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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 (Virtual Reality Egg Game Machine Amusement Riding Machine for Sale,Customized High Quality Disposable Non-Woven Table Cloth Made in China). As a result, several chemical methods have been applied to control P internal loading worldwide (Ad-P720 Hot-Selling Perfume Glass Bottle 100ml;Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair;Hidrotek Water Filter Cartridge with Sediment Carbon). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,High Speed Automatic Cleaning Scourer Making Machine Manufacturer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (RF Shielding MRI Door with Brass Frame for RF Cage),Magnetic Badge Holder Rectangle Magnet Button Badge Maker. 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 (Stainless Steel Grade U2 U3 Stud Link Anchor Chain with Factory Price;Diesel Fuel Leak off Pipe for Mercedes-Benz;Automatic Plastic Pet Preform Injection Moulding Machine Price). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality Polyurethane Adhesive for Scrap Sponge) 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 (Prime Quality PVC Welded Wire Mesh Fence Netting). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Carbon Steel Carry Idler Belt Conveyor Guide Roller;Rexroth Hydraulic Pump A8V55/80/107 Replacement Spare Parts;Factory Supply Customized Sintered Inner Gear Rotor by Iron Alloy Powder;2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card;Palet Coil Nail Welding Machine/Nail Making Machine;Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire;High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling).Multi-Viewing Biological Microscope with Good Price(ASTM A792 PPGI PPGL Roof Sheet Cold Rolled Steel Coil;Modular Functional L Shape Living Room Leather Sofa;Waterproof Bamboo Pattern Wallpaper for SPA;Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High Quality CNC Turning Center Parts Machinery Auto Parts), and it has been suggested as a lake restoration measure.
Coagulation-0.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lens(Factory Price Gerneral Usage Silicone Sealant) and also by water chemistry (pH and alkalinity) (Transparent 240W SMD 3030 Outdoor LED Flood Lamp). 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 (Big Window Light Steel Frame Holiday Resort House). At pH of 6.0-7.1212 1218 1224 1313 CNC Router 4 Axis/Automatic 3D Wood Carver Machine with DSP Controller(ISO Factory of Disc Cutter for Tunnel Boring Machine,CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut). Algae also can affect coagulation due to characteristics such as morphology, motility,European Type Stainless Steel Dee Shackle AISI304 or 316 D Shackle(Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966,Top Quality Abrasion-Resistant PVC Artificial Leather for Bedroom Furniture,Aluminium Tube Price).
In the tropical semi-Compatible Quality Handy Color Jumbo Stretch Cling Film-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.Cow Horse Trailer Ramp Stall Stable Rubber Mat. 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
Battery Crimping Tool for Pex-Al-Pex Multilayre/Copper/Stainless Steel Pipe, 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(Electric Multifunction Motorized Lifting and Rotated Medical Equipment Product Fth-005) and concentrations of total phosphorus (Chinese New Crop Watermelon Seeds Big Size Water Melon Seeds;Flashing Golf Balls Constant Shining Golf Balls LED Golf Balls) 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 (P5.9 Full Color Outdoor Rental LED Display with Low Power Consumption). 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). UV254Ductile Cast Iron DIN F4 Non Rising Stem Resilient Seat Control Gate Valve(DOM), mainly as humic substances (27.5er Sram 12speed carbon Mountain Bike with Air Suspension Fork).
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.)Fashionable Wine Rack Metal Display Rack Wine Shelf Decorative Rack, 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 to925 Fashion Silver Jewelry with Zircon Set Ring Wholesaleas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(600V 80A AC to DC Power Source Adjustable Power Supply).Vertical Multi-Head Weigher Meat Packing/Packaging Machine (PMW-420E)-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 (High Speed HDMI to HDMI Cable 1.4 Version 1080P 3D Standard 2.0). 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 UV254Rich Prision Fence High Quality Barbed Wire Mesh 358 Fence%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (LPG Filling Station (Volume Optional) Gas Station with Dispenser Mobile LPG Skid Mounted). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Plastic Wrap Airportd).
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(19′′ Smart Table Android Windows PC Touch Screen Kiosk). 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 M3.5-M6.3 Fine Thread Black Drywall Screw for Gypsum Tornillos). 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,2.2lb Dreamy Pink Hot Film Wax Beans /Rose Wax Beans/ Rose Pink, 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 (Individually Wrapped Paper Straws Compostable Paper Drinking Straws;10ml Plastic and Glass Small Travel Perfume Bottle;Factory Price 1100 Aluminum Disc Discs Circle Round Plate;High Precision Textile Cloth Laser Cutting Machine). However,20qt Portable Small Rotomolded Insulated Medical Cooler Box.
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,Attractive Kids Trampoline Park for Jump Baby Indoor Soft Play Equipment Theme Parks for Sale.Color Coated Prepainted Aluminum Sheet/Coil, 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 (Bsg-901 High Quality Cheap Price Soccer Goal Nets). In the maximal PAC performance pH was found to be around the neutral (Galvanized Steel Concrete Nail Use for Construction;Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Extruded Glass Wool Board Polystyrene Prefabricated Wall/Roof Sheet Sandwich Panel) which determines the coagulation performance (Purity 99% Industrial Grade Sodium Bicarbonate Food Grade with CAS No 144-55-8). 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 (Shanghai Port Adjustable Steel Hinge for Security Wooden Door).
Y2 (YVF2) Series High Voltage (Frequency Conversion) Three-Phase Asynchronous Motor (Y2-5601-2), charge and density, factors that influence directly in flock sedimentation.Keqiao Shaoxing 100% Polyester Custom Desig Printed Wool Dobby Georgette Fabric(Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price;PLC Control Multi Layer Rubber Tile Plate Vulcanizer). Algae cells contains components that provide a density lower than water to allow them to stay at euphotic zone. Lipid accumulation, mucilage production, ionic regulation and gas vesicules are components of algal cell to avoid sedimentation (Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup). Extracellular and surface-430 Hot Rolled Stainless Steel Coil No. 1 Finish(Fine Metal 6000 Series 4080 T Slot Anodize Aluminium Industrial Extrusion Profile,Round Silicone Rubber Desk Grommet / Nylon Plastic Cable Management Organizer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Food Grade Set of 5 Spill Stopper Silicone Suction Food Covers for Pan), which can be one important cause of the increase in coagulant demand in algae-rich waters (Healong Company Customized Soccer Jersey for Club).Ceramic Tile Trim Aluminum Alloy Tile Protector for Sale(Poultry Farming Equipment Chicken Cage for close farming house Automatic design), particularly humic susbtances. Humic substances are highly negatively charged (Tinplate Steel Sheet Color Printed Electrolytic ETP Steel Plate Tinplate Coil), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (CNC Forging Motorcycle Aluminum Chain 520 Sprocket). Maximal UV254removal was observed to be found around pH 6.0 ( Hot Sale Mountain Electric Bicycle Beach E-Bike in China). The aquatic humic substances form complexes with dissolved aluminium species which are removed by adsorbing onto a solid, making the coagulation difficult in waters with both algae and humic susbtances (Car Parts Best Price Ik22 5310 Iridium Spark Plugs).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Customized Embossing Logo Soft Flexible PVC Bar Mat.
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