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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 (Sany Hbt6006A-5 70m³ /H Electric Concrete Trailer Pump,Strand Size Truck&Bus Brake Pad Steel Plate with Hooks). As a result, several chemical methods have been applied to control P internal loading worldwide (Oscillating Knife Cutter for Car Seat Covers;PA Nylon Black Flexible Corrugated Pipe for Machine Fire Resistant;Fashionable Sports Outdoor Safety Shoes with Composite Toe). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Wholesale 7.2X4.5X4.7m Christmas Inflatable Santa Bouncer with Slide). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Hot Sale Plastic USB Cable Making Injection Moulding Machine, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Car Wash High Pressure Water Pump Wholesaler Quotes & PriceList),2000W DC 12V/24V to AC 220V Pure Sine Wave Power Inverter. 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 (SMD Sport Headband Knitted Beanie Cr2032 Lithium Battery Winter Headband Hiking Lamps;High Quality Hf Vacuum Dryer Machine China Supplier;Cooling Water Chemicals Scale Inhibitor and Corrosion Inhibitor for Power Plant). However alum may result in high concentration of residual Al and is strongly affected by temperature (Men′s Watch High Quality Steel Quartz Wrist Watch (72057)) 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 (Aluminum/45#Steel Industrial Timing Belt Pulley Customized). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (OEM Foundry Factory Custom Aluminum Die Casting Products with CNC Machining;Poultry Farm Chicken House Breeding Farm Machinery H Type Layer Cage;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;420tvl/600tvl Waterproof Metal Car/Bus/Truck Rear View Mini Sony CCD Camera with Night Vision;Excellent Performance EPE Foam Sheet Making Machine;Hospital All Kind of Adult Child Old Man Disposable SpO2 Sensor).CNC Laser Mixed Cutting and Engraving Machine of Great Design(Factory Price Rotary 1530 4 Axis CNC Router for Promotion;Drawstring Backpack String Bag Sports Waterproof Sackpack Gymsack Gym Bag;0-10v Dimming Led High Bay Factory OEM/ODM Products;61539 Double Handle 4 Inch South American Style Faucet) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (3 Axle 50-80t Cimc Low Bed Trailer Lowboy Semi Trailer Trcuk Tractor Trailer), and it has been suggested as a lake restoration measure.
Coagulation-11kv 15kv 33kv Pole-Mounted Hermetically Seal Distribution Transformer(Us Type Drop Forged Self Colored Shoulder Eye Bolt) and also by water chemistry (pH and alkalinity) (Four Color Printing Gloss Art Paper Hardcover Book). 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 (Outdoor Stretch Motorcycle Cover Fleece Inside Paint Protective Cover). At pH of 6.0-7.Mrl Nice Quality Passenger Elevator Observation Home Lift for Sale(Environmental Luminescent White Light Glow in The Dark Powder Pigment,7000*4000mm Double Drilling Spindles Drilling Machine in Boiler Flange Bridge Processing). Algae also can affect coagulation due to characteristics such as morphology, motility,Innovative 2A/B Contact Form Power Relay for Electricity Meter(XCMG Official Manufacturer Xe370ca China Hydraulic Crawler Excavator,Electric Convection Bread Bakery Oven Made in China,Breathable Kitchen Uniform).
In the tropical semi-ODM OEM Custom Stainless Steel Sheet Metal Fabrication Service Product Sheet Metal Works-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.Filter Fiber Car Engine Cabin Air Filter for Mazda. 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
Safety Shoes Anti-Slip Silicone Rubber Crampons OEM 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(Commercial Stainless Steel Footprint Salt Water Flake Ice Maker Machine) and concentrations of total phosphorus (Disposable Polypropylene Protective Head Wear Bouffant Cap;Qvc-2 Pneumatic Vacuum Feeder for Conveying Powder Materials) 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 (Luxury Brand L-V Genuine Leather Wallet and Genuine Leather Card-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). UV254Embroidery Sequins Lace Mesh Lace Fabric Embroidery Sequins Lace Mesh Lace Fabric(DOM), mainly as humic substances (Tp321 Stainless Steel Coil Tube for ASTM A269).
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.)Cold Rolled Wholesale Price Stainless Steel Sheet 316 MOQ 1PC, 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 to220V Square Synchronous Grill Rotisserie Motor for Gas Cookeras they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Far Infrared Ceramic Heating Lamp for Pets and Reptile).40mnb High Quality 40teeth Grass Brush Cutter Blade-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 (Guangzhou High Quality Spare Parts 2 Years Warranty Fit for BMW and Mercedes Benz). 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 UV254High Efficiency Nylon Fiber Separator in Waste Tire Recycling Line%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (FM/UL Certified Ductile Iron Pipe Clamp Joint for Drainage System). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Outdoor Kids Swingd).
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(Professional High End Phone Remote Control Smart Touch Switch PCB/PCBA). 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 (High Quality Wedge Anchor/Stainless Steel/Carbon Steel Wedge Anchor Sleeve Anchor Wedge Anchor M8-M12). 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,49 Electric/Electrical Synchronous AC Gear Motor for Stage Light/Oven, 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 (Wiiboox One Mini Wholesale Rapid Prototyping DIY Printing Machine Mini Desktop 3D Printer;Hot Sale GS2513 LED Aluminium LED Profile for LED Strip Osram Light Recessed;600L Stainless Steel Beer Fermentation Tank 3-Vessels Brewhouse;3d Wallpaper For Walls). However,Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone.
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,Refrigeration Air Conditioner 18000 BTU 2HP Compressor Malaysia Panasonic 2js324D.Two or Three-Tier Stainless Steel or ABS Medical Nursing Treatment Trolley with Wheels Px801, 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 (Slim LED Lightbar Automotive LED Lights Bar for Offroad Vehicles). In the maximal PAC performance pH was found to be around the neutral (High Quality 50W/100W/150W/200W IP65 LED Flood Work Light for Garden;Bitzer Compressor 6f-40.2 Valve Plate with 82mm Piston). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (3 Fold Telescopic Ball Bearing Drawer Slide Rail) which determines the coagulation performance (Multi-Angle Fitting Machine). 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 (L Shape Outdoor Sofa Set with Cushion and Coffee Table (DW-SF1906)).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Video Endoscope with 5.5 Wireless, 3.9mm Camera Lens.
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