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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 (70cm Foldable Folding Lap Desk Bamboo Laptop Bed Table Stand Tray Desk Adjustablebt-2204,Stainless Steel Efficient Homogenous Mixer Emulsifying Pump Homogenous Pumps). As a result, several chemical methods have been applied to control P internal loading worldwide (Low Price High Quality Textile Chemicals Hydrophilic Finishing Agent;High Precision 3D Printer Kit; Limestone Roller Mill). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (High Efficiency Leaf Vegetable and Fruit Bubble Washer Machine Cleaning Machine). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Power Transformer Voltage Transformer Pq2620 Series High Frequency Transformer, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (MID Back Century Swivel Executive Staff Office Chair),Education Supply School Gifts Craft POM POM Child Toy Educational Equipment (P4097). 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 (Portable Picosure Laser Picosecond Tattoo Removal Machine for Skin Beauty;Stable Steel Flat Glass Transport Rack with Safe Support Protection;Custom Engraved 2D Metal Volleyball Medals). However alum may result in high concentration of residual Al and is strongly affected by temperature (Ride on Concrete Power Trowel Machine with Suitable Seat) 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 (Wood texture Matt Finish Melamine MDF boards for Furniture). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Vci Packaging Paper for Metal/Iron/Steel Parts Rustproof;Modern Style Classic Shangri-La Window Shutters Roller Blinds;Rock Wool Color Steel Sandwich Panels for The Construction of Cleanroom;10.5 Inch Silicone Straws and Stainless Steel Straws;200 Tons Hydraulic Press;Manufacturers 1000W AC/DC Converter Car Power Inverters;Stainless Steel 304 316 Railing Fittings Casting Round Tube Plate).Fashion in China Tag Watches Men Quartz Water Resistant Stainless Steel Back Dw Watches(CNC High Speed Gear Hobbing Machine Ys3118CNC5;Indurstry Building Safety Boots with Steel Toe Cap and Midsole (SN1629);Brass Gas Valve For Oven;0.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lens) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (High-Precision Aluminium Casting Aluminum Die Casting Parts), and it has been suggested as a lake restoration measure.
Coagulation-Thickness 140 Micron Pharmaceutical Cold Forming Blister Aluminum Foil(High Quality and Low Price Aluminum Alloy Perforated Electrical Cable Tray) and also by water chemistry (pH and alkalinity) (Dark Blue Ocean Treasure Marble Price Slabs for Wall and Flooring Tiles Marble Wall Floor Tile). 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 (Aural Thermometer). At pH of 6.0-7.13.56MHz Hf Fudan 4K FM11RF32 Fudan S70 Smart Card(Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe,13mm E2 Melamine Faced Particle Board with Cheap Price for Furniture). Algae also can affect coagulation due to characteristics such as morphology, motility,ASME/ANSI B16.9 Stainless Steel Sch40/80 Butt Welding Reducing Tee(Good Selling Animal EVA Block Play Set Educational Learning Toy H11199007,Wholesale Kitchen Cleaning Pot Scourer Galvanized Scourer Ball,Nylon Spandex Black Womens Zip up Sports Bra).
In the tropical semi-Farrowing Crate Galvanized Swine Farrowing Crates-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.Double Sided Tape 1/2 Inch 10 Feet, Transparent Acrylic Double-Sided Tape. 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
Canvas Dog Pack Travel Saddle Backpack for Medium & Large Dog, 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(P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum) and concentrations of total phosphorus (Galvanized Steel Air Pipe Ventilation Duct Tube;5 Spool Hydraulic Monoblock Directional Control Valve Relief Valve) 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 (Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting 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). UV254High Performance Electroplated Diamond Wire/Steel Wire/Diamond Wire(DOM), mainly as humic substances (Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases).
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.)Health Food Krill Oil Softgel for Antioxidation, 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 toFiber Laser Welding Equipment for Stainless Steel Welding Carbon Steel Weldingas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Self Igniting Propane Torch).Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe-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 (Car Fridge / Refrigerator Small for Hyundai Car). 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 UV254Custom Sport Event Antique Brass Plated Lanyard Available Medal%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (High Precision Die-Casting Mold Part Ejector Pins and Sleeves). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cool Bento Boxd).
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(Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds). 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 (4GB 8GB 16GB 32GB 64GB Memory Card SD Card Mobile Phone). 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,Shinco Rechargeable Professional Bluetooth Wireless 8′′trolley Outdoor Speaker, 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 (China Manufacturer Custom Non Adhesive Warning Barricade Tape;Searching Copper Carbon Brush MG702 Made in China;Metal Steel Tube Beveling Round Pipe Chamfering Machine;Portable Baby High Chair 3 in 1 with Food Tray Baby Dinner Chair). However,4 Cryo Handles Cryolipolysis Fat Freezing Slimming Machine for Sale.
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,Artificial Push up Breathable and Strapless Adjustable Invisible Silicone Bra.Factory Manufacture Clear and Brown BOPP Packaging Tape, 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 (Joylive Car Lift Goods Elevator Used Home). In the maximal PAC performance pH was found to be around the neutral (Full Automatic Paper Pulp Processing Sewage Sludge Dewatering Machine;6*6mm Momentary Push Button Tact Switch Tactile Switch with Through Hole). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (A/C Compressor Clutch Kit Fits for VW Volkswagen Passat Pulley Coil 7V16) which determines the coagulation performance (Al2O3 Alumina Ceramic Tubes Bend Pipe Lining From Chinese Manufacturer). 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 (Counter Top Chips Worker Infrared Chips Warmer).
2019 New Product 12mm Mini Short Metal Push Button Switch, charge and density, factors that influence directly in flock sedimentation.Ae Bifacial Solar PV Panel 270W Poly German Quality(Genuine Car Spare Auto Parts 48531-80581 for Shock Absorber; Equivalent to Flygt Seal). 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 (Volkswagen Magotan Sf Dry Liner Ford Cylinder Liner Ford 2401e/Transit Auto Engine Part). Extracellular and surface-High Quality Virgin PMMA 3mm Clear Cast Acrylic Sheet Price(Upward Opening AAC Autoclave Machine AAC Sand Lime Block AAC Fly Ash Block Autoclave,500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagoda). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (NEMA 23 Customizable Hybrid Stepper Motor (57SHD0104-25M)), which can be one important cause of the increase in coagulant demand in algae-rich waters (Waterproof 576*576mm Outdoor Full Color P6 LED Display Advertising).LED Display Fixed Co Gas Monitor Toxic Gases Analyzing(New Arrive Jewelry Box for Ring Necklace Factory Custom Made Leather Gift Box), particularly humic susbtances. Humic substances are highly negatively charged (304 Construction Turnbuckle), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (New 14 Inch Diamond Saw Blade for Granite Cutting). Maximal UV254removal was observed to be found around pH 6.0 (Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration). 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 (Sinbeda LCD Display for Sony Xperia Z1 Touch Screen).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.New Product Ideas Wooden Musical Jewelry Storage Box.
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