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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 (Modular Concrete Batching Plant by Twin Shaft Mixer 3000/2000,Stainless Steel Welded Reinforcement Wire Mesh for Concrete Slab). As a result, several chemical methods have been applied to control P internal loading worldwide (Virtual Reality Egg Game Machine Amusement Riding Machine for Sale;Ad-P720 Hot-Selling Perfume Glass Bottle 100ml;Whole Sale Banquet Tiffany Classic Stackable Gold Louis Dining Chair). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Hidrotek Water Filter Cartridge with Sediment Carbon). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Crafts Cell Phone Holder Solid Color Polyester/Nylon Phone Strap, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Air Conditioner Parts Malawi),High Quality Big Power 40kw Hybrid Inverter for No Battery Backup Solar System. 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 (9.7 Inch Poe Android Touch Screen Tablet with Vesa Mounting;Stainless Steel Grade U2 U3 Stud Link Anchor Chain with Factory Price;Diesel Fuel Leak off Pipe for Mercedes-Benz). However alum may result in high concentration of residual Al and is strongly affected by temperature (Automatic Plastic Pet Preform Injection Moulding Machine Price) 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 (Rlbx97-a Square LED Explosion-Proof Low-Ceiling Light). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (High Quality Polyurethane Adhesive for Scrap Sponge;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;Circular Diamond Saw Blade for Cutting Porcelain Ceramic Tile;2750OE Hico 12.7mm Width Plastic Magnetic Stripe Card for VIP Card;Quick Link Cotton Baling Wire with Single Double Loops Bale Tie Wire).Clear Plastic Transparent Sealable Freezer Food Vacuum Storage Packaging Nylon Bags for Sale(High Automatically Vacuum Hydraulic Oil Filtration Equipment for Oil Recycling;ASTM A792 PPGI PPGL Roof Sheet Cold Rolled Steel Coil;Low-Alloy High-Tensile JIS Spfc490 Structural Carbon Steel Plate;Modular Functional L Shape Living Room Leather Sofa) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Dish Plate Dryer and Sterilizer 60liter Using UV and Ozone), and it has been suggested as a lake restoration measure.
Coagulation-Gnt/Gunate Industrial Solid Tyre Forklift Tire (10-16.5 12-16.5)(High Quality CNC Turning Center Parts Machinery Auto Parts) and also by water chemistry (pH and alkalinity) (Factory Price Gerneral Usage Silicone Sealant). 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 (Hot Selling Cheap Hunting Pet Dog Collar (YL95924)). At pH of 6.0-7.Customized Metal Forge Machinery Wrought Iron/Steel/Aluminum Drop/Open/Die Forging(Transparent 240W SMD 3030 Outdoor LED Flood Lamp,ISO Factory of Disc Cutter for Tunnel Boring Machine). Algae also can affect coagulation due to characteristics such as morphology, motility,Hot Sale Environmentally Friendly Outdoor WPC Wall Panel Decking(CNC Parts Sfu2510 25mm 400mm Fdr Ball Screw with Nut,Commercial Strength Gym Equipment Adjustable Bench (Incline/ Flat/Decline) L-966,1086 Shiny Diamond Glitter Wallpaper for Decoration).
In the tropical semi-Factory Direct Sale Baseball Uniform for Adults-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.130lm/W LED High Bay UFO Lamp Fixture with Different Watts 100W 150W 200W. 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
Die-Casting Aluminum 500*1000mm Fullcolor Module P3.91 Indoor Movable LED Signs Board, 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(Aluminum CNC Al5052 / Al6061 / Al6063 Machining Turning Parts for Mil-Spec Electronics) and concentrations of total phosphorus (Electric Multifunction Motorized Lifting and Rotated Medical Equipment Product Fth-005;Wholesale Custom Printed Eat Bamboo Fiber Pet Dog Travel Personalized Water Feeding Feed Bowl) 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 (Banbury Rotors 3L Lab Plastic and Rubber Mixer Machine). 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). UV25413.56MHz Logo Printing Mini NFC Epoxy Card for Access System(DOM), mainly as humic substances (P5.9 Full Color Outdoor Rental LED Display with Low Power Consumption).
