light for Kids Slide-on Slippers). Algae also can affect coagulation due to characteristics such as morphology, motility,Building Material Colorful Stone Coated Metal Spanish Roofing Tile(Plastic PVC Car Mat Making Line / PVC Coil Carpet Car Seat Cutting Machine,Duct Outdoor Single-Mode Gyfy Fiber Optic Cable,Aluminum Wire Mesh).
In the tropical semi-Frosted White Grey Blue Painted Glass Candle Jar with Wood Lid-made lakes are used for water supply despite of constant blooms of toxic cyanobacteria. Direct application of PAC into these lakes have been proposed as a cheap tool for water quality management, but no previous study have investigated the effectiveness of PAC in removing turbidity and phosphorus in these lakes.Sculpture Wood Carving CNC Router Machine Engraver. The performance was evaluated in terms of turbidity and phosphorus removal and also for humic substances and chlorophyll-a.
2. Material and Methods
2.1. Raw water
Custom Printed Corrugated Paper Display PDQ Packaging Carton Box Manufacturer Supplier Factory, Brazil: Gargalheiras, Passagem das Traíras, Boqueirão, Dourados, Cruzeta and Timbaúba reservoir. The samples were kept in laboratory, at room temperature, by up to 48h before the start of the experiments. The turbidity (NTU; Turbidimeter AP2000), concentrations of chlorophyll-a(Factory Price 50W LED Corn Bulb E26/E39/E27/E40 Base Indoor and Outdoor Industial Lighting) and concentrations of total phosphorus (FRP Insulated PU Foam Composite Panel for Refrigerated Truck Body;Kmart Fitness Equipment Nz) were measured to caracterize the raw water.
2.2. Coagulant dose
The coagulant used were polyalumnium chloride (PAC; PANFLOC TE1018 – Pan-Americana S/A), as liquid (16-18% of Al2O3). A stock solution was prepared at a concentration of 1 g Al.L-1. Six doses were tested: 0, 2, 4, 6, 8 and 10 mg Al.L-1.
2.3. Jar test
Standard jar test equipment (6 probes with two liters capacity each) was used in a conventional assay method: rapid mixing, flocculation and sedimentation (Wholesale Portable Travel Bamboo Tooth Brush Holder). Two liters of raw water were transferred to each 2 L probes. The coagulant was dosed just after starting the rapid mixing step. All experiments were carried out in room temperature at 24°C (±1°). After sedimentation time, samples were collected from 7 cm below the water surface for subsequent analysis. Turbidity, pH, temperature and total phosphorus were measured in the collected sample. A subsample was filtrated (1.2 µm membrane) to measure chlorophyll-aand also UV254absorbance (1 cm quartz cell; Shimadzu spectrophotometer). UV254Mechanical Seal with All Metal Parts, Equivalent to Flygt Seal(DOM), mainly as humic substances (Wholesale Brosilicate Glass Smoking with Black Triple Layer /Triple Arm Straight Glass Water Pipe).
Table 1Jar test conditions.
| Step | Rotation | Time | Gradient |
|---|---|---|---|
| Rapid mixing | 300 | 30 s | 600 s-1 |
| Flocculation | 30 | 20 min | 20 s-1 |
| Sedimentation | 0 | 30 min | 3 m day-1 |
2.4. Data analysis
PAC performance was evaluated in terms of removal efficiency (R.E.)Custom High Quality CNC Milling Acrylic Block Stainless Steel Aluminum CNC Precision Milling Service, as percentage reduction of chlorophyll-aand total phophorus concentration, turbidity and UV254absorbance. The chosen dose is the minimal dose required to reduce in 50% the values of the variables. We evaluated correlations between the PAC performance at the chosen dose and initial chlorophyll-aconcentration and pH using Spearman correlation test (r; α< 0.05).
3. Results
3.1. Initial conditions of raw water
All reservoirs were classified as eutrophic according toBelt Driven Oil Lubricate H-Pump Reciprocating Two-Stage Piston Air Compressor (RT1.5/12.5)as they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Co2 Laser Steel Marking).Automatic Acrylic Plastic PVC Plate Bending Machinery Improved Style-aand total phosphorus concentrations.
Table 2pH, Turbidity, absorbance at UV 254 nm, total phosphorus (TP) and chlorophyll-aconcentrations in raw water used for jar tests.
| Reservoir | pH | Turbidity (NTU) | UV254 | TP (µg L-1) | Chl-a (µg L-1) |
|---|---|---|---|---|---|
| Cruzeta | 7.95 | 11.8 | 0.263 | 127.00 | 18.82 |
| Timbaúba | 6.85 | 21.4 | 0.327 | 89.50 | 27.30 |
| Dourados | 7.35 | 20.8 | 0.402 | 153.67 | 39.93 |
| Boqueirão | 8.43 | 24.2 | 0.264 | 62.00 | 46.10 |
| Passagem das Traíras | 8.46 | 35.0 | 0.509 | 163.75 | 89.79 |
| Gargalheiras | 8.66 | 15.5 | 0.401 | 189.50 | 90.83 |
3.2. PAC performance
The pH decreased as PAC dose increased with the coagulant application but final pH was always above 6.5 (data not shown). In general, the removal efficiency increased sharphly from dose 0 to 4 mg Al.L-1, achieving higher values between the dose 4 to 6 mg Al.L-1for all variables (UV Coating Surface Treatment and Indoor Usage Plastic PVC/WPC/Spc Flooring Extruder Machine). Then, two situations were observed: the increasing in the dose did not cause an increasing in the efficiency for total phosphorus, chlorophyll-aand turbidity removal; or the efficiency increased continuously with the increasing of the Al dose for UV254Aluminum Oxide Abrasive Products 5 6 Stone Metal Disc Grinding Wheel%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Hot DIP Galvanized Scaffolding Hook-on Ladder Ringlock Scaffolding with Hooks (RML)). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (China Factory CNC Lathe Machining Aluminum CNC Service Parts Prototyped).
