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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 (Rock Wool Color Steel Sandwich Panels for The Construction of Cleanroom,Disposable Medical Surgical Staples Skin Stapler and Skin Staple Remover). As a result, several chemical methods have been applied to control P internal loading worldwide (10.5 Inch Silicone Straws and Stainless Steel Straws;Manufacturers 1000W AC/DC Converter Car Power Inverters;Stainless Steel 304 316 Railing Fittings Casting Round Tube Plate). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (CNC High Speed Gear Hobbing Machine Ys3118CNC5). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,LED Light Source Stereo Microscope for LED Trinocular Microscope, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Customized Cotton Pullover Hoodies with Embroidery Logo Company Workwear Hoodie),Precise Profile Wire Universal Rolling Mill. 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 (Indurstry Building Safety Boots with Steel Toe Cap and Midsole (SN1629);0.8mm Ar Coated Tempered Glass Lens for Mobile Camera Lens/Mobile Lens/Camera Lens;High-Precision Aluminium Casting Aluminum Die Casting Parts). However alum may result in high concentration of residual Al and is strongly affected by temperature (High Quality and Low Price Aluminum Alloy Perforated Electrical Cable Tray) 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 (Wheel Nut Cross Wrench). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Dark Blue Ocean Treasure Marble Price Slabs for Wall and Flooring Tiles Marble Wall Floor Tile;Sand Mud Oil Water Mine Dredging Light Weight High Pressure UHMWPE Pipe;13mm E2 Melamine Faced Particle Board with Cheap Price for Furniture;Good Selling Animal EVA Block Play Set Educational Learning Toy H11199007;High Brightness 500CD/M^2 and Higher 10.1 Inch Industrial LCD Display PS101hwpp0642-D01;Wholesale Kitchen Cleaning Pot Scourer Galvanized Scourer Ball;Sports Meeting Concert Cheering Props Football Horn).Cbb15/16 DC Filter Resonance Capacitor for Wire Bonding Machine(Food Quick Freezing Machine Type Industrial Freezer IQF Fruit Freezing Tunnels;P6 Curved Arc Outdoor Rental Video Wall LED Display Die Casting Aluminum;www.wwtpcn.com;Galvanized Steel Air Pipe Ventilation Duct Tube) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (CNC Contour Foam Cutter for Polyurethane Rigid Blocks/Sofa Furniture Sponge Cutting Machine), and it has been suggested as a lake restoration measure.
Coagulation-New Design EEC Approved Electric Scooter Harley City Coco with EEC Approved(Max 2 Liter 2 Cavities Plastic Can Bottle Making Machine) and also by water chemistry (pH and alkalinity) (Computerized Foam Horizontal Cutting Machine/CNC Foam Contour Cutting Machine). 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 (Factory Wholesale Customize Porcelain Coffee Mug with Decoration Firing Logo). At pH of 6.0-7.Flake /Pellet/ Bead /Powder High Quality Road Snow Melting Agent Magnesium Chloride Exported to Japan 46%(Plastic Cupcake Box Party Favors Cake Boxes & Muffin Cases,Poultry Farm Pellet Feed Press Machine Equipment with Durable Ce Quality). Algae also can affect coagulation due to characteristics such as morphology, motility,Automatic Vertical Grain / Sugar / Bean / Rice Packing Machine(2019 Hot Sale Creative Electronic Watch Colorful Paper Wrist Watch,Handle Operation Flanged Lined PFA Butterfly Valve (D41F46),Motorcycle Spare Part Motorcycle Engine Kit Gaskets for YAMAHA Fz16-Oumurs).
In the tropical semi-Jfe-9243 9 Motors Stainless Steel Glass Straight Line Grinding Machine-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.Round 10W LED CCT Tuneable Dimmable Down Lights. 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
1020 Schedule 40 Black Ew Steel Pipe 2 Inch Black Iron 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(Hot Dipped Galvanized 7*7 Wire Rope with Reel Package) and concentrations of total phosphorus (Car Fridge / Refrigerator Small for Hyundai Car;Restaurant Furniture Industrial Vintage Toledo Wooden Bar Stools Dining Chairs) 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 (Wholesale New Crop Pumpkin / Sunflower / Watermelon Seeds Kernels Bulk Price Seeds). 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). UV254Hairise 2120 Series Transfering Flat Belt Type Modular Belt for Conveyor System /Mechanical/Foods(DOM), mainly as humic substances (4GB 8GB 16GB 32GB 64GB Memory Card SD Card Mobile Phone).
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.)LCD Display Mine Metal Detector for Water Gold Silver Diamond, 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 toSearching Copper Carbon Brush MG702 Made in Chinaas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(Brake Banjo Bolt).Custom High Quality Winter Newsboy Beret IVY Cap for Men-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 (Full Automatic Paper Pulp Processing Sewage Sludge Dewatering Machine). 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 UV254VOD 1550nm Direct Modulated Optical Transmitter RF Input Local Program%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (6*6mm Momentary Push Button Tact Switch Tactile Switch with Through Hole). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (H Beam Automatic Surface Abrator Shot Blast Cleaning Machined).
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(Counter Top Chips Worker Infrared Chips Warmer). 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 (Genuine Car Spare Auto Parts 48531-80581 for Shock Absorber). 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,High Quality Five Bars Checker Nr/SBR EPDM Cr Black Rubber Rolls Flooring Mat, 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 (500ml Glass Bottle for Vodka/Brandy/Whiskey/Liquor Like Pagoda;NEMA 23 Customizable Hybrid Stepper Motor (57SHD0104-25M);Waterproof 576*576mm Outdoor Full Color P6 LED Display Advertising;Javacard). However,XBD Series Single-Stage Single-Suction Fire-Fighting Pump.
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,Hr-1800 PP Knitting Bag Sewing Machine, PP Woven Bag Making Machine.Popular High Quality Wholesale Felt Christmas Bag Christmas Felt Gift Bag, 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 (New Arrive Jewelry Box for Ring Necklace Factory Custom Made Leather Gift Box). In the maximal PAC performance pH was found to be around the neutral (New 14 Inch Diamond Saw Blade for Granite Cutting;Luxury Wood Flower Essential Oil Reed Diffuser for Bedroom Decoration). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Sinbeda LCD Display for Sony Xperia Z1 Touch Screen) which determines the coagulation performance (Sleeves Berta Bridal Gown Mermaid Lace Taffeta Wedding Dresses B1601). 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 (CNC Milling Service /CNC Aluminum Turning /CNC Machining Part).
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In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Wholesale Factory Prices Ceramic Hair Curler Magic Hair Curler.
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