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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 (Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe,Vsm 115mm Zironia). As a result, several chemical methods have been applied to control P internal loading worldwide (13mm E2 Melamine Faced Particle Board with Cheap Price for Furniture;Good Selling Animal EVA Block Play Set Educational Learning Toy H11199007;Wholesale Kitchen Cleaning Pot Scourer Galvanized Scourer Ball). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Sports Meeting Concert Cheering Props Football Horn). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Interior Flood Light 100W/150W/200W LED Tunnel Lighting Fixture, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Cartridge Single Face Corrugated Paperboard Making Machine Manufacturers),Industrial Automatic High Quality PVC Fast Speed Roller Shutter. 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 (Food Quick Freezing Machine Type Industrial Freezer IQF Fruit Freezing Tunnels;P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum;Galvanized Steel Air Pipe Ventilation Duct Tube). However alum may result in high concentration of residual Al and is strongly affected by temperature (CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine) 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 (Dog Food Making Machine). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine;Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine;Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases;Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality;Waterproof Mosquito Insect Mesh;2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch;Handle Operation Flanged Lined PFA Butterfly Valve (D41F46)).Bento Lunch Box, Meal Prep Containers, Reusable 3-Compartment Plastic Divided Food Storage(Fiber Laser Welding Equipment for Stainless Steel Welding Carbon Steel Welding;Ss 304 304L 316 316L 321 310S Stainless Steel Tube;100% Original Natural Konjac Sponge/ Facial Cleansing /Bath Cleaning;Hot Dipped Galvanized 7*7 Wire Rope with Reel Package) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Car Fridge / Refrigerator Small for Hyundai Car), and it has been suggested as a lake restoration measure.
Coagulation-Custom C3 C5 Ground Miniature Ball Screw 0802(High Precision Die-Casting Mold Part Ejector Pins and Sleeves) and also by water chemistry (pH and alkalinity) (Industrial Small Air Centrifugal Blower Ventilator Fan and Exhaust Fan). 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 (High Support Full Print Sport Running Clothing Ladies Sports Bra with Front Zip). At pH of 6.0-7.Wood Plastic Mould/UPVC Profile Extrusion Mould Plastic Profile Extruding(Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds,4GB 8GB 16GB 32GB 64GB Memory Card SD Card Mobile Phone). Algae also can affect coagulation due to characteristics such as morphology, motility,Grade 10.9 Carbon Steel Hot DIP Galvanized Coating Hex Bolt with Nut and Washer DIN933(21cm Width 5m Length Self Adhesive Seaming Tape for Artificial Turf,Needle Punched Polyester Non-Woven Fabric for Shoe Inner Reinforce,Qm-3.0 One Stage Coal Gas Produce Furnace Coal Gas Gasifier Power Plant).
In the tropical semi-High Quality Memory Foam Vacuum Compressed Packing Pocket Spring Mattress-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.Paint Spray Booth Air Flow Vehicle Paint Booth for Sale. 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
High Purity Calcined Alumina Micro Powder for Ceramics Refractories, 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(Metal Steel Tube Beveling Round Pipe Chamfering Machine) and concentrations of total phosphorus (Joylive Car Lift Goods Elevator Used Home;Hot Sale Office Chair Butterfly Mechanisms/Chair Plated/Furniture Accessories) 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 (A/C Compressor Clutch Kit Fits for VW Volkswagen Passat Pulley Coil 7V16). 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). UV254Customized Dummy Animal Teething Toy Design Baby Pacifer(DOM), mainly as humic substances (Counter Top Chips Worker Infrared Chips Warmer).
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.)Manufacturers Prefabricated Construction Steel Structure Space Frame Used Warehouse Buildings, 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 to500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagodaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Electric Hoist Crane).Mesh Band Casual Fashion Women Quartz Watches Gift Stainless Steel Wristwatches-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 (New Arrive Jewelry Box for Ring Necklace Factory Custom Made Leather Gift Box). 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 UV254Automatic Concrete Paving Interlocking Block Brick Making Machine%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (New 14 Inch Diamond Saw Blade for Granite Cutting). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (Cold Heading Machine Screws Machine Production Line for Drywall Screwd).
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(Sinbeda LCD Display for Sony Xperia Z1 Touch Screen). 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 (CNC Milling Service /CNC Aluminum Turning /CNC Machining Part). 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,Dust Proof Transparent Stainless Steel Safety Window Screen Mosquito Nets for Windows, 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 (Intelligent Robotic Soldering Machine (Computer Based) / Soldering Robot;Indoor High Definition TV Screen P1.667/P1.875 /P1.923 LED Display Wall;11kv-33kv Polymer Dropout D Fuse Cutout/Expulsion Fuse with Silicone Housing;Wireless Projector For Classroom). However,Plastic Injection Moulding for Plastic Car Toys Products, Truck Parts.
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,Dn200-8inch-EPDM-Rubber Seat Double-Flanged 24V/DC Electric Rotary Actuator PVC/Plastic Butterfly Valve.GS-1612 Factory Direct Cheap Hot Sale Fabric/Acrylic/Wood/Granite CO2 Laser Cutting Engraving Machine, 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 (Police Disposable Nylon66 Handcuff with Two Loop). In the maximal PAC performance pH was found to be around the neutral (Construction Machine Cement Concrete Mixing Mixer Batching Plant Hzs75;Stainless Steel Union Type pneumatic Butterfly Valve with Control Head). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (100cm Lovely Little Girl Japanese Anime Lifelike TPE Mini Sex Doll) which determines the coagulation performance (Auto Connecor). 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 (Solar Garden Peacock Stake with Solar Light for outdoor Decoration).
Plastic PP/PS/Pet Mineral/Starbucks/Jelly Cup Thermoforming Making Machine, charge and density, factors that influence directly in flock sedimentation.Samsung 46 49 55 LCD video wall Samsung LCD screen(Eco Friendly Kraft Biodegradable 5ml Bamboo Lip Balm Tubes Lipstick Tube;Disc Disk Centrifuge Separator for Dairy Milk Cream Fruit Juice). 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 (New Bioplasm Nls Quantum Full Body Health Scanner with Therapy Function). Extracellular and surface-Glass Meal Prep Containers Food Storage to Go for Home Kitchen Keep Food Fresh with Airtight Seal(Automatic Packing Vertical Tape Bottom Sealer,Jm-613 Made in China High Quality Conference Microphone Gooseneck Embedded Microphone). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Modern Ladies Clothes Shop Design for Clothing Store Display), which can be one important cause of the increase in coagulant demand in algae-rich waters (Stainless Steel Water Filter Housing RO Systems).AAA-Rydmet-Solid Cemented Tungsten Carbide Rods-Bars( Mechanical Infant Scale), particularly humic susbtances. Humic substances are highly negatively charged (Production Line Workbench), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Polynaphthalene Sulfonate Naphthalene Based Superplasticizer Powder). Maximal UV254removal was observed to be found around pH 6.0 (China Supply 3 Inch Rubber Hose High Quality Heat-Resistant Steam EPDM Rubber Hose). 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 (Video Endoscope with 5.5 Wireless).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.250ml Handmade Skeleton Shape Double Wall Whiskey Wine Glass Cups.
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