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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 (15 Years Factory OEM Plastic Injection Molding Kid Learning Machine Parts,Safety Label Creator). As a result, several chemical methods have been applied to control P internal loading worldwide (Fast Building Luxury Mobile Modular Container House Material Living Container Buildings;Ifm Induction Furnace Manipulator Pushing Scrap Steel Reducing Melting Time;Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice). The most used technique is the precipitation and inactivation of phosphorus by coagulants, especially those based on aluminium (Al) (Adhesive Cut Table Heat Press PU Flex Vinyl/Film for T-Shirt). When Al salts are added to water, Al+3preferable reacts with PO4-3and forms a precipitate,Girl Bedroom Mermaid Design Cute Sweet Silk Cotton Printing Duvet Cover Comforter Cover Quilt Cover, flocculation and subsequent sedimentation. Besides this, coagulation and flocculation are also able to remove inorganic and organic suspended particles (Poultry Farm Layer Chicken Battery Cage for Sale In Philippines Nigeria Kenya),Yz25c China Ophthalmic Equipment Wireless Binocular Indirect Ophthalmoscope. 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 (New Model Polished Porcelain Glazed Marble Ceramic Floor Tiles for Project;Wholesale Sport Wear Mens Gym Running Polyester T Shirt;Compatible Physio Control 11996-000033 NIBP Hose). However alum may result in high concentration of residual Al and is strongly affected by temperature (Plastic Polypropylene Honeycomb Core Is The Ideal Component for Any Lightweight Assembly) 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 (7 Touch Panel Kit). A number of laboratory and field experimental studies has shown the superior performance of PAC in both turbidity and phosphorus removal (Custom PVC Shrink Capsules for Liquid Bottle;Newest Double Color WPC 3D Wood Grain Plastic Composite Flooring;Three-Phase Electronic Multi-Function Watt-Hour Current Meter;Valve Wheel Adjustable Hydraulic Impact Torque Wrench;IP65 22mm LED Pilot Light 24V 220V Indicator Lamp Ad26b22D;Fashion Double Striped Non-Slip Entrance Mat;Sofa Cushion Wholesale Customized Pillow Cover Home Decorative Throw Pillow).Waterproof Travel Portable Makeup Bag Wash Gargle Bag(DC Colorful Battery Operated Small Hand Fan for Outdoor Use;1 Inch Dn25 2 Way Brass Male Thread Electric Control Water Motorized Ball Valve;Glass Olive Oil Bottle/Olive Oil Glass Bottles;TPR Vibration Protection Cut Resistant Safety Work Glove for Industrial Purpose Use) and turbidity even at low dose (1.5 mg Al.L-1) in shallow lakes (Wholesale Comfortable Men′s Winter Leather Snow Boots), and it has been suggested as a lake restoration measure.
Coagulation-Car Repair Equipment Underground Garage Lift with Double Scissor Lifts(Promotion Cheap Woven Wristbands Event RFID Woven Wristband) and also by water chemistry (pH and alkalinity) (Non Woven Wheel for Stainless Steel Polishing and Grinding). 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 (Indoor 3mm Biggest Advertising LED Screen for Events). At pH of 6.0-7.Volkswagen Magotan Sf Dry Liner Ford Cylinder Liner Ford 2401e/Transit Auto Engine Part(High Quality Free Sample Woven Label for Garment Accessories,Rls9 Zz-2RS Ls11 Lj-1-1/8 Cixi Inchi Wheel Roller Ball Bearing). Algae also can affect coagulation due to characteristics such as morphology, motility,High Temperature Multi-Jet Ultrasonic Heat Measure Meter(Shenzhen Customized Metal Stamping Parts Fabrication Service,Narrow Hub Connection Brake Discs for Sprockets (TLK603 RLK603 55X110),Hot Stamping Uphostery Fabric Suede Fabric for Sofa and Furniture).
In the tropical semi-Equivalent to Sew-Eurodrive R Series Inline Helical Gearbox (R38~R168)-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.Hypoallergenic Polyester Duvet Insert for Hotel Bedding (DPF17060. 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
20L Semi Automatic China Bottle Pet Blower, 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(PVC Marble Panels UV Sheet Cheap and High Quality Artificial Marble) and concentrations of total phosphorus (China New Technology Swimming Pool Heat Pump (MDY50D);D523A) 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 (12-288 Core Single Mode Loose Tube Fiber Optic Cable with Aluminum Tape). 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). UV254Apple Shape Kneading Shiatsu Massage Pillow with Heating(DOM), mainly as humic substances (Sancore Nappa Leather Back Sticker Huawei Mate20/PRO Phone Case).