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.)Automatic Monochrome Crystal Shoe Injection Molding Machine, 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 toHigh Purity Medical Psa Oxygen Generator/Concentrator Manufacurer with Low Costas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Fitness Running Shirt).Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer-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 (Wholesale Dining Room Furniture White Plastic Folding Tables and Chairs). 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 UV254Thermoplastic TPE Granules Making Machine for Grass Filling%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Speed HDMI to HDMI Cable 1.4 Version 1080P 3D Standard 2.0). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Manufacturer Durable Aluminium Material in-Ground Swimming Pool Cover Reeld).
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(CNC Machinery Parts Aeroplane Spare Parts Motor Engine Parts). 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 (19′′ Smart Table Android Windows PC Touch Screen Kiosk). 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,7 Inch Ultrasonic Digital Video Reverse Parking Sensors for Truck, 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 (Metal Enclosure Withdrawable Distribution Switchgear Cabinet Low Voltage;Individually Wrapped Paper Straws Compostable Paper Drinking Straws;10ml Plastic and Glass Small Travel Perfume Bottle;3-6mm Am-57 Decorative Acid Etched Frosted Art Architectural Mirror). However,Hf Vacuum Dryer Machine with Advanced High Frequency Technology.
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,Forged Custom Exterior French Door Wrought Iron Double Entry Doors.New Model Cheap Unique Fashion Jewelry 925 Sterling Silver CZ Stud Earrings for Girls, 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 (Factory Price 1100 Aluminum Disc Discs Circle Round Plate). In the maximal PAC performance pH was found to be around the neutral (Bsg-901 High Quality Cheap Price Soccer Goal Nets;Galvanized Steel Concrete Nail Use for Construction). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Az70 Hot Dipped Aluminum-Zinc Alloy Aluzinc Gl Galvalume Steel Coil for Roofing) which determines the coagulation performance (Refrigerant Leak Detector). 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 (Extruded Glass Wool Board Polystyrene Prefabricated Wall/Roof Sheet Sandwich Panel).
Joylive Car Lift Goods Elevator Used Home, charge and density, factors that influence directly in flock sedimentation.Beer Fest Aluminum Banner Stand Advertising Fabric Pop up Display Light(Shanghai Port Adjustable Steel Hinge for Security Wooden Door;Excellent Quality Compact Key Cutting Machine Sec-E9 for Cutting by Code with Affordable Price). 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 (PLC Control Multi Layer Rubber Tile Plate Vulcanizer). Extracellular and surface-Poultry Farm Chicken House Breeding Farm Machinery H Type Layer Cage(Hg-Ot-102st Infrared Thermal Imaging Sighting Tracking Night Vision Telescope,Auto Medical Products Printer Cylinder Silk Screen Printing Machine for Plastic Cup). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Round Silicone Rubber Desk Grommet / Nylon Plastic Cable Management Organizer), which can be one important cause of the increase in coagulant demand in algae-rich waters (Food Grade Set of 5 Spill Stopper Silicone Suction Food Covers for Pan).Factory Supply 2-Deoxy-D-Glucose CAS 154-17-6(Healong Company Customized Soccer Jersey for Club), particularly humic susbtances. Humic substances are highly negatively charged (6 Inch Rubber Seal Aluminium Handle Wafer Butterfly Valve), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Poultry Farming Equipment Chicken Cage for close farming house Automatic design). Maximal UV254removal was observed to be found around pH 6.0 (CNC Forging Motorcycle Aluminum Chain 520 Sprocket). 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 ( Hot Sale Mountain Electric Bicycle Beach E-Bike in China).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Diesel Engine Mobile Rotary Screw Scroll High Pressure Air Compressor.
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