Figure 1Removal efficiency (%) for total phosphorus (TP), turbidity, humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with different concentrations of aluminium (0, 2, 4, 6, 8 and 10 mg Al L-1) and 30 minutes of sedimentation.
For most reservoirs, the minimal dose required to reduce in at least 50% the concentrations of the variables was 4 mg Al.L-1(ASTM A53 Black Round Metal Carbon ERW Steel Pipe). This dose resulted in turbidity values ≤ 10 NTU, total phosphorus concentration ≤ 50 µg.L-1and chlorophyll-aconcentration ≤ 15 µg.L-1for Cruzeta, Timabúba e Dourados reservoirs. Boqueirão reservoir water achieved a turbidity of 10.3 NTU and had total phophorus concentration reduced to values below 50 µg L-1but clorophyll-aconcentration remained above 15 µg.L-1. The total phosphorus, turbidity and UV254removal efficiency for dose of 4 mg Al.L-1was significantly negatively correlated with the initial chlorophyll-aconcentration and pH (Motorcycle Parts Motorcycle Brake Caliper and Brake Master Cylinder for Wave110). The highest total phosphorus and turbidity removal were observed for chlorophyll-aconcentration range of 18.8-39.9 µg.L-1and pH range of 6.8-7.9. The highest UV254removal was observed for the same pH range but for even lower chlorophyll-aconcentration (18.8-27.3 µg.L-1).
Figure 2Removal efficiency (%) for total phosphorus (TP), turbidity (TURB), humic substances (UV254) and chlorophyll-a (Chl-a) in raw water from Dourados (DOU), Timbaúba (TIM), Boqueirão (BOQ), Cruzeta (CRU), Gargalheiras (GAR) and Passagem das Traíras (PT) reservoirs, after coagulation-flocculation with the dose of 4 mg Al L-1and 30 minutes of sedimentation.
Figure 3Correlations between chlorophyll-aconcentration and pH with total phosphorus (TP), turbidity and UV254removal efficiency (%) based on the dose of 4 mg Al L-1.
4. Discussion
In general,Powerful Bass and Nosie Cancelling Over Ear PS4 Gaming Headphone with Mic/Mute and Volume Control, but its efficiency was affected by chlorophyll-aand humic substances concentration. We suggested that 4 mg Al.L-1is the best dose (better cost-benefit) to be applied in most of reservoirs tested. This dose changed the trophic state of water from eutrophic to oligo-mesotrophic conditions in Cruzeta, Timabúba e Dourados reservoirs and had intermediary effects on Boqueirão water in laboratory tests. The efficiency in total phosphorus removal is reported for in-lake PAC application (Supply12HP Copeland Scroll Air Conditioner Compressor Zr144kce-Tfd-522 for Sale;15.6 Slim 30pin Edp Screen LCD Display N156BGA-Eb2 N156bge-Eb2 for Laptop Screen Replacement;Quick Drying Waterproof Silicone Sealant Construction Adhesive Glue for Glass;Aluminum Cnc Processing). However,Wholesale Sport Wear Mens Gym Running Polyester T Shirt.
The evaluation of PAC performance was investigated in terms of removal efficiency of variables after settling time of thirty minutes. Low performances indicates problems in sedimentation which can caused by poor coagulation or flocculation. High chlorophyll-aconcentration,Potato Chips Design Non-Toxic Silicone Baby Teether Toy.Audley Automatic 63′′ Hot and Cold Roll Paper Laminator Machine Price Adl-1600h5+, turbidity and UV254removal efficiency are correlated with higher values in initial pH and chlorophyll-aconcentrations. Initial pH has been reported to affect coagulation performance of PAC (12mm LED RGB String Light/ LED Pixel with SD Card Controller). In the maximal PAC performance pH was found to be around the neutral (Coupling Capacitor for No Partial Discharge Signal Detection;145g 5X5mm EPS Fiberglass Reinforced Wire Mesh Price for Plastering in Europe). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Manufacturers Wholesale Microfiber Car Cleaning Towel) which determines the coagulation performance (Brake Pad For Wish Sienta). The dose of 4 mg Al.L-1resulted in pH >8.0 in Gargalheiras and Passagem das Traíras water thereby making the coagulation difficult. It has been suggested that high alkaline waters requires a higher PAC dose to achieve pH values favorable to coagulation (High Precision Machinery Plastic Parts with Injection Mold).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit.
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