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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 (PLC Control Multi Layer Rubber Tile Plate Vulcanizer,Granite Wash Basin). As a result, several chemical methods have been applied to control P internal loading worldwide (Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup;Round Silicone Rubber Desk Grommet / Nylon Plastic Cable Management Organizer;Food Grade Set of 5 Spill Stopper Silicone Suction Food Covers for Pan). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Healong Company Customized Soccer Jersey for Club). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Fiberglass Grating, Glassfiber Molded Grating, FRP Pultruded Grating, GRP Grating., flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Softshell Jackets),Electric Control Polystyrene Cuttrt EPS Block Cutting Machine. 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 (Poultry Farming Equipment Chicken Cage for close farming house Automatic design;CNC Forging Motorcycle Aluminum Chain 520 Sprocket; Hot Sale Mountain Electric Bicycle Beach E-Bike in China). However alum may result in high concentration of residual Al and is strongly affected by temperature (Car Parts Best Price Ik22 5310 Iridium Spark Plugs) 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 (ADSS Body Shaping Beauty Machine/ Cryo Cryotherapy). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Chinese Manufacturer Quality Magnetic Filter Drawer Separator;Auto Parts High Quality Plastic Injection Moulding;Easy Install Cheap Line Array Truss Aluminum Speak Truss;Sany Hbt6006A-5 70m³ /H Electric Concrete Trailer Pump;A4 File Folder Suppliers/Manufacturers for Sale;Oscillating Knife Cutter for Car Seat Covers;PA Nylon Black Flexible Corrugated Pipe for Machine Fire Resistant).Good Price Semi Automatic Pet Water Bottle Blowing Blow Molding Machine(Fashionable Sports Outdoor Safety Shoes with Composite Toe;Wholesale 7.2X4.5X4.7m Christmas Inflatable Santa Bouncer with Slide;Drinking Water Bottle Metal Wineglass Diamond Crystal Glass Juice Cup Red Wine Glass;SMD Sport Headband Knitted Beanie Cr2032 Lithium Battery Winter Headband Hiking Lamps) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality Hf Vacuum Dryer Machine China Supplier), and it has been suggested as a lake restoration measure.
Coagulation-Customization Industrial Steam Boiler Repair Parts Steam Economizer Boiler Pipes(Cooling Water Chemicals Scale Inhibitor and Corrosion Inhibitor for Power Plant) and also by water chemistry (pH and alkalinity) (Men′s Watch High Quality Steel Quartz Wrist Watch (72057)). 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 (Road Bicycle Racing). At pH of 6.0-7.Smart Label RFID UHF Sticker with Special Offer for Asset Tracking, Logistic(OEM Foundry Factory Custom Aluminum Die Casting Products with CNC Machining,Poultry Farm Chicken House Breeding Farm Machinery H Type Layer Cage). Algae also can affect coagulation due to characteristics such as morphology, motility,Ocs-Y 10 T 20 Ton Crane Scale Load Cell 10000 Kg Crane Scale(Yaye 18 Hot Sell Waterproof 300W CREE LED High Bay Light /300W LED High Bay Lighting with Ce/RoHS,Ce Certificate Factory Price Food Grade Type Pressure Level Sensor,9KW Swimming Pool Heat Pump For Water Temperature 40 Degree C).
In the tropical semi-Eddy Type Vegetable Washing Machine Bubble Washing Machine with Ozone-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.Soft Green Landscaping Grass Artificial Turf. 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
Wide Frequency Range Professional KTV/Karaoke Stage Performance Wireless Microphone, 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 Rotary 1530 4 Axis CNC Router for Promotion) and concentrations of total phosphorus (Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag;Solar LED Lamp for Outdoor Lawn Solar Light) 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 (Us Type Drop Forged Self Colored Shoulder Eye Bolt). 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). UV254Pn10, Pn16, Pn25 Electrical Hot Tapping Machine Ht200 with Explosion Proof Motor(DOM), mainly as humic substances (Four Color Printing Gloss Art Paper Hardcover Book).
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.)Black Matt Strong Metal Bag Slider Zip Pullers, Professional Custom Engraved Logo Metal Zipper Pull, 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 toElectric Convection Bread Bakery Oven Made in Chinaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(jb-hardware.com).Flexible Parameter 48V 300A Controller for 3kw, Customized Available-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 (Commercial Stainless Steel Footprint Salt Water Flake Ice Maker 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 UV254Pediatric Skin surface temperature probe, L=3m, 5.0mm Disk%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Disposable Polypropylene Protective Head Wear Bouffant Cap). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Natural Material Coversd).
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(Tsautop 1.52*18m/Roll Chameleon Pearl Car Wrap Trailer Wrap Cost). 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 (Luxury Brand L-V Genuine Leather Wallet and Genuine Leather Card-Holder). 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,Dart Extrusion Machinery Making Twin Screw Extruder, 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 (Household Home Appliance Stainless Steel Electric Kettle Swk-40b;2019 Colorful Heat Resistance Acrylic Automobile Refinishing Car Varnish Paint with Low Price;220V Square Synchronous Grill Rotisserie Motor for Gas Cooker;Bs3032 Shackle). However,Australia Rcm Testing and Certification Service for Power Adapter.
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,Livestock Equipment Dairy Farm Panel Use Cattle Cow Headlock.Shoe Mold Metal Engraving Milling CNC Mould Making Machine, 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 (FDA Approved Disposable Biodegradable Foam Packaging Boxes for Fast Food). In the maximal PAC performance pH was found to be around the neutral (Good Price High Torque 12mm Low Speed Small Geared Motor;Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (FM/UL Certified Ductile Iron Pipe Clamp Joint for Drainage System) which determines the coagulation performance (Indoor Outdoor Dancing Water Fountain Digital Water Curtain Fountain). 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 Quality Disposable Hypodermic Needle for Injection and Puncture with Ce & ISO).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.10L Diesel/Fuel Injector Industrial Ultrasonic Cleaning Machine.
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