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 Canned Aloe Vera Cube Dicing Cutting Cutter 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 Efficiency Cleanroom Mini Pleat HEPA&ULPA Air Filter Media Packas they had chlorophyll-aconcentrations >15 µg L-1and total phosphorus concentration >50 µg L-1(R600A DC Compressor 12/24VDC Qdzy35g for Car Refrigerator Freezer).Plywood for Packing Furniture 10-25mm Plywood Price-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 (Factory Supply Urban Outdoor Street Mobile Sweeper Road Sweep Truck with Brushes). 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 UV254Centrifugal Casting Tin Bronze Bushing with Machining%. None Al dose was efficient in removing at least 50% of total phosphorus, turbidity, UV254and chlorophyll-afor Passagem das Traíras reservoir (Spraying Rubber Asphalt Emulsion Waterproof Coating/Liquid Rubber Coating). The increasing in Al dose from 6 to 10 mg Al.L-1decreased the chlorophyll-aremoval efficiency for Cruzeta and Passagem das Traíras reservoirs (High Quality Flatlock Plus Size Black Crop Top and Sport Leggingsd).
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(Hotel Wall Mounted Infrared Battery Electric Liquid Automatic Soap Dispenser). 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 (Jumbo Drilling Rig with Three Arms (HFG-33J)). 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,Factory Manufacturer CNC Dual Use Combined Metal Sheet Plate & Tube Pipe Fiber Laser Cutter, 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 (Jq350 Small Electric Vertical Pan Cement Blender Concrete Mixer;Xaja Truck Light Wire Automotive Cable Trailer Wiring Harness;En71 Approved Baby Electric Toy Bike Kids Battery Motorcycle;m.well-pcb.com). However,Hot Sale Mimaki Ujf-A3hg UV LED Curing Platform Inkjet Printer.
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,Fenbendazole CAS43210-67-9 Pesticide Vetetinaries Good Manufacturing Practice.Chinese High Quality Plastic Spice Jars for Vinegar and Sugar Jam Organizer, 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 (Siboasi Best Selling Badminton Shuttlecock Feeder Machine). In the maximal PAC performance pH was found to be around the neutral (ISO Linyi Apitong 28mm Marine Plywood Container Spare Parts; medical disposable clothes). Coagulation is favorable for a pH range of 6.0-7.0 due to presence of positively charged Al species promoting flock formation (Custom Fashion Apple Mobile Wooden Phone Case for iPhone (6/7/8/6s/8s Plus/Xs Max/Xr/Xs/8plus)) which determines the coagulation performance (Reci W2 W4 W6 W8 Laser Tube for Laser Machine). 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 (Pneumatic CNC Router 1325 Multi Heads Pneumatic Furniture Cutting Machine).
Advanced Twin Roller Mill with Stock Bender (XK400B), charge and density, factors that influence directly in flock sedimentation.Customized Design OEM Manufacturer Alloy Watches for Men (JY-AL050)( Welding Parts;PA66+GF Polishing Injection Auto Plastic Parts Mould Manufacturer). 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 (High-Class Sld-6121 Paper Sticker High Speed Slitting Machine). Extracellular and surface-Smelting Furnace Dust Collector Fiberglass Bag Filter(Aluminum Milling Service,Ultrasonic Welding Machine for Cutting Sponge Scouring Pad Scourer). Lipopolysaccharide on cell surface ofMicrocystis aeruginosaproduced by the excess of growth exhibited inhibitory effects on PAC coagulation (Safety Shoes Anti-Slip Silicone Rubber Crampons OEM Factory), which can be one important cause of the increase in coagulant demand in algae-rich waters (Outdoor Artificial Wood Plastic Playground Equipment on Promotion (HK-50011B)).Fashion Excellent Quality Full Color Small Quantity Hardcover Book Printing(China Factory Forged Clevis Grab Hook Crane Lifting Hook Made in China), particularly humic susbtances. Humic substances are highly negatively charged (Non Slip Rug Grip), which increases with increasing the pH and by adsorbing onto the surfaces of natural particles (Food Grade Glass Storage Glass Jar for Spices Candy Foods Dried Vegtables Canned Fruit). Maximal UV254removal was observed to be found around pH 6.0 (LG936 LG938 Front End Loader Parts Gas Spring 29330011391). 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 (Colorful LED Electric Submersible Pond Rockery Fountain Water Pump).
In summary we consider PAC application a good restoration technique for Cruzeta, Timbaúba and Dourados reservoirs.Metal Building Industrial Shed/Pre-Engineered Long-Span Steel Structure Frame Building.
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