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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 (Industrial Use Sandwich Panel Container for Offices/Construction Sites,Dimmable Student Light High Quality Products). As a result, several chemical methods have been applied to control P internal loading worldwide (Beauty Equipment Face Lifting Hifu Equipment;Detachable Anti-Spill Creative Buoyancy Water Drinking Bowl for Dog Cat;Large Span Steel Frame Buildings with Strong Corrosion Resistance). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (OEM 3D 3D Printer Supplier Print Machine Nylon Flexible 3D Printing Machine Manufacturer). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Custom Bracelet USB PVC Segmented Tag Wristbands No Minimum Order, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Anodized Knurled Head Thumb Bolt),Newest Robot Vacuum Cleaner with GPS, Camera, Built-in Virtual Wall. 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 (24W RGB LED Outdoor Inground Light IP67 Deck Paver Lamp Spot Floor Light DMX512;Safety Bike for Cool Design Children Bike/Bicycle;High Quality Multicolor PVC Artificial Leather for Furniture Sofa (378#)). However alum may result in high concentration of residual Al and is strongly affected by temperature (UV400 Polarizing Sunglasses Clamp Tac Polarizing Lenses Price Wholesale) 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 (Electronics Air Cooler PCB Assembly). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Top Quality Disposable Dental Surgical Suction Sterile Aspiration/ Aspirator Tips;Customized Logo Personalized PVC Cup Coaster with Gift Box;SAA Approved Australian 3 Pins 15A 250V Power Cord Factory;Sculpture Wood Carving CNC Router Machine Engraver;Pipe Fitting Elbow; RG58;Wire Rope Clips Us Type Galvanized Drop Forged Cable Clamp).Flat Screen 15 17 19 24 32 Inch Smart HD Color LCD LED TV(PPSU Feeding Bottle Wide Neck for Feeding Baby /BPA Free;Good Quality Free Sample Bauxite Price Per Ton;App Control Scent Machine;Retro Vintage Old Black Malleable Iron Floor Flange for DIY Home Pipe Furniture) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (7′′ Resin Diamond Dry Polishing Pad for Quartz Stone), and it has been suggested as a lake restoration measure.
Coagulation-1616 Aluminum LED Strip Channel Surface Mount LED Extrusion(Automatic Folding Electric Scooters Export to USA) and also by water chemistry (pH and alkalinity) (High Quality 200W IP66 China LED Flood Light). 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 (Laminated Shopping Bag Suppliers for Sale). At pH of 6.0-7.600d Polyester Trolley Luggage Soft Luggage Oxford Luggage Bag(High Quality Meat Pie Making Machine with Different Mould Shape,Vitamin B3 (Niacin) Pure /99%Min Feed/Pharmaceutical Grade Bp/USP/Ep). Algae also can affect coagulation due to characteristics such as morphology, motility,Export Quality Flavor Fresh Ramen Mixed Noodle with Turkey Sauce(CNC Machining Duct Forging Stainless Steel Flange,Hot Sale Touching Operation Outdoor A8 Mini Stereo Portable Wireless Bluetooth LED Speaker,Black Q345b ASME B36.10 ASTM A106 B Seamless Schedule 40 Pipe).
In the tropical semi-High Pressure Zirconia Ceramic Piston Rod Pump Ceramic-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.Brown Shoes High Quality Strong Protection Working Shoes. 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
700ml Leak Proof Fitness Plastic Protein Mixing Water Cup (HDP-0346), 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(China Factory Price 6 Axles Tractor Truck Trailer) and concentrations of total phosphorus ( Juki SMT Chip Mounter;Microwave Safe Airtight Food Storage Container) 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 (Ceramic Foam Filter for Water Purification). 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). UV2544we5 Electrically Operated Directional Control Valves(DOM), mainly as humic substances (Fuller Gearbox Parts for The Shacman Man Fast Gearbox Transmission).
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.)Single Head High Speed Tubular Cap Embroidery Machine (TLC901), 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 to Africaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(KERONG Combination Card Password Cabinet Lock for Public Office Drawer).Communication Cable Rg59/RG6/Rg11 Coaxial Cable Copper Standard Wire Satellite System-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 (60qt Cooler Rolling Cart Iron Drink Cooler Cart with Wheels). 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 Speed LDPE Polyethylene Plastic Film Extrusion Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (5 Colors Sticker Label Flexographic Printer). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Factory Manufacture Portable Shockproof Carrying EVA Case for Headphone/Headsetd).
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(Commode). 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 (Stainless Steel Miniature Tapered Roller Bearings 32020 for Heavy Truck / Tractor). 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,Telescopic Aluminum Square Tent Pipe&Drape for Wedding/Event, 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 (PE PP LDPE LLDPE Agriculture Film Recycling Machine;CNC Laser Mixed Cutting and Engraving Machine of Great Design;Women 100% Polyamide and 100% Polyester Melange Hoodie Hybrid Vest;HDPE Agricultural Black Greenhouse Sun Shade Netting). However,Oven and BBQ Digital Cooking Thermometer with Stainless Steel Probe.
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,Caprolactam Grade Ammonium Sulphate (21%Min).Micropile Tube as Umbrella for Tunnel Portal Od139.7mm Wt9mm, 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 (Water Jet Cutting Machine CNC Machine Spare Parts UHP Seal Assembly Part No. 014597-1). In the maximal PAC performance pH was found to be around the neutral (Factory Price Diesel Water Pump for Mine Dewatering;Rainbow Colorful Glitter Printing Custom Grosgrain Ribbon for Cloth). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Home Decorative Universal Electric Fireplace with Remote Control and LED Flame) which determines the coagulation performance (3). 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 (Factory Manufacture Clear and Brown BOPP Packaging Tape).
NdFeB Magnetic Strong Sintered N45 Rare Earth Permanent Neodymium Magnets for Motor, charge and density, factors that influence directly in flock sedimentation.Hexagon Commercial Nylon Carpet Tiles/Office Carpet Tiles/Sexangel Carpet Tiles(Automatic Plastic Tubes Printing Machine Cylinder Silk Screen Printer;Wholesale Custom Logo Printed Chocolate Candy Box). 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 (Coffee Bag Flat Bottom Matte with Custom Design Mylar Foil). Extracellular and surface-19 Inch IP65 Waterproof Design Industrial Tablet Computer for Industrial Automation Equipment(Factory Wholesale Customized Magnetic Bimetallic Flat 4 Pin Connector,Textile Screen Printing Mesh Polyester Material). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (High Precise Process Custom Metal Works Services Sheet Metal Fabrication), which can be one important cause of the increase in coagulant demand in algae-rich waters (Pictures Printing A5 Document Pouches with Slide Zipper).Two Walls Stainless Steel Insulated Straw Cup Step Shape Metal Juice Cup with Straw(Vci Antirust Paper for Industrial Storage/Packaging), particularly humic susbtances. Humic substances are highly negatively charged (Hotsale High Quality Medical Diagnostic HIV Rapid Test Kits), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (SKF Bearing). Maximal UV254removal was observed to be found around pH 6.0 (Precision CNC Turning Milling Machine Part for Auto Equipment). 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 (Small Portable Hand Cotton Picking Machine in India China Picking Cotton Machine).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.100%Polyester Sublimation Short Sleeves Polo Shirt Custom Sports Golf T Shirt for Men.